Crowsnest Conservation Society

When Birds Become Vicious

FROM: Crowsnest Conservation WildEd

A glimpse of movement at the periphery of your vision while you are on your favourite trail through the trees. A sharp and fast-approaching ‘kee-kee-kee-kee’ call. The whoosh of feathers just above your head. And suddenly you are simultaneously diving for cover and searching the sky. No, this isn’t a scene from Alfred Hitchcock’s famous movie The Birds, but perhaps it instills a similar sense of fear if you have experienced a northern goshawk swoop before.

As with most animals, birds may exhibit aggressive behavior towards a perceived threat. The spring nesting season represents the time when birds are more likely to respond aggressively towards an encroaching person or animal. Defensive behaviours include vocalizations like loud, high-pitched, or sharp calls, posturing with fluffed feathers to look larger, swaying back and forth, feigning injury, and pursuing the attacker.

The most frequent encounters involve songbirds or raptors that make their nests in and around human-populated areas, but strong responses are known from many species including American robins, gray catbirds, gulls, terns, northern mockingbirds, blue jays, red-tailed hawks, Cooper’s hawks, Swainson’s hawks, northern goshawks, broad-winged hawks, and peregrine falcons.

Interestingly, studies have shown that some species choose to nest closer to other aggressive bird species to gain protection and increased nest survival. For example, a Simon Fraser University study showed that great blue herons nesting within 200m of a bald eagle nest received protection from other predatory eagles and had higher nesting success across the heron colonies despite some losses to the guardian eagle.

If you have a feisty songbird around your neighbourhood or encounter an aggressive raptor in the bush, remember they are feeling distressed rather than vindictive. The behaviour will abate as their young grow and fledge from the nest. For most neighbourhood songbirds, this nestling period lasts about two weeks (though they may produce more than one brood per year) while the period lasts a few weeks for raptors. If possible, avoid the area until this happens. If avoidance is not possible, carry an umbrella or pole with a flag above your head when walking nearby or, if you must work in the area of a protective parent bird, tie a helium-filled balloon to your waist. Birds, especially raptors, will strike the tallest object. In the event that a person or pet is attacked by a bird, and the skin is broken, wash the wound and treat it with antiseptic. Birds do not carry rabies or other diseases communicable in this way.

Removal of the nest after it has been vacated may decrease the likelihood of the problem reoccurring the following year as birds sometimes reuse nests. Removal of an active nest and/or eggs is prohibited by law (Alberta Wildlife Act). But what if removal of the nest did trigger a vindictive bird the following spring – would we face a Crowsnest Pass version of The Birds?


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Mail:     P.O. Box 242, Crowsnest Pass, AB, T0K 0E0
Office:  12707-20 Avenue, Crowsnest Pass, AB
Phone: (403) 753-2040