Abstract
Modelling territorial occupancy and reproductive success is a key issue for better understanding the population dynamics of territorial species. This study aimed to investigate these ecological processes in a Eurasian Eagle-owl (Bubo bubo) population in south-eastern Spain during a seven-year period. A multi-season, multi-state modelling approach was followed to estimate the probabilities of occupancy and reproductive success in relation to previous state, time and habitat covariates, and accounting for imperfect detection. The best estimated models showed past breeding success in the territories to be the most important factor determining a high probability of reoccupation and reproductive success in the following year. In addition, alternative occupancy models suggested the positive influence of crops on the probability of territory occupation. By contrast, the best reproductive model revealed strong interannual variations in the rates of breeding success, which may be related to changes in the abundance of the European Rabbit, the main prey of the Eurasian Eagle-owl. Our models also estimated the probabilities of detecting the presence of owls in a given territory and the probability of detecting evidence of successful reproduction. Estimated detection probabilities were high throughout the breeding season, decreasing in time for unsuccessful breeders but increasing for successful breeders. The probability of detecting reproductive success increased with time, being close to one in the last survey. These results suggest that reproduction failure in the early stages of the breeding season is a determinant factor in the probability of detecting occupancy and reproductive success.
Highlights
Territory occupancy and reproductive parameters of territorial species have aroused great interest in population ecology and biodiversity conservation studies, since they allow researchers and managers to explain population trends in relation to ecological and disturbance covariates [1,2,3]
An analysis of the territorial occupancy dynamics showed that the probability of a territory being occupied in a given year is mainly determined by its occupancy status in the previous year (S1 Table)
Our models showed no evidence of annual variations in the probabilities of territorial occupancy, nor of differences between the northern and southern zones of the study area (S1 Table)
Summary
Territory occupancy and reproductive parameters of territorial species have aroused great interest in population ecology and biodiversity conservation studies, since they allow researchers and managers to explain population trends in relation to ecological and disturbance covariates [1,2,3]. Territorial occupancy and reproductive success of Eurasian Eagle-owls
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