Author/Editor		Tome, Davorin
Title		Changes in the diet of long-eared owl Asio otus: seasonal patterns of dependence on vole abundance
Type		članek
Source		Ardeola
Vol. and No.		Letnik 56, št. 1
Publication year		2009
Volume		str. 49-56
Language		eng
Abstract		Aim: To investigate seasonal variability in the diet of long-eared owl Asio otus using long-term data and to investigate the influence of the main prey species abuuclance in the field. Location; Ljubljansko barje (46degrees 00 minutes N, 14 degrees 30 minutes E), Slovenia; in the period 1988 to 2001. Methods: Pellet analyses for investigating the diet, snap-trapping for investigating abundance of prey in the field, aufocorrelation function for investigating the periodicity of changes. Results: Common vole Microtus arvalis was the main prey of the long-eared owl, and wood mouse Apodemus sylvatacus and field vole Macrotus agrestis the two most important alternative prey species. The proportion of common voles in the diet varied from year to year, reaching a peak every five year. On a seasonal basis the owls caught significantly more common voles in the warm than in the cold periods of the year, but only when they were abundant in the field When they were scarce, no consistent pattern in seasonal changes of proportions was observed. Conclusions: Diet of the long-eared owl clanged considerably with the season; the within year pattern of changes was dependent on abundance of the main prey in the fleld.
Descriptors		BIRDS ANIMAL NUTRITION SEASONS