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

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.This study was joint funded by the RSPB and Natural England through the Action for Birds in England partnership

Sexually Segregated Housing Results in Improved Early larval Survival in Zebrafish

Large-scale aquaculture facilities require highly optimized husbandry protocols that maximize fecundity and embryo health while minimizing cost and effort. Although zebrafish are being increasingly used for preclinical drug screens, functional genomic research and toxicological and behavioral studies, many of the basic husbandry procedures that are used for these fish have not been thoroughly tested. In this study, the authors compared the breeding success of zebrafish housed in sex-separated and those housed in mixed-gender arrangements. They observed a significant increase in fecundity (egg production) between the first and the third breeding and found that egg survivorship tended to increase during successive pairings. The authors also found that zebrafish had higher fecundity, egg viability and seemed to have a higher breeding success rate when males and females were housed separately than when they were housed together

Patterns of genetic variation and covariation in ejaculate traits reveal potential evolutionary constraints in guppies

Ejaculates comprise multiple and potentially interacting traits that determine male fertility and sperm competitiveness. Consequently, selection on these traits is likely to be intense, but the efficacy of selection will depend critically on patterns of genetic variation and covariation underlying their expression. In this study, I provide a prospective quantitative genetic analysis of ejaculate traits in the guppy Poecilia reticulata, a highly promiscuous livebearing fish. I used a standard paternal half-sibling breeding design to characterize patterns of genetic (co)variation in components of sperm length and in vitro sperm performance. All traits exhibited high levels of phenotypic and additive genetic variation, and in several cases, patterns of genetic variation was consistent with Y-linkage. There were also highly significant negative genetic correlations between the various measures of sperm length and sperm performance. In particular, the length of the sperm's midpiece was strongly, negatively and genetically correlated with sperm's swimming velocity—an important determinant of sperm competitiveness in this and other species. Other components of sperm length, including the flagellum and head, were independently and negatively genetically correlated with the proportion of live sperm in the ejaculate (sperm viability). Whether these relationships represent evolutionary trade-offs depends on the precise relationships between these traits and competitive fertilization rates, which have yet to be fully resolved in this (and indeed most) species. Nevertheless, these prospective analyses point to potential constraints on ejaculate evolution and may explain the high level of phenotypic variability in ejaculate traits in this species