Data from: Impact of spatial variation of a crucial prey, the molecricket, on hoopoe territory occupancy and reproduction

Direct benefits accrued from securing a territory of sufficient quality are important determinants of individual fitness and population persistence. Food supply is one of the main factors of animal territory quality, with spatial and temporal variation in prey availability largely dictating reproductive output and thus population dynamics. In a Swiss hoopoe population, molecrickets Gryllotalpa gryllotalpa, the most profitable prey locally, can constitute most of the food biomass delivered to chicks by parents. We first investigated the impact of molecricket prey on hoopoes' fitness-related traits by quantifying the spatial variation in the food allocation pattern of both male and female parents to chicks across the whole population range; and second, analysed the impact of this prey on current reproduction and, using a 11 year dataset, on the temporal occupancy rate of each territory. We found considerable but spatially repeatable variation, over the years, of molecricket biomass in the diet provisioned to chicks. This spatial heterogeneity in chicks' diet composition was mirrored both in the history of territory occupancy (2002-2012) and in current reproductive success (2012). Territories with a greater biomass of molecrickets in chicks' diet produced more fledglings in better body condition. Yet, these effects on current reproduction were exclusively demonstrated for male parents, corroborating that paternal provisioning patterns play a predominant role in hoopoe reproductive success. This study demonstrates how a single, very profitable prey species might affect spatial variation in territory settlement and individual reproductive success in a regionally endangered bird species, with potential consequences for its population dynamics and persistence.

获取足够优质领地所带来的直接收益，是影响个体适合度（individual fitness）与种群存续（population persistence）的关键决定因素。食物供给是决定动物领地质量的核心因素之一，猎物可获得性（prey availability）的时空变异在很大程度上支配着繁殖产出（reproductive output），进而调控种群动态（population dynamics）。在瑞士的戴胜（hoopoe）种群中，当地最具收益价值的猎物蝼蛄（Gryllotalpa gryllotalpa）可占到亲代投喂雏鸟食物生物量的绝大多数。本研究首先通过量化整个种群分布范围内雌雄亲代向雏鸟投喂食物的分配模式的空间变异，探究了蝼蛄猎物对戴胜适合度相关性状（fitness-related traits）的影响；其次，依托11年的观测数据集，分析了该猎物对当期繁殖成功率的影响，以及各领地的时间序列占用率。研究发现，多年来雏鸟饮食中的蝼蛄生物量存在显著但具有空间可重复性的差异。雏鸟饮食组成的这种空间异质性（spatial heterogeneity），与2002-2012年的领地占用历史以及2012年的当期繁殖成功率均形成呼应。雏鸟饮食中蝼蛄生物量更高的领地，其出飞幼鸟（fledglings）数量更多且体况（body condition）更佳。然而，这类对当期繁殖的影响仅在雄性亲代中得到验证，这证实了雄性亲代的投喂模式（provisioning patterns）在戴胜繁殖成功中发挥着主导作用。本研究揭示了单一高收益猎物物种，如何影响一种区域濒危鸟类的领地定居空间差异与个体繁殖成功率，并可能对其种群动态与存续产生潜在影响。