Depleted suburban house sparrow Passer domesticus population not limited by food availability
Depleted suburban house sparrow Passer domesticus population not limited by food availability
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耗尽的郊区家麻雀数量不受食物供应的限制
作者：
W. Peach;J. Mallord;N. Ockendon;C. Orsman;W. Haines
在高度改变的城市环境中，限制野生脊椎动物数量和数量的环境因素知之甚少。家雀是一种全球广泛分布的物种，其城市人口最近经历了大幅下降，特别是在欧洲。这些下降的环境驱动因素仍然未知。在之前的一项研究中，我们发现繁殖季节无脊椎动物的可用性限制了郊区麻雀种群的繁殖成功率，而不是种群规模。在这项研究中，我们通过实验测试了全年食物供应是否限制了人口和人口规模。补充喂养包括提供无脊椎动物猎物（在繁殖季节）和无限制的高能种子（全年）在33个麻雀殖民地分布在伦敦郊区连续两年。33个未开垦的殖民地作为控制。补饲增加了雏鸟的丰度，但对越冬存活率和种群大小没有影响。我们的结论是，这种枯竭的郊区麻雀数量不受食物供应的限制，主要基于食物供应的保护努力不太可能成功。我们还测试了麻雀丰度的跨种群变异是否与一系列潜在的环境压力因素相关，包括捕食者丰度和污染。在含有大面积种子丰富栖息地和低二氧化氮空气污染水平的地方，麻雀的数量更丰富，或者在数量上表现出更积极的时间变化。空气污染对城市鸟类健康的潜在影响值得进一步研究。
Little is known about the environmental factors that limit the demography and abundance of wild vertebrates in highly modified urban environments. The House Sparrow Passer domesticus is a globally widespread species whose urban populations have recently undergone substantial declines particularly in Europe. The environmental drivers of these declines remain unknown. In a previous study we showed that invertebrate availability during the breeding season limited reproductive success but not population size in a suburban sparrow population. In this study we test experimentally whether year-round food availability limits demography and population size. Supplementary feeding involved the provision of invertebrate prey (during the breeding season) plus unlimited high-energy seed (year-round) at 33 sparrow colonies spread across suburban London over two successive calendar years. Thirty-three unfed colonies served as controls. Supplementary feeding increased fledgling abundance, but had no impact on overwinter survival or population size. We conclude that this depleted suburban sparrow population is not limited by food availability, and conservation efforts based primarily on food provision are unlikely to succeed. We also tested whether cross-colony variation in sparrow abundance was correlated with a set of potential environmental stressors including measures of predator abundance and pollution. Sparrows were more abundant, or showed more positive temporal changes in abundance, at localities containing large areas of seed-rich habitat and low levels of nitrogen dioxide air pollution. Further research is merited into the potential impacts of air pollution on the fitness of urban birds.