Observations of the Turkey Vultures

John Carton, Chuck Hird, and a group of dedicated Turkey Vulture watchers have been sharing and compiling information about the Turkey vultures on the 2012 Missouri Vulture Live Cam (http://www.ustream.tv/missouriturkeyvultures). Thanks to their dedication and hard work, we have these observations to date. Some of their comments are cross-referenced to the following web-accessed literature source:
http://www.zoo.org/animal-facts/turkeyvulture

Background
This barn loft setting is in Marshall Missouri, at a barn where a pair of turkey vultures have successfully raised a hatch in each of the last three years. They have actually been returning to this loft for more years prior to the last three, however photo documentation has been accomplished only in the last three years (photos by John Carton may be viewed at http://www.flickr.com/photos/johncarton/).
Encouraged by the Missouri Department of Conservation to share information with Bob Anderson, director of the Iowa based Raptor Resource Project, the owner did so. Following a short planning process, a resolve was made by the Raptor Resource Project to establish this site as the “first ever live cam for nesting turkey vultures”. In late Fall 2011, the camera and computer monitoring equipment was installed at the site by Bob Anderson himself, with John Carton and the owner assisting. A professional electrician and neighbor on this street in Marshall volunteered all of the necessary trenching and installation of the conduit and electrical wiring.

Return of the Vultures
The first returning turkey vultures to this live cam site were observed on April 1st.

Presenting Adult Interactions
Initially several adult vultures visited the loft. Individual mature adult vultures look very much alike, so it is not possible for us to distinguish how many different individuals actually visited. On several occasions three birds were present together, and viewers reported seeing four on at least one occasion. At no time were four positively identified by a contemporary camera panning.

Gender Identification of This Mated Pair
While the physical appearance of adult male and female turkey vultures is apparently not differentiated, we are able to distinguish between the parents of this mated pair by a dark horizontal line extending across the brow of the male bird from the top of one eye to the top of the other. We know by deduction that this “distinguished eyebrow” bird is the male, only because we actively observed the egg laying by the other via this live cam. We presume this eyebrow marking is an individual difference rather than a gender distinction, however more observations of other birds is necessary.

Dad Turkey Vulture. Note the brow ridge.

Mom Turkey Vulture. Her head is smoother.

Tending The Nesting Area
On each visit to the loft, the individual vultures walked about the loft floor, each time apparently locating the straw mat area that would later become their nesting spot. While there, each repeatedly pecked at any objects on the floor mat, and repeatedly picked up and snapped into pieces the various lengths of straw. Each bird also displayed a “nest forming” behavior by squatting down on the floor litter and turning circles to create a depression. While each accomplished this behavior individually, there were several occasions when both birds were present at the same time, displaying the “nest turning” behaviors side by side. If this was in fact an interactional behavior (rather than just a parallel behavior) I had the distinct impression that it represented a relationship patterning behavior preparatory to the upcoming egg-laying and incubation periods when both parents would be called upon to tend the nest for extended relief periods (future live cam observations of the pre-egg laying period will be needed to confirm or revise this impression).
This video shows some 'nest-prep' activities:


Egg Incubation
Reference source cites incubation period of 38-41 days. My observations in prior years at this Marshall Missouri site was more like 30 to 35 days. This year’s web cam documented 1st egg laid on May 9, 2012 with 2nd egg following about May 12th.

Parenting Role Differentiation
Generally, adult vulture gender differentiation appears to be minimal.

A. Incubation related behaviors: reference source cites both parents incubate the eggs. Live cam observations confirm same. Noting that actual time measurements have not been laboriously taken, neither parent appears to pend greater or lesser time sitting on the eggs, or taking longer breaks.

B. Chick feeding related behaviors: reference source cites both parents feed the hungry chicks with regurgitated food.

Head Movements 
Periodically both adult birds have displayed rapid side to side head movements, as if a reflex movement. At times the head shakes have been as rapid as perhaps 5-6 per second, causing some viewers to speculate they were being bothered by insects or perhaps mites in their ears. Other times the head shakes have been slower frequency, one or two movements at a time, separated by several seconds between “shakes”. Occasionally in conjunction with the side-by-side head movements the adult bird has abruptly struck its beak against an adjoining wall, making a resounding “clunk” sound. I have wondered whether these characteristic head movements may have the function of clearing it’s nostrils for detection of new scents to detect potential presence of danger. When potential danger is detected, as by a sudden outside noise, the bird’s head is thrust up and it is not clear whether the side-to-side head movements accelerate at those times. More observations are warranted.

“Egg-Sitting” Patterns 
As noted above, both parents share in incubating the eggs, acting in shifts and rarely if ever both present in the loft at the same time. Typically one bird leaves alone, and later either that bird or its mate returns. The unattended time period for the eggs has generally been for as much as 20 minutes to an hour. On only one occasion, after the first egg was laid and before the second, was the egg left unattended overnight.

Egg-Turning Behaviors 
At each separation and return to the eggs, the attending parent gently turns the eggs with its beak. The method typically includes a positioning of the feet under the eggs, while extending the beak over the eggs and nudging them one at a time between the toes and on top of the feet. In the process of egg repositioning, the adult bird often moves its entire body in a rotating motion over the eggs, sometimes half a circle and sometimes completely, carefully turning and nudging each egg along using the side of its beak. This egg positioning takes place in a very deliberate unhurried manner, completed as the parent resumes sitting with the eggs nestling snugly infolded under its breast and crop area. There is no apparent gender differentiation in the egg tending behaviors between the parent birds.

Adult Interactions (Cont)
 A. Pre-egg Laying Interactions:
From the time of the vultures return to this loft, the adult birds have displayed a very minimum of physical interactions with one another. From their April 1st through the first week of May the two primary birds (that became identified as the mated pair) generally arrived individually at the loft, their arrival times ranging from as little as five minutes to as much as a half hour from one another. On other occasions one would arrive alone, remain a while and leave without our seeing the other. On nunerous occasions a third bird that some viewers came to call “limpy”, because of an apparent limping walk, was present with the primary pair. This caused speculation that “Limpy” might be an offspring of the primary pair that has still nit completely separated from them. That of course is only speculation at this time, however interesting as a possibility. In general the adult vultures presented themselves as highly independent and not inclined to any physical contact with one another. Their apparent wariness to allow any physical closeness seemed to wane after a few weeks visiting the loft, at which time they agreeably stood side by side occasionally touching at the shoulders, peering out the loft window, until one would abruptly fly off leaving the other to sit there perhaps five minutes or so before it too would leave. At no time was any actual breeding behavior observed at the nesting site. As they sat at the windows and walked about the loft floor there appeared to be some pattern of pursuit on the part of one toward the other, with a not-so-determined returned rejection by the other (viewers were inclined to dub the pursuer as the male, and the rejecting interest as the female, but the cues were always very subtle and physical appearance of male and female is very similar).

B. Adult Interactions During Incubation Period:
While both parents have tended the eggs in a similar manner, they have done so entirely independently from one another. At no time since the eggs appeared have both birds been observed in the loft at the same time, and the third bird called “Limpy” has not been present at any time. There has been absolutely no reciprocal adult bird behaviors during this time, such as one bird bringing food to the sitting bird. The sitting bird has left at intervals, which is presumed to find food for itself, and to defecate (since there is little if any sign of defecation inside the loft or around the nesting area). Rarely, if at any time has the other parent been present at the loft at the time the sitting bird requires a break. None-the-less, within 15 - 30 minutes of a sitting bird’s departure from the eggs, either that same bird or its mate arrives to resume the sitting (again without any observed interaction with one another).

Michelle, Travis, and Peregrine Questions

Michelle and Travis hatched two young falcons on 5/13/12, and the questions are already flying! I'll try to answer a few of the most common here.

1. Why are they nesting in gravel? I wish the hatchlings had grass or something softer!
Historically, peregrine falcons nested in two places: on cliffs and in trees. To quote: "Although the peregrine falcon is currently considered a cliff-nester, records indicate that it once nested in tree cavities (Goss 1878, Ridgway 1889, Ganier 1932, Bellrose 1938, Spofford 1942, 1943, 1945, 1947, Peterson 1948). The peregrine still uses cavities in broken-off trunks in Europe (Hickey 1942), but the hole-nesting population of America apparently disappeared with the felling of the great trees on which they depended (Hickey and Anderson 1969)."

Either way, peregrines did not build nests out of branches, twigs, or grasses. Cliff nesting birds use ledges or potholes. These commonly have some kind of substrate: sand, pebbles, dirt, and so on. The male and female dig and wiggle out a scrape, or shallow cavity, into which the female lays her eggs. The substrate provides drainage, cups the eggs, and helps keep them from breaking on the edges of the underlying rock. We use 80 pounds of pea gravel in our nest boxes to simulate a substrate and protect the eggs.

