Experimental diversionary feeding of red kites Milvus milvus reduces chick predation and enhances breeding productivity of northern lapwings Vanellus vanellus

Abstract

For ground-nesting and colonial bird species, predation of eggs and chicks can exert a strong negative effect on population growth and recovery. For declining populations of waders breeding on lowland wet grassland predation management tools are available to reduce the impacts of mammalian predators (e.g. lethal control, exclusion) but potential solutions are limited when raptors, which are often themselves protected by law and not easily excluded, are responsible for predation. Diversionary feeding (DF), where predators are provided with alternative food to replace the target prey species in their diet, has been tested successfully by providing food close to nesting raptor pairs to target specific individuals. Where many individuals are involved in predation at a single prey colony, or where locating or accessing nests is difficult, provisioning DF close to the focal prey colony may be a more practical solution. Here, we test the efficacy of providing DF in this way to reduce predation by red kites, a reintroduced and increasingly abundant protected raptor in the UK, on the chicks of northern lapwing, an internationally declining wader species. We conducted a five-year field experiment, comparing kite predation rates and breeding productivity of lapwings in years before, during and after DF. Rates of kite predation on lapwing chicks were substantially and significantly reduced in DF years due to the successful elimination of a May-June peak in kite predation by DF which coincided with the kite chick provisioning and lapwing chick rearing periods. These annual reductions in kite predatory strike rates were concurrent with marked increases in overall annual lapwing productivity, which more than doubled on average in DF years and were on a scale sufficient to facilitate lapwing population recovery. DF attracted other potential predators of lapwing eggs and chicks, and more kites were attracted to feeding stations than were initially targeted by DF, but neither had any measurable impact on lapwing breeding success during DF years or after its cessation. With increasing populations of many raptor species, predator-prey conservation conflicts are expected to increase. DF proved to be a highly effective predation management tool for a high-density wader colony on lowland wet grassland where intensive kite predation limited breeding success. Although evaluation of the effects of using DF continuously over several years is needed, targeting multiple predator individuals close to the focal prey of conservation concern may be an important predation management tool where accessing individual raptors at nest sites is impractical.