Corticosterone levels in relation to trace element contamination along an urbanization gradient in the common blackbird (Turdus merula)

Abstract

In a rapidly urbanizing world, trace element pollution may represent a threat to human health and wildlife, and it is therefore crucial to assess both exposition levels and associated effects of trace element contamination on urban vertebrates. In this study, we investigated the impact of urbanization on trace element contamination and stress physiology in a wild bird species, the common blackbird (Turdus merula), along an urbanization gradient (from rural to moderately urbanized areas). Specifically, we described the contamination levels of blackbirds by 4 non-essential (Ag, Cd, Hg, Pb) and 9 essential trace elements (As, Co, Cr, Cu, Fe, Mn, Ni, Se, Zn), and explored the putative disrupting effects of the non-essential element contamination on corticosterone levels (a hormonal proxy for environmental challenges). We found that non-essential trace element burden (Cd and Pb specifically) increased with increasing urbanization, indicating a significant trace element contamination even in medium sized cities and suburban areas. Interestingly, the increased feather non-essential trace element concentrations were also associated with elevated feather corticosterone levels, suggesting that urbanization probably constrains birds and that this effect may be mediated by trace element contamination. Future experimental studies are now required to disentangle the influence of multiple urban-related constraints on corticosterone levels and to specifically test the influence of each of these trace elements on corticosterone secretion.

City sicker? A meta‐analysis of wildlife health and urbanization

“…Toxic metals like cadmium, lead, and mercury can bioaccumulate in tissues through food consumption and are more abundant in urban populations, as seen in common blackbirds ( Turdus merula ; Meillère et al . ) and common perch ( Perca fluviatilis ; Olsson et al . ).…”

“…For instance, urban predators like bobcats (Lynx rufus) can be exposed to anticoagulant rodenticides from consuming contaminated prey (Serieys et al 2015). Toxic metals like cadmium, lead, and mercury can bioaccumulate in tissues through food consumption and are more abundant in urban populations, as seen in common blackbirds (Turdus merula; Meillère et al 2016) and common perch (Perca fluviatilis; Olsson et al 1999). Although toxicant exposure can have downstream effects on wildlife health, including abnormal development, reproduction, and immune function (Hawley et al 2009;Serieys et al 2018), the biological relevance of relatively higher toxicant concentrations is less clear, especially across species.…”

Reduction in baseline corticosterone secretion correlates with climate warming and drying across wild lizard populations

“…In wild populations, a range of chronic stressors from anthropogenic disturbance, including exposure of animals to unregulated ecotourism (Ellenberg, Setiawan, Cree, Houston, & Seddon, 2007;French, DeNardo, Greives, Strand, & Demas, 2010), habitat pollution (Crino, Klassen Van Oorschot, Johnson, Malisch, & Breuner, 2011;Meillère et al, 2016;Wikelski, Romero, & Snell, 2001) or landscape fragmentation (Janin, Léna, & Joly, 2011;Martínez-Mota, Valdespino, Sánchez-Ramos, & Serio-Silva, 2007) may result in chronic elevation of baseline GC level, population declines and increased risks of rapid population extinction. There is also some direct evidence that lower corticosterone level may improve fitness of individuals exposed to desiccation and thermal stress in terrestrial ectotherms (Jessop, Letnic, Webb, & Dempster, 2013).…”

Metal Accumulation in Blood Plasma and in Femora of Feral Pigeon (Columba livia) Free Living in Smelting, Urban and Rural Area in Kosovo

“…Meillere, found that the burden of Cd and Pb increased with increasing urbanization in the common blackbird (Turdus merula) [31].…”