2. How long can the babies go without eating?
The hatchlings consume the egg yolk shortly before hatching, which gives them enough nutrition  for 24 to 48 hours. However, they don't usually have to go very long. Their first feeding was at 11:49am CST this morning.

3. What do falcons eat?  Falcons eat other birds. We've found the remains of pigeons, woodpeckers, coots, finches, blackbirds, ducks, cuckoos, and many other birds stashed in and around nests. In general, the adults catch a bird by diving or stooping on it. If the impact doesn't kill it, the adults use their tomial tooth - a notch in their beaks - to bite through their prey's cervical vertebrae. They pluck their prey prior to eating: "feather falls" have helped me locate Peregrine falcons at the Mayo Clinic and the Dairyland Alma power plant. 

Adult peregrine falcons eat about 2 1/2 ounces (70 grams) of food per day. Using a rough back-of-the-envelope calculation, males average 587 grams of weight and females average 1205. So males eat roughly 11% of their body weight each day. I'm guessing - and this is a guess - that females do the same, so Michelle probably eats a little more than Travis does. It has been speculated that  gender-based size differences allow male and female birds of prey to eat from a slightly different prey bases, widening the available food supply.

So based on this calculation, I'd need to eat about 16.5 pounds of food every day to keep up with Michelle.

4. How fast will the babies grow?
Peregrine falcons double their birth weight in 6 days, and are 10 times hatch weight in three weeks.
Like the eaglets, they start with a fluffy white coat of baby down. We'll start to see brown juvenile feathers emerging at about 20 days of age. By 40 days, the young birds will be sleek brown juvenile falcons.

Over the next few weeks, we'll see a lot of eating, sleeping, and pooping. Poop is a great way to locate the nests and perches of many kinds or birds. See bird poop? Look around for the bird!

5. Will Cain and Abel Syndrome be a problem here?I don't want to say 'No', but I haven't seen it at any of the other Peregrine falcon nests we watch. There is an ample food supply and Michelle and Travis are very good at caring for their young.

6. Mom and Dad are talking to the babies!
Yes, they are! We've already heard Michelle echupping encouragingly to her young immediately before their first feeding. We'll also hear the young food begging (which one website describes as 'screea screea screea'), and kakking: an alarm, defense, and 'annoyance' call. Peregrine falcons are  very vocal. I've had unhappy babies set my ears to ringing more than once.

7. Does the nest smell bad?
It depends! Some falcons are great housekeepers, while others (I'm looking at you, Hibbard plant falcons) let prey remains pile up in the nest. If the nest is messy, the young birds smell interesting to human banders - not bad, but not pleasant: a complex, spicy smell.

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Things that helped me learn and write about Peregrine falcons:

• Bob Anderson. He knows more about Peregrine falcons than anyone I know. I should see if he'd be willing to echup on video: it is really amazing. Any mistakes in this blog are mine, not his!
• http://www.na.fs.fed.us/spfo/pubs/wildlife/nesting_birds/birds1.htm (nesting birds)
• http://redandthepeanut.blogspot.com/2012/02/notch-in-peregrine-falcons-beak.html (tomial tooth. Very nice photograph and drawing).
• http://falconcam.travelers.com/falcon-faqs.html (falcon facts)
• http://www.pfht.org/LinkClick.aspx?fileticket=nBU15gWur5w%3D&tabid=79 (falcon facts)

Watching Bald Eagles

Bob took a turn operating the controls at the Bald eagle camera this morning. He was fascinated by Dad, who brought in three suckers in one hour. Suckerfish are 'rough' fish: generally considered undesirable by humans, they have large scales, fleshy lips, and a 'sucker' mouth that is wonderful for attaching to rocks and scouring river bottoms for food. They spawn in shallow water during the spring, when water temperatures reach between 47 and 60 degrees Fahrenheit. The Iowa DNR tells us that males move upstream in large schools, congregating and defending spawning territories that contain gravel riffles and rubble shoals. While suckers are spawning, eagles are raising a family. Suckers make easy prey: they are relatively exposed, there are a lot of them, they congregate in one area, and they don't leave until spawning is done. "Think about it," Bob said. "We are watching them eat food they evolved with over eons."

Bald eagles have several excellent adaptations for fishing. An eagle's powerful toes, locking talons, and spicules - tiny projections on the bottom of its feet - help it grasp and hold slippery fish, as do the serrations on the roof of its mouth. The black pigment on its wing feathers strengthens them against breakage when it dives into the water. Its nictitating membrane and the boney ridge over its eyes - so noticeable in Mom - helps protect its eyes from sunlight and reduces glare. Bald eagles eat a wide variety of prey, but they are fishers par excellence.

So how old are Bald eagles as a species? Birds begin to appear in the fossil record between 144 and 66 million years ago. These ancestral birds gradually diverged into separate species. Kites, the ancestors of today's Acciptiridae, emerged tens of millions of years ago. Like modern eagles (but not all Acciptiridae) they are believed to have scavenged and hunted fish. The first eagles descended from kites roughly 36 million years ago, and the earliest known fossil remains that closely resemble the bald eagle date back to about a million years ago.

Plio-pleistocene Bald eagles in North America might have shared the landscape with mammoths, dolichohippine horses, camelops, glyptotherium, terror birds, and stegomastodon, as well as more familiar bats, birds, rodents, and fish. Did they build the same kinds of nests? Did they raise their young the same way? Did eagles feed on suckerfish even back then? We don't know: birds don't preserve very well. Still, the thought that Bald eagles flew over an ice-age North America gives me the shivers. So much of what was is gone now, but eagles and sucker fish are still with us.

Fast-forward to a shallow stream 15,000 years ago. Suckers are making their way upstream to spawn. Suddenly, an eagle swoops down and hooks one to bring to its waiting young, who are clamoring hungrily in the nest above. Dad has food. His legacy will survive into a future he can't imagine.

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Things that helped me learn and write about this topic:

• Personal communication, Bob Anderson
• http://www.ncbi.nlm.nih.gov/pubmed/19241464 (Plio-pleistocene eagle predation)
• http://www.profleeberger.com/files/Berger_further_evidence_taung_main_article.pdf (Plio-pleistocene eagle predation)
• http://si-pddr.si.edu/jspui/bitstream/10088/7069/1/James-05-Auk-Paleogene_birds.pdf (Paeogene fossils and the radiation of modern birds)
• http://www.iowadnr.gov/Fishing/IowaFishSpecies/FishDetails.aspx?SpeciesCode=SHR (Iowa DNR, suckerfish)
• http://tinyurl.com/7q8u99d (Fauna of Pleistocene North America)
• http://www.eagles.org/vu-study/biology/structure-and-anatomy.php (eagle adaptations)
• http://www.pbs.org/wnet/nature/episodes/american-eagle/bald-eagles-evolutionary-ancestors/4274/ (eagle adaptations and evolutionary history. Much of this information came from the book THE BALD EAGLE, by Stalmaster, Mark V. 1987, published by University Books, New York.)
• http://bss.sfsu.edu/holzman/courses/Fall02%20projects/bald%20eagle.html  (bald eagle evolutionary history). Nice job, Michael Rochelle!

It was fun to read about plio-pleistocene life forms. It reminded me of very loved books from my childhood that I haven't thought about in ages: brightly colored children's science books about the ice age with fantastic illustrations of mammoths, saber-tooth tigers, and so much more. What a treat to think of them again!

They Grow Up So Fast!

The eaglets in Decorah are 27, 26, and 24 days old. Their darker second down has been in for days, and pinfeathers are beginning to show on the edges of their wings, signaling the emergence of their first juvenile contour feathers. Here is how it works. Each feather arises from a feather follicle in the skin. The pin feathers, or feather follicles, contain undeveloped contour feathers. As the contour feathers develop and emerge from their follicles, they push the down feathers off. The down will remain attached to the contour feathers until it rubs off.

Other changes: the eaglets are more proficient at walking and pooping. They are a lot bigger, although their growth curves (when expressed in weight gain per day) will begin slowing sometime in the next three to six days. The overall size of their footpads should already have started slowing down but the growth of their juvenile contour feathers is just taking off : like many animals, parts of the eaglets' bodies grow at different rates.

