Breeding performance and nest-site selection of Woodchat Shrikes Lanius senator near the southern edge of their breeding distribution

Abstract

AbstractNumerous Woodchat Shrike (Lanius senator) populations, and Laniidae in general, are globally declining. A deeper understanding of their breeding ecology, including their nest-site selection and breeding performance, from hatching success to post-fledging survival, could contribute to their conservation. We studied breeding Woodchat Shrikes near the southern edge of their breeding range in Northern Israel, monitoring breeding pairs throughout the breeding season from March to July 2023 in three study areas at the slopes of the Golan Heights in a semi-open shrubland. We collected data on birds’ nesting success, including hatching and fledging success, as well as on breeding pairs’ productivity and post-fledging survival of Woodchat Shrikes. Furthermore, we gathered information on nest-site characteristics. In this part of their range, Woodchat Shrikes breed in relatively high densities, opportunistically selecting nest-sites within the area. Most pairs had at least two brood attempts and up to four were recorded. On average breeding pairs laid 4.63 eggs per brood, with a decreasing brood size later in the season. Breeding performance was not related to the nest-site characteristics with the exception of nest height above the ground, which had a positive influence on nesting success. The breeding performance of Woodchat Shrikes was relatively low compared to other studies, particularly when considering fledging success. Nest predation was likely a predominant cause for nest failures here; however, breeding pairs were able to substantially increase their breeding success with replacement broods. Compared to the low nesting success, the post-fledging survival was relatively high, indicating much higher predation pressure on nests compared to fledglings.