Shekar Esha Sai, Nyaguthii Brendah, Farine Damien R
Division of Ecology and Evolution Research School of Biology, Australian National University Canberra Australia.
Department of Biological Sciences Birla Institute of Technology and Sciences-Pilani, Hyderabad Campus Hyderabad India.
Ecol Evol. 2025 May 23;15(5):e71236. doi: 10.1002/ece3.71236. eCollection 2025 May.
Nesting birds face significant risks of predation, prompting parents to invest in nest defense. However, not all environments are the same, and parental investment may vary across different environments. Urbanization often leads to habitat changes and an increase in generalist nest predators, potentially driving a higher risk of reproductive failure for birds. This may require urban-breeding birds to invest more time and energy in nest defense, in addition to balancing other essential activities, such as incubation, foraging, and feeding their young. Here, we assess the impact of urbanization on nest defense by white-winged choughs (). We predicted that (1) urban habitats have a greater abundance of nest predators compared to natural habitats, and that (2) nest defense would correspondingly be higher in urban-breeding white-winged choughs. We also predicted that (3) nest defense in the white-winged choughs would increase with the age of the brood, in accordance with the nest defense theory, irrespective of their habitat. Our results confirm a significantly greater abundance of avian nest predators in urban areas, and that nest defense is significantly higher in urban groups compared to groups in natural habitats. However, we found no significant increase in nest defense with the age of the brood. Our study confirms that the increase in nest predator abundance can cause urban birds to face different trade-offs, and have to invest more in nest defense. This reflects one effect of urbanization on the composition and behavior of urban wildlife.
筑巢的鸟类面临着巨大的被捕食风险，这促使亲鸟投入精力进行巢穴防御。然而，并非所有环境都是相同的，亲鸟的投入在不同环境中可能会有所不同。城市化通常会导致栖息地变化以及泛化性巢穴捕食者数量增加，这可能会使鸟类面临更高的繁殖失败风险。这可能要求在城市中筑巢的鸟类除了平衡其他重要活动，如孵卵、觅食和喂养幼鸟之外，还要在巢穴防御上投入更多时间和精力。在此，我们评估城市化对白翅澳鸦巢穴防御的影响。我们预测：（1）与自然栖息地相比，城市栖息地有更多的巢穴捕食者；（2）在城市中筑巢的白翅澳鸦的巢穴防御相应会更高。我们还预测：（3）根据巢穴防御理论，无论栖息地如何，白翅澳鸦的巢穴防御都会随着雏鸟年龄的增长而增加。我们的研究结果证实，城市地区鸟类巢穴捕食者的数量显著更多，而且与自然栖息地的群体相比，城市群体的巢穴防御显著更高。然而，我们发现巢穴防御并没有随着雏鸟年龄的增长而显著增加。我们的研究证实，巢穴捕食者数量的增加会使城市鸟类面临不同的权衡，并且必须在巢穴防御上投入更多。这反映了城市化对城市野生动物的组成和行为的一种影响。
