The crow – a bird for the times
by Stan Hirst
Some years ago the Elders, in casting about for a suitable logo to represent our image, chose the owl. They said it was a universally recognized symbol of wisdom and beloved by all, unless you happened to be a mouse. Now we’re stuck with this goggle-eyed fowl on the blue background you see over on the right. My fellow elders will likely disagree with me but I think we may have erred. We should have opted for a more adaptable, resourceful and smarter bird as an icon. We should have gone with the common or garden crow,
Consider their merits. Crows are adaptable in their choice of domicile. They typically nest in tall coniferous or deciduous trees, but readily opt for hedgerows or shrubbery as well. In urban areas they often nest on window ledges or the sides of buildings. They believe sincerely in gender equity and family support. Both sexes build the nest during a period of 1 to 2 weeks, from mid-March to mid-July, depending on latitude and elevation. Females incubate four to five eggs for 18 days, and are fed at times by the male or sometimes by offspring from the previous year.
Crows are omnivorous and eat whatever is available—insects, spiders, snails, fish, snakes, eggs, nestling birds, cultivated fruits, nuts, and vegetables. The crow population in the B.C. Lower Mainland has increased over the past 40 years as burgeoning human populations and urbanization have reduced forest cover, creating open foraging areas and generating food sources such as garbage that crows have been adept at exploiting. We too might have to adapt similar foraging habits here in B.C. as our productive land base is progressively depleted by subdivisions, highways, hydroelectric dams and drought.
Crows are gregarious – surely a useful trait in these trying times. They roost communally during the non-breeding season for the same reason many other birds do—to avoid predation and to share information about food resources. As winter moves in the birds form large roosts when they congregate at sunset. The birds disperse from their roosting areas early in the morning and follow each other to traditional foraging sites. Generally, the larger the roosts the greater the dispersal distances during the day. Feeding and roosting sites may be many kilometres apart.
Crows are regular in their habits, just like elders. They typically commute along regular flight paths, stopping at traditional feeding and staging sites along the way, where they usually vocalize loudly and noticeably. Large roosts usually number in the hundreds or even thousands, but can reach truly huge numbers, e.g. up to 2 million birds in the mid-western U.S.
Ornithologists speculate that roosting crows return to the same tree night after night, possibly even to the same branch. Some studies have shown that crows who occupy superior positions in the group hierarchy are more likely to take sleeping spots in the higher branches. That alone would seem a good indicator of intelligence.
Intelligent they certainly are. Crows are ranked amongst tool-using wild creatures, along with parrots, finches, monkeys and chimpanzees, and have been observed to use twigs to dig worms and insects out of holes. They are commonly observed to post sentries at foraging sites to alert feeding crows of danger.
Crow intelligence has been tested on the university campus in Seattle. Researchers donned masks and then captured and tagged a group of resident crows. They released the birds and checked their reactions on subsequent days when they wore the same masks and, alternatively, when they walked about maskless and when wearing a different set of masks. The results were somewhat in excess of what the researchers expected. Tagged crows would not react to people clad in unfamiliar masks, but they scolded and dive-bombed researchers wearing the same masks as the people who had initially captured and tagged them. Not only that, untagged crows in the neighbourhood rapidly caught on and joined in the dive-bombing.
This all confirmed what had been seen in other behavioural studies on crows, i.e. they communicate with one another in an advanced fashion. Its a contentious point whether crows actually employ what could be called “language”, but they do obviously communicate information to one another. Some researchers have surmised that different crow populations might have different ‘accents’. Its a common belief in the American mid-west that crows will modify their daily or seasonal movement patterns to avoid farms or localities where other crows have been killed in the past. The avoidance response has been reported as persisting amongst subsequent generations of crows. Attractive idea, although at this point one might ask for a little more evidence.
One of the B.C. Lower Mainland’s most remarkable natural ornithological spectacles is still occasionally to be seen in Burnaby. Pre-roosting crows gather in the evening in their thousands around Still Creek near Willingdon and Lougheed. The site serves as a central location from which the crows can radiate out to feed around the Lower Mainland, flying as far afield as the North Shore and Richmond.