Prothonotary warbler (Protonotaria citrea) COSEWIC assessment and status report: chapter 4
Distribution
Global range
The Prothonotary Warbler breeds throughout much of the eastern U.S., and north to southwestern Ontario (Figure 1). It is most abundant in the southeastern U.S. and up the Mississippi River, becoming decidedly less common in the northern part of its range.
Figure 1. Global breeding (grey shading) and wintering (black shading) range of the Prothonotary Warbler (modified from Ridgely et al. 2003).
The Prothonotary Warbler's wintering range extends from southern Mexico through Central America and northern South America. Its centres of winter abundance are reported to include northern Venezuela, Colombia (Bent 1953; Lefebvre et al. 1992; Lefebvre et al. 1994), coastal Panama (Lefebvre and Poulin 1996), and coastal Costa Rica (Warkentin and Hernández 1996; Woodcock et al. 2005). However, extensive quantitative surveys of wintering populations have not been conducted.
Canadian range
Figure 2. Current and historical breeding occurrences of Prothonotary Warblers in Canada.
Being at the northern edge of its range in southwestern Ontario, the Prothonotary Warbler has been primarily found nesting along and adjacent to the Lake Erie shoreline (e.g. Holiday Beach, Point Pelee, Wheatley, Rondeau, Long Point; Figure 2). Nesting has occurred regularly at one site along the Lake Ontario shoreline (Hamilton), and rarely at one site along the Lake Huron shoreline (Pinery Provincial Park) and along the St. Clair River. In some inland sites in southwestern Ontario, territorial but apparently unmated males may defend territories in suitable habitat (e.g. Brant, Halton, Peel, Middlesex, and Huron counties), but such occurrences are not enduring and inland nestings have rarely been documented. It formerly nested at Turkey Point, Point Abino, Lobo, and near Orwell and Copenhagen.
Rondeau typically supports about half of the Canadian population in any given year. The Long Point region and Holiday Beach are also important breeding areas.
In the last two decades, about 15 different locations have been occupied in Canada. Based upon the range envelope of known and probable breeding occurrences in Canada (Figure 2), the Prothonotary Warbler’s Extent of Occurrence (EO) encompasses about 15,000 km². Based upon a maximum population of 20 pairs and a maximum territory size of 2 ha, the species’ Area of Occupancy (AO) is no more than 0.4 km².