Morphological differentiation of brown-headed cowbirds in the Okanagan Valley, British Columbia

Article Abstract:

Brown-headed cowbirds (Molothrus ater) found in the Okanagan Valley, British Columbia, Canada, were found to have different body measurements from western subspecies M. a. artemisiae and M. a. obscurus. This morphological difference implies that Okanagan Valley cowbirds are not hybrids of the two subspecies. It also suggests that these birds have been around enough for morphological differentiation to have taken place. These findings contradict the hypothesis that, due to the recency of the arrival of the cowbird in the area, cowbird hosts do not recognize the parasite's eggs.

Natural history, British Columbia, Cowbirds, Morphology (Animals), Animal morphology

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Northern hawk-owls in the nearctic boreal forest: prey selection and population consequences of multiple prey cycles

Article Abstract:

A study of hawk-owls in the southwestern Yukon, Canada, revealed prey selection and availability to directly influence the species' population density, thereby indicating the importance of prey composition in specific habitats in their survival. This species sustained itself mainly on voles, including Microtus, and depended on larger prey during nesting stages.

Analysis, Predation (Biology), Owls, Habitat selection

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Roost site selection of great horned owls in relation to black fly activity: an anti-parasite behavior

Article Abstract:

Issues concerning the relationship between the change in roosting behavior in great horned owls and the emergence of ornithophilic black flies in the North and South Americas are discussed. Particular attention is given to ground roosting rates.

Behavior, Flies, Diptera, Horned owl, Roosters, Great horned owl

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