![]() ![]() They found that in 81% of cases corvid removal made no impact on prey abundance or productivity. published a comprehensive literature review of 42 studies across 9 countries that looked at the impacts of corvid removal on a variety of avian groups including gamebirds, passerines, waders and other ground nesting birds. Prey abundance or productivity is monitored and compared at the end of the trial. These studies are straightforward and essentially create two populations, a control population that has been unmodified and a second where the predator in question has been actively removed. Why do we think that crows aren’t responsible for the any observed decrease in feeder birds? Predator removal studies. Crows themselves are subject to these same predators and very few of their young will make it to adulthood. The vulnerability of young birds is in fact why the breeding strategy of many birds is to have multiple clutches over the course of the breeding season. ![]() ![]() Raccoons, squirrels, foxes, hawks, owls, bullfrogs, rats, mice, and of course cats will all gladly eat birds, especially eggs and nestlings. It’s important to keep in mind, however, that crows are one of many, many animals that are eating the young and adults of other bird species. I once saw a crow take down an adult house sparrow in an attack so quick and dexterous I only realized what had happened after the crow had already started eating its meal. Now, let’s be clear, crows will absolutely kill and eat eggs, nestlings and even adult birds if they can get their hands on one. Later that same week I would watch of pair of adult crows chase hopelessly after a cooper’s hawk that had taken one of their offspring. An adult robin calling frantically while a crow munched on one of its young. I came across this grizzly scene while conducting research in Bellevue. ![]()
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