In Its Southern Edge of Distribution, the Tawny Owl (Strix aluco) Is More Sensitive to Extreme Temperatures Than to Rural Development

SIMPLE SUMMARY: Tawny Owls occur in a wide range, with Israel being the southernmost country where they occur. This country’s climate is warming rapidly and it also undergoes an extensive urban and agricultural development. However, it is unknown to what extent these processes would endanger the Tawny Owls living there. To gain insight about this question, we surveyed Tawny Owls in the field, tracked the number of hatchlings in their nests, and also analyzed how their diet varied between different environments. We trained models of Tawny Owl distribution, number of hatchlings and diet using climate and land use variables to figure out to what extent climate change and development impact this species’ Israeli population. We found that Tawny Owls prefer relatively cool, rainy and wooded areas within Israel, and occur more often in villages compared to open fields. Tawny Owls raised more hatchlings in pine forests, especially when spring temperatures were moderate and following rainy winters. Tawny Owls preyed predominantly on Günther’s Voles everywhere, but took more birds in rural environments compared to forests. Our results suggest that climate change, which would increase spring temperatures and decrease rainfall, is a larger threat to Tawny Owls in Israel than rural development. ABSTRACT: Populations at the warm edge of distribution are more genetically diverse, and at the same time are more susceptible to climate change. Between 1987–1996, we studied Tawny Owls in Israel, the species’ global southern edge of distribution and a country undergoing a rapid land cover transformation for over a century. To assess the potential impacts of land cover transformation, we modelled the species’ most suitable habitat and climate and analyzed how climate and habitat affected the nesting success and prey selection. Moreover, we monitored Tawny Owl juveniles’ survival and ontogeny from eggs to dietary independent young, to find out whether the Israeli population is a sink. While the species distribution model correctly predicted the Tawny Owl’s densest areas of occurrence, it failed to predict its occurrence in adjacent regions. The model also predicted that areas included in the species’ historical range remained suitable habitats. The number of fledglings increased with precipitation and in rural settings but was adversely affected by extreme temperatures. While voles dominated the diet in all habitats, the Tawny Owl’s diet is considerably more variable than other Israeli owls. Our results suggest that the Tawny Owl can adapt to rural-agricultural environments, but is susceptible to climate change.