Thursday, November 30, 2017

Bird kills, no 30-year take permit required!

An amendment from the House Committee on Natural Resources to House Energy Bill H.R. 4239 effectively guts the Migratory Bird Treaty Act by absolving oil and gas companies from responsibility for bird deaths in oil pits, on power lines, and from other energy-related infrastructure, including wind power projects. Are energy-related deaths really a problem for birds? Well, four of the Decorah eaglets that we know have been electrocuted and electrocution was the biggest source of mortality in Golden Eagles in a multi-year study recently published by the National Wildlife Health Institute, so we certainly think so. But beyond that, Audubon put together these figures:
Who needs a 30-year take permit under this law? NO ONE. Remember how angry everyone was about the 30-year take permit on bald and golden eagles? THIS IS WORSE. Phone your representative and add your voice to Audubon and the American Bird Conservancy's protests. You can use this tool to get contact information based on your zip code: Do it now!  

While we're on the dismal topic of legislation that is bad for birds, here's a list of  bills aimed at the Endangered Species Act:

H.R. 717 by Rep. Pete Olson (R-Texas) would require consideration of the economic costs of protecting an animal or plant on the endangered species list and remove deadlines for completing the listing process. Deadlines assure completion of a process: removing them does the opposite.
  • The Endangered Species Act provides many exceptions and alternatives to allow economic growth within the framework of environmental protection. Between 1998 and 2004, less than one percent of the 429,533 development projects that underwent Section 7 consultation were temporarily put on hold. Only one project could not proceed; the rest were implemented after modification. Removing the deadlines for completing the listing process will allow opponents of listing to prevent it through endless rounds of comment submissions and information stonewalling. 
H.R. 1274 by Rep. Dan Newhouse (R-Wash.) would automatically deem any information submitted by a state or local government to be the “best available” science even if such information were contradictory, out-of-date or fraudulent, weakening the listing process for endangered species. Your voices will become less significant than the voice of state and local governments in decisions involving the listing of endangered species.
  • Under present law, the service considers any information submitted on the biology, distribution, or threats to the species when making their decisions. When we asked you to comment on the 30-year take proposal in 2016, we did our best to provide you with scientifically accurate information - the same information that we used in our own comments. Although their decision wasn't perfect, your input helped to improve it. Under the proposed law, your comments won't be weighted as heavily as the comments of state and local governments, whether those comments are accurate and truthful or not. 
H.R. 3131 by Rep. Bill Huizenga (R-Mich.) would hamper citizen enforcement and participation in the implementation of the Act’s provisions. Undercutting the ability of citizens to bring lawsuits would make the agency more prone to improperly consider politics in its listing decisions and prevent imperiled species from receiving protections in a timely manner.  Citizen suits are the primary mechanism by which the ESA is enforced against government agencies and private entities.
  • A real-life example: Citizen suits have required the EPA to conduct scientific assessments and make effects determinations for numerous pesticides, thereby protecting animal and human health. You can learn more about that here: These assessments happened only after the lawsuits were brought.  
  • Another real-life example: In Beech Ridge, the Animal Welfare Institute and other environmental groups brought an ESA citizen suit against Beech Ridge Energy LLC, a wind project developer in West Virginia. The project was found to violate the “take” prohibition in ESA section 9 with respect to an endangered bat, resulting in restrictions on the timing and duration of the wind turbine operation. Their actions helped protect an endangered bat and the project was still able to move forward, albeit with some restrictions.
  • Speaking of wind turbines, the American Bird Conservancy and the Black Swamp Bird Observatory filed a citizen suit regarding the installation and operation of a wind turbine at Camp Perry, which is sited in a major bird migration corridor, is located in close proximity to numerous bald eagle nests, and is likely to kill species protected under the Endangered Species Act. Construction on the project was halted (and yes, we signed their petition):
H.R. 2603 by Rep. Louie Gohmert (R-Texas) attempts to limit the Endangered Species Act’s provisions for exotic game species that have been imported into the United States for trophy hunting. If taken literally, this legislation would remove the need for conservation permits of exotic game species, eliminating a critical funding source for overseas conservation of those very species. Removing or limiting oversight for the importation of live exotic animals is a bad idea given how easily exotics can become invasives.
  • This bill addresses the importing of live exotic game species into the United States for hunting. For example, zebras are imported into the United States for hunting in Texas, Mr. Gohmert's home state. You can also hunt the scimitar-horned oryx, gemsbock, kudu, bongo antelope, addax, wildbeest, and so on. While some people find trophy hunting distasteful, it is legal, the ranches have helped conserve very rare species (some of them claim to have the only populations of these species in the world), and the required conservation permits help fund overseas conservation. However, H.R. 2603 removes the need for conservation permits, taking away funding and oversight. Given how rare some of these species are, and how easily exotic species become invasive species - take a look at the "Snow Monkeys of Texas" for an example - both things are needed. I recommend starting with this article to learn more about exotic animal hunting in the United States. 
H.R. 424 by Rep. Collin Peterson (D-Minn.) would reinstate a 2011 decision by the U.S. Fish and Wildlife Service to remove federal protections for gray wolves in the western Great Lakes states. In 2014 a federal judge found numerous scientific and legal deficiencies with that 2011 decision and brought back protections for gray wolves. The legislation would invalidate the court opinion and preclude all judicial review into the future.
  • Why does this have to do with birds, or anything other than gray wolves? H.R. 424 is seeking to overturn a federal judge's ruling that the original 2011 decision was flawed legally and scientifically. But nothing precludes anyone from calling for removal of the gray wolf again - it isn't a system where listing or delisting can only be required once. This bill sets a process for completely ignoring standards by overturning decisions through the legislative process. If it wins, the process - which circumvents the Endangered Species Act  - will be applied in other laws to other species. 
Again, we encourage everyone to call their representatives and stand up for the Endangered Species Act! You can use this tool to get contact information based on your zip code: The American Bird Conservancy also has an ESA petition tool here:

