Ardea
Official journal of the Netherlands Ornithologists' Union

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Exnerova A., Jarosik V. & Kristin A. (2002) Variation in foraging mode of the Northern Wheatear Oenanthe oenanthe. ARDEA 90 (2): 275-284
The variation in foraging behaviour was investigated in the Northern Wheatear Oenanthe oenanthe in three structurally different habitats: early succession stages of spoil-banks, suburban wastelands, and grasslands. In each habitat, data were collected by visual observation of foraging behaviour and by assessment of foraging territories during two breeding seasons. Two searching modes were recorded: active foraging by hovering and running on the ground, and sit-and-wait foraging by perching. The foraging mode appeared highly flexible, varying from almost entirely active to almost entirely sit-and-wait. Also the importance of different searching techniques varied among the habitats. The proportion of perching decreased from grasslands through wastelands to spoil-banks. Running was more important in spoil-banks and wastelands than in grasslands, and hovering in grasslands than in wastelands and spoil-banks. The shift of foraging mode was related to density and height of vegetation cover. Foraging territories were larger in grasslands than in spoil-banks and wastelands. The results are discussed in the light of the syndrome hypothesis that predicts that species-specific constraints limit intraspecific variation in searching mode


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