Thursday, July 14, 2016 10:59 AM
On the surface, one might imagine that birds lead a rather carefree and casual existence. But actually, for birds, competitive forces play a huge role in their success. The competition persists year-round but ramps up at nesting time when birds must vie for quality territories, nesting sites and capable, reliable mates. Behavior-wise, the spring period is highlighted by bouts of vigorous singing and showy courtship and territorial displays.
Red-Bellied Woodpecker (Photos by
Now as hordes of hungry fledglings fill the mid-July woods, the prime competitive focus shifts to acquiring sufficient food resources. During the critical fledging period, nature pours forth a nutritious bounty of animal and plant matter to support developing birds.
Since summer food sources are abundant for most species, competition for food is often strongest and most transparent wherever temporary food bonanzas occur. The bonanza category must include any well-stocked bird feeders located in backyards.
I confess to maintaining an assortment of feeder and food types just outside my front window: black-oil sunflower, sunflower meaties, smaller seed scattered sparingly on the ground for sparrows; some niger seed for the finches, a half orange loaded with grape jelly to satisfy the resident catbird family, a cylindrical wire feeder to dispense cracked nuts. And let’s not forget the two nectar feeders for hummingbirds. In early June I had purchased a 10-pack of suet cakes that was since consumed by four species of woodpeckers and others.
Quite honestly, adult birds could likely survive well if we didn’t feed them at all. Fledglings may receive an advantageous nutritional boost though. Average mortality rates for fledglings are reportedly about 42% within the first week or two of leaving the nest. These young songbirds lack basic skills, can’t fly well, can’t defend themselves and must rely heavily on parental guidance.
The daily spectacle of feeder activity in my yard provides opportunities to observe birds’ social interactions and individual behaviors. Social interactions within the same species (intraspecific) or between diverse species (interspecific) serve as a workable system of avian communication.
Feeders tend to draw into close proximity an array of species that would otherwise forage more widely to secure food. There is a general pecking order, with larger or more aggressive birds ruling the day — most of the time. Yesterday a tiny Downy Woodpecker showed its impatience with a Gray Catbird lingering too long at a suet cake. At first, the woodpecker rubbed its bill vigorously against an upper branch. This is termed as displacement behavior, a non-physical means to communicate frustration or threat from another bird without engaging in actual physical contact. Next the Downy looped within mere inches of the catbird’s head several times, dislodging the bigger bird from the suet.
If you watch birds at feeders, you may notice other distinctive behavioral traits that are used to discourage intruders or predators. Birds frequently adopt body postures that make them appear larger and less vulnerable. This includes puffing and fluffing of contour feathers, spreading wings widely or drooping their tails. The Northern Mockingbird flashes its prominent white wing and tail patches as warning displays in territorial disputes.
When a hawk arrives on scene, birds may assume a freeze posture. Chickadees, titmice and nuthatches will cling tightly to tree trunks or become totally motionless for several minutes until the threat subsides. Predators can detect motion more readily than an object at rest.
Specialized alarm sounds, such as singing louder than normal, drumming, bill clacking and hissing, are employed by some species to defend territories or avert intruders.