Timing of breeding in an ecologically trapped bird

In human-modified environments, organisms may prefer to use habitats where their reproductive performance is lower compared to alternative options. Many such ecological traps occur in seasonally changing environments. Although the timing of breeding has been shown to impact reproductive performance in a variety of organisms, it has never been considered as a potential mechanism underlying ecological traps. We address this issue with a migratory bird, the Red-backed shrike, breeding in a human-modified, farmland-forest landscape. Shrikes prefer breeding in forest clear-cuts where their reproductive performance is lower than in less attractive farmland. We compared brood size and quality of early (first broods) and delayed breeders (replacement broods) between the two habitats. We found a stronger seasonal decrease in reproductive performance in preferred forest clear-cuts than in farmland. Food resources were slightly more abundant in forest than in farmland at the beginning of the seaso...在受人类活动改造的生境中，生物有时会倾向于选择相较于其他可选生境更不利于其繁殖表现的区域。此类生态陷阱（ecological trap）多出现于季节动态变化的生境中。尽管已有研究证实繁殖时序会对多种生物的繁殖表现产生影响，但繁殖时序从未被视作生态陷阱形成的潜在机制。本研究以栖息于受人类改造的农-林复合景观中的迁徙鸟类——红背伯劳（Red-backed shrike）为研究对象，对该问题展开探讨。红背伯劳倾向于在森林皆伐迹地繁殖，但其在此类生境中的繁殖表现却低于吸引力相对较弱的农田生境。本研究对比了两种生境中，早期繁殖个体（首窝雏鸟）与延迟繁殖个体（补窝雏鸟）的窝卵数与雏鸟质量。研究发现，相较于农田生境，偏好性的森林皆伐迹地中，繁殖表现的季节衰减幅度更为显著。在繁殖季初期，森林中的食物资源相较于农田仅略为丰富...