How do major roads affect barn owls? Distribution, space use, food source and mortality

摘要: Road network expansion is known as one of the main factors responsible for decline Barn Owl (Tyto alba) populations in Europe, although full causes this are still poorly understood. In context authors evaluated several issues related to Owl’s ecology, Southern Portugal, when interacting with major roads: (a) effect highway distance on owl’s occurrence pattern, (b) behavioral vicinity roads, (c) role road verges an attraction factor due prey abundance, and (d) owls’ spatial temporal patterns mortality. To assess species (presence/absence) broadcasted adult calls 122 sites at distances from roads detected 47 individuals. From set environmental road-related variables tested using logistic regression, only showed a significant positive influence presence (β= 0.995; p<0.05). Space use crossing rates were investigated basis seven radio-tagged individuals (4 ♂, 3 ♀), captured their nests located close (<5 km). The rate was low (one per 34.19 hours radio-tracking). Of tracked four (3 1 ♀) had sample sizes strong enough provide robust estimates home-range size (Fixed Kernel Density Estimator 95%) just peripheral overlap between home-ranges (ranging 2.61 km² 9.37 km²) observed. overall abundance small mammals, assessed through live-trapping, significantly higher (n=248) than two other dominant land uses (cork oak woodlands (n=35), croplands (n=64), suggesting that could be suitable habitat hunting. Between 2004 2007, 373 road-kills 314 km national surveyed (0.30 Owls kills.km-¹.year-¹). A number casualties registered fall winter months dispersion juveniles occurs, while lower mortality frequencies end summer early spring, corresponding hatching fledgling periods. Mortality hotspots revealed strongly altitude (β =-0.026; p<0.05), eucalyptus or pine forest cover =-0.001; p<0.05) percentage cropland areas crossed by =0.332; Although do not seem act effective barriers Owls’ movements, pattern affected linear structure. Moreover, potential density does have foraging behavior adults.