Tuesday, November 28, 2017

2017 by the Numbers! #GivingTuesday #Budget

To help kick-off Giving Tuesday on Tuesday, November 28, we wanted to talk about what got done this year. Here are the things your donations helped us get done! Please donate to the Raptor Resource Project to help us continue our work in 2017 and beyond!

New Projects
In 2017, we expanded our educational partnerships with Luther College and the Fish and Wildlife Service, kicked off the Robert Anderson Memorial Scholarship Fund, and began working on short  videos to expand our online educational program. We:
  • Began a banding station in collaboration with Luther College. We were awarded a grant by the Iowa Department of Natural Resources’ Conservation Education Program to develop a collaborative educational partnership with the Luther College Center for Sustainable Communities and Environmental Studies. The proposal included the construction of a raptor banding station at Hawk Hill on the NW corner of the Luther campus. The station was masterminded by Dave Noble, who built it with the help of Dave Kester, John Howe, and amy Ries. It is managed by RRP’s board member and master bander permit holder Dave Kester, who is working closely with Emily Neal of the Luther College Center for Sustainable Communities and Environmental Studies.  The partnership strengthens the connection between academia and non-profit conservation to provide students with unprecedented direct access to conservation research.  Our first year is almost done and we are excited to continue this valuable program in 2018 and beyond! You can read more about it here!
  • Kicked off an educational endowment in Bob Anderson's name.  The Robert Anderson Memorial Scholarship Fund is managed through the NE Iowa Community Foundation and we have a running start at funding it to the goal of reaching a sustaining level of $25K.  When we reach that goal, we will offer our first scholarship at Luther College in his honor.  We have witnessed the type of students we envisioned during the first year of our raptor banding station at Hawk Hill.  With good momentum and visibility of the fund, we may reach that goal by the end of 2018! If you are interested in donating to the endowment, please visit
  • Filmed with Sustainable Driftless Inc and Untamed Science to collect footage of falcon banding and create some educational short videos, including a video about Bob's falcon recovery. We also collected data about how peregrine falcons react to the presence of drones, which was shared with other banders and members of the North American Flyway Council. you can read our report and observations here:
  • Embarked on a collaborative project to create a live cam with the US Fish & Wildlife Service that will help educate people about the importance of the Mississippi River Flyway to raptors and other birds.  Imagine a live display where field trip classrooms and home viewers can observe bald eagles, pelicans, tundra swans, passerines, and countless varieties of ducks and waterfowl!  
Online Interaction and Education
We also kept busy with our online interaction and education program! Since January 1, 2017, we have:
  • Provided 1,785 hours of chat on the Decorah eagles channel, including 449 hours of dedicated educational chat. Our Decorah North group provided 576 hours of moderated chat. 
  • Posted 368 times on Facebook. Topics and photos included the Decorah Eagles, the Decorah North Eagles, the GSB Peregrine falcons, the Fort St. Vrain eagles, tracking D27, Robin Brumm's trips to Decorah, peregrine falcon banding, nest box work, and many other topics related to our nests and birds. Posts were shared from Neil Rettig Productions, SOAR, the Cornell Laboratory of Ornithology, and Jim Brandenberg's 365 Nature project. 
  • Wrote 31 blogs. We addressed questions about the eagles, the nests, nest intruders, eaglet growth and development, eagle vision, eagle dreams, hunting and fishing lead free, prey remains in the nest and much more!
  • Started an ad-free stream in partnership with We now offer ad-free streams of the Decorah Eagles, the Decorah North Eagles, and the Great Spirit Bluff falcons! Those can be watched at Explore or on our website at
I need to give a shoutout to our amazing volunteer moderators. I have said it before and I will say it again - our volunteers make our pages the best on the web and we could not provide our online educational program without their help!