If human children play house, the eaglets are playing nest. We've seen the eaglets tussle with cornhusks, move debris around the nest, nibble on everything from food to mom's tailfeathers, 'attack' prey, and explore. Socially, they spend a lot of time interacting with one another and with their parents: they alternately dominate and cuddle, observe Mom and Dad (especially when food is involved), and 'help' with nest chores. This behavior is all part of their growth and development. We sometimes think of play as being unimportant or trivial, but play lets young animals 'practice' the skills they need for adulthood, cements bonds between players, and is pleasurable to those playing.
Here are some videos that show our eaglets growing, playing, and practicing:

• Licking and nibbling food: http://youtu.be/orftNS4laWc
• New pinfeathers: http://youtu.be/-P_vTOPgzZs
• Wingercizing: http://youtu.be/NyM5Pif4Fqs
• Mom and eaglets play with cornhusks: http://youtu.be/3CtOk7Obt8w

Sherri Elliott's daily 'Whattas' on our facebook page provide a wonderful round-up of eaglet daily and developmental events: https://www.facebook.com/pages/Raptor-Resource-Project/103786266324668?sk=notes. I wasn't able to find any information on Bald eagles and play, but here are some play links worth looking at.

• Ravens and Play: http://www.spiegel.de/international/spiegel/0,1518,476266,00.html
• The Primal Power of Play: http://youtu.be/3KanfLqKXYg
•  Ticklish Rats: http://animalwise.org/2011/11/09/the-ticklish-laughter-of-rats/

I think we should all get out and play after this post is done!

We've been asked how soon we can tell if the eaglets are male or female. The short answer is that we can't tell for sure unless we capture them and take measurements or a blood test. Having said that, Gary Bortolotti notes that sexual dimorphism begins to appear in some variables after 20 days of age. Initially, size depends more on hatch order than anything else, but after 20 days, gender begins to play a role. Females are bigger than males and have correspondingly wider wingspans, bigger feet, and thicker tarsi. Without proper measurements we are speculating, but speculation is part of the fun.

Bob is anticipating that fledge will happen mid-June: a little less than two months from now. Over the next few weeks, we'll see the eaglets get bigger. Dark brown juvenile feathers will replace their fuzzy grey down and we'll see even more wingercizing and play as they transition from nestlings to flighted hunters. Have fun watching!

We are also waiting for the Great Spirit Bluff Peregrine falcon nest to begin hatch on May 2nd, and the Turkey vultures to lay sometime between May 1 and May 7. There will be a lot to see, laugh at, and learn from.

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Things that helped me learn about and write this post:

• Sherri Elliott's Whattas
• 'Top Three Questions' from the Ustream mods and chatters
•  Bortolotti, Gary: Physical Development of Nestling Bald Eagles With Emphasis on the Timing of Growth Events: http://elibrary.unm.edu/sora/Wilson/v096n04/p0524-p0542.pdf
• Conrad, Jim: Feathers. http://www.backyardnature.net/birdfthr.htm
•  Discover Magazine Q&A with Jaak Panksepp, Rat Tickler.

Birds and Weather

We've heard a lot of concerns about weather from nest watchers.  Following the nicest March anyone in the American Midwest can remember, we've had tornado outbreaks, high winds, damaging storms, large fires, and snow. The Decorah Bald eagle nest has been tossed around by wind, the Fort St. Vrain eaglets died of exposure following a spring storm, and the Dairyland Power Genoa cam was damaged by lightning. We get asked daily if we can't do something about the weather: shore up nests, build roofs, and even take young birds from their nests. The short answer: No. I wrote about intervention in an earlier post. We intervene in the case of obvious, acute danger, but weather is a chronic condition that all of us have to live with.

High winds, severe storms, and fire are nothing new. If animals couldn't survive them, they wouldn't be here. The birds we watch are well prepared for the weather challenges they face.

• 
  It's Cold and Wet! Feathers are wonderful insulators and adult Bald eagles have roughly 7,000 of them. Light and fluffy down feathers trap air, while flight feathers hook together like a zipper, forming a continuous 'vane'. Preening releases an oil that coats the outer layer of feathers, which further protects adult birds from moisture: the outer feathers may get wet, but the bird's body does not. We've watched the adult eagles shake off rain and sleep under a blanket of snow. They are well prepared for cold, wet weather.
  
  As of this post, all of the Decorah eaglets have their second down. Unlike the first fluffy white down, the 'wooly' second down has insulative properties. Mom and Dad will still protect the eaglets from rain and snow, but they are able to thermoregulate now.

• 
  It's Hot! We've had a lot of questions about panting this spring. Like dogs, eagles don't have sweat glands. They control heat by panting, radiation through their unfeathered legs and feet, and perching in the shade. March was unusually warm and the cottonwood doesn't leaf out until April, so the eagles spent a lot of time in direct sunlight. We also got to see a little more of the eaglets than we usually do: many cam watchers commented on how lively, naughty, and busy this year's brood has been. The dry, hot weather means that the eaglets spend more time exploring the nest than huddled under Mom or Dad, and everyone spends more time panting.

• 
  It's Windy! Adults and young hunker down against high winds and storms. Some of their behavior appears instinctive and some is learned. The first year Mom nested here, she turned tail to the wind and was blown out, nearly taking a young eaglet with her. That hasn't happened since. The adults minimize their profiles during high winds, keeping wings tucked in, tails low, and young birds protected. Young birds curtail nest exploration and play, sheltering under Mom or Dad until the wind dies down.  When the adults do get pushed around by sudden wind gusts, they don't grab at the eaglets, and the eaglets are not especially aerodynamic at this point.
  
  We've also heard from watchers concerned that the Decorah Bald eagle nest will fall/has fallen. The nest weighs approximately 1300 pounds, is tightly woven of strong wood, and is wedged securely into the limbs of a cottonwood tree. The tree is healthy, with no large dead limbs, and near a good water source.  Can we say that the nest will never fall? No. But is it likely to fall? Also no. The nest is very secure and the tree is healthy and relatively secluded from wind. If the nest or tree did go down, we'd be on site as quickly as we could.

In short, we can't do anything about the weather. Fortunately, the birds we watch are equipped to survive it in all but the direst cases. The Decorah nest in particular benefits from an ample food supply, experienced parents, and a relatively sheltered location. Last year, we watched them respond to cold weather and late snowstorms. This year, we've watched them respond to warmer, windier conditions: they've spent more time off the eggs and young babies, and their 'hunker down' time has been more likely to be a response to wind than rain or cold weather.

Here are a few videos that show the Decorah eagles under various weather conditions:

• April 16th, 2011: Snow storm. http://www.youtube.com/watch?v=ibPf2D87Dg4
• June 15th, 2011: Wind storm. http://www.youtube.com/watch?v=6j90phejogY&feature=youtu.be
• March 10th, 2012: High wind. Mom floats in with crib rail. http://youtu.be/Rpx0bHOwY0I
• March 15th, 2012: Panting. http://youtu.be/X-HBBqYfB_M
• March 30th, 2012: Thunder storm. http://youtu.be/abDevjFZX3U

Things that helped me write and learn about this topic:

• Bob Anderson, personal communication
• RRMod, personal communication
• Feathers: http://askabiologist.asu.edu/explore/feather-biology
• Feathers: http://www.baldeagleinfo.com/eagle/feathers.html
• General Info: http://www.learner.org/jnorth/1997/critters/eagle/AnswerEagle.html#49
• General Info: http://en.wikipedia.org/wiki/Bald_Eagle
• A Model of Energy Consumption in Bald Eagles: http://elibrary.unm.edu/sora/Wilson/v097n02/p0148-p0160.pdf
• Our forum members. Thanks for your notes and caps!

If you would like to learn more about how animals survive cold weather, I highly recommend Winter World: The Ingenuity of Animal Survival by Bernd Heinrich. If you would like to know more about animals in summer, I highly recommend Summer World: A Season of Bounty, also by Bernd Heinrich.

Fort St. Vrain Colorado Bald Eagle Nest Fails

We are sorry to announce that the Fort St. Vrain eagle nest in Colorado has failed. A violent storm soaked the nest and remaining two young, who died of cold. This is the second time this has happened at this nest, which is in a remote and hard to reach area. This brings up some questions we are often asked. When is it right to intervene in a nest? Is it ever wrong to intervene in a nest? How do we decide when to intervene?

Intervention isn't always possible. Neither the Fort St. Vrain nor Decorah Bald eagle nests can be easily and safely accessed once babies are in the nest. A bucket truck isn't an option and we can't shoot a line. Those of you who watched Decorah in 2011 might remember the saga of the dreaded red twine. None of us wanted to watch an eaglet die from gangrene or infection, but going up to the nest could have resulted in the death of one or more of the eaglets if they were hit by a bolt or jumped from the nest once we intruded on it. Sometimes we can't intervene.

It isn't always clear when intervention is needed. Several years ago, a female falcon named Alma died after hatching five babies. The babies were 20 or so days old - far past needing brooding. We debated at length whether to go up and retrieve them. Since Dairyland Power Alma can be remotely monitored, we decided to let Dad try raising all five. He did a wonderful job and all five fledged without intervention. Many things that might seem to us to require intervention - a parent dying, things that go bump in the night, loud noises, hungry babies - are a regular part of life for the birds we watch. Intervention isn't always necessary.

