National Repository of Grey Literature 2 records found  Search took 0.00 seconds. 
Nest defence and predator recognition by Arctic tern \kur{(Sterna paradisaea)}
ŠPIČKA, Jan
In the presented work, I describe the behaviour of Arctic terns (Sterna paradisaea) toward predator species that differ in the threat they represent to them and to their nests. I presented textile dummies of great black-backed gull (Larus marinus), peregrine falcon (Falco peregrinus), common raven (Corvus corax) and common eider (Somateria mollissima), piece of wood as a harmless stimulus, and human intruder in sitting position near the tern nests. Experiments were conducted on the Varanger peninsula in Norway. The tern behaviour was recorded and analysed to see any dummy species related differences.
Ravens respond to unfamiliar corvid alarm calls
DAVÍDKOVÁ, Marika
The following work encompasses a research in the behaviour of the common raven (Corvus corax). I tested the responses of the common raven to heterospecific alarm calls of various bird species that differ in familiarity and taxonomical relatedness to ravens. Two other corvid species (jays) and two non-corvids (gulls) were presented. The ravens were given stimuli from one jay and one gull - one of which was always familiar to the tested ravens (European) and one unfamiliar (American). The results suggest that familiarity is not as important as the membership to the Corvidae family.

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