Monitoring, Banding, and Recovery
Our peregrine falcon program is key part of who we are and what we do! In 2017, we:
  • Monitored over 50 peregrine falcon and bald eagle nest sites and potential territories in Minnesota, Wisconsin, Iowa, Illinois, and Colorado.
  • Banded 58 falcons at 22 sites in Minnesota, Wisconsin, Iowa, and Illinois between May 25 and July 5th! Our northernmost territory was in Cohasset, Minnesota and our southernmost territory was in Peoria, Illinois. As always, we reported all banding and follow up data to the Bird Banding Lab and the Midwest Peregrine Society.
  • Installed a tracking platform on D27, who is still going strong near Strawberry Point in Iowa! 
  • Retrieved the bodies of two falcons from the Great Spirit Bluff nest for autopsy. The Raptor Center concluded that they died from black fly bites. 
Thanks to our utility, industrial, and landowner partners for all of their help and support! A huge thanks to Brett Mandernack for including 'our' eagles in his studies and for sharing all of the data about their whereabouts and fates. Thanks also to David and Ann Lynch and Brian Malaise for their help with the transmitter project. We couldn't do it without all of you!

Camera Research and Installation
John Howe, Kike Arnal, David Kester, Amy Ries, Richard Meredith, Bill Heston, Tina Lopez, John Kaczmarek, and Liam Grainger installed a total of fifteen new cameras and  microphones at N1, N2B, Decorah North, Fort St. Vrain, GSB, and Xcel Energy's Sherco and Allen S. King plants this year. We did our three eagle cam sites between August 22 and September 29th, when the eagles are at their loosest point of attachment to their nests! It was a busy season but the upgrades in video and sound were well worth it! The installations took roughly 950 hours total.

We also replaced the Great Spirit Bluff nestbox! Our caring, dedicated livecam viewers helped greatly by raising funds to replace the original box installed by Bob Anderson and Dave Kester in 2003. It served fourteen productive years and produced 41 falcons, making it one of our most productive cliff sites. Rather than completely re-designing the box, we transitioned to a design built by John Howe that resembles a cliff eyrie. The lack of a back exposes the falcons to the bare rock of the cliff, and the added insulation allows it to better retain the temperatures of the massive rock face.

John Howe put in hundreds of hours researching, ordering, and testing cameras this year. While the majority of our installs are done in September and October, camera and streaming research take place year-round.

Other Stuff
  • We threw our annual After The Fledge party between July 13th and July 16th. Almost 100 eagle fans and volunteers had a blast celebrating the Decorah eagles and Decorah itself! Pagent Decorah added a very cool boat ride on Sunday this year, and we're looking forward to doing it again next year!
  • We upgraded our website and our live streams to give users a safer, easier, and faster way to watch our eagles and falcons on a variety of platforms, including mobile devices and tablets!
  • We added new remote volunteer camera operators to increase our coverage. This has given us new insights into the lives and habitat of the birds we watch!  
Our Budget
In 2017, our annual expenses are hovering around $254,000 per year. They break down like this:

