The first Saturday of May saw the return of the Yellow Warblers to Lakeside Park in Mississauga. These brilliant yellow birds are easily mistaken from a distance for male Goldfinches. Both catch the sun in a startling way. Their flight patterns, though, can help identify them from a distance. Goldfinches tend to fly up, glide through a falling descent, then fly up again, in a line shaped sort of like that of a child drawing waves for water. Yellow warblers have a more steady even flight.
I hadn’t seen this particular behaviour before, though, so I stopped to watch: for over 20 minutes! Two Yellow Warblers were chasing each other as quickly as possible in curved arcs. There were three trees in a triangle spaced about 10 metres apart above a tangle of dogwood and rose bush canes. The lead bird would head to one of the three trees, and either land or, more often, swerve suddenly up again and head off towards the next tree, followed in hot pursuit by the other.
At first I thought this was a territorial dispute. But neither bird yielded. The incredible amounts of energy they were using made it seem unlikely that this prolongued racing was territorial.
Next I wondered if this was a pair of birds exuberantly sharing the skies. They would only land for less than a second before they were off again, making photography a challenge. But although I looked closely at each photo I took once home, neither seemed to be a female. (It is remotely possible all of my photos are of one of the birds, but it doesn’t seem that likely.) The radiance of the colouring also suggested both birds were male.
Were they feeding? The behaviour did look very similar to the flights of the Rough Banked Swallows I had watched along the shore of Lake Ontario. Certainly there were lots of insects in the air while I was watching. I was being annoyed by both black flies and the air was dancing with clouds of some larger winged insect similar to stoneflies. Perhaps they were merely feeding on the wing. The Cornell University bird website does say that Yellow Warblers will spend some time feeding in the air.
I don’t actually have the answer for what motivated this almost non-stop race. It was beautiful to watch, though, as the bright yellow birds shot by, swooping and swerving against a brilliant blue sky. Spring is certainly here.
Do you have Yellow Warblers in your yard or park? Have you had to watch closely to decide whether it’s a goldfinch or a warbler working through your lilacs? Please share your experiences with a comment.