Flight Maps

Will Four ever disperse? We've been asked that question via facebook, email, and our forum. Only Four can answer that question, but I thought it might be worth looking back at D1 and D14 for clues.

D1's first flights, 8/01/11 to 8/12/11

The map above shows D1's first flights. She fledged in June, at 81 days of age, and we attached the transmitter to her on July 18, 2011. The maps shows her exploring her natal territory, traveling simple, short back and forth paths as she learns proficient flying, food-finding, and navigational skills.

D14's first flights, 8/01/12 to 8/12/12

D14 was 78 days old when he fledged in late June, He is less centered around the nest and hatchery than D1 was, but his initial exploratory flights are very similar. Like D1, he is flying short, simple back and forth paths as he gains skill and experience. 

Four's first flights, 8/01/14 to 8/12/14

Four's fledge occurred at approximately 76 days old, in late June. Like D1 and D14, her early flight pattern is relatively simple  - a lot of short back and forth explorations. Her first "loop" occurred on August 10 and was just 1 mile long (.5 miles out and back). 

So when does a hatch year eagle stop exploring and start dispersing? D1 was quite obvious. On August 13 2011, she flew north 14 miles toward the Iowa/Minnesota border. By September 6, she was 262 miles north of the nest. She turned south and came back to Decorah, arriving back in NE Iowa on December 24, 2011. Before leaving on August 13, she had never been recorded more than .98 miles from her natal nest.

D1's 2011 dispersal

The map above displays D1's entire dispersal. On August 13, she went from local travel along simple paths to long-distance travel along more complex paths. Her large loop included several smaller loops with fewer of the simple back and forth flights that we saw her first weeks on the wing.

D14's 2012 dispersal

Unlike D1, D14 spent more time flying around the Decorah area and left town twice: once on September 5, for a 24-mile flight south, and once on September 22, for good. So did he disperse on September 5 or September 22? My money is on September 22. D14's movements seem to indicate a higher degree of pre-dispersal restlessness, but he didn't leave permanently until September 22. Like D1, he went from local travel along simple paths to long distance travel that included looping flight. Unfortunately, he died of electrocution on November 6 near Rockford, Iowa. The loss of D14 was tragic for personal and research reasons. Everything we could have learned from him ended in his premature death.

As their flight paths show, D1 and D14 spent some time acquiring skills and strength before dispersing. They needed to be able to fly strongly, work with the wind, find food, and navigate. We have recently begun seeing some increased complexity and distance in Four's flights. Only time will tell if and when she disperses, but Four's flight paths and recent calf-eating excursion seem like good signs. Stay tuned! You can make your own D1, D14, and Four maps here: http://www.raptorresource.org/maps/personal.php

Four, 9/1/14 to 9/17/14

3rd Decorah Eaglet Found?

We've confirmed a fledgling eagle without a transmitter a little over one mile from the nest. While we can't know for sure, we are quite hopeful that this is our missing eaglet, especially when we compare the data with D14, who was tracked in almost the same location on 6/27/12. We'll be watching to see if the eaglet comes back to N2, appears in N1, or is seen over at the fish hatchery. In the meantime, please stay back and give the eaglet plenty of room if you see it on the ground. Bob reported that the eagle was flying very proficiently this morning.

The NWZ just got a little larger! Thanks to Frank Ermel for the tip and photo. We aren't trying to ID this eaglet at all right now - we've got our hands full just keeping track of everything that's going on. We hope to have an ID post for everyone later today or sometime tomorrow.

A link to D14's late June/early July map for comparison: http://www.raptorresource.org/maps/pdf_maps/761-Map-07-05-12.pdf

11/27/12: D14 Announcement

We are sorry to announce that Bob Anderson found D14 dead yesterday near Rockford, Iowa. D14, a 2012 hatch year bald eagle from Decorah, Iowa, was electrocuted after landing or trying to land on a power pole. Bob immediately notified the utility company. D14's body will be sent to the National Eagle Repository, where his feathers and other parts will be distributed for use in Native American religious ceremonies. Bob and Brett Mandernack did a close exam

ination of D14's body. He was healthy and butterball fat. There were no signs of wear from the transmitter or backpack.

How common is electrocution? A federal study done in the 1990s identified impact injuries, poisoning, gunshot, and electrocution as the top four sources of bald eagle mortality. We haven't seen it in Decorah until this year, but D14's transmitter was the only reason we were able to follow him after he left the nest. New poles commonly have bird safety devices since bird electrocutions are not only tragic, but can cause fires and power supply disruptions. However, many old poles remain and safety devices don't always work. It's been known since the 1920s that power lines and poles can present a danger to birds. As Bald eagle (and presumably other large bird) populations expand, more electrocutions may happen.

D12, a sibling of D14, was electrocuted earlier this year. A group calling themselves The Memorial for D12 Facebook Group (aka The Raptor Nation) responded by working with Alliant Energy, Puget Sound Energy, Decorah High School, and Decorah Building Supply to develop and fit bird-safe perches for the hatchery. I have a blog post and links about that here:http://raptorresource.blogspot.com/2012/11/bird-safe-power-poles.html.

If you'd like to initiate a perch project in your area, please talk with your local power company. The following links provide wonderful sources of information:

Avian Power Line Interaction Committee: http://www.aplic.org/
D12 Memorial Group story: http://raptorresource.blogspot.com/2012/11/bird-safe-power-poles.html
Avian Protection Devices: http://www.srpnet.com/environment/aviandiagram.aspx
D12 Perches: http://www.flickr.com/photos/68092929@N03/8203641600/

All raptors - all wild animals - face myriad dangers in their lives. It is easy to forget that watching and tracking them doesn't protect them. We'll miss following D14.

09/17/12: D14 and D1

D1 is on the move! She's roughly 77 miles of her northernmost point right now, although she's a little north of the southernmost point we've tracked her at this month.http://www.raptorresource.org/maps/latest.php

Back in Decorah, Bob took some time to track D14 this afternoon. He writes: "I had a bit of free time this AM so I tracked down D14. He was perched in a white pine tree on the top of a bluff overlooking the Upper Iowa River. There were two adult eagles perched nearby. I returned to this area a few hours later and got a beep pointing down stream. I got a booming signal when I pointed the yaggi at three immature eagles soaring high over the river. They were so high up I could not tell which one was wearing the transmitter."

D14 along the Upper Iowa River

D14 with other eagles