However, intervention is sometimes both possible and necessary. We give Spartrix to nestling falcons when they have Frounce. We do our best to create raccoon-proof nesting sites for birds - eagles and falcons can handle most challengers, but raccoon are a serious problem. We recommend putting grounded young birds in a high place, safe from traffic, people, and other animals. When it is possible and necessary, we intervene.

Death is part of the natural order, but that doesn't make it any less sad when it happens. I am glad that the rest of our Colorado nests appeared to have made it through. We watch these animals and love them, but they belong to no one but themselves. Their lives are a gift we are privileged to share.

How Do I Recognize the Difference Between Nestlings?

We're getting questions in chat, facebook, and via email about how to recognize one Decorah nestling from another. We've got some information here: many thanks to ThinkingWoman, Tekon and Birdsohio for the information and help!

What Can I Look For?
Looking for the clues that distinguish one nestling from another is like trying to looking at the difference between little brown bird A and little brown bird B. Subtle differences make all the, well, difference. Other clues (the type of down and emergence and length of pin feathers, for example) can provide clues about the bird's age. Training yourself to see these differences will not only help you identify D12, D13, and D14, but will also help greatly with bird identification in the field - even if the field is your bird feeder or computer screen.

• Size. As time goes on it may be more difficult to note size differences. Initially, those differences will be based on age. Once the eaglets achieve full or close to full growth, size differences will be largely gender-based. Even within the context of gender, however, there will probably always be at least subtle size differences. In Bald eagles as in other raptors, females are larger and males are smaller.
• Coloring. Actual colors will be similar, but shades of the color may be quite different. Look for patterns of light and dark, and any identifying marks.
• Type of Down. Does the nestling have natal down (white and fluffy), or the thicker wooly secondary down also called thermal down? More information on plumage stages can be found here: http://www.swbemc.org/plummage.html.
• Pin Feathers. Are pin feathers starting to come in? Note the location of emerging pin feathers. We've used pin feather length to help identify the age of young peregrine falcons when banding them.
• Hairdo. This is one way we learned to differentiate nestlings last year. Does the eaglet have a crew cut, a mo-hawk, or an Elvis-style hairdo? Are the eaglet's "bangs" straight across, or do they come to a single point, or is there a double point like an "M" or a "W"?
• Facial Features - Around the Eyes. Look at the area around the eyes - do you notice a streak or a dot, or a dark mask as contrasted with a lighter mask?
• Facial Features - Beak Size and Coloring. Does one eaglet have a larger beak as compared to the others? Look at the coloring on the beak. Is the beak tip dark, or perhaps the darker coloring extends to mid beak.
• Leg Coloration and Foot Size. What color are the eaglet's legs? How big are its feet? Is there anything noticeable about the talons? We've seen blue-legged and white-taloned peregrine young. Color differences can provide a valuable clue.
• Behavior: Is this a noisy or a quiet eaglet? Is this a busy eaglet or a lazy eaglet? Does this eaglet prefer to rest alone or with a sibling? What nest area does the eagle frequent the most? All of these behaviors can provide identification clues.

Learning observation skills may help you to be a better ornithologist or biologist or scientist - or simply help you identify birds for own pleasure. On May 1st, 1805, Lewis and Clark identified a plover for the very first time. Click here to read a little about their observations.

Here are some observations that might help identify D12, D13, and D14. See if you can spot them, or share your own in the comment section. Of course these are my observations on April 10, 2012. Yours may be different. At the rate they are growing, mine will!

D12

• Has a 'sad-looking' beak that stops midway of eye.
• Has a ^ above the blackening of the eyes.
• Has a skinnier neck than D13 and is whiter for now.

D13

• Has a more messy look of blacking around eye.
• Has a 'drip' under left eye.
• D13's beak goes back to back of eye, and has  a jiggy-jag to it.
• Is getting larger than D12.

D14

• Is the smallest so far.
• Doesn't miss a meal.
• Has a strong neck
• Knows how to bonk D12 and D13

Nest Roundup

It's been a busy couple of days for everyone! Here is a complete RRP nest round-up:

• Two eaglets in Decorah. D12 hatched on 3/27/12 and D13 hatched this morning.
• Two eaglets in Fort St. Vrain, Colorado
• Two peregrine eggs at Great Spirit Bluff. We're waiting for one or two more.
• Three GHO owlets in Valmont, CO. These guys are growing fast!
• One peregrine egg at Xcel's Sherco power plant
• Several goose eggs at EagleCrest. Hatch is anticipated between April 3 and April 7.
• Turkey Vultures are back in Missouri, although no one has settled into the nest yet.

We have a nest calendar at http://www.raptorresource.org/calendar/ that we try to keep current, although the birds sometimes get ahead of us. We maintain photo albums on our facebook page and our flickr account, and have videos on our youtube page:

• Flickr: http://www.flickr.com/photos/68092929@N03/sets/
• Facebook: https://www.facebook.com/#!/pages/Raptor-Resource-Project/103786266324668
• You Tube: http://www.youtube.com/user/ries96

If you missed D13 hatching this am, here's a video:

The Emergence of D13

We have Pip in Decorah!

Cap by bbsak:

THE DECORAH EAGLE DICTION-AERIE AND ALPHA CODES

This topic is a combination of numerous codes and explanations guaranteed to assist you in viewing or discussing the eagles.

With Eggstraordinary Graditude to chatters, and many other EAs who contributed to our eggspanding vocabulary of Eagle-ese / Eaglish we proudly present the Decorah Eagles Diction-Aerie for you to print out, mantle over, and devour the knowledge presented by the Fledge-U-Ating Eagle 101 Class of 2011. (Original post on Facebook by Sherri Elliott)