  • Staff and contractor compensation will cost an estimated $142,000 this year. We hired John on January 1st of 2017, paid two busy contractors (Amy and Dave), and incurred additional expenses hiring climbers and helpers for four camera projects and the new nest box installation at Great Spirit Bluff. These were extensive projects, with roughly 500 hours spent on the Decorah and Decorah North installs in September alone. Although Iowa’s Conservation Education Program helped pay for our banding station with Luther College, we still need to compensate master banders and our master builder! We are committed to paying a fair wage for work, which means that everyone we contract with is compensated at a living wage or better. 
  • Camera equipment and IT expenses – cameras, microphones, cables, encoders, software, licensing fees, website costs, and so on – will come in at around $42,000. HD and 4K cameras are amazing, brilliant, and breathtaking…but they don’t come cheap.
  • Office and field supplies – paper, printer expenses, new ropes, slings, rappelling tools, hardware, zip ties, screws, silicon gel, rope bags, harnesses, lumber, paint, tape, bands, banding equipment, and trapping equipment – will cost about $7,500. Given all the trips we made to the hardware store this year, I think it’s a pretty good deal! Several of us also pay for our own climbing equipment instead of having RRP do it, which helps keep expenses lower and gives Amy a great excuse to go shopping! 
  • Office and land rental fees cost $7,500.
  • We can’t work or drive the company vehicle without insurance! Although it isn’t nearly as exciting a topic as eagles or falcons, John did an excellent job negotiating insurance, which will cost us $1,300 this year. This was a decrease from last year, and we have better coverage, too! Other things I would put in the necessary-but-ho-hum category include vehicle expenses ($4,500), fundraising fees and gifts ($6,000), accounting ($4,000), postage and delivery ($5000 – and that’s with the non-profit rate!), and our endowment funding ($2,000 and please consider donating to the Bob Anderson Memorial Scholarship fund). 
  • Travel and meetings cost us $8,000. While this might sound expensive, Amy alone put over 30,000 RRP-related miles on last year. This number would be much higher if Amy and John didn’t donate a significant amount of their travel. Although we don’t usually go too far from home, we put a lot of miles on during banding and camera season! Despite our mileage donations, I suspect that this number will be a little higher than projected.
  • Printing and copying isn’t cheap! We’re projecting a total of $12,000 for this year. That includes two large newsletter printings, all of our thank you letters and envelopes, and any printing related to talks, events, and presentations.
  • Speaking of events, After the Fledge will cost about $1,500 this year. You should come next year – it is a great celebration of our eagles!
  • And finally, grants to partner organizations will total $10,000.

Our income is generated by a combination of donations from viewers, grants from corporate partners, and (new this year!) a grant from the Iowa DNR’s Conservation Education program. But donations from viewers like you remain our biggest single source of income. We sincerely appreciate your generosity and support of the Raptor Resource Project mission. Would you please help us make a difference with your donation? Thank you so much for your support and we hope you enjoy watching in 2018!

Wednesday, November 22, 2017

A Reflection and a Thanksgiving

November 23rd would have been Bob Anderson's birthday. I assume that our friend and founder would finally have achieved his dream of retirement - or at least semi-retirement - and be busy with his book by now. Given the thankful nature of the season, it seems like a good time to take stock of where the Raptor Resource Project has been, where it plans on going, and what I have to be thankful for.

For those of you who don't know, Bob founded the Raptor Resource Project to propagate and release peregrine falcons. He was the first person to successfully breed peregrine falcons in Minnesota. MF-1, one of the first falcons he produced and released, became the first returned falcon to breed in the mid-continent following the species' extirpation in the mid-1960's. It took an incredible amount of work to keep the peregrine falcon from joining the long list of species that will be mourned on the remembrance day for lost species. I am thankful that the peregrine falcon is still with us. Where we have a will, we have a way.

Falcon MF-1. Produced by Bob, she was the first falcon to return and breed in the wild mid-continent. 
I am thankful to have met Bob. He responded to an ad my little writing business was running back in 1994. I began by writing grants, but very quickly moved into field work. Did I want to attend a banding and take pictures? Yes! Did I want to hold falcons? Yes! Did I want to rappel? Yes yes yes! The writer William Least Heat Moon said in the Wonsevu chapter of the book PrairyErth that "I'm not sure what to make of it, but I think a dream can set you on another path." Bob's dream of restoring the peregrine falcon set many people's lives on another path.

