Prothonotary warbler (Protonotaria citrea): residence description

Section 33 of the Species at Risk Act (SARA) prohibits damaging or destroying the residence of a listed threatened, endangered, or extirpated species. SARA defines residence as: “a dwelling-place, such as a den, nest or other similar area or place, that is occupied or habitually occupied by one or more individuals during all or part of their life cycles, including breeding, rearing, staging, wintering, feeding or hibernating” [s.2(1)]. With respect to a listed wildlife species that is an aquatic species or a species of bird protected under the Migratory Birds Convention Act, 1994, the prohibition applies wherever residence of the species is found. For any other listed wildlife species, the prohibition applies automatically when the residence of the species is on federal lands and will only apply on non-federal lands if an order is made pursuant to sections 34 or 35 of SARA. Under section 97 of SARA every person who contravenes section 33 of the Act commits an offence.

The following description of residence for the Prothonotary Warbler (Protonotaria citrea) was created for the purposes of increasing public awareness and aiding enforcement of the above prohibition.  Prothonotary Warblers are known to have one type of residence--the nest.

Species information

Common name
Prothonotary Warbler
Scientific name
Protonotaria citrea
Current COSEWIC status & year of designation
Endangered 2000
Occurrence in Canada
Ontario (Fig 1)
Rationale for designation
This species is facing a significant range-wide decline primarily due to habitat loss and degradation. It has undergone a drastic decline in Ontario where it is estimated that there are currently only 13 pairs at two sites Footnote1.
Figure 1. Current and historical distribution of the Prothonotary Warbler (Protonotaria citrea) in Canada.
Image of map (see long description below)
Long description for Figure 1

Figure 1 shows the current (pre-1981) and historical (1981-2006) distribution of the species in southern Ontario. There are approximately three times more current than historical distribution data. Most of the locations are found along the northern coast of Lake Erie and the southern coast of Lake Huron. A few locations are found between Lake Huron, Lake Erie and Lake Ontario.

1 The nest

Physical characteristics and context

Any place used as a nest by Prothonotary Warblers is considered a residence. Prothonotary Warblers generally nest in wooded swamps where standing water remains throughout the breeding season; they also nest in other wet areas such as wooded borders of ponds and reservoirs, backwaters along large rivers and other water courses, floodplain forest, and shrubby margins of wetlandsFootnote1.  Nests are usually situated in open areas within extensively flooded mature or semi-mature deciduous swamps dominated by silver maple (Acer saccharinum), ash (Fraxinus spp.), and yellow birch (Betula alleghaniensis)Footnote2.  Swamps of this type in Ontario are rare, and represent a late successional stage from marsh to deciduous forestFootnote1. The nest is built in naturally formed cavities or abandoned cavities excavated by other small species such as downy woodpeckers (Picoides pubescens) or black-capped chickadees (Parus atricapillus)Footnote2. The cavities are typically small, shallow, and situated 0.5-2.5 m from the ground within dead or dying treesFootnote1,Footnote2 (Figure 2). Prothonotary Warblers also frequently use man-made nest boxes provided in these situationsFootnote2.

Eggs, usually 4-5, are glossy white with evenly distributed or clumped spots ranging from dull or reddish brown to pale lavendarFootnote3.  Only females incubate eggs, a period which lasts 12-14 days; both parents feed hatchlings, which fledge at approximately 10-11 daysFootnote3.

Figure 2. Prothonotary Warbler nest site (in stump)
photo of Acadian Flycatcher nest


The nest provides a container in which Prothonotary Warblers lay and incubate eggs, and rear hatchlings. The adult male may partially fill several tree cavities with mosses, one of which is often selected by the female, who completes nest construction over 3-8 daysFootnote3. Non-functional nests built by males are termed “dummy nests.” The quantity and quality of potential nest cavities may influence pair formationFootnote3.

Damage/destruction of residence

Federal Policy defines damage or destruction of a residence as:

Any alteration to the topography, geology, soil conditions, vegetation, chemical composition of air/water, surface or groundwater hydrology, micro-climate, or sound environment which either temporarily or permanently impairs the function(s) of the residence of one of more individuals.

Any activity that destroys the function of the nest would constitute damage or destruction of the residence. This would include, but is not limited to, altering standing or slowly flowing water, understory structure, canopy closure, dead trees, cavities, and mossy logs and hummocksFootnote1,Footnote2. Examples of activities that may result in such alterations include drainage or infilling of swamp forests, removal of standing dead timber in occupied forests, reduction in the aerial extent of occupied forests, logging that significantly opens up the tree canopy, and residential/estate development adjacent to occupied forests.  The latter three activities can result in encroachment of invasive plants and/or an increase in the number of nest site competitors, predators, nest parasites, or otherwise induce sensitive species to abandon the site.

Period and frequency of occupancy

Prothonotary Warblers return to Canada for the breeding season in early to mid MayFootnote3,. Nest construction likely begins soon after arrival, and active use of the site lasts for at least 5 weeks. Only one brood is typically produced in Canada, but second broods appear to be fairly common in extreme southern Ontario. Moreover, pairs will typically re-nest if the first clutch is destroyed, so nest activities may occur through July. Nests are frequently reused within and between yearsFootnote1,Footnote3, indicating that residence protection must extend at least 5 years beyond the last known time of occupancy.

Special Considerations

Because of the species’ biology, there are two special considerations that must be made in determining the legal definition of a Prothonotary Warbler nest residence: a) occupation of artificial nest boxes that are specifically erected to benefit the species (with written landowner permission), and b) “dummy” (non-functional) nests.

In both cases, the national recovery team advises that these special cases will be treated as “residences” under SARA. However, at the discretion of the recovery team, nest boxes may be moved, removed or modified outside the nesting season. Moreover, unless there is an explicit, written agreement to install and maintain nest boxes from landowners, nest boxes can be moved or removed by the landowners at their discretion, at any time outside the breeding season (1 May to 1 August).

Additional information

For more information on the Prothonotary Warbler, please visit the species' profile website.

For more information on SARA, please visit the SAR Registry.

Recommended citation

Please cite this document as:

Government of Canada. Species at Risk Act Public Registry. Residence Descriptions. Description of residence for Prothonotary Warbler (Protonotaria citrea) in Canada. December 2006. 

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