WCV to Attach Transmitter to Bald Eagle

The Wildlife Center of Virginia, working in partnership with the Virginia Department of Game and Inland Fisheries, will be attaching a transmitter  to one of the three Bald Eagles being released on July 27. [The release will take place at the historic Berkeley Plantation, on the James River below Richmond, at 11:00 a.m.]

The transmitter will allow VDGIF eagle biologists, Wildlife Center staff, and visitors to the Wildlife Center's website to track the eagle’s travels for up to two years.

While the final determination will be made on the day of the release, Wildlife Center staff expects that the transmitter will be attached to NX.  The three eaglets were banded while still in the nest by the Center for Conservation Biology; the three bands are NV [male], NX [female], and NZ [female].

The banded bird will become part of an ongoing research study being undertaken by VDGIF.  Department biologist Jeff Cooper has fitted five Bald Eagles with these GPS transmitters in the past three years, and he will be at Berkeley Plantation on Release Day to outfit the bird with the transmitter.  Working with him will be Michael Lanzone of Cellular Tracking Technologies, the firm that manufactured the transmitter.

Questions and Answers regarding the transmitter:

Q:  How does the transmitter work?

A:  These types of transmitters use satellites to record GPS information.  By using a cellular network to transmit data, the transmitters are able to provide GPS points every 15 minutes.  Data is temporarily unavailable when the birds fitted with these units fly out of cell phone range, but all information is stored and readily available once the bird is back in range.

In this particular case, there is great cell coverage up and down the Eastern Seaboard so we’ll likely be able to receive consistent data.  While there may be some days when the eagle doesn't check-in, those will likely be rare.

Q:  How often will we be able to see where the eagle is?

A:  We should be able to receive a data update every 24 hours, which will report the eagle’s movements.  A standard time will be set on the transmitter so that data comes in at the same time each day.  However, receiving the data also depends on if the bird is “in-range” at the check-in time.

For example, if the transmitter is set for a data download at 3:00 pm EST – we will receive that information at 3:00 p.m. each day.  However, if the bird flies out of cell phone range one day from 2:55 p.m. to 3:05 p.m., the data will not be received that day.  It will be stored, however, so that if the eagle is back in range the following day, all movements can be tracked.

Please bear in mind that the WCV will be checking in to the tracking system to receive the data – and we will have to upload the data and maps to our website.  Because there is a human working on providing this information, we will not be able to upload maps every day to the website.  We hope to be able to provide updates two to three times a week. 

Q:  How long will the transmitter last?

A: These types of transmitters have lithium batteries but also are adapted with solar chargers.  They have a lifespan of about two years. 

It is important to bear in mind that the mortality rate in young birds of prey (including eagles) is very high. One study determined that the mortality rate in the first year of young raptors is as high as 72 percent.  Another study sites that only 11 percent of eagles survive until three years of age.  Other data indicates that perhaps only one in ten eagles survive until five years of age.

Q:  How is the transmitter attached to the bird?

A:  The transmitter is attached using Teflon tape straps. The transmitter sits on the back over the shoulders and the straps form an “X” under the feathers across the chest. The transmitter is very light and weighs only about 100 grams. 

Q:  Will the transmitter fall off after two years? 

A:  This transmitter is permanent and will either stay on for the lifespan of the bird or will be taken off if the battery is dead and the bird is ever caught.

Q:  What do we hope to learn from the information?

A:  For the Wildlife Center, this is a fantastic opportunity for a post-release study on one of our rehabilitated raptors.   There have been very few studies done in this area.  We look forward to watching the movements and behaviors of a bird that has been at our facility. 

We’ll also be contributing information to an ongoing research study.  As noted above, DGIF Biologist Jeff Cooper has fitted five Bald Eagles with GPS transmitters in the past three years – and he is currently tracking three of them.  This study looks at the data received from these Bald Eagles to determine the range and behavior of Bald Eagles in Virginia’s coastal plain.   Migratory behavior is studied as biologists are able to see how far Bald Eagles move in the winter season.  The data is also used to discover communal roost sites of Bald Eagles.

Additionally, the data will play an important role in modeling how these birds use airspace.  By looking at heights at which the eagles fly, average distances, and other specifics, biologists are able to relate this eagle behavior to real-life issues, such as airstrike data.