The Diction-Aerie
Air-obics - Extending wings and catching a bit of air.
Anthropmorphism - projecting human characteristics onto animals.
Apteria - area on breast with no feathers; aka -brood patch.
Balloon Mantle – a puffball of feathers exhibited by E3.
Beak Geeks - people that are avidly watching them daily.
Beak Lips – area of beak sides to corner of mouth.
Beakering – sibling disagreements.
Beakoff - eaglets fake fighting with their beaks.
Bedreagled Eaglets – raggedy look after bad weather.
Bird Nerds – people that are avidly watching them daily.
Bling – unidentified accoutrements brought to the nest from Nest Depot - usually brightly colored.
Branch Office – Mom & Dad spend most of their time in this space adjoining nest after eaglets grow into juvies.
Branching - eaglets hopping from one branch to another prior to fledging.
Breakfish – first meal of the day.
Cameritisi Permanentitis Bugitis – bug on camera lens, also known as camera bugs.
Cere – fleshy, membranous covering of the base of the upper mandible.
Claw Floss – name given to Pinky, the baling twine.
Cleaning Coma – behavior emulating Dad’s cleaning skills, but generally tiring quickly, lapsing into face plant.
Clown Clomp – comical eaglet first steps learning how to walk.
Clown Feet - oversized feet/talons that the eaglets haven't grown into yet, nor know what to do with.
Convocation – group of eagles in tree or on ground.
Corn Husk – outer dried corn covering coveted in nest.
Corn Husk Pillow – said item used as head rest.
Corn Stalk – building material for nest crib rails.
Clutch – number of eggs laid in a nest.
Crop - area in neck where food gathers first before entering stomach if it is full.
Crop rotation - food moving from the crop to the stomach for digestion (and filling up again).
Cuddle Huddle - all the e's close together for safety/warmth in a group.
Cuddle Puddle – horizontal E cuddle sprawl.
Decorah - the idyllic location in Iowa where our family set up its Home-Tweet-Home
Decorah Drop – nap flop.
Decorah Front Porch – our place to watch the EEeee's.
Decorah Shimmy - back and forth motion that Mom/Dad use to position themselves over the eggs/eaglets.
Decorahating – beautification of the nest.
EA'S - Eagle Addicts, aka: Eagle-holics.
E-ddicts – those who watch eaglets and stay in pajamas all day.
E-Gulp - swallowing food whole.
E-Heap – pile of eaglets.
E-Lump - same as cuddle huddle.
E-Pology - Submission bow or another act of 'sorry' after a sibling altercation.
E-Team – long suffering worrywarts who love eaglets.
Eagle Condo – eagles in penthouse, smaller birds in lower stories.
Eagle Kneivel – daredevil or showoff behavior.
Eagle Time – no time that has anything to do with human time.
Eagleholics Anonymous – 12 step recovery program for eagle addiction..
Eagleholics - (Eagle-holics) people that are avidly watching them daily.
Eaglestock/Eaglefest - 206+ million viewers united on web cam broadcast.
Eagle-ese – our unique vocabulary, also known as Eaglish.
Eagleibrium – balance achieved only by eagle walking.
Eaglemaniacs – people who eat, drink and sleep eagles, with not much real sleep actually occurring.
Eagleicious Delicious – any delightful E behavior.
Eagletecture – construction skills used by Dad to create the nest.
Eaglish - all the words we made up for this dictionary.
Eagulp – swallowing food whole.
Ealergies – involuntary sneezing reaction.
Eyas stage - fresh from nest
Face Plant - off balance eaglet plopping into nest face first, perhaps going into food coma.
Feaking - cleaning a beak.
Feathairdresser – wind redecorating Mom’s hair.
Featherline – e’s hairline feather growth giving them distinguishable identifiers.
Fish Fledge – result of food fight when intended meal accidently goes off the nestbowl.
Fishereagle – Dad, Dad, Dad.
Flappathon – endurance contest of e’s getting pumped up.
Fledge – taking the leap from branches to the air of the big beyond.
Fledge Fest – gathering of EA’s making road trips to witness fledging.
Fly-By – parent checking in, but not landing, and with or without food.
Fly-By-Fake-Out - parent flying by with food to lure E's out of nest.
Flying monkeys – teenlets similarity when wingersizing to the Wizard of Oz flying army. Hum the song: oh weeee oh...ohhhh oh when seeing this behavior.
Food Coma - state of suspension E's go into after eating too much.
Fret of chatters - a group of chatters worried about the eagles.
Flapadoodle: Amusing flurry of wing flaps performed by Mom, sometimes Dad, while sitting (incubating) the eggs. Generally occurs in middle of night and scares the heck out of everyone watching.
Flapping Jacks - eaglets exercizing their wings.
Fledge-U-Ation – eaglets graduate to fledging.
Fritching - itching new emerging feathers.
Gnat – larger than noseeums and especially fond of the eagle's head area resulting in eagle neck jerk twitching.
Gnat Gnat – a term of endearment used interchangingely for nite nite by EAs.
Gnat Scat Boogie – the e’s headtwich dance.
Guy-liner – one way to identify Dad is black liner around his eyes.
Hallux – rear locking talon, also known as eagle thumb.
Hard Penned – feathers firmly attached to bone.
Hoppersizing – up and down movement, usually in conjunction with wingersizing.
Hop-Squash – exhuberent nest hop resulting in a sibling step on. Usually E2 gets hop-squashed.
Hoppiness – what else would you do after a good feed and found you had wings? Happy-Hop!
Hover Mantle – mantling behavior parallel to the prey of the day.
Hovering – catching air with outspread wings while staying in a fluttering suspended motion.
Hugbrella – wingstretch from one e to another.
Kettle - group of eagles in the air.
Juvie sprawl – juveniles taking up extra nest space spreading wings out while napping.
Leap Eagle – hopping over a sibling.
LEGO Eagle – pixilated image of our eagles.
Lumpasizing - E's staying close together or sleeping in a pile.
M.O.D.S – Master Ornithological Data Searchers; also gatekeepers of the RRP FB page or chat.
Mantle - The action of a bird spreading its wings, fanning the tail & arching over prey, to hide it from other predators, including other birds or siblings. From Old English/Norse for cloak. (E3 delighted us with several distinct mantles: Balloon Mantle and Ninja Mantle).
Master Mantler – E3 showed extraordinary mantle diversity.
nest depot - nearby areas where corn husks, branches, horse hair, or nesting material is available.
Moist Fowlettes – wet eaglets.
Mombrella – Mom covering her eaglets with her wings, mostly in inclimate weather. (see also poptent).
Moonwalk – backup walk prior to a poop shoot.
Muskrat jerky – poor thing which gets picked on by the e’s w qhen unearthed from the nest.
Nare – nostril holes on the beak.
Nest Depot – wherever Mom & Dad can find new décor for the nest; ie- horsehair, corn husks, branches, straw.
Nest guests – anyone watching the UStream video.
Nest Potatoes – eagles lazily lounging, usually after eating.
Nestication – staying put in nest or branches; too relaxed to pack and fly off.
Nestogarbage – nest garbage or debris.
Nestoration - The act of rearranging or redecorating the nest
Nestovers – uneaten food found in the nest.
Netiquette – a level of decorum expected on Decorah’s RRP Facebook page.
Nictitating Membrane – transparent inner eyelid, also known as the third eyelid protecting the eye.
Numb Butt – affliction caused by sitting at the computer too long.
Ninja Mantle – heightened Zen-Like state of mantle & hover (first exhibited by E3 on 5-29-11)
Obstacle Occlusion – varying perspectives of the reality of the nest.
Outstinkt - eaglets knowing instinctively to PS out of the nest.
Owl – urban legendary creature purported tohave attacked eagle nest; totally mythical.
Pffffftt! – the distinct sound coming from a PS.
PS - poop shoot - evacuation of the bowels.
Pancake – flat eagle in sleeping position.
Pet Pillow - using your sibling as something to rest a part of your body on.
Pinky – name given to pink/red bailing twine brought into the nest, that inadvertently wound around E2’s foot.
Piscivore - fish eater.
Poop Art - original whitewash gouache on the nearby trees; a takeoff of the 1960’s Pop Art Movement.
Poopcassio - PS artist.
Poptent - Dad standing over the chicks with wings spread keeping them safe from snow/rain/wind or predator.
Porch Peeps - The E's adoring EA's who sit on an evereggspanding porch overlooking the beloved cottonwood tree to pay homage to our eagles.
Post D-Epartum Depression – condition to what will happen to EA’s when eagles leave the nest.
Predicure - manicure for a predator.
Prey Buffet - whatever the parents happened to bring for dinner.
Prey Toy – meal tidbit used as plaything.
PSFS – print screen finger syndrome synonymous with copy, print and save web stream photo captures.
RWS - restless wing syndrome.
Ramage - true feathers coming in.
Raptor – a bird of prey, regal in the birddom. (Latin, one who seizes, from rapere).
Reversed Sexual Dimorphism – the female eagle is generally bigger than the male – opposite of other species.
Rictus - wide open mouth.
Screech-fest - sound associated with food fest.
Screagling – screeches made by e’s.
Screeeeeeee – typed sound the e’s make in one or multiple vocalizations; can interchange with squeeeeee.
Screaching – sound associated with food frenzy.
Separation eagxiety – the anxiety tht the last eaglet feels when it is left in the nest alone, sans siblings.
Shaking Juvie Syndrome – trying to get the gnats off ones head by shaking it.
Spicules – the rear talon.
Sprawled Eagle – eaglet sleeping with wings spread covering a larger mass area than spread eagle.
Spread Eagle - eaglet sleeping with wings spread (see also sprawled eagle).
Squabbit – what we call the newest furry snack when we can’t figure out if it is a squirrel or a wabbit.
StarBeaks – EA’s favorite corporate cawfee. Most popular blends: Decorah Decaf and Mocha Mantle.
Sub-Adult - juvenile eagle.
Sweagle Dreams – sweet eagle dreams.
Syrinx – flap between esophagus and lungs that eagles make vocalization sounds.
Tail Wiggle-Waggle – movement of the eaglets tail after they realized they had one.
Tarsus – the section of vertebrate foot between the leg and metarsus.
Tippytalon – eaglets doing the ballerina thing.
Tweagles – juvenile teen eagles.
Tween Preen – Eaglets in their ‘awkward’ phase trying to get their feathers unfurled.
Twiggs - playing with branches like Lincoln logs.
Twittering - calls made by young eaglets.
U.I.A. – unidentified animal brought in as prey.
Whatta - The best way to start a sentence!
Wilson – name given to the beloved cornhusk that resembled the volleyball in the film “Castaway”.
Windteruption - high wind day that causes the e's to lay low.
Wingercizing - excercizing the wings.
Wingpits – self explanatory.
Wing Smackdown – exhuberent wingersizing between two or more eagles resulting in a takedown.
Wing Whack - one eaglet stretching his wing while laying down and hitting his/her nearby sibling with it.
Wonderstruck - The overwhelming feeling produced by the EEeee's.

