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Winter 2009

 

Wild Watch

CROWS

portrait of crow standing on rock
Photo by Bob Steiner

by Heidi Mullendore

I squinted through my binoculars, trying to make the small feeder birds come into focus through my wavy, 80-year-old windows. It had been snowing steadily all afternoon, turning the yard into a holiday postcard, with cardinals and sparrows in the snow against the background of green hemlocks.

Suddenly, a black shadow swooped down, startling me as well as the sparrows. Several more gleaming black forms swooped down from my roof, scattering the sparrows from their feast. The birds, American crows (Corvus brachyrhynchos), settled in to scavenge a meal, while more cackled from the tops of the maples.

Feathers gleaming richly in the weak winter sunlight, the crows seemed more interested in games, tossing seeds and diving at each other, while fat snowflakes fell around them. Several more materialized through the veil of snow and noisily greeted each other.

Winter seems to be the prime time for crows. Maybe it is because the distractions of showy colors, foliage and flashy flowers have faded, leaving the underlying grays, whites and browns of the landscape to reveal the animals once safely hidden by summer’s lush growth. It is against winter’s bare bones that crows stand out, flaunting and strutting in all their glory.

It delights me to watch crows play. I have seen crows in the evening, diving into the downdrafts from cliffs, turning and falling, then rising back up to dive again with flockmates. Few birds capture my attention as do crows, for their singular intelligence and playful, even mischievous, nature. Crows are members of the family Corvidae; large, bold birds with strong bills and beaks, rounded wings and stiff, bristle-like feathers covering their nostrils. This avian family also benefits from large cranial size, evincing problem-solving abilities, playfulness and a complex social system. Corvids, especially crows and ravens, are considered among the most intelligent of all birds.

flock of crows taking flight over corn field in winter
Photo by Bob Steiner

 

In the yard, one saucy fellow perched on top of the "squirrel-proof" feeder. The crow was using its perch to access the nearby tube feeder. It waited until other crows wandered beneath to send a cascade of seeds onto its startled brethren.

Crows are often overlooked by most of us -- they are considered to be far from fascinating. Their solid black plumage isn’t as attention-getting as, say, goldfinches, tanagers or orioles. Their strident "caw, caw, caw" is certainly not melodious for one of Pennsylvania’s largest songbirds. And they are commonly seen in every county in the state.

Crows are not specialists in any sense of the word. They live anywhere, are found in almost any habitat, and they’ve been described as eating anything that isn’t nailed down or moving too fast. Their diet varies greatly; they’re known for scavenging carrion and garbage, but will forage for small critters such as mice, frogs, eggs, nestlings, insects, and also seek out grains and nuts. Given a chance, a crow will try anything once. American crows will even store food temporarily in caches in trees, in crevices or buried under leaves. Corvids are especially adept at remembering the locations of hundreds to thousands of caches. As such, the Corvidae are dispersers of seeds, thus playing an important part in forest regeneration.

C. brachyrhynchos were once considered to be farm pests, for stealing grain and damaging crops. They are still frequently poisoned or shot, although it has long been reported that crows aren’t remotely as destructive as farmers once charged.

The crows beneath my feeders carried on like children in a schoolyard. Several of the bigger crows were strutting around and showing off. Another kept flicking snow at a friend, as though trying to get attention. Several played at tossing around twigs, while one blustered with what seemed to be the corvid equivalent of swearing.

After several minutes, two more crows flew into an adjacent tree, one of which fluffed up its neck feathers and bobbed its head vigorously, while its companion looked away, as though bored with the whole scene.

American crows are, in a word, expressive. Their harsh, repeated caws are most familiar, but they utilize an amazing array of calls that serve a variety of functions, such as defending territory or announcing predators or intruders. There are even gentle warbles and trills for romancing mates or expressing love to family members. Crows are dramatic birds, displaying a repertoire of emotions ranging from anger, sadness and love to arrogance. No wonder the word "crowing" is such a descriptive and fitting idiom.

Despite a penchant for play, crows are all business when it comes to family. Indeed, the bored crow perched high above the schoolyard players was most likely on guard duty, keeping an eye on the sky for predators and ready to alert the flock at the first sign of trouble.

Simultaneously jumping into the air as if in response to a signal, the flock and newcomers suddenly took wing, scattering seeds in their wake and fading into the snow, as if they were spectres vanishing from sight.

The crows were likely on their way to the evening roost. In winter, large numbers of crows gather in communal roosts, moving around until finally settling in at their nightly roost. Years ago, near Reston, West Virginia, I saw what looked like hundreds of crows flying west. I stood watching thousands of crows fly and gave up after 15 minutes. By the time I left, the stream of crows on their way to their evening roost still hadn’t abated.

Many cities have decried winter gatherings of crows as being messy and raucous. All over the country where large flocks of wintering crows intrude upon human populations, people take defensive measures, using pyrotechnics and noise to scare away the crows. They even take to poisoning crows, although it is unlikely that crows associate the poison source with their human neighbors.

Could crows use these gatherings to pass along information about foraging areas or feeding sites? Or are large roosts simply easier to guard and defend against predators? Many theories exist, but the fascinating social implications are no match for angry citizens, whose primary concern is protecting their homes, cars and towns from the unbelievable noise and mess from a large roost of thousands upon thousands of American crows.

Large roosts make life easier for individual crow families. During the breeding season, which begins in February, crow family members help to bring food to nestlings, as well as act as an ongoing source of protection after the young birds have left the nest. Since crows do not begin to breed until age two, the yearlings remain around to aid their monogamous parents in raising the hatchlings. Strong family bonds are maintained by ongoing play, preening each other (called "allopreening") and foraging in small groups. Crows are fierce protectors of flock and family, even forming groups of 50 to 100 to take flight and mob any predator in the area so vigorously that the offending owl or hawk flees.

This strong and intelligent species is a survivor and yet is vulnerable to a threat that has appeared just in the last 20 years. The American crow is the biggest avian victim of West Nile virus. Few seem able to survive the disease, and death occurs within one week of infection. Crow populations, which have risen in the 20th century, are now at risk and are declining in some areas.

Because of its susceptibility to West Nile virus, the American crow is considered an indicator species, alerting scientists to the movement of the disease. Fortunately, Pennsylvania doesn’t appear to be at the forefront of the storm of West Nile virus, as indicated by crow mortality. Robert Mulvihill, bird researcher at the Powdermill Avian Research Center in southwestern Pennsylvania, reports that incoming data for the next Breeding Bird Atlas have shown little evidence of declining populations, even at the height of the epidemic. "Based on my own casual observations," says Mulvihill, "crows have remained abundant and ubiquitous in this part of Pennsylvania."

As the last of the crows disappeared into the soft curtain of snow, and their laughing calls faded, I was glad for their raucous presence. The American crow is a familiar part of the Pennsylvania landscape, flying high over the trees and cackling on the wind. Hopefully this most engaging species will remain as such; survivors carrying on despite threats of humans and disease.

WILD!WATCH columnist Heidi Mullendore is the Environmental Education Specialist at Canoe Creek State Park Heidi Mullendore

 

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