Mechanisms underlying the road effects on owls: move towards mitigation.

The negative effects of roads on wildlife are recognized as important contributors to the global biodiversity crisis but the underlying mechanisms remain poorly understood, a fact critical for appropriate management strategies. At this stage, a way to optimize mitigation measures is to move from the description of mortality and distribution patterns towards the study of individual behavioral responses to roads and the environmental variables that control them. In this study, using mortality and the broadcast of territorial calls records, we examined the effect of road- and landscape-related factors on distribution and mortality of barn owl Tyto alba, tawny owl Strix aluco and little owl Athene noctua. We also analyzed fine-scale movements of radiotracked barn owls, estimated the mortality risk based on the highway crossings and compared the expected with the observed mortality. Our results show that owls tend to occur far away from the major roads. We recorded high mortality rates (59 ind./100 km/year) in road sections with low traffic and within suitable habitat. Barn owls, in particular, define their home-ranges nearby highways if there is available habitat and tend to be road-killed in the same places where they successful cross the highways. The risk of being killed per crossing event is 0.018, resulting in an expected mortality of 48-96 barn owls/100 km/year. These estimates were much higher than the observed daily mortality (6.2 ind./100 km/year). The high death toll imposed by roads may decrease density regionally over the years by acting as a demographic sink that often remains unoccupied and where dispersing individuals tend to settle. Thus, road managers must reduce road mortality risk by discouraging owls from flying along the road verges (e. g. frequent mowing and ploughing) and raising the height of the roadside verges to encourage owls to fly above the traffic in high incidence of road mortality.

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Date of creation 2024-09-17
Date of last revision 2024-09-17
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Metadata identifier 7438f12b-25f9-5512-bcf2-07f5d0057b65
Metadata language Spanish
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ISO 19115 topic category biota
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INSPIRE identifier ESPMITECOIEPNBFRAGM568
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"{\"type\": \"Polygon\", \"coordinates\": [[[-18.16, 27.64], [4.32, 27.64], [4.32, 43.79], [-18.16, 43.79], [-18.16, 27.64]]]}"
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  1. 2012 IENE International Conference. Programme and book of abstracts
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Name of the dataset creator Grilo, C., Sousa, J., Leitao, I., Reto, D., Ascensao, F. y Revilla, E.
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