One of the most obvious signs of spring is the arrival of songbirds, filling our world with colour and song. There is a pattern to the spring migration that is consistent from year to year. Among the first to arrive are the red-winged blackbirds, appearing in mid-March and filling the air with their loud “check” calls and raspy “gurg-a-lee” song. Next come the shiny grackles with their squeaky shrieks and the killdeers calling their name. Then, in April, white-throated and song sparrows can be seen in shrubbery making subtle little “tseet” sounds and occasionally breaking into beautiful song. April also brings the Hermit thrushes, which although drab in colour, will soon fill the north woods with their fluty evening refrain. Most of these birds are able to arrive sooner because they only fly as far south as the United States to spend the winter, or because they can eat seeds or fruits rather than depending entirely on insects for food.
By late April it is warm enough for insects to appear, providing an important food source. At this time birds from further south arrive. Brightly coloured Baltimore orioles, rose-breasted grosbeaks and yellow-rumped warblers can be spotted among emerging leaves. Then the floodgates open, and by mid-May huge numbers of birds that winter in Mexico, Central and South America and the Caribbean pour in, including thrushes, vireos, and the colourful warblers, which are a delight to bird watchers. These little jewels are difficult to get a good look at because they never stop moving as they forage for insects, breaking into song between mouthfuls. But skill with binoculars and a little patience can bring great rewards, with as many as 15 species of warblers to be seen in one morning in local woodlands. Backyards with some native trees and shrubs can also attract passing migrants, and it is not unusual to see a spectacular scarlet tanager or warblers that breed in the northern boreal forest foraging in the heart of the city during mid-May.
Life is not easy for migrants. Those that travel long distances must find suitable habitat and food resources on the tropical wintering grounds and everywhere in between. Many dangers must be faced en route. Cats, windows, and office towers take the lives of millions. Early arrival of the warm weather followed by a sudden cold snap can kill large numbers of insect-eating birds such as swallows; or it can bring out the insects before the birds arrive to consume them. Needless to say, migratory birds are a conservation concern, in part because they are highly vulnerable to weather extremes caused by a changing climate. The more we learn about them and appreciate them, the more likely we are to help. Landscaping with native trees and shrubs that provide food for birds during migration is a great place to start.
Ken Towle, Terrestrial Ecologist at the Ganaraska Region Conservation Authority