The calendar may say otherwise, but as far as our local bird population is concerned, spring has arrived. Many of our full time resident birds are already nest building, and the air is full of bird song. In addition many of our migrant species are also starting to arrive, and are wasting no time getting into the swing of things. It is hard to drive the back roads around Oliver without noticing the very loud spring song of Western Meadowlarks, and American Robins.
To me, anyway, the wonder of spring migration is one of the most fascinating annual events in the natural world. Why do birds migrate anyway to various parts of North America from locations as far away as the southern tip of South America? The answer, not surprisingly, is the drive to reproduce. We often think of our spring and summer birds as coming home, but, in reality they are actually leaving their real homes to take advantage of a variety of conditions where we live which helps them to maximize their reproductive capabilities. For tropical and neo tropical birds they are willing to risk everything to leave areas that are warm all year round with a reasonably plentiful food supply to come up to our latitudes because: 1) There is less competition for food, especially insects. 2) During the height of our spring and summer, we have many hours of daylight which increases their abilities to find food for a burgeoning family.
What triggers this drive to migrate, and how do they do it? Another mystery, only partially understood. First of all it is generally accepted that migrating birds are ” hardwired ” to do so. Once they decide to go they are guided by the relative position of the sun to the horizon, and, for birds that migrate at night, the position of the stars, and planets to guide them during their migratory routes. To say they face challenges along the way is to totally understate the situation. Many migrating birds, especially those that end up on the East side of North America, will stage along the northern shores of the Yucatan Peninsula in Mexico. When the wind is favourable, i.e.; from the South, they will take off, and attempt to fly across the Gulf of Mexico, usually overnight. If the wind shifts to the north in their transit, many will perish by drowning in the gulf as they ” run out of steam ” while traversing, or they will be so exhausted by the time they reach shore, that they are easy prey for other birds that feed on smaller birds, like certain species of hawks or falcons. Many, ( but not all ), migratory birds that end up on our side of the continent ” choose ” to follow the land route as they head north. Their biggest challenge is to avoid the many predators that are waiting for them as they head north. So, next time you see beautiful, colourful neo tropical birds around Oliver, like the Western Tanager, or Bullock’s Oriole, you may want to think about all the risks they took to get here.
Finally, one of the most fascinating aspects of spring migration involves the hummingbirds that arrive here annually, during the month of April. For those of you who put out hummingbird feeders, and may keep records of when your first hummingbirds arrive at your feeder; ( usually male Rufous ), it is totally amazing how these birds show up basically TO THE DAY, on an annual basis. How do they do that, irrespective of the weather?? For the record, the South Okanagan has four species of hummingbirds that spend some time with us each season- the most in Canada; Rufous, Calliope, ( the smallest North American hummingbird ), Black chinned, and Anna’s ( usually in late summer ).
As always, if you have birding questions, or comments feel free to e-mail me at firstname.lastname@example.org.