Living in the city: can anyone become an ‘urban exploiter'?

Abstract

Aim As urban landscapes expand, shifts in biodiversity are occurring. This is leading biogeographers and ecologists to consider human‐dominated landscapes in their current work. One question that arises is: what characterizes those species that are widespread in the most highly urban environments compared with those restricted to less urbanized areas in the city? Here, we aim to identify the traits that enable species to become urban exploiters, i.e. to dominate highly urbanized surroundings. Identifying these traits may help us better predict and possibly mitigate the biotic homogenization occurring in these areas. Location Israel in general, with special focus on the city of Jerusalem. Methods Combining literature and field‐based data for birds in Israel we compared phenotypic, behavioural and life‐history traits between urban exploiters and urban adapters. The latter occur in urban landscapes, but are characteristic of the less urbanized parts of the city. We then examined the trends along a finer field‐sampled gradient of increasing urbanization from sub‐natural to downtown areas within the city of Jerusalem. Results Urban exploiters and adapters differed primarily in social structure and migratory status: exploiters were significantly more social and sedentary than urban adapters. Clear trends were also seen for dietary preferences along a gradient of increasing urbanization in Jerusalem, such that, with increasing urbanization, the proportion of granivorous species increased whereas the proportion of species feeding on invertebrates declined. In contrast, neither relative brain size nor behavioural flexibility, as measured by feeding innovations, differed significantly among urban exploiters and adapters in Israel or along the urbanization gradient in Jerusalem specifically. Main conclusions The results of our study suggest that being successful in more vs. less urbanized environments in the city is not necessarily a factor of brain size nor of how flexible and behaviourally innovative the species is; rather, it depends on a combination of traits, including diet, degree of sociality, sedentariness and preferred nesting sites.

Supplementary feeding restructures urban bird communities

“…Many introduced bird species in urban areas around the world are granivores or omnivores, which is ideal for capitalizing on supplementary food resources. In most countries, though, there are also native granivores and omnivores present (32,33)usually the primary targets of feeding-with which introduced species must compete.…”

Perda de diversidade taxonômica e funcional de aves em área urbana no sul do Brasil

“…A relação negativa entre o tamanho das espécies -em relação à massa -e a intensidade de urbanização que observamos é oposta ao padrão encontrado em outros estudos (González Oreja et al, 2007;Kark et al, 2007;Croci et al, 2008;Conole & Kirkpatrick, 2011). Ou seja, enquanto em Pelotas as aves tenderam a ser maiores em níveis baixos de urbanização, em outras regiões as aves tenderam a ser menores.…”

“…A urbanização pode ser determinante em alterar ou mesmo suprimir alguns atributos funcionais de assembleias de aves, já que engloba vários fatores de modificação de habitat (Kark et al, 2007;Flynn et al, 2009). Conforme Blair (1996) sugeriu, espécies que conseguem ultrapassar o filtro ambiental imposto pela urbanização intensa podem ser chamadas de "tolerantes urbanos" em contraponto aos "intolerantes urbanos", cujos atributos são incompatíveis com estes ambientes.…”

Larger