Urbanization, Trace Metal Pollution, and Malaria Prevalence in the House Sparrow

Abstract

Anthropogenic pollution poses a threat for the environment and wildlife. Trace metals (TMs) are known to have negative effects on haematological status, oxidative balance, and reproductive success in birds. These pollutants particularly increase in concentration in industrialized, urbanized and intensive agricultural areas. Pollutants can also interfere with the normal functioning of the immune system and, as such, alter the dynamics of host-parasite interactions. Nevertheless, the impact of pollution on infectious diseases has been largely neglected in natural populations of vertebrates. Here, we used a large spatial scale monitoring of 16 house sparrow (Passer domesticus) populations to identify environmental variables likely to explain variation in TMs (lead, cadmium, zinc) concentrations in the feathers. In five of these populations, we also studied the potential link between TMs, prevalence of infection with one species of avian malaria, Plasmodium relictum, and body condition. Our results show that lead concentration is associated with heavily urbanized habitats and that areas with large woodland coverage have higher cadmium and zinc feather concentrations. Our results suggest that lead concentration in the feathers positively correlates with P. relictum prevalence, and that a complex relationship links TM concentrations, infection status, and body condition. This is one of the first studies showing that environmental pollutants are associated with prevalence of an infectious disease in wildlife. The mechanisms underlying this effect are still unknown even though it is tempting to suggest that lead could interfere with the normal functioning of the immune system, as shown in other species. We suggest that more effort should be devoted to elucidate the link between pollution and the dynamics of infectious diseases.

Maternal effects, malaria infections and the badge size of the house sparrow

“…Finally, other variables associated with the vector-controlled zone, most notably the insecticide itself or agriculture-associated pollutants that region which also sustains higher agricultural use, could weaken the sparrows' immune system and increase malaria susceptibility, as previously shown by Bichet et al (2013), though that effect was most evident in sparrows of highly urbanised areas.…”

Habitat urbanization and its effects on birds

“…In urban areas enhanced levels of bioaccumulation of heavy metals has already been demonstrated in many common bird species, e.g. in the House Sparrow Passer domesticus (Swaileh & Sansur 2006, Kekkonen 2011, Bichet 2013, the House Wren Troglodytes aedon or the American Robin Turdus migratorius (Hofer et al 2010). The detrimental, synergistic effects of such pollutants on birds' physiology is also documented by several studies (e.g.…”

Growing in Cities: An Urban Penalty for Wild Birds? A Study of Phenotypic Differences between Urban and Rural Great Tit Chicks (Parus major)

“…Thus, cities are characterized by multiple abiotic and biotic modifications of the natural environment such as fragmentation (Crooks et al, 2004), human disturbance (Sauvajot et al, 1998;Fernández-Juricic, 2002), and increased pollutions: noise (Slabbekoorn and Peet, 2003;Meillère et al, 2015b), light (Dominoni et al, 2013;Spoelstra and Visser, 2014), electromagnetic (Engels et al, 2014), and chemical pollution (Roux and Marra, 2007;Isaksson, 2010;Bichet et al, 2013). Urbanization is also associated with altered predation risk (Fischer et al, 2012;Møller and Ibáñez-Álamo, 2012), inter and intra-specific competition (Duckworth, 2014), disease prevalence (Bichet et al, 2013;, food type and abundance (Robb et al, 2008;Harrison et al, 2010;Galbraith et al, 2015). All these modifications raise new important selective constraints for wild vertebrates, and as a consequence, biodiversity is overall impoverished in cities (Clergeau et al, 2006;McKinney, 2008).…”