Prothonotary warbler (Photo by Bill Hubick)

Prothonotary warbler

A dazzling flash of gold darts about in the understory of swampy woodlands. The “zweet zweet” calls can be heard echoing through the trees. The prothonotary warbler is named for its bright plumage, which resembles the yellow robes worn by prothonotaries of the Roman Catholic church.

What does it look like?

The male and female of this species are similar in appearance: they have long, black bills and black eyes, golden heads and breasts that are flanked by blue-grey wings and olive-green backs, with white on the underside of their tails. The prothonotary warbler is a small bird, measuring 14 centimetres in length and, at 14 grams, weighs almost as much as an empty soda pop can.

(Click on the image to enlarge)

Where does it live?

The prothonotary warbler is the only warbler in Canada that nests in small tree cavities. They make use of cavities that downy woodpeckers or black-capped chickadees have excavated, and will also readily occupy specially designed nest boxes. The males select the nest cavities and begin the nest building process by bringing moss to the cavity. Once the male attracts a mate, the females finish the nest building process using grasses and other plant materials. The tiny nest cup is only two inches wide!

In the summer months, prothonotary warblers nest in wooded swamps, ranging from southeastern United States to the southwestern Ontario.

These warblers make their summer homes in mature forests made up of tree species, such as white oak, blackgum, silver maple, willow and yellow birch. All of these can be found in Backus Woods in Ontario — one of the last places in Canada that still supports a small population of breeding prothonotary warblers.

In the winter months, prothonotary warblers can be found in the mangrove forests of Central America, Dominican Republic, Puerto Rico, Ecuador, Colombia, Venezuela and Guyana.

What is this species’ conservation status?

The global breeding population is estimated to be around 1.6 million, and has declined one per cent per year from 1966 to 2015, according to the North American Breeding Bird Survey. The prothonotary warbler is endangered in Canada according to the Committee on the Status of Endangered Wildlife in Canada and is listed under the Species at Risk Act.

What is NCC doing to protect habitat for this species?

As the primary threat to the species in Canada is loss of swamp forest habitats, protecting the species’ breeding habitat in Ontario is vital. The Carolinian forests in the Nature Conservancy of Canada’s (NCC’s) Backus Woods property support the birds at the northern limit of their range, in southwestern Ontario. NCC and Bird Studies Canada (BSC) have partnered to create a long-term research agreement, to monitor prothonotary warblers and other rare forest birds at Backus Woods. NCC uses the information from BSC to inform its conservation goals and actions for the property, which has seen the population rebound 100 per cent since 2002.