Most of the power plant people originally involved in our utility-peregrine program have retired, but a new generation of men and women have replaced them in this unique marriage of industry and conservation. The peregrine would not be where it is today without their help and whole-hearted involvement in the program. Together we've put up nest boxes and internet cameras, cared for falcons, eagles, and kestrels, and looked at ways to make generation and distribution safer for our birds. I am thankful to have worked with the fine men and women employed at America's power plants. The utility-peregrine program is an example of the ways in which humans can support wildlife even in the unlikeliest of areas. You guys are awesome...and great fun, too!

Banding at Xcel's Allen S. King plant in 2010
Bob was also working on his cliff release project. Back in 1994, he began to believe that nest-site imprinting was preventing the crossover of peregrines from power plants to cliffs. The Iowa DNR was very interested in working with Bob, so he picked up lock, stock, and barrel to move down to Bluffton, Iowa in 1996. He did a successful pilot release on the Upper Iowa river in 1997 and released a total of 19 falcons from Hanging Rock at Effigy Mounds National Monument in 1998 and 1999. The Upper Iowa hackbox can still be seen from the river, although the Effigy Mounds hackboxes are long gone. In 2000, our cliff-released falcons became the first falcons to return to the cliffs of the Mississippi. I remember going to see them quite well, since I was very pregnant with my last son. I did a lot of crazy things for and with Bob, but the only time I remember him being really worried about me was just after I huffed and puffed my way up the back of Queen's Bluff. Pat Schlarbaum's story about peregrine recovery includes information about our cliff releases. It can be read here: I am thankful to have played a small piece in this story, and very grateful to the men and women of the Iowa DNR who supported Bob's work.

Falcons raised for cliff release, 1997
In 2006 and 2007, Bob was working with Neil Rettig on the movie American Bald Eagle. After the two wrapped up, Bob said "Wouldn't it be fun to put this nest on the internet?" We made Bob's dream a reality in 2009, when the Decorah Eagle Cam uploaded an image to Xcel Energy's website every two minutes. In 2010, Luther College hosted a live feed. In 2011, we moved to Ustream and the Decorah eagles became a worldwide sensation. While we celebrated the eagles, Bob also mourned the loss of his dear friend and fellow falconer Rob MacIntyre, the 'mad scientist' who was featured so prominently in the movie RaptorForce. Rob did a lot of the work on our earlier cam systems, and his death was a real blow both personally and professionally. I am thankful to have known him and his wonderful wife Jan. They brightened every room they entered.

Rob and Bob
While Bob never lost his drive to recover birds of prey, he suddenly had a new focus. He was deeply engaged in using our bird cams to reach learners and provide a palliative window to the outside for ill, injured, and bedridden people. Online education became a major focus, but cameras still needed to be researched and purchased, and HD was increasingly looking like the next step. Enter John Howe! John began working with Bob to research cameras and camera technologies, including solar/wireless technologies (Rob installed our first solar/wireless system back in 2003) and HD. The longer Bob worked with John, the more he was impressed. Shortly before Bob's death, he let us all know that John was to follow him as Director of the Raptor Resource Project.
John and Bob
This brings us up to the present. In the two years since Bob's death, John has worked diligently to keep up with camera and streaming technology, deploy cameras, expand our online educational offerings, honor Bob's legacy, and secure funding (an organization doesn't run very long without money). He has more than proven himself as a director and a leader. I am thankful for John Howe and only wish that Bob was here to see the positive change that John has brought to the Raptor Resource Project.

