Notes From the Field: 2023 Colonial Waterbird Census

by Allison Polinksi, Coastal Scientist

If you have ever taken the ferry to Bald Head Island, you may have noticed a small island in the Cape Fear River that is filled with large colonies of waterbirds, especially White Ibis, flying back and forth. This is Battery Island, which hosts the largest colony of wading birds in North Carolina. Colonial wading birds include egrets, herons, and ibis, and there are an estimated 10-15,000 nesting pairs on Battery Island. There are eight species that nest on Battery island annually: White Ibis, Glossy Ibis, Great Egret, Snowy Egret, Cattle Egret, Little Blue Heron, Tricolored Heron, and Black-crowned Night Heron. 

On Tuesday, May 11th our Chief Scientist, Dr. Beth Darrow,  and Coastal Scientist, Allison Polinski, participated in the North Carolina Colonial Waterbird Census on Battery Island with Audubon North Carolina and Wildlife Resources Commission. The goal of this census is to track trends in abundance and distribution of colonial nesting waterbirds. The census is done every three years to minimize disturbance, but it did not happen in 2020 due to Covid-19, so this was the first one since 2017. Battery Island is closed to the public during the spring and summer months to protect the nesting birds from human disturbances.

Our conservation team worked with volunteers and staff from organizations throughout the Cape Fear region to complete transects while navigating through the dense forest to find, identify, and count nests. Lindsay Addison, Coastal Biologist with Audubon, taught the key identifying features of eggs and chicks for each species before beginning the transects. White Ibis were the most abundant, with speckled eggs and black chicks. Great Egrets have large blue eggs, while Pelicans have large white eggs. Tricolored Herons, Little Blue Herons, and Snowy Egrets all have small blue eggs. To find the nests it was necessary to crawl, climb, duck, and be aware of the hundreds, if not thousands, of nests and chicks while navigating through the colony. It was a rewarding and unique experience to observe colonies of nesting colonial waterbirds and collect data during the census!