标题：Linking agri-environment scheme habitat area, predation and the abundance of chick invertebrate prey to the nesting success of a declining farmland bird
摘要：Across Europe, farmland bird populations have continued to decline since the 1970sowing to the intensification of farming practices. Studies of such declines have tendedto focus specifically on either the impacts of habitats (nesting and foraging), nest predators or prey availability on bird demographics. The study presented here providesnew insights into the relative effects of each of these factors on yellowhammer nestsurvival. The yellowhammer was selected for this study as it is a UK Red-Listed birdspecies whose population is in decline across much of Europe.2.We use a long-term dataset of 147 nests, monitored between 1995 and 2007, to provide an insight into how yellowhammer nest survival is influenced by nesting habitat(nest concealment and nest height), foraging habitats (habitat coverage within 100 mof nests), the removal of nest predators (magpie Pica abundance as an inverse measureof avian predator removal through gamekeeping) and food availability (measured witha D-vac invertebrate suction sampler).3. Our results indicated that yellowhammer hatching success was negatively relatedto the coverage of spring agri-environment scheme habitats, a group which representsinvertebrate-rich agri-environment habitats, but hatching success increased with nestheight. Fledging success was positively related to the coverage of the seed-rich habitat wild bird seed mixture. The farm-level abundance of yellowhammer chick-foodinvertebrates declined over the study period.4. Our results highlight the importance of simultaneously considering multiple agentsthat shape avian breeding success, that is their ability to produce offspring, to informconservation management. Our key finding for land managers relates to the positive relationship between the proportion of seed rich foraging habitat within theyellowhammer’s average foraging range and yellowhammer fledging success, whichshows that a habitat intended primarily to provide winter food resources is also important to breeding birds. Chick food abundance in this habitat was, however, similar to broadleaf and cereal crops. We recommend that this habitatshould be provided near to potential yellowhammer nesting sites and adjacent toinvertebrate-rich agri-environment scheme habitats such as beetle banks and conservation headlands to further boost invertebrate resources for a declining farmlandbird.
