Approximately 20% of nests monitored by Audubon Florida's EagleWatch occur on man-made structures, including cell or power line transmission towers. In some counties — like Pinellas and Hillsborough — more than half of the monitored nests are on artificial structures. Statewide, wildlife officials estimate the number of eagles nesting on artificial structures to be closer to 8%.
EagleWatch seeks to understand how nest substrate may impact nesting success and predict future trends in nest site choice through analysis of monitoring data and the Auxiliary Banding study. The goal of the Auxiliary Banding study is to determine if the type of nest structure a chick hatches in influences its future nest site choice once it has matured.
Working with EagleWatch, all juvenile eagles treated and released by the Audubon Center for Birds of Prey are given a colored auxiliary leg band with a unique and easy-to-read alphanumeric code. The color of the band is tied to the type of nest in which the chick is born: green bands for chicks from nests in trees and black bands for chicks from nests on artificial structures.
Because it takes juvenile eagles five years to reach sexual maturity, this is a long-term, ongoing study. Now in its third year, the study has banded and released 41 juvenile eagles. Knowing it can take up to eight years or more for a banded bird to be resighted, the Center for Birds of Prey staff were thrilled to receive three band reports this season.
Fledgling auxiliary band no. K20, released in Central Florida in June 2018, was seen all the way in West Virginia a few weeks later on his first migration north. In February, a Pinellas County EagleWatch volunteer at Lake Tarpon spotted Immature auxiliary band no.
K05 which had been released two years earlier in Orlando, providing data on both the long-term survival and interstate movement of juvenile eagles.
A third, Pre-fledgling auxiliary band no. K22, was placed in a foster nest in Eustis in February. After fledging, he was reported in Ohio two weeks after his last sighting in Florida. Sadly, this eagle was recovered after a fatal vehicle strike, highlighting the stark reality that 50% of juvenile eagles don’t survive their first year.
The juveniles banded during the inaugural year of the study should begin nesting in about two years. We are eagerly anticipating future findings from this study!