Nhlapo Kagiso B, Cunningham Susan J, Sumasgutner Petra, Ganswindt Andre, McKechnie Andrew E, Ngcamphalala Celiwe A
FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, University of Cape Town, Cape Town, South Africa; Department of Biological Sciences, University of Cape Town, Cape Town, South Africa.
FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, University of Cape Town, Cape Town, South Africa.
Horm Behav. 2025 Apr;170:105724. doi: 10.1016/j.yhbeh.2025.105724. Epub 2025 Mar 18.
Urban wildlife must cope with diverse challenges and stressors, including human presence. However, in addition to being a disturbance, humans can provide energy-rich food and protection from predators. We evaluated the impact of human presence on red-winged starlings (Onychognathus morio) in a highly urbanised environment using faecal glucocorticoid metabolite (fGCM) concentrations as a stress-related biomarker. We performed an adrenocorticotropic hormone (ACTH) challenge to validate a non-invasive method for quantifying glucocorticoids in red-winged starlings. Using this method, we quantified fGCMs in excreta collected from free-living starlings during weekdays (high human presence) and weekends (low human presence) to determine the birds' responses to fluctuating human numbers. Following the ACTH challenge, starlings' circulating glucocorticoid (GC) concentrations increased by 127 % within 30 min and the corresponding fGCM concentrations increased within 1 h of injection. Of the four enzyme immunoassays (EIA) tested, an 11-oxoaetiocholanolone EIA, performed best, detecting a 310 % increase in fGCM concentrations post-ACTH challenge and suggested a 1-h lag between injection and peak fGCM excretion in this species. Human foot-traffic was significantly higher on weekdays compared to weekends, yet free-living red-winged starlings showed overall 30.4 % lower fGCM concentrations on weekdays compared to weekends. Red-winged starlings consume a higher proportion of anthropogenic food on weekdays than weekends and we cannot rule out the possibility that diet-related alteration in gut passage time affect fGCM concentrations. However, the correlation between fGCMs and human foot traffic may also suggest urban red-winged starlings benefit from human presence. Our results raise the possibility that, under certain conditions, the benefits associated with human presence outweigh potential negative effects associated with human activity, at least during the non-breeding season.
城市野生动物必须应对各种挑战和压力源，包括人类的存在。然而，人类除了会造成干扰外，还能提供能量丰富的食物并保护它们免受捕食者的侵害。我们在高度城市化的环境中，以粪便糖皮质激素代谢物（fGCM）浓度作为与压力相关的生物标志物，评估了人类存在对红翅椋鸟（Onychognathus morio）的影响。我们进行了促肾上腺皮质激素（ACTH）刺激试验，以验证一种用于量化红翅椋鸟体内糖皮质激素的非侵入性方法。使用这种方法，我们对工作日（人类活动频繁）和周末（人类活动较少）从自由生活的椋鸟收集的排泄物中的fGCM进行了量化，以确定鸟类对人类数量波动的反应。在ACTH刺激试验后，椋鸟的循环糖皮质激素（GC）浓度在30分钟内增加了127%，相应的fGCM浓度在注射后1小时内增加。在所测试的四种酶免疫分析（EIA）中，11-氧代雄烷醇酮EIA表现最佳，检测到ACTH刺激试验后fGCM浓度增加了310% ，并表明该物种在注射后1小时出现fGCM排泄峰值。与周末相比，工作日的人流量明显更高，但自由生活的红翅椋鸟在工作日的fGCM浓度总体上比周末低30.4%。红翅椋鸟在工作日消耗的人为食物比例高于周末，我们不能排除肠道通过时间的饮食相关变化影响fGCM浓度的可能性。然而，fGCM与人类人流量之间的相关性也可能表明城市红翅椋鸟受益于人类的存在。我们的结果提出了一种可能性，即在某些条件下，与人类存在相关的益处超过了与人类活动相关的潜在负面影响，至少在非繁殖季节是这样。
