Chestnut-sided Warbler (Dendroica pennsylvanica)

Photo by Dennis Malueg Chestnut-sided Warbler by Dennis MaluegChestnut-sided Warbler distribution map


Population Information

Federal BBS information can be obtained at by clicking on Trend Estimates and selecting the species in question. All estimates are for 1966-2005.

Life History

Habitat Selection

The Chestnut-sided Warbler nests in thickets of blackberry, raspberry, alder, maple, or hazel within the forest understory. The nest is built among a group of upright stems or in a crotch between two branches (Richardson and Brauning 1995). This species was formerly more restricted to patches of early-successional growth created by natural disturbances, such as fire, wind, or beaver activity (Askins 2000). Today, the Chestnut-sided Warbler commonly occurs in regenerating forest openings created by logging or other disturbances. Common features of Chestnut-sided Warbler habitat include a thick shrub layer, relatively open tree canopy, and high volume of coarse woody debris (Burris and Haney 2005). Niemi and Hanowski (1984) found highest densities of the Chestnut-sided Warbler in Minnesota where there was greater basal area and higher density of shrubs >1 meter in height. Tree species composition appears less important than forest structural features; however, Robbins (1991) reported Chestnut-sided Warblers to be largely absent from conifers. In Wisconsin, it breeds in early-successional deciduous woodlands dominated by hardwood shrubs, saplings, or scattered trees and open clearings with a brushy understory (Robbins 1991, Gostomski 2006). The Chestnut-sided Warbler prefers relatively large tracts of habitat. Temple (1988) estimated 65 hectars to be the minimum size required for 50% occupancy in southern Wisconsin. 

Habitat Availability

The Chestnut-sided Warbler expanded its range following the extensive forest cutting of eastern North America, being one of the few Neotropical migrants that has benefited from human activities (Richardson and Brauning 1995). Historically, it was abundant throughout Wisconsin (Kumlien and Hollister 1903) but is now concentrated in the northern third of the state (Gostomski 2006). The early successional habitats favored by this species are increasingly threatened by human development. This is especially concerning in southern Wisconsin where agricultural and urban expansion has limited suitable habitat to just a few scattered locations, including the Baraboo Hills (Mossman and Lange 1982) and Kettle Moraine State Forest. In central Wisconsin, this species is mostly associated with county forests and state wildlife management areas in Clark, Eau Claire, Jackson, Marathon, and Shawano counties. In the extensive forests of northern Wisconsin, early-successional habitats are less limited due to the prevalence of logging activities in the region. The Chequamegon/Nicolet National Forest, Northern Highland/American Legion State Forest, and Douglas, Lincoln, and Marinette county forests are important breeding areas.

Population Concerns

While the Chestnut-sided Warbler increased its range and density after forest clearing in the 1800s, recent declines (post-1960) have been noted in some areas of North America (Richardson and Brauning 1995). Breeding Bird Survey (BBS) data suggest a significant annual decline range-wide for Chestnut-sided Warblers (Sauer et al. 2005). In Wisconsin, population trend data are somewhat more equivocal. BBS and Chequamegon National Forest Bird Survey data indicate a non-significant annual increase, but data from the Nicolet National Forest Bird Survey suggest an insignificant decrease (Sauer et al. 2005, Danz et al. 2007). Robbins (1991) cited this species as being a fairly common to common summer resident in central and northern Wisconsin respectively, but rare in the south. Recent Breeding Bird Atlas work also documented fewer breeding attempts in southern Wisconsin compared to the north. Atlas observers confirmed breeding in approximately 31% of the quads surveyed from 1995-2000 (Gostomski 2006).

Overall, populations appear relatively stable in Wisconsin, but are at low densities in some areas (i.e., southern Wisconsin) in response to forest fragmentation, forest maturation, and urbanization. Human development resulted in the loss of suitable habitat in most of southern Wisconsin and remains a concern for northern Wisconsin. Howe et al. (1996) identified the Chestnut-sided Warbler as one of 15 species of highest conservation priority in the Nicolet National Forest. It is a common Brown-headed Cowbird host throughout its range, though this is not well-studied in Wisconsin (Peck and James 1987, Richardson and Brauning 1995).

Recommended Management

The Chestnut-sided Warbler benefits from forest clearing and management that promotes dense growth of young trees and shrubs (Richardson and Brauning 1995). Managers should maintain early-successional vegetation across a variety of forest types and ownerships. In areas prioritized for early-successional species, clearcuts and management techniques that closely mimic natural disturbance regimes can be used to maintain a mosaic of successional stages (Schulte and Niemi 1998, Askins 2000, Jobes et al. 2004). However, Robinson and Robinson (1999) reported that the creation of canopy gaps through selection cutting of mixed hardwood forests can provide habitat for shrub-associated species from one to five years post-harvest, rarely up to 11 years post-harvest. Powerline corridors within a forested landscape may provide suitable breeding habitat if managed for a thick shrub layer (Askins 2000). Herbicide application and brush clearing in these areas should be avoided during the breeding season. Conservation and management strategies for this species should be focused in the following ecological landscapes in Wisconsin: the Northwest Lowlands, North Central Forest, Northern Highlands, and Northeast Sands.  

Research Needs

More information is needed on habitat relationships and territoriality on the wintering grounds (Richardson and Brauning 1995). In Wisconsin, more research on breeding densities and reproductive success among forest types may help guide future management efforts. Also, studies investigating minimum patch size requirements within these landscapes are needed.

Information Sources


Contact Information

Kreitinger, K., Y. Steele and A. Paulios, editors. 2013.
The Wisconsin All-bird Conservation Plan, Version 2.0. Wisconsin Bird Conservation Initiative.
Wisconsin Department of Natural Resources. Madison, WI.

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