Authors: CARRASCAL, L. M. and TELLERÍA, J. L.
Published: Volume 36(2), December 1989. Pages 149-160.
Language: Spanish
Original Title: Comportamiento de búsqueda del alimento y selección de especies arbóreas: anÁlisis con el Agateador Común (Certhia brachydactyla) durante el invierno
Keywords: Certhia brachydactyla, optimal foraging, tree species selection and winter.
Summary:
The winter foraging behaviour of Certhia brachydactyla was studied at a mixed forest including two tree species which differed in the amount of food available to the brown tree-creepers: oaks had high food availability, whereas beeches had relatively lower food availability. Despite this dífference in food availability, there were no significant differences between both tree species in the residence times, intake (pecking) rates or distances flown to reach them. The observed similarity of foraging behaviour is seemingly attained by concentrating the searching activity on the substrate with highest food availability (lichen and moss patches). Nevertheless, travelling speed (hopping rate) is higher on beeches, since the birds are obligated to go across the unproductive bare trunk surfaces (which account for a larger proportion of the total tree surface in the case of beeches) in the shortest possible time. In addition, brown treecreepers tend to minimize the distance flown from one oak to another. The observed utilization of beeches and oaks does not differ significantly from the one that would be expected taking into account the densities of both types of trees, their respective values of food availability and the travelling costs within each tree species.
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