Already a subscriber? Sign in Don't have a subscription? Subscribe Now
Chestnut-sided Warbler
Setophaga pensylvanica
– Family
Authors: Richardson, Michael, and Daniel W. Brauning
Revisors: Byers, Bruce E.

Welcome to the Birds of North America Online!

Welcome to BNA Online, the leading source of life history information for North American breeding birds. This free, courtesy preview is just the first of 14 articles that provide detailed life history information including Distribution, Migration, Habitat, Food Habits, Sounds, Behavior and Breeding. Written by acknowledged experts on each species, there is also a comprehensive bibliography of published research on the species.

A subscription is needed to access the remaining articles for this and any other species. Subscription rates start as low as $5 USD for 30 days of complete access to the resource. To subscribe, please visit the Cornell Lab of Ornithology E-Store.

If you are already a current subscriber, you will need to sign in with your login information to access BNA normally.

Subscriptions are available for as little as $5 for 30 days of full access! If you would like to subscribe to BNA Online, just visit the Cornell Lab of Ornithology E-Store.


Breeding male Chestnut-sided Warbler, Tompkins Co., NY, May.
Figure 1. Distribution of the Chestnut-sided Warbler.

A bird of scrubby second-growth areas and forest edges, the Chestnut-sided Warbler is one of the few Neotropical migrants that has benefited dramatically from human activities on the North American continent. Virtually unreported in the time of Audubon and other early American naturalists, this species has increased greatly in numbers with the clearing of primeval forests and the subsequent growth of scrubby habitats. A bird of early successional habitats (e.g., abandoned farmlands and regenerating clear-cut areas), it now can be among the most abundant breeding warblers in second-growth deciduous woodlands. Its populations have greatly expanded since the early 1800s. Despite some declines since the 1960s, this species appears to maintain healthy populations, and management does not seem warranted.

Distinctive in breeding and winter plumage, this warbler is a specialized forager, eating mainly insects, with some fruit on its wintering grounds. Highly mobile, it searches the undersides of leaves, often moving with its tail cocked.

Males use two song classes. The well-known song, generally described as Please, please, pleased to meetcha, belongs to the accented-ending class of songs and is used before the arrival of females, and early in the nesting cycle; it is believed to be used to attract females. Unaccented-ending songs, a second class, are used as the nesting cycle progresses and in aggressive encounters against other males. The two song classes are learned separately. Birds require visual contact with tutor males to fully develop their repertoires.

During the breeding season the Chestnut-sided Warbler is strongly territorial, with a monogamous mating system, although male bigamy has been noted. Pairs raise at least one brood per year, with some renesting.