So where do we go from here? We are sustained by our mission: to preserve and strengthen raptor populations, expand participation in raptor preservation, and help foster the next generation of preservationists. We follow our vision: to deepen the connection between people and the natural world, bringing benefits to both.
  • Education: We served 1,270 educators through our educational video stream and chat in 2018. We also added a kestrel live stream in partnership with Neil Rettig Productions and Cornell University and completed the second fall of our research and educational banding station in partnership with Luther College. Teachers Deb Ripple and Lori Carnes have started to produce curriculum for our educational program and teachers are also sharing ideas on a platform started by Lori. 
  • Preserving and Strengthening Raptor Populations: Despite the rain and lower hatching success this year, we banded 72 falcons in 2018. We will continue to monitor our nests, band falcons, consult on nestboxes and habitat for a variety of species, provide input on conservation issues, and work with federal and state wildlife agencies to benefit of birds of prey. We are also looking at ways to strengthen existing partnerships and build new ones. How can we connect our passionate followers with organizations looking for volunteers? How can we work closer with our utility and industry partners on providing or improving habitat for the many birds that nest on or use utility land and water in other ways? How can we advocate for birds of prey? We have done a lot, but we can do more. We stand on the shoulders of giants!
  • Fostering the Next Generation of Preservationists: We've begun an educational endowment in Bob's honor. Please follow this link to learn more and to donate! We hope to fund our first students next fall.
  • Connecting People with the Natural World: John upped the ante on our cameras! We are currently providing top-notch, HD, ads-free streams through Explore, and streams plus live chat at our website. John's current camera installations are also letting us take a look at life outside our nests - an important part of understanding and caring for the eagles and falcons we watch. A challenge for me: how do we develop quantifiable data from the thousands of hours of footage and anecdotes we've collected? Our knowledge has already changed since we first began watching the eagles (remember eagles are always monogamous?), but there is so much more to learn! 
So what else am I thankful for?
  • I am thankful for our amazing volunteers. In addition to your incredible work, my life is better for having known you. I've said it before and I'll say it again...your work makes us the best site on the web!
  • I am thankful for fans of the Decorah eagles and our other birds. Please, keep emailing and mailing your stories and art. You have deepened our lives an immeasurable amount.
  • I am thankful to our Board for providing direction and guidance. 
  • I am thankful for an unexpected and unlooked for gift: the honor to be part of the Raptor Resource Project's work. My 1994 self - I was 28 years old! - had no way of knowing what saying 'Yes' to Bob's first request would lead to. Bob, we will remember and celebrate you until we join you.
Thank you, everyone. I'm going to close with a link to a favorite blog I did on Bob back in 2012: Watching Bald Eagles. In re-reading it, I affirmed my own goal to help our eagles' futures stretch as long as their past. May Mom and Dad's progeny survive into a beautiful future, and may falcon MF-1 have thousands more descendants! Long may they all fly!

The Raptor Resource Project wishes you and yours a very Happy Thanksgiving!

Friday, November 17, 2017

Eagle eyes!

Has anyone ever called you eagle-eyed? Relative to humans, bald eagles have larger, sharper eyes that see further, collect more details, and produce stereoscopic vision to greatly improve depth perception.

A bald eagle's visual acuity begins with its eye size and shape. Dad's somewhat tubular eyes occupy over 50% of the volume of his skull, as compared with less than 5% in us spherically-eyed human types.  He can voluntarily adjust the curvature of his large cornea and lens (we're restricted to involuntary adjustments of our relatively smaller lenses only), which lets him rapidly change focus and increases the size of images reflected on to his retina. His two-lens system functions very similarly to a pair of binoculars, letting him see small objects in great detail at a distance and changing focus quickly as he flies - extremely important when hunting for squirrels, avoiding tree limbs, and locking talons with other eagles!
Eagle Eye Versus Human Eye. See end of blog for note.
The differences don't stop there. Our retinas would die without blood vessels, which supply oxygen but also scatter light and cause blind spots or shadows since light isn't reflected through them. But Dad's retinas don't have blood vessels! A pleated structure called the pecten supplies oxygen to Dad's eyes, preventing blood vessel-related light scattering and blind spots, and leaving more room to pack in light-sensitive rods and color-sensitive cones. In short, Dad's lack of retinal blood vessels enhances his visual acuity and ability to resolve detail. Large, razor-sharp images are reflected through his cornea and lens on to a much denser, clearer field of photosensors than our retinas have. How much denser? According to Keith Bildstein, the cone density of birds of prey is roughly 5 times greater than that of human beings. Dad sees farther than us, focuses better than we can, and collects more visual information about the world around him with his HD retinas!

Not enough visual acuity for you yet? Dad has two deep foveae compared to our single shallow one.  His more densely packed and deeper central foveae function in monocular vision, while his forward facing temporal foveae function in binocular vision. A densely cone-packed trench - Helen McDonald refers to it as a sort of smeared third fovea - connects Dad's central and temporal foveae, which helps him track moving objects as he switches from one mode of vision to the other, and lets him scan the horizon without moving his head. He can also fuse images from both foveae to produce a virtual reality-like stereoscopic image, which greatly improves his depth perception and ability to lock on objects. When Dad cocks his head sideways and looks skyward with one eye, he is using his monocular vision and his central foveae to scan for movement. When he looks forward intently, he is using his binocular vision and his temporal foveae to bring whatever he's looking at into sharp focus. Watch for those behaviors in the nest!