Alpha Codes
A = Ant
AD = Additive
B = Bugs
BB = Beak Biting
BH = Branch
BFP = Big Front Porch
BG = Beak Geeks
C = Cat
CA = Camera
CH = Cornhusk
CHP = Corn Husk Pillow
CL = Clutch
CP = Crop
CS = Cornstalk
CT = Cottonwood
D = Dad, Daddy
D1 = Dog (This was prior to D1, being named D1)
DE = Decorah
E = Eagle or Eagles (1,2,3)
EA = Eagleholics Anonymous
EG = Egg
EPU = Eagle Parental Unit
E101 = Eagleholics 101
E-lumni = Eagleholics 101 Graduates
F = Fledglings
FS = Fish
FC = Food Chain
FP = Faceplant
G = Gnats
GR = Grunt
H = Horse
H1 = Human 1, Human 2 (at farmhouse)
HA = Hatchery
HC = Hatch
HV = Hovering
I = Icing On The Lens
IB = Incubate
IA = Iowa
IF = Infrared
J = Juvies
JK = Jerky
K = Kleenex
KU = Kudos
L = Leaves
LT = Light
LV = Love
LE = Lens
M = Mom, Mommy
M1 = Mod
M2 = Mod II
M3 = Mod III
MB = Mombrella
MK = Muskrat
MT = Mantle
N = Nest
NIC = Nictitating
NS = Nestorations
O = Owl
P = Parent(s)
PA = Panning
PCH = Porch
PCP = Porch Peeps
PE = Pellet
Pfffft = Poop shoot sound
PX = Pixels
PR = Preen
PS = Poop Shoot
PT = Poptent
PTZ = Pan, Tilt, Zoom
Q = Quiz
R = Rabbit
RF = Raptorfan81
RRP = Raptor Resource Project
S = Stream
SA = Separation anxiety
SN = Snow
T = Tree
TA = Talon
TF = They're Fine
U = Unconditional Parent Love
UFO = UFO
UST = UStream
UV = Ultraviolet light
V = Victory Of The Fledge
VB = Victory Branch
VE = Venison
W = Wilson
WGZ = Wingersizing
WI = Wind
X = Xtra Knowledge
XO = Kisses & Hugs
Y = Branch
Z = Zoom
ZS = Zzzzzzzzzz's

Special Additions:

eeeeeeeeeeeeeeeee = E1
eeeee eeeee eeeee x infinity = E2
eeeee eeeee eeeee (3x) = E3 (and with a grunt, eating)

Happy watching!

Peregrine Falcon FAQ

While we wait for eggs to hatch in Decorah, Valmont, and Fort St. Vrain, I thought I would talk a little bit about Peregrine falcons. Prior to the Decorah Bald eagle cam, Peregrine falcon recovery was what we were known for, to the extent we were known at all.

In Flight
The Peregrine is the fastest animal in the world, diving or stooping at speeds that can reach over 200 miles per hour. Almost everything about it is built for speed, from the baffles in its nose  to the jagged edges of its slim, stiff feathers and long, pointed wings.

The falcon catches other birds in flight by diving on them from above.  As she begins her stoop, she rolls, cups her wings around her body, and tucks in her feet. This change in shape streamlines her profile, yielding an aerodynamic raindrop that can cut through the air at high speeds.

Photo used with permission of Karen Carroll, http://www.birdsofprey.net

As she plummets her nictitating membrane, a transparent 'third eyelid', protects her eyes from dust and debris in the air and a secretory gland helps keep her corneas from drying up. A special cone or baffle in her nose regulates the amount of air entering her nasal cavity, allowing her to breathe and protecting her from damage. A curved flight path keeps her prey in view and reduces her aerodynamic drag. Before she strikes her prey, she'll experience G-Forces estimated at between 25-27 Gs.

The Peregrine meets her prey feet-first. She slows first, unfurling her wings and tail, and dropping her feet. After striking and stunning or killing it outright, she'll loop around in mid-air to retrieve it and take it to a safe place for plucking and eating.  

Falcon Belinda at Xcel Energy's Allen S. King plant aims at a reporter.

Lifestyles of the Fast and Furious
Falcons are roughly crow-sized. Females are about a third larger than males, although they both have bluish to slate grey backs,  barred or streaked white to rusty underparts, and a black hood. Adults have black beaks and yellow feet, although their babies may initially have bluish feet.  This is natural and not a cause for alarm.

Both males and females are highly territorial. Like eagles, Peregrine falcons are relatively monogamous (polygamy has been documented, but isn't common) and may or may not migrate. Unlike eagles, they are relatively solitary birds.

Traditionally, Peregrine falcons nest on cliffs, laying their eggs directly on a scrape they created in a gravel or sandy substrate.  In the midwest, Peregrine falcons generally:

• Lay eggs in late March or early April
• Hatch in late April to early May, or 33 days after the first egg is laid.
• Begin flying in mid-June or later, or about 40 days after hatch.

Peregrines make excellent, attentive parents. The babies cannot thermoregulate (control their temperature) until they are about 10 days old, so Mom spends a great deal of time huddling over them while Dad feeds everyone. As the babies age, both parents spend time hunting. The eyrie is small and the babies, which have among the fastest growth rates in the animal kingdom, are large and hungry. They eat, sleep, poop, and go from white fuzzballs to sleek brown juveniles in about five weeks.

Once they begin flying, the young peregrines spend a lot of learning how to fly and hunt: something that looks a lot like play to most human observers. Their parents will continue to provide some food for their newly fledged young who are not yet self-sufficient.  Come fall, the adults may or may not migrate, but their children will disperse. In our experience, the young falcons tend to leave in September. Once they are gone, they are gone. If they do come back to the nest, their parents will defend it from them. 

What to expect when falcons are expecting
The new Great Spirit Bluff nest cam wonderfully documented falcon courtship. The falcons engaged in  ledge displays on the roof of the nest box, bowing and calling loudly.


As courtship progressed he made a scrape, digging into the gravel with his breast and pushing with his legs to create a depression (males and females will do this - our video shows the male).


Finally, both falcons bowed and e-chupped over the scrape.


The male also courts the female with food. Our video shows him bringing it to the nest box, but falcons also transfer prey midair. There seems to be a little bit of food fight here as well, but think some courtship was going on.


She will probably lay three to four reddish speckled eggs sometime in March. Peregrine falcons do not begin full incubation until after egg number three is laid, so it is normal for her to spend time - even quite a bit of time, depending on how warm it is - away from eggs number one and two. Her eggs should begin hatching 33 days after the third egg is laid.

Mae's eggs, Xcel Energy Allen S. King Plant.
Some egg color variation is normal.

During incubation, she will experience hormonal changes that help keep her incubating. She may appear sleepy or lethargic, and will spend a lot of time picking at gravel and sitting more or less quietly on her eggs. She does most of the incubation, although the male will spell her briefly. The male is smaller and may have a harder time covering all of the eggs, depending how many are laid. We can also expect to see egg rolling (Brent, at the Allen S. King plant, is well-known for this) and some shimmying. This is not a particularly active time for the falcons: I've heard Bob refer to incubation as the 'egg doldrums'.

My reference list:

• Bob  Anderson
• Video makers razzle and chico70
• http://blogs.bu.edu/biolocomotion/2011/12/12/why-can-the-peregrine-falcon-fly-so-fast/
  (peregrine falcon and speed)
• http://blogs.bu.edu/biolocomotion/2011/10/07/the-fastest-animal-on-earth-the-peregrine-falcon/
  (peregrine falcon and speed)
  http://jeb.biologists.org/content/203/24/3755.abstract (curved flight plans and sideways vision)
  http://www.dvrconline.org/raptoradapt.html (raptor adaptations)
  http://www.airspacemag.com/flight-today/falcon.html (Falling with the peregrine falcon)
  http://www2.ucsc.edu/scpbrg/pefabehavior.htm (pefa behavior)

Eggs!

We are getting a lot of questions about eggs and hatching.  It takes 35-37 days for Bald eagle eggs to hatch, 24-28 days for Canada goose eggs to hatch, and about 28 days for great horned owl eggs to hatch. Despite the differences in incubation times, very similar things happen in the eggs of all three species. 

What happens within the egg shortly before hatching starts?

The rapidly developing embryo...

• Grows large enough to take up nearly all the space.
• Positions its body so that its head is at the large end of the egg next to the air space.
• Begins to breathe with its lungs. Ever crack an egg and see the white membrane inside? Before the chick pokes its beak through this membrane into the air space, a special tissue called the CAM supplies oxygen to the developing embryo. Gases, including oxygen, leave and enter the egg by diffusing through the pores in its shell, across the outer and inner shell membranes, and into the blood in the capillaries of the CAM. From there, the blood circulates through the embryo and provides it with oxygen - no lungs required until the membrane is broken. 
• Consumes most of the remaining albumen and yolk. When I was young, I thought that birds formed from the yolk. Not so! The yolk provides food and energy for the embryo.

The chart below outlines major developmental points in the lifecycle of a developing chicken embryo. At 20 days, the chicken is almost large enough to break the membrane and begin hatching. The timing would be a little different in the case of Bald eagles, Canada geese, and Great Horned owls, but the stages of development are the same.

Successive changes in the position of the chick embryo and its embryonic membranes. (From A. L. Romanoff, Cornell Rural School Leaflet, September, 1939.) (Fig. 9). Website: http://chickscope.beckman.uiuc.edu/resources/egg_to_chick/development.html

So how do birds hatch?

