Journal archives for February 2020

February 19, 2020

ID and Flight Physiology

Time: 3:30-5:00 PM
Date: 2/19/2020
Location: Centennial Woods Natural Area
Weather: 30 Fahrenheit, slightly overcast, slight wind
Habitat: Forest, forest-edge

If American Crows weren't easy enough to identify already, their flight pattern should immediately reveal what they are. Firstly, crows rarely fly alone, I believe I only observed 2 flying solo. Rather, they fly in small to intermediate sized groups, or "mobs." Additionally, American Crows have a very controlled, rhythmic flapping pattern, with the occasional burst of gliding. The rhythmic beat of their wings gives an impression that they are flying in a straight line. Black-capped chickadees, on the other hand, have a very different flight pattern; they rapidly flap their wings to quickly dart from tree to tree, with an almost undulating pattern.

Despite the fact that both American Crows and Black-capped Chickadees have elliptical wings, their differences in flight make sense. Considering the Crows relatively large size and their tendency to mob they don't need to fly fast to escape predation; they have even been observed chasing larger predatory birds. Additionally, their tendency to forage on the ground makes it so that flying fast isn't necessary. The Black-capped chickadees makes faster flight necessary. Their preference for forest-edge habitats combined with their tiny size makes darting rapidly between trees necessary, most black-capped chickadees fly for less then 15 meters (Cornell Lab of Ornithology). Additionally, the rapid wing beats allow for stabilization while they forage for insects along a branch, particularly when they do it inverted. Although rare, black-capped chickadees have been observed hovering and mid-flight catching to consume insects, both of which require rapid wing beats.

Although the American Crows were more then abundant this observation was relatively devoid of birds. The weather was prefect for winter birding, not too cold and just ever so slightly overcast, leading me to believe the time of day and where I was searching is to blame for the lack of diversity. Given Crows propensity for flocking around dusk, I would make my next observation before noon, possibly even in the morning when birds are most active. Additionally, I spent a majority of my time looking near Centennial Brook, where the habitat type is more forest-edge. Next time in Centennial Woods I will avoid forest-edges and strictly observe in overstory forests.

Posted on February 19, 2020 23:03 by benjaminrosen benjaminrosen | 2 observations | 0 comments | Leave a comment