Monday, December 15, 2014

Wildlife Animosity: Crows and Owls

crowsAnimosity is an emotion not solely restricted to humans, as several forms of wildlife occasionally display an outward aversion to specific creatures, even through such an antagonistic attitude seems to have little to no value to their current survival.

Perhaps the best example of such an overt repulsion of one animal for another is the crow’s reaction to seeing an owl at this time of year. Upon detecting one of these round-faced predators, a crow quickly starts producing a squawking caw designed to summon any other crows in the immediate area. It is believed by some naturalists that a crow, upon hearing this alarm sound, will relay the information to others unable to hear the initial call that an owl has been spotted. This is an attempt to assemble as sizeable a mob of birds as possible.

In winter, most crows migrate to the lowland valleys surrounding the interior of the Park; however, there always seem to be a few hardy individuals that remain, especially around our larger villages and hamlets, so that when the call goes forth that an owl has been detected, these scattered individuals are quick to assemble in order to display their hatred for this nocturnal predator.

As more crows arrive at the scene of an owl sighting, the intensity of this vocal bout of harassment increases. Eventually, one bird begins to dive at the owl in an attempt to flush it from its perch. With the presence of additional reinforcements, more individuals join in the physical intimidation of the owl, forcing it to take to the air to escape the threats. A large species, like the barred owl, may be forced to retreat from a prime hunting spot on a forest edge to an area well back into the woods before the mob of crows relents in its aerial pursuit. A smaller species, like the saw-whet, may be successful in outmaneuvering the following flock in a dense stand of conifers and take cover in a thicket of boughs where its presence may go unnoticed by the mob.

This aggressive action by the crows toward an owl outside their nesting season seems illogical, as an owl poses no danger to an adult crow, nor does it compete with this scavenger for food or other resources, especially in winter. By expending time and energy to drive an owl from an area, the crow seems to be jeopardizing its own survival in our harsh climate with its limited sources of nutrition. However, some researchers believe that such aggressive actions by the crow helps to maintain its confrontational image in the mind of the owl, which could make driving them from an area around a future nest during spring an easier chore. Because owls prey on nestling crows, having such a predator in an area in which a family of crows typically establishes a nest could be detrimental to the survival of the hatchling crows.

As a general rule, crows strongly prefer to inhabit open, agricultural settings, or places in the Park in which human activity is common. In the Adirondacks, owls tend to concentrate their time in unbroken patches of forests, especially in mature woodlands in which old, or dead trees that are useful in locating a nest are more abundant. However, despite this attraction to undisturbed woodlands, owls are often lured to forest edges, such as near roads, around electrical transmission lines, along golf course fairways, and lake shores. Along such ecological borders there typically exists a higher concentration of the small mammals and birds on which owls are known to prey. It is also in such open settings where crows occur, and encounters between the two are most likely to occur.

In order to avoid being detected by either a crow, or a prey species, an owl perches close to the trunk of a tree and puffs its body plumage up to allow the protective coloration of this material to cause it to blend into the background. The feathers of an owl also help insulate it against the cold and enable this bird to remain 15 to 20 feet above the forest floor for hours without shivering or moving to keep warm. The natural camouflage of an owl and its ability to remain still make it nearly impossible for a human to spot such a bird as it sits on a perch watching and listening for any signs of prey nearby.

Over the past few months, I have noticed on three separate occasions a barred owl in my neighborhood, all because my attention was drawn to a spot in the woods by a frenzied mob of crows. Also, as a rule, only 2 or 3 crows infrequently occur around my house in winter, so when a dozen of these black scavengers gather in the same spot, squawking and carrying on, it is a sure indication that an aerial predator is at the center of the commotion. Undoubtedly, this is the same barred owl that finds hunting in the area rewarding enough to tolerate the harassment to which it is exposed on occasions.

I am not sure how this bird will react in another three month when the few resident crows are joined by their very numerous friends and relatives that have spent the winter elsewhere. For now, however, the mice, voles, shrews and other small critters that are everywhere around my home this year can’t wait for that period in early spring to arrive.

Photo: Large flock of Crows, courtesy EPA.

Tom Kalinowski

Tom Kalinowski is an avid outdoor enthusiast who taught field biology and ecology at Saranac Lake High School for 33 years. He has written numerous articles on natural history for Adirondack Life, The Conservationist, and Adirondack Explorer magazines and a weekly nature column for the Lake Placid News. In addition, Tom’s books, An Adirondack Almanac, and his most recent work entitled Adirondack Nature Notes, focuses on various events that occur among the region’s flora and fauna during very specific times of the calendar year. He also spends time photographing wildlife. Tom’s pictures have appeared in various publications across the New York State.




4 Responses

  1. Jim S. says:

    I overheard an owl saying ” I fought the caw and the caw won”. Perhaps they should read about the diversity of the Adirondacks articles.

  2. John Jongen says:

    While the crow is not a strict vegetarian (it prefers carrion over live predation) it seems to have a primeval aversion of carnivorous predators. That includes the Red-tail Hawk and presumably other carnivorous members of the raptor family that are a lethal threat to the ubiquitous and highly successful ravens and crows around the world.

    • A says:

      Yeah I’ve seen it happen with hawks as well.. And that’s down here in “the city”. It’s not just crows though… I’ve seen very small birds do it too.

  3. A says:

    Some animals are antagonistic toward each other… For instance buffalo will attempt to kill lions even when it’s not “necessary”… Male lions will go out of their way to kill hyenas… Not just to kill them – but mutilate them as well – when there is no threat. There are plenty of other examples.