To create a 3-D'ish stereoscopic image, click on this image to enlarge it.
Cross your eyes until a third image forms between the left and the right image.

So given that Dad's visual system combines image detectors, tracking devices, binoculars, high-definition cameras, and virtual reality headsets, how far can he see? Accounts differ, but we've watched Mr. North respond to a squirrel in his nest from 550-600 feet away with no problem at all, and we've seen eagles at both nests respond to nest intruders long before they come into our view. Sources suggest that bald eagles can resolve:
  • A 2-millimeter insect from 18 meters away
  • A mouse from 446 feet away
  • An ant from the top of a ten-story building
  • The faces of basketball players from the back of a large arena
  • A rabbit from over three miles away
As if that weren't enough, Dad also sees more colors than we do! In addition to perceiving red, green, and blue, a fourth cone allows him to see into the ultraviolet spectrum. Drops of oil in each cone selectively filter out certain colors, giving Dad greater sensitivity to different color shades and allowing him to see polarized light. These adaptations allow him to see the urine trails or prey, signal mate health, and may help him navigate as well. 

Helen McDonald states that Dr. Andy Bennett, a researcher in the field of avian vision, considers the difference between human vision and bird vision as that between black-and-white and color television. Bald eagle eyes see a world that is brighter, sharper, more colorful, and far more detailed than our own. I wish I could see like they do!

Did you know?
Bald eagles have three eyelids! Their clear nictitating membrane helps keep their eyes free of debris while they are flying. A specialized gland associated with the membrane produces an antibody (lysozyme) that helps keep their lens free of infection.

Despite these advantages, bald eagles have one big disadvantage - a blind spot directly in front of them. I was not able to find any information about the size of the spot, but it is most likely increased by their relatively prominent brows and large beaks. We've seen them hit one another - and in Dad's case, the tree trunk! - and this might also be another reason why collision-based trauma is a leading cause of death for bald and golden eagles. 

We can't see stereoscopically like bald eagles can unless we trick our eyes! You can learn more about stereoscopes here, or check out a video of images here!

Things that helped me learn and write about this topic
If you have a bird-lover in your life, I highly recommend the top two books
Note: The image of the eagle's eye that I used can be found at several websites, including However, it looks a little bit more like an owl's eye to me. Having said that, I'm not an expert and eagles and owls have fairly similar eyes, so I decided to use it.

Tuesday, November 07, 2017

When will our eagles lay eggs? Bald eagle breeding in Iowa and Florida

We're getting some questions about why the Decorah Eagles aren't laying eggs yet. Are they going to lay eggs? Will the nest be productive? The short answer is 'Yes' - the Decorah eagles historically lay eggs in February, while the Decorah North Eagles laid eggs in March in 2015, and in February in 2016. The longer answer is more complicated. If you don't want to read it, skip down to the bottom of the blog for breeding season information.

Bald eagle breeding season: not the same everywhere
We know that Bald Eagle breeding season varies by latitude. While breeding chronologies differ from nest to nest and state to state, in general:
  • In the SE United States, bald eagles may begin laying eggs in November
  • In the SW United States, bald eagles may begin laying eggs in December.
  • In the northern United States, bald eagles may begin laying eggs in mid-January.
  • In Alaska, bald eagles may begin laying eggs in late March or early April.
Bald eagles lay eggs earlier than many other diurnal raptors, or daytime birds of prey, and eagles in the southeastern US lay eggs earlier on average than their counterparts in other places. This is more unusual than it looks. Roughly speaking, a non-tropical bird's year can divided into two big parts: the photosensitive period and the photorefractory period. In the northern hemisphere, the photosensitive period starts when daylight length begins increasing after the winter solstice in late December. Birds' gonads swell and produce sex hormones, leading to productive mating and egg-laying. During the photo-refractory period, which starts after eggs are laid, birds' gonads shrink and mating becomes less frequent or stops altogether. Bald eagles in Florida are an interesting exception to this rule, since they begin laying eggs as early as November, when daylight length is still decreasing and their gonads should be (but obviously aren't) senescent. 