The embryo has breached the membrane, is breathing air with its lungs, and is head up, with its head positioned at the large end of the shell.

• Our embryo  uses its egg tooth, a small temporary structure on the op of its beak, to cut through the shell from inside. The eggshell is thinner and weaker than when it was laid, since the growing embryo absorbed calcium from the shell for its bones. The embryo rubs its egg tooth against the shell, which cuts a small hole.
• As it rubs it rotates its body, slowly cutting a ring around the shell.
• When the cut is complete, the hatchling bird pushes its body against the shell, forcing it apart.  It works itself free of the shell membranes and halves. Viola - a baby bird!

Here is a time-lapse video of a chicken hatching. The hatchling pips, or makes a hole in the shell, and begins rotating.

Altricial versus precocial
Our hatchlings face very different challenges. Canada geese are precocial - that is, they are relatively mature and mobile from the moment of birth. Eagles and owls are altricial, which means the young are helpless and require parental care. Bald eagle and Great Horned owl parents bring food into the nest for their young, often caching or storing prey for later consumption. This means that eaglets and owlets don't need to leave the nest or procure food until they fledge. The young goslings leave the nest within 24 hours of hatching and do not return to it. While their parents continue to provide protection and care, the goslings feed themselves.

The precocial goslings are also able to thermoregulate right away, unlike the eaglets and owlets. altricial birds require their parents (or a parent) to apply warmth until their down feathers are developed enough to insulate them. The eagle parents and mother owl will spend a great deal of time huddling over their young after they have hatched.


Resources

The following resources helped me write and understand this:

• http://chickscope.beckman.uiuc.edu/resources/egg_to_chick/development.html (egg development)
• http://en.wikipedia.org/wiki/Altricial (altricial birds)
• http://en.wikipedia.org/wiki/Precocial (precocial birds)
• http://www.unt.edu/honors/eaglefeather/2007_Issue/dzialowski4.shtml (CAM, respiration)

Things are getting busy! Here is a recap of all the action going on at our various nests. Remember, the estimates are estimates only - hatch could begin a little sooner or a little later at any location.

Valmont Great Horned Owls
We anticipated hatch would start on  03/10/12, but regular cam watchers think it may come a little sooner. The Valmont Owl fans are very dedicated and worth listening to, so you may want to check this one out sooner rather than later. Cam link: http://www.farmyou.com/falcon_cams/index.html and click the Valmont Owls link in the list on the left.

EagleCrest Canada Geese
This site has been full of surprises. The hawks have made a nest elsewhere, leaving an open nest tray for...geese? The Canada geese nesting here have laid five or six eggs despite an owl scare. We estimated hatch starting on 03/21/12. To watch EagleCrest's Wild Kingdom, follow this link:
http://www.ustream.tv/eaglecresthawks

Fort St. Vrain Bald Eagles
The Colorado Bald eagles laid eggs a little earlier than the Decorah pair, but I don't know what I was thinking when I estimated the 24th. I am estimating March 21 here. Remember, this is an estimation only. Cam link: http://www.farmyou.com/falcon_cams/index.html and click the Xcel Fort St. Vrain Eaglecam link in the list on the left.

Decorah Bald Eagles
We are anticipating hatch will start somewhere between March 23 and March 25. Cam link: http://www.ustream.tv/decoraheagles

Great Spirit Bluff FalconsThe Great Spirit Bluff falcons have been seen copulating and making a scrape, so we anticipate the female will be laying eggs soon. We are trying very hard to get band numbers here - we believe the male is P/(something) but we aren't quite sure about the bottom character yet.

Other Cams and Nests

• Missouri Turkey Vultures: Waiting for them to come back
• Riverview Tower Peregrines: Waiting for them to come back
• Dairyland Power Alma and Genoa: Falcons are back in both locations
• Red Wing Grain: Falcons are back. A fight between three of them was witnessed by plant staff on March 7th.
• Hibbard Power plant: falcons are on the grounds. We are considering cleaning out the nest box here ourselves.
• Agri-Bunge, McGregor, IA: Falcons Bonnie and Clyde are back.

We'll keep you all posted as nests begin hatching. Since I don't like to leave without photos or a video, here is a video by Mick from Great Spirit Bluff this morning. This is the male falcon (the proper word is tiercel). The male is making a scrape in preperation for nesting.

How big is the Decorah Bald eagle nest?

Our moderators are often asked about the size and weight of the nest. The short (and very rough) answer? The nest is roughly 5 feet high by 6 feet wide at the bowl, and weighs about 1367 pounds.
This should give you about the right idea of its size, if not its shape.

So how do you know that?
We haven't measured or weighed the nest, but I can do some rough back-of-the envelope calculations that should come close. We are going to pretend that the nest is a neat cone shape, if only because it is closer to cone-shaped than to anything else. This photograph of Bob lying down in the nest was taken two or three years ago.

Bob is around six feet tall and the nest is a little bigger now than it was then, so I am going to go ahead and estimate it at 6.5 feet in diameter, which gives it a base radius of 3.25. The nest was roughly 4.5 feet high when I was up there in October, but the nest is irregularly shaped and the eagles have been working on it, so I am going to go ahead and estimate it at five feet high. Fortunately, this isn't rocket science! Estimations are acceptable.

The formula for calculating the volume of a cone is (1/3) * pi * radius2 * height. So, (.3333) * 3.1415 * 10.5625 * 5 = 55.3 Or you can just go to an online calculator. I checked my answer at http://www.cleavebooks.co.uk/scol/calcone.htm

Now that we have our volume, we need to think about what the nest is made out of. It is in a cottonwood tree, in a neighborhood with other cottonwood trees, maples, and oaks. We can therefore assume that some of the branches are cottonwood, some are maple, and some are oak. Cottonwood weighs about 28 pounds per cubic foot, oak weighs about 46 pounds per cubic foot, and maple weighs about 46 pounds per cubic foot. Since I can't tell which is which by looking at them, we'll take an average of the three, which equals 40 pounds per cubic foot. 40 * 55 yields an estimated weight of 2212 pounds, or a little over one ton.

Earlier today, I gave 2212 pounds as the final weight. Wrong! It was pointed out to me that the nest is not a cone of solid wood - the branches are woven together and it has spaces, albeit tightly packed ones. I cast around a bit for a way to determine this unmeasurable space and finally decided to use the fibonacci ratio of 61.8%. This number, which is also referred to as the golden ratio, or the golden mean, turns up quite a bit in natural series, especially ones that involve spirals. Don't believe me? Check this out: http://science.howstuffworks.com/environmental/life/evolution/fibonacci-nature1.htm

Once I factored in fibonacci, my final estimate becomes 1367 pounds. Still a creepy thing to think about when you are dangling 50 feet above the ground on a rope attached to cottonwood limbs above the nest.

How big are Mom and Dad?
We don't know for sure, since we haven't captured and measured them, but we estimate about 8-9 pounds for Dad and 11-12 pounds for Mom. Their wingspan is most likely between 6.5 and 7 feet.

So how do you know that?

Again, we don't know exactly. Bald eagles vary in size. Bald eagles in Florida are much smaller than those in Alaska, probably because being large helps animals retain heat in cold weather (check out Bergmann's rule: http://en.wikipedia.org/wiki/Bergmann%27s_rule). Iowa has cold winters, so our eagles should be on the larger end of the scale. According to wikipedia (http://en.wikipedia.org/wiki/Bald_Eagle):

• The bald eagle's body length varies from 28-40 inches (70-102 centimeters)
• The bald eagle's wingspan measures between 5.9 and 7.5 feet (1.8 and 2.3 meters)
• The bald eagle weighs between 5.5 and 15 pounds (2.5 and 7 kilograms)
• Females average 13 pounds (5.8 kg) and males average 9 pounds (4.1 kg)

Kay Neumann from SOAR (Save Our Avian Resources) has a lot of experience weighing and measuring bald eagles that come into her rehabilitation center. Although these eagles are often sick or injured, and so may be a little lighter than a healthier eagle, she said:

"Males are weighing in the 8 to 9 pound range, and females are in the ten and eleven pound range. I’ve heard the Raptor Center (Amy's note: the Raptor Center at the University of MN) say from 8 to 12 pounds, and that seems about right for our Iowa birds too. The record holder is a 14 pound female, but she may have been a Canadian bird. So there is quite a bit of a range – just like people, eagles come in different sizes.

It is a bit deceiving in that they look as big as a turkey – 20 pound birds. Turkeys are designed to wander around on the ground and look for seeds while eagles are designed to fly and so built quite differently. An eagle has hollow bones and feathers for strong but light construction - just like a plane."

How big are the eggs?

