- Scientific name: Setophaga pensylvanica
Species of Greatest Conservation Need (MA State Wildlife Action Plan)
Description
Chestnut-sided warbler (Setophaga pensylvanica)
Breeding male chestnut-sided warblers have a distinct yellow crown, chestnut on the flanks, and black facial markings with black and white stripes along the back and a white underside. Nonbreeding adult males maintain chestnut-colored flanks but are otherwise less striking with an olive-colored crown and back and a gray face and underside. Breeding females are distinguished from males by having a greenish color to the crown, less black facial markings, and chestnut coloration on the sides. Immature birds have fewer dark markings along the back and little to no chestnut coloration. Although their song can be variable, it is often likened to the phrase, “pleased, pleased, pleased to meet you.”
Life cycle and behavior
The chestnut-sided warbler’s breeding season starts in May when they arrive from Central and South America and the Caribbean. Chestnut-sided warblers build cup-shaped nests in low bushes in young deciduous woodlands and lay 3-5 creamy white to green eggs with brown speckles. Females incubate these eggs for about 11-12 days, and the young fledge after about 9 to 12 days of hatching. Fall migration typically begins between late August and late September.
Population status
Chestnut-sided warbler (Setophaga pensylvanica)
According to the Breeding Bird Survey, in Massachusetts, the chestnut-sided warbler has undergone significant decline since 1966, particularly in the eastern part of the state due to a reduction in breeding habitat. This species remains relatively common within suitable habitat in the western and central portions of the state.
Distribution and abundance
The chestnut-sided warbler is a Neotropical migrant that breeds throughout Massachusetts and the rest of New England. Its breeding range expands south to northwest New Jersey and southeast Pennsylvania following the Appalachian Mountains into Georgia. North of New England, chestnut-sided warblers breed in southern Saskatchewan, east through Manitoba to the Maritime Provinces. The wintering range includes Central America, Caribbean Islands, and northern South America.
Habitat
Chestnut-sided warbler nesting habitat includes young deciduous forests (<20 years post-disturbance). Historically, habitat for this species was created naturally through strong storms, fire, and beaver activity. With natural disturbances minimized today, such habitat can be created through forestry practices. This warbler colonizes young forest soon after disturbance and places its nests in a shrub within a couple of meters from the ground. During migration, chestnut-sided warblers use a wide variety of forested habitat types in varying stages of succession.
Healthy habitats are vital for supporting native wildlife and plants. Explore habitats and learn about conservation and restoration in Massachusetts.
Threats
The primary threat for chestnut-sided warblers is the loss and degradation of suitable breeding habitat. This is of particular concern in Massachusetts, which has the lowest proportion of its forest habitat in an early successional stage of all the states in the Northeast. As with other migrant songbirds, the chestnut-sided warbler is susceptible to collisions with buildings and other manmade structures, especially during their nocturnal migration. As a low shrub nesting bird, they are also more vulnerable to predation by domestic cats.
Conservation
Chestnut-sided warblers rely on disturbance dependent habitat as they thrive in brushy open habitat. With the suppression of natural processes like wildfires, these habitats have become less common, contributing to long-term population declines. Habitat conservation efforts should focus on retaining and protecting semi-open land plots including young forest habitat through prescribed fires and management that involves natural regeneration. Conservation efforts should also attempt to reduce the threat of collisions with glass, wind turbines, and communications towers as chestnut-sided warblers have historically collided with these on their nocturnal migrations.
References
Byers, B. E., M. Richardson, and D. W. Brauning (2020). Chestnut-sided Warbler (Setophaga pensylvanica), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.chswar.01
Petersen, W.R., and W.R. Meservey. 2003. Massachusetts Breeding Bird Atlas. Massachusetts Audubon Society and University of Massachusetts Press, Amherst, Massachusetts.
Sauer, J.R., J.E. Hines, J.E. Fallon, K.L. Pardieck, D.J. Ziolkowski, Jr., and W.A. Link. 2014. The North American Breeding Bird Survey, Results and Analysis 1966 – 2013. Laurel, MD.
Walsh, J., and W. Petersen, editors. 2013. The Massachusetts Breeding Bird Atlas 2. Massachusetts Audubon Society. Scott & Nix, Inc. New York City, NY.
Contact
| Date published: | May 14, 2025 |
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