The Daily Bird/Warbler Week: Chestnut-sided Warbler

May 11, 2020

Chestnut-sided Warbler
Setophaga pensylvanica

Edited from a version published in June 2016

by Mike Aurelia
Videos and photos by Gilles Carter
The male Chestnut-sided Warbler is one of Connecticut’s most colorful warblers. These warblers are found in older fields going through successional changes as shrubs and saplings multiply, and on the edges of deciduous forests. This common Setophaga warbler can deal with both wet and dry habitats.

What it looks like: The breeding male has a bright yellow cap with extensive chestnut coloring on its flanks. Its back has yellow and black stripes; there are solid black markings on its face. The female is drabber, with a greenish yellow cap, less black on the face, and chestnut only on the upper sides of the breast. Non-breeding males and females are similar, with a greenish yellow crown and back with less chestnut on the flanks.

Where and How to Find It: This time of the year, Chestnut-sided Warblers are migrating through and can be found in numerous habitats. They nest in old field and scrubby habitat throughout Connecticut, a declining habitat type as forests mature and fields get developed and converted to lawns.

Nesting occurs within six feet of the ground in woody shrubs. The female builds a small nest while the male watches. Though the male doesn’t help with the brooding he does help with defense and feeding of the young. A typical nest holds four eggs, usually a ground or creamy white in color and spotted, and the eggs usually hatch in 11 to 12 days.

Like many warblers, Chestnut-sideds are almost wholly insectivorous and focused on the larva and adults of butterflies and other flies, though in a pinch they can tackle some fruit.

In the fall these birds migrate to Central America and the northern most tip of South America.

Conservation Status: The Chestnut-sided Warbler is considered a species of least concern. This is due to the fact that the species can quickly adapt to changes or significant openings in deciduous forests where shrubby habitats can develop within a few years.

Cutting for trees and allowing fields to pass through succession all result in creating more habitats for this warbler. The Chestnut-sided Warbler therefore benefits from habitat restoration work being done at Connecticut Audubon’s Croft, Smith Richardson, Chaney, Deer Pond Farm, and Bafflin preserves.

Mike Aurelia is former member of the Connecticut Audubon Board of Directors. Gilles Carter is a current Board member.