Dawson Trail Dispatch, written by Norm Gregoire, September 2023
Page 27 https://issuu.com/dispatch222/docs/dawson_trail_dispatch_september_2023
As summer nears its end on the tall-grass prairie, we begin to slowly notice changes in the surrounding environment. The weather cools and the colours in our trees and grasses begin to change shades, and if you pay attention to the sky, there is a noticeable increase in bird movement. In our area, the most noticeable flying migrants may be the Canada geese or sandhill cranes, but there are dozens of smaller species flying south every day. The golden-winged warbler is one of these many migrants that may be hard to spot, but if you are lucky enough to see this showy songbird, it could be a highlight of your autumn birding season!
There are many species of warblers in Manitoba, so correctly identifying them can take some practice. Compared to other Manitoban warblers, the golden-winged has gold wing patches and a golden crown, the latter of which is most distinguishable in males. Both sexes are grey in colour and have long tails, slender bodies, and pointed bills. Males have a distinct black bib on their throat and a black eye patch, while the throat and eye patch of females appear lighter in colour.
The process of identifying the golden-winged warbler can be further confused as they do interbreed with another species, the closely named blue-winged warbler, and give birth to hybridized offspring. These offspring, named Lawrence’s warbler and Brewster’s warbler, were thought to be completely separate species until relatively recently. This interbreeding of the golden-winged and blue-winged is a major reason why, over the last few decades, the golden-winged warbler’s Canadian population has decreased by approximately eighty percent! The blue-winged warbler’s historic breeding range is more southerly compared to the golden-winged; however, over the years, they have slowly made their way north. Interestingly enough, it is thought that the Manitoban population of golden-winged warblers is the most genetically pure in the world.
Habitat loss, prey insect decline, and direct competition for resources from blue-winged warblers also play a part in the declining golden-winged warbler population. Important to note is that where brown-headed cowbirds are present, they may parasitize up to one-third of the local golden-winged warbler nests. The female brown-headed cowbird will observe nests in the area and will sneak in and lay an egg when the occupants are away. They lay a single egg in dozens of nests throughout the summer and are not picky when it comes to what species of bird will play host to their young. The brown-headed cowbird egg hatches quickly, and the chick grows rapidly and will outcompete the other chicks for food that is brought to the nest by the parents. This is a clever strategy for the brown-headed cowbird, with unfortunate outcomes for the host species, including the golden-winged warbler.
The golden-winged warbler tends to nest near or on the ground in openings on the edge of forests. This transitional zone is usually in the first stages of regeneration. In well-concealed nests, generally three to six eggs are laid and only take a week and a half to hatch. After the nesting period, the family will move into more mature forests.
The golden-winged warbler is a species that many of us are not familiar with and may not have had many encounters with, but it is still an important part of our ecosystem. They may have some factors working against them, but I am hopeful that they will continue to be seen in the tall-grass prairie for years to come. For further information, please contact me at info@sharedlegacymb.ca.