Frequently Asked Questions about GPS Transmitter (NC99)

Bald Eagle NC99 (patient #14-1955) was fitted with a GPS transmitter prior to his December release at Natural Chimneys Park. This is the fourth Bald Eagle that the Wildlife Center is tracking. The make and model of this GPS transmitter is the same as the ones C35 and C46 are wearing.

Q: Why was this eagle fitted with a transmitter?

A: This is a fantastic opportunity for a post-release study of a young rehabilitated raptor. There have been very few studies done in this area. Proceeds from the sale of the 2015 Garden of Eagles calendar were used to purchase this transmitter.
We look forward to watching the movements and behavior of a young bird that has been at our facility.

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 bird fitted with a units fly out of cell phone range, but all information is stored and readily available once the bird is back in range.

This transmitter are designed to send data every day; the staff might change that variable to less frequent check-ins after the eagle has been monitored post-release for awhile.

Q: How are the transmitters attached to the birds?

A: GPS transmitters are fitted on eagles with Teflon straps – similar to how a human would wear a backpack.

Q: Won’t the transmitter weigh the eagle down?

A: No, the transmitter is very light and weighs less than 80 grams. In general, when transmitters are fitted onto eagles and other large birds, it is recommended that the weight of the backpack not exceed three percent of the bird’s body weight. This transmitter is less than two percent of the bird’s body weight.

Q: How long will the transmitter last?

A: These types of transmitters have lithium batteries but also are adapted with solar chargers. The biologists estimate these particular transmitters will last between one to two years. They are still learning about the battery life in these transmitters due to the different data parameters.

Q: Will the transmitter fall off after the battery expires?

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 eagle is ever caught.

When the GPS transmitter is placed on a bird, the vital part of the fitting that secures the backpack in place is the piece of line that holds the two straps together. While cotton string can be used, the biologists working on this study prefer working with an alternative material. West Virginia University Professor and Cellular Tracking Technology biologist Dr. Todd Katzner prefers using a stronger woven line that won’t break down. Dr. Katzner, who has been attaching transmitters to birds for more than 15 years, feels that this option is safer for the birds in the long run because it is unlikely to partially fall off, leaving a dangling strap that could entangle the bird.

Generally speaking, the tear-away variety are used when researchers want to recover the transmitters.

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

A: The tracking device should record a data update every morning, as long as the bird is within cell phone range.

Please bear in mind that the WCV staff 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 should be able to provide updates once or twice a week.

Q: Will the eagle fly long distances?

A: We’ll have to wait and see! In general, a Bald Eagle’s daily activity depends on the age of the bird and the season. According to the Birds of North America online, some studies suggest that immature eagles only spend about two to five percent of each day [24-hour period] in flight. More than half of their time is spent roosting, and about a third of their time is spent perching.

Some eagles choose to stay in Virginia year-round; Bald Eagle NX, for example, has remained in or very near Virginia since her August 2011 release. Many other Bald Eagles travel around the Eastern Seaboard; C35 has flown from Virginia to Delaware, New Jersey, Pennsylvania, and Maryland. We’ll have to tune in to see the adventures of this young bird.