Did you know that causing harm to a migratory bird or destroying its nest or eggs is illegal and contravenes the Migratory Birds Convention Act, 1994 (MBCA) and its regulations ? Before cutting down or pruning trees, this is something to consider. If your backyard is home to a bird family, causing them stress by destroying their habitat during the time they are intensely concentrating on the hard work of brooding, feeding and tending to young can have dire consequences.
Although birds vary in their tolerance to human proximity during the nesting period, they may abandon nests containing eggs or young if they feel threatened, even if they are situated in a tree merely in the vicinity of the one being felled. Tree cutting activity can also potentially result in nest and/or egg destruction or the killing of nestlings. Likewise, if scared off the nest too early, the survival chances of fledglings are limited.
While people often tend to think of birds as nesting during the springtime, that isn’t necessarily the case. Nesting times actually range from early spring to late summer depending on the species and geographical location. Most songbirds are among those birds born without feathers (known as altricial young) and are unable to fend for themselves for a while after hatching. However, it is important to keep in mind that “nesting period” doesn’t only refer to the time when the babies are still in the nest. Many bird parents continue to care for and feed their fledglings during the critical developmental period where the young birds learn to forage for themselves.
For example, a Downy Woodpecker (Picoides pubescens) chick will take its first flight at age 18-21 days. It will leave the nest cavity by making a short flight to the nearest branch and then most likely sit there motionless for the rest of the day. In the meantime, the parents occasionally return to feed it while also returning to the nest to feed the remaining nestlings. A fledgling remains under parental supervision for at least three weeks after fledging as it learns to forage on its own. During this time Woodpecker parents teach their young to be alert to predators as well as how to locate food sources, which may even include leading them to backyard feeders!
American Robin (Turdus migratorius) nestlings fledge at around 12-14 days of age and become fearful of intruders several days before the “big event” approaches. As a consequence, if frightened at this stage, the young birds may fledge prematurely. If the parents find them after this happens they’ll likely feed them, but the fledglings’ chances of survival are greatly reduced as they become easy targets for lurking predators. Normally, an adult male Robin will continue to feed its young after fledging, while the female continues to feed the babies remaining in the nest. Then, once the entire brood has left the nest, both adults will continue to feed them for several days afterwards.
Another common backyard feeder bird, the Chipping Sparrow (Spizella passerina), usually fledges at 12 days of age; but survival is greatly limited If hatchlings are scared off the nest prior to 9 days of age. Even after leaving the nest at a more respectable maturity, the young remain very vulnerable. Chipping Sparrow fledglings continue begging for food from their parents for another 3 weeks before beginning to search for food on their own.
While people often assume that there aren’t birds nesting on their property, keep in mind that just because you don’t see a nest in a particular tree, it doesn’t mean there isn’t one! Birds are very good at camouflaging their nests (for good reason!). Different species build their nests at different heights, and those high up among the leaves may be extra hard to spot. Tiny Hummingbird nests are probably one of the hardest to find. Incidentally, the Ruby-throated Hummingbird, the only Hummer species that breeds here in Quebec, is one of the birds that nests later in the summer. Some birds species will build their nests on or quite low to the ground, something the careful gardener should also be mindful of when doing yard work.
Consult the Bird Studies Canada Nesting Query Tool here.