American Crow

American crows are undoubtedly one of the most intelligent and adaptable birds around. Highly gregarious and with complex social systems and behaviours they are a delight to watch. They are also very efficient nest robbers and predators of young birds.

Predation of eggs and chicks by crows are a normal part of the ecosystem however in urban and suburban areas the large number of crows and their ability to capitalize on the abundant food sources available is bad news for nesting birds, putting further pressure on the few species which are able to nest in such an environment.

Situated between Lake Washington and University Village Mall, Montlake Fill in Seattle has a lot to attract crows. Both the lake and the mall provide ready sources of food, while the ponds provide both a place to bathe and a easy source of invertebrates while the ponds are drying out in summer. This is bad news for the local Killdeer and American Robins.

When it comes to robbing nests, crows adopt one of two strategies, either systematically searching an area or sitting and watching birds, waiting for a change-over in incubation or more commonly to track where parents are returning to a nest to feed chicks. The distraction displays by the Killdeer or mobbing by robins does little to deter them and probably provides an incentive as the birds get more frantic the closer to the nest the crow gets.

This Spring within a week of laying the first egg, two of the three killdeer nests at Montlake Fill were robbed. In both cases the eggs were removed unbroken and the nest cup was torn up which suggests predation by birds rather than mammals - there are plenty of rats and a few racoons in the area. Prospects for the third nest which is situation near to a grove of tall dogwood trees do not look good. In the ten years I have lived in the area I can only recall one or two years when the Killdeer were able to fledge young. In most years the nests are predated early and any subsequent attempt at nesting also fails. Killdeer can be found nesting in a lot of the open spaces around the city so more successful pairs provide a pool of birds which will re-colonize the area should any territories become available. However this only compounds the problem as the area has lots of playing fields and is probably very attractive to Killdeer so birds that might have been successful elsewhere are drawn into an area where they have little chance of success.

Washington State Department of Fish & Wildlife just declared and open season on crows starting in October this year. While in one sense this might be welcome, I think that the benefits are likely to more more political rather than ecological. Not only will the debate polarize along predictable lines with people in favour of hunting and rural rights on one side and animal rights on the other, the effect of an increase in hunting is likely to be minimal and it will detract from a more practical if not mundane solution to the problem - simply ensuring that the streets and parking lots are clean, garbage is collected and lids on garbage cans and dumpsters are secured.