Influence of growing up in the city or near an airport on the physiological stress of tree sparrow nestlings (Passer montanus)

Abstract

Urbanization constitutes one of the major transformations of natural habitats, creating new areas characterized by multiple potential wildlife stressors. Birds that live in highly anthropized zones are confronted with physiological and behavioural challenges caused by these stressors. Here, we investigated if several health parameters differed between three subpopulations of tree sparrow nestlings subjected to different levels of anthropogenic pollution, and particularly noise pollution: a quiet rural area, a noisy rural area adjacent to an airport and a heavily urbanized area. We compared body condition, oxidative stress markers and baseline corticosterone levels, expecting urban nestlings to be in overall worse condition as compared to rural (rural and rural airport) birds. In addition, we expected nestlings exposed to aircraft noise to show intermediate stress levels. We found that rural-airport nestlings had the highest levels of antioxidant capacity of plasma and did not differ from rural counterparts in the rest of the parameters. By contrast, urban nestlings were in slightly worse body condition and had lower antioxidant capacity than rural and rural-airport individuals. Our results suggest that aircraft noise does not constitute a significant stressor for nestlings. In contrast, urban conditions constitute a more challenging situation, negatively impacting different physiological systems. Although nestlings seem able to buffer these challenges in the short-term, further research should explore the long-term potential consequences of early exposure to these conditions.

Begging calls and mouth colouration as predictors of breeding success in blue tits

“…Despite the large difference in breeding success between the Sierra Nevada and Choupal populations (87% vs. 27% respectively; Appendix S1), nestling mouth colouration did not differ between the two locations but vocal and postural begging did. Urbanization often negatively impacts avian reproductive success and nestling development and condition (Grabarczyk et al., 2022; Redondo et al., 2021; Seress et al., 2012). Caterpillars, the main component of the blue tit nestling diet (García‐Navas et al., 2014), show lower biomass and availability in urban and suburban habitats than in forests (Narango et al., 2018; Senar et al., 2021; Seress et al., 2018), which might imply that Choupal blue tit parents cannot adjust their feeding rate to nestling begging rate, making that hungry nestlings beg for longer and, ultimately, leading to reduced breeding success.…”