So why do Florida bald eagles lay eggs so early? One possibility: daylight length, especially in south Florida, is a poorer predictor of the season than it is in Decorah, Iowa. This might free the gonads of Florida eagles from the circannual light-based cycle of swelling and shrinking that regulates northern bird breeding. In Fort Myers and elsewhere in south Florida, the difference between the longest day and the shortest day is just 3 hours and 21 minutes, compared to 7 hours and 26 minutes in Decorah.

Birds that live in habitats where environmental cues such as photoperiod are poor predictors of seasons must rely on cues other than daylight length to regulate their circannual clocks. So if daylight length isn't especially important in SW Florida, what is? Check out the chart below.

Annual Averages, Fort Myers, FL

Daylight length isn't a great predictor of seasons in Fort Myers, but rain sure is! And what comes with rain? Clouds! The Max Planck Institute for Ornithology suggests that equatorial (and possibly near-equatorial) birds use daytime light intensity instead of length to regulate their internal clocks and breeding cycles. Under this scenario, the rapid increase in daylight intensity that begins in early September swells SW Florida eagle gonads and begins their annual breeding season. How tightly coupled is the increase in light intensity with the onset of the breeding season? Check out this cloud cover chart from Fort Myers...
Cloud Cover Chart, Fort Myers, FL
Two things. Firstly, the cloud cover chart for Fort Myers, Florida, somewhat resembles the daylight length chart for Decorah, Iowa. Like the daylight chart, it has a steep-sided trough that shows rapidly changing light availability, even though we are measuring intensity instead of length. Secondly, the breeding cycle of eagles in SW Florida appears to be tightly coupled with light intensity. Their overall cycle is quite similar to that of northern eagles, but the external cue that fires breeding behavior appears to begin in September or October instead late December. Of course, laying eggs in November and December also allows nesting eagles along the Gulf coast to avoid the hurricane/rainy season, which runs from June 1st through November 30th, and takes advantage of seasonally available flushes of food when eaglets are at their most vulnerable. Fledglings will have two to three months to gain their wings and hone their hunting skills before light intensity drops and the rainy/hurricane season starts up again.

This results in a chicken/egg quandary for me. Gulf coast eagles appear to be responding to a change in light intensity instead of length. Given the timing of the hurricane/rainy season, it also seems very likely that laying eggs in November and December results in higher offspring survival rates among eagles along the Gulf coast. Is the difference in southwest Florida/Gulf coast breeding cycles the result of an evolutionary process over generations, or does the ability to change breeding cycles and circannular clocks quickly lie dormant in bald eagles and other organisms? This might be important to know given the weather and climate changes facing us today. We wish the best of luck to the southwest Florida eagles this year!

Important events in Decorah, Decorah North, and Fort St. Vrain
Interested in key events at the Decorah, Decorah North, and Fort St. Vrain nests? Mark your calendars as follows!
  • In the nests we watch in Iowa and Colorado, bonding and copulating behaviors become more pronounced and frequent after the winter solstice. Female eagles begin laying eggs 5-10 days after productive copulation begins. This usually happens in mid-February at all of our nests, but can change if an eagle takes a new mate. New mates often seem to push nesting chronology a little later, especially in the first year. 
  • Each egg is laid about 3-5 days apart, and incubation starts with the laying of the first egg. However, eagles may spend more time off their eggs in warmer weather. 
  • Eagle eggs begin hatching roughly 35 to 39 days after they are laid. This usually begins in late March at all of our nests. Hatch can take more than 24 hours for any given egg.
  • Eaglets spend 75-80 days in the nest before fledging. This usually happens in mid to late June at all of our nests.

Did you know?
Fledglings appear to leave the SW Florida nest in May, just as cloud cover begins increasing and light density drops. Fledglings in Decorah leave the nest area between August and mid-October, just as daylight length goes into a steep decrease. It is interesting to speculate that these behaviors are driven by the same circannual clock that drives eagle breeding biology.

Circannual clocks drive circannual rhythms, or biological rhythms that occur on an annual basis - in northern birds, think nesting and migration. But we are also driven by circadian clocks, which keep us in sync with Earth's day/night cycle. Clock genes are extremely influential, affecting the activity of most other genes in the body in one way or another. To read more about our internal clocks, try starting here: and here:

Things that helped me learn and write about this topic: