Prothonotary Warbler (Protonotaria citrea)

Prothonotary WarblerProthonotary 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.

*Note: There are important deficiencies with these data. These results may be compromised by small sample size, low relative abundance on survey route, imprecise trends, and/or missing data. Caution should be used when evaluating this trend.

Life History

Habitat Selection

The Prothonotary Warbler breeds in moist bottomland forests that are seasonally flooded or permanent wetlands. Along the Mississippi River in Wisconsin, Prothonotary Warbler breeding habitat contains a variety of overstory trees, including eastern cottonwood, black willow, silver maple, green ash, and river birch. Dominant understory plants include woodbine, wood-nettle, jewelweed, violet, and poison ivy (Flaspohler 1996). Essential habitat characteristics include slow-moving, medium to large rivers (Flaspohler 2006), dead trees with suitable cavities for nests, flat terrain, and sparse understory (Petit 1999). Prothonotary Warblers also prefer large forest tracts. Sallabanks et al. (2000) documented a positive correlation between Prothonotary Warbler abundance and swamp forest patch size.

The Prothonotary Warbler is the only eastern warbler that nests in tree cavities. It uses either natural or woodpecker-excavated cavities in dead snags or limbs of live trees, as well as nest boxes (Petit 1999). Trees with nest cavities average 15 to 20 cm in diameter at breast height (Kahl et al. 1985, Blem and Blem 1991). Average nest height is 2 m above the ground or water surface. Nests usually are placed over water, either slow-moving or still (Petit 1999).  

Habitat Availability

Wisconsin is on the northern edge of the Prothonotary Warbler’s breeding range (Petit 1999). It is a fairly common migrant and summer resident along the Mississippi and lower St. Croix rivers and an uncommon migrant and summer resident along the lower Wisconsin River (Robbins 1991) and Wolf River. Bottomland hardwood and other floodplain forests have fared better than many of Wisconsin’s native habitats due to the difficulty of converting them to other land uses. Nevertheless, only 8% of presettlement floodplain forest remains in moderate to high quality condition (Mossman 1988). Invasive plant species, particularly reed canary grass, may impede regeneration in floodplain forests. Development pressures also continue to threaten remaining floodplain forest tracts (WDNR 2005).

Population Concerns

Breeding Bird Survey (BBS) data suggest a significant population decline range-wide for the Prothonotary Warbler. However, its status is not well known in Wisconsin where it is not adequately monitored by BBS methodology (Sauer et al. 2005). It is a regular but localized breeder in the southern half of the state. During the six-year period (1995-2000) of the Wisconsin Breeding Bird Atlas, observers documented breeding activity in 5% and confirmed nesting in 3% of the surveyed quads (Flaspohler 2006).

The Prothonotary Warbler’s habitat specificity makes it highly vulnerable to loss of forested wetlands on the breeding and wintering grounds (Petit 1999). Stream channeling, flood control, and logging practices can reduce habitat suitability and availability (Petit 1999). Brown-headed Cowbird parasitism also is a concern. Brood parasitism rates are higher for the Prothonotary Warbler than for any other cavity-nesting species (Friedmann 1963, Friedmann et al. 1977) with rates reaching 26% in Wisconsin (Goffin 1994 cited in Matteson 1994, Flaspohler 1996). Parasitized nests suffer high mortality and low fledging rates (Petit 1991). Finally, the House Wren is considered a major competitor, causing approximately 33% of mortality to eggs and young in Michigan (Walkinshaw 1941).

Recommended Management

Management efforts for Prothonotary Warblers should focus on maintaining large blocks of floodplain forests (WDNR 2005), particularly along the Mississippi, Rock, Wisconsin, lower Wolf, and Yellow rivers. Management practices that retain trees with nest cavities and/or retain snags and stumps in floodplain forests would likely benefit this species. Nest box programs in fragmented or degraded riparian areas may provide alternative nesting substrates. Conservation and management strategies for this species should be focused in the following Wisconsin ecological landscapes: Central Lake Michigan Coastal, Central Sand Plains, Southeast Glacial Plains, Western Coulee and Ridges, and Western Prairie (WDNR 2005).  

Research Needs

Targeted surveys in appropriate habitats are needed to better understand the Prothonotary Warbler’s population status in Wisconsin. A better understanding of minimum area requirements and the health of floodplain forests in Wisconsin would help future management efforts here. Studies investigating success rates of natural cavity nests in habitats of different quality are warranted. More information is needed on the impacts of mangrove forest loss on the wintering grounds (Petit 1999).

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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