The eagle eggs are oval, white, and roughly the size of a tennis ball. The Center for Conservation Biology at the College of William and Mary has a wonderful post on this:

http://eaglenest.blogs.wm.edu/2011/03/04/what-size-are-bald-eagle-eggs/

Bald eagle eggs weigh about 4.2 - 4.5 ounces (120-130 grams) and range from 2.3 to 3.14 inches (6-8 centimeters). They are 1.96 to 2.3 inches (5-6 centimeters) wide. They are hard-shelled. Everyone knows that eggs can't get too cold, but they also can't get too hot. Cam watchers have noticed the eagles seeming to spend a little more time off the eggs this year. This may be in response to the (relatively) warm winter. For more about the eggs, check out this blog: http://raptorresource.blogspot.com/2012/02/we-have-first-decorah-eagle-egg-of-2012.html

How big an animal can a bald eagle kill? For instance, can a bald eagle kill a deer? How much weight of prey can a bald eagle carry to the nest?

We don't know the biggest animal that a bald eagle can kill, although I have some prey weight estimates based on animals we have seen them carry up to the nest. Golden and Harpy eagles kill large prey, including deer, but I have not been able to find a reliable report of a bald eagle killing an adult deer. In general, a Bald eagle won't kill you and carry you away if you weigh over about 4 pounds.

The internet gives a lot of interesting answers when about bald eagles and prey weight. I think the Carolina Raptor Center gives the best answer: they can lift half of their weight and carry 1/3 of their weight. Based on these estimates:

• Mom can lift about 5.75 pounds and carry about 3.8 pounds
• Dad can lift about 4.25 pounds and carry about 2.8 pounds

These estimates are in line with the prey we have seen brought into the nest, which has included:

• Fish. The Decorah bald eagles seem to prefer fish to everything else, which means that the majority of their prey is probably around 1 -2 pounds. No muskies, but a lot of trout and sometimes suckers.
• Muskrats. Wikipedia tells me that adults weigh from 1.5 to 4 pounds
• Wild rabbits. Weight reports really vary, but estimates tend to start around 3-4 pounds for adults. The young are considerably lighter. 
• Gray squirrels. Again, estimates vary but in general adults weigh .8 to a little over 1 pound.
• Various birds. Again, I don't know how much they weigh exactly, but the average would be under a pound.

Having said that, I don't think I will ever forget this capture, taken in 2009. One of the adults (probably Mom) brought in the head of a dead fawn (young deer). A newly born fawn might be just inside the range of an eagle's carrying capacity (3 to 5 pounds), but we think the deer was most likely road kill, especially given how deteriorated its body appears to be.

Click here for a look at the area around the eagles nest.

Resources that helped me write this:

• Personal communication from Kay Neumann of SOAR: http://www.soarraptors.org/ Thanks, Kay! (size and weight of bald eagles)
• The Carolina Raptor Center:  http://www.carolinaraptorcenter.org/ (carrying capacity of bald eagles)
• The Raptor Center at the University of Minnesota:  http://www.raptor.cvm.umn.edu/ (size and weight of bald eagles)
• Cleave Books: http://www.cleavebooks.co.uk/scol/calcone.htm (estimating cone size)
• Center for Conservation Biology at the College of William and Mary: http://eaglenest.blogs.wm.edu (egg size and weight)
• Various wikipedia pages for bald eagle info, estimates on the weight of prey animals and wood, including: http://en.wikipedia.org/wiki/Bald_Eagle
• Auburn University: https://fp.auburn.edu/sfws/sfnmc/class/cotton.html (cottonwood)
• Fibonacci numbers: http://science.howstuffworks.com/environmental/life/evolution/fibonacci-nature1.htm

What is infrared light, and why can't eagles see it?

We are starting to get a lot of questions about the night-time illumination of the nest, so I thought I would write a little bit about visible light, invisible light, and our IR illuminators. What we see - the world of visible light - is just a tiny fraction of all the types of light that exist. Infrared light, gamma rays, X-rays, ultraviolet light, microwaves and radio waves are all types of invisible light. Like visible light, they are different because the length of their waves is different.

The illustration below shows the electromagnetic spectrum in its entirety.  The IR portion hangs just off the red end of the visible spectrum.  It spans the frequency range from 780 nm to 300,000 nm (.78 to 300 um) and has a longer wavelength and lower frequency than visible light (click the image to embiggen it):

Illustration courtesy Wikipedia: 
http://en.wikipedia.org/wiki/File:EM_spectrum.svg

Birds have very different eyes than we do. They have four color cones instead of three, more cones and rods to see color and light with, a higher proportion of cones to rods (at least in diurnal birds), and different peak sensitivities to light. As the graph below illustrates, we have narrower spectral sensitivity than birds and are much less sensitive to certain wavelengths of light. However, like humans, birds do not see above about 700 nanometers. While some birds range into UV, IR light is as invisible to them as it is to us.

Illustration courtesy of "Color Vision in Birds": http://www.webexhibits.org/causesofcolor/17B.html

So how can we use an IR illuminator to see the birds if we can't see IR light?
Researching and writing about this stuff makes me want to read a trashy romance novel, but I'll put that aside for now and forge ahead. Here is how it works. The IR spectrum starts at about 780 nm. The LED IR illuminators used on our camera emit 'invisible' light at a wavelength of 850 nm:  well above the 700 nm visibility limit we share with birds, but well below the high-energy 'hot' end of the spectrum.  LED illuminators are also smaller and have lower requirements and range than bulb-type illuminators.

The camera and illuminators are located roughly five feet from the eagles. The illuminators shine IR light on the nest. The IR sensor detects the light and focuses it onto a CCD (Charge Coupled Device) imager chip, which has a spectral response of up to roughly  1,000nm. The chip maps IR wavelengths of light down into the visible spectrum via tiny electric charges generated by IR light falling on to an array of tiny sensor cells. Since the photo-sensitive cells don't distinguish between colors, the camera generates a monochrome image. I suspect it is really a LAB color space, but that is far outside the scope of this discussion. If you feel really nerdy, follow this link to learn more about LAB color spaces. There is a lot more to color than RGB, even for us trichromates! http://en.wikipedia.org/wiki/Lab_color_space.

Can the eagles hear or see the PTZ camera?
The cameras use servo motors to drive the camera along a 360 degree path, which minimizes the amount of time and work it takes to arrive at any given destination. These motors are very quiet - the camera was designed for surveillance - and encased in hard plastic. I suspect that the eagles can't hear the servos; certainly, we don't hear the servos and the microphone is much closer to the camera than to the eagles. If the eagles can hear the servos, the sound is not any more alarming to them than the other noises that make up their sonic landscape - traffic on the nearby road, people at the fish hatchery, wind, tree branches, the brook, the horses, and so on.

Although the young eaglets went through a period last year of seeming quite fascinated by the camera - we wondered if they were interested in their reflections - the eagles ignore it generally. Since it rotates around a 360 degree axis, there does not appear to be much movement (think of a spinning top) and the camera is behind a dome, which helps conceal it. If the eagles can detect movement, it isn't bothering them. Again, a lot of things around them move. Since the camera isn't trying to eat or threaten them, it doesn't really concern them.

In short...
Mammals and birds can't see IR light - to the eagles, the nest is dark at night - but our camera can. We use low power IR illumination devices that are roughly five feet from the eagles. They are not hot and do not emit dangerous radiation or noises. A chip inside the camera does the work of converting the IR image into visible light via tiny electric charges. However, because the chip does not detect color, the image is monochrome.

Experimenting with IR light
To see IR light for yourself, take a television remote, which works via IR. Press a button and look at the LED on the end. You won't be able to see anything. Now, take a digital camera or phone camera (I used an Android HTC), point it at the remote to take a photo, and press a button on the TV remote. You should now, through a digital device with a higher spectral sensitivity than either we or the eagles have, be able to see the infrared light. Like our camera, your camera uses a CCD chip that maps IR down into visible light for humans. But neither we nor the eagles can see IR without technological assistance. Again, the nest is dark at night.

What about the cameras?
A lot of people are interested in knowing more about our cameras. Read this blog post for more information: http://raptorresource.blogspot.com/2013/01/what-cameras-do-you-use.html

The following sources helped me understand all this:

• Personal communication with Travis from 2mcctv, aka our camera salesman. Thanks, Travis!
• http://www.dptips-central.com/infrared-light.html (cameras and infrared)
• http://miguelpedroso.com/Articles/article_nightvision.pdf (light and IR illuminators)
• http://www.onceinnovations.com/downloads/spl.pdf (The Science of Poultry Lighting)
• http://en.wikipedia.org/wiki/Bird_vision#Light_perception (bird vision)
• http://www.jaycar.com.au/images_uploaded/ccdcams.pdf
• (CCD camera explanation)
• Color Vision in Birds": http://www.webexhibits.org/causesofcolor/17B.html
  color vision, birds, and much more
• My husband Ken, who came up with the real-world experiment.