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

Abstract

Urban sprawl is associated with deep and intense modifications of the natural habitats of wild vertebrates. Although, many species are unable to cope with such an environment, a few species can be found in cities and can help us assessing the impact of urbanization on wildlife. Urban-related environmental modifications are multiple and some of them seem beneficial while others seem rather detrimental to wild vertebrates. Moreover, the impact of these modifications on wild vertebrates is likely to vary depending on the phase of the annual life-cycle. Therefore, it is challenging to get a comprehensive picture of the impact of urbanization on wild vertebrates. Overall, urbanization is usually associated with reduced breeding performances in wild birds, but the impact of urbanization on the phenotype and quality of developing offspring has been less studied. In this study, we specifically investigated the impact of urbanization on several proxies of individual quality in great tits (Parus major). We concomitantly measured body size (tarsus length and body mass), plumage coloration, and telomere length in 14-days old chicks issued from 4 populations (two pairs of urban/rural populations located in two different geographical areas of France). First, rural chicks were significantly taller and heavier than urban birds although this impact of urbanization on body size/body mass appears only true for the most urbanized site. Interestingly, body size was also affected by the geographical area of capture, suggesting that regional environmental conditions may attenuate or exacerbate the influence of urbanization on nestling growth. Second, the carotenoid-based yellow plumage of rural nestlings was more colorful than that of urban birds, independently of the area of capture. This suggests that urban birds probably have a low-carotenoid diet relative to rural birds. Finally, telomere length did not differ between rural and urban chicks. These results suggest that urbanization probably imposes large developmental constraints in wild vertebrates and that this impact may primarily be related to constraining nutritional conditions.

Urbanisation lowers great tit Parus major breeding success at multiple spatial scales

“…In addition to the previous, many urban bird studies lack a quantitative characterisation of degree of urbanisation ), instead deriving conclusions from qualitative urban-rural contrasts, typically by comparing urban parks to forests (Isaksson and Andersson 2007, Björklund et al 2010, Bailly et al 2016, Biard et al 2017, Salmón et al 2017. To address these issues, in this study we utilised a nested sampling design involving study sites with a priori quantified degrees of urbanisation at two different scales (Merckx et al 2018).…”

Urban Great Tits (Parus major) Show Higher Distress Calling and Pecking Rates than Rural Birds across Europe

“…To acquire a robust insight into the relationship between urbanization and distress behavior, we assayed three different distress behaviors (distress calling rate, pecking rate, and breath rate) in seven replicate pairs of urban and rural/forest populations across Europe. Previous work on this species has revealed many differences between urban and rural great tits in terms of morphology (Horak et al, 1995;Senar et al, 2014;Biard et al, 2017), physiology (Andersson et al, 2015;Salmón et al, 2016;Toledo et al, 2016), genetics (Björklund et al, 2010;Riyahi et al, 2015), life-history (Berressem et al, 1983;Schmidt and Einloft-Achenbach, 1984;Isaksson and Andersson, 2007;Hedblom and Soderstrom, 2012;Bailly et al, 2015;Vaugoyeau et al, 2016;Charmantier et al, 2017), population dynamics (Horak and Lebreton, 1998), and behavior (Slabbekoorn and Peet, 2003;Salaberria and Gil, 2010;Riyahi et al, 2017). Urban great tits have been found to be more explorative and less neophobic than rural tits (Tryjanowski et al, 2016;Charmantier et al, 2017;Riyahi et al, 2017), to display shorter flight initiation distances (Møller et al, 2015), and to show a higher problem solving performance than rural birds (Preiszner et al, 2017).…”

Higher frequency of extra-pair offspring in urban than forest broods of great tits (Parus major)

“…Further, food availability and its seasonal distribution may also contribute to the differences in extra-pair mating behaviour between urban and forest populations. Caterpillars, the main food of great tits during the breeding season, are scarce in cities (Biard et al . 2017; Seress et al .…”

“…2014) and reduced reproductive success per breeding attempt (Bailly et al . 2016; Biard et al . 2017; Seress et al .…”

“…Individual quality and/or signals like song and plumage ornaments in birds are often relatively poorly developed in urban habitats, including the great tits’ yellow plumage coloration (Halfwerk et al . 2011; Biard et al . 2017), black breast stripe (Senar et al .…”