Who is that eagle with a transmitter?

We started to get reports in January of an eagle with a transmitter near Lock and Dam 14, which stretches across the Mississippi river between Le Claire, Iowa and Hampton, Illinois. Like most large lock and dam systems, LD 14 has open water even in the coldest weather, making it a popular place for wintering bald eagles. Of course wintering bald eagles attract photographers, and some of those photographers noticed that one of the eagles had a transmitter on its back. Could this be D1?

Bald Eagle ACE, photo credit Ted Thousand

A few things about the eagle: it was a mature adult, its backpack had no antenna and a clearly visible ID number, and it was left leg-banded. Our transmitters have an antenna and Brett tends to band the right leg, not the left (he made an exception for D25 this year in the service of easy ID). Brett suggested I talk with the Rock Island Fish and Wildlife Service to see if they knew anything about it. Bingo - they did!

Sara Schmueker is a USFWS biologist. She told me that mystery eagle #35959 is part of a Midwest Bald Eagle telemetry study conducted by the U.S. Fish and Wildlife Service, West Virginia University, and U.S. Geological Survey.  He is nicknamed "ACE" because he was caught right outside the Army Corps of Engineers - Mississippi River Project Office below Lock and Dam 14 in January of 2016, when he was six years old. ACE summers up in Ontario, Canada - not too far from some of the eagles Brett is studying - and winters at LD 14. Let's take a look at his map!

ACE's Travel Map

Two things stood out for me. Firstly, ACE's trip through Wisconsin is remarkably similar to some of D1's trips and fits the model we proposed here: https://raptorresource.blogspot.com/2016/11/where-did-all-these-eagles-come-from.html. Secondly, ACE's trip appears to have brought him near to the North Nest area, if not exactly at the nest. Sara told me that around 30 eagles are currently carrying units for this study. Had some of them gotten even closer? I decided to check the study's web page at https://www.fws.gov/midwest/rockisland/eagle/telemetrystudy.html to find out!

The answer to the first question was 'Yes'! Several eagles had passed directly through the area of the North Nest, which is a sort of bottleneck for eagles on the west side of the river, based on the map. I was also amazed by the flights of what I am going to call the Yellow and Blue eagles, which flew from East Central Iowa all the way up through Nunavut to the Beaufort Sea. According to Google Earth, this is a straight-line distance of over 1800 miles - and neither of these eagles flew in a straight line! And finally, a few of these eagles appear to have passed by Eagle Valley on the east side of the river. I like to think that Brett could have spotted them on one of his observational trips, even if he didn't see their transmitters.

Sara told me that team has an end goal of 50 or more eagles with transmitters, which will each provide about five to six years of data to inform management and conservation of the species. Their partners include some names that will be familiar to our followers: the American Eagle Foundation, Alcoa, ITC Transmission, MidAmerican Energy, the Avian Power Line Interaction Committee, the American Wind and Wildlife Institute, FWS, WVU foundation, and the Peregrine Fund. This is a fascinating project and I really encourage people to go to the FWS website to learn more about it. Again, the address is https://www.fws.gov/midwest/rockisland/eagle/telemetrystudy.html.

A huge thanks to everyone who contacted us about this eagle - it was very interesting to learn about and helped make some great connections! Another huge thanks to Sara Schmueker for her study and the information she provided. Bob would have found this absolutely fascinating. Please stay safe, D24 - we want to know what you do this summer!

We suspect that some people are wondering why our platforms use antenna given that ACE's platform doesn't have one. While we don't have details for all of the eagles in the FWS study, ACE is wearing a cellular platform that uses the same spectrum a cellular phone does. Our eagles are wearing satellite platforms that use a different spectrum, as described here: https://raptorresource.blogspot.com/2016/08/eagle-tracking-can-you-do-something.html. There are advantages and disadvantages to each system: the cellular platform doesn't require an antenna, but only provides data in areas that have a cellular connection. The satellite platform provides data from everywhere, but requires an antenna. We are continuing to research tracking technology as the technology advances so we can make the best decisions for the health and safety of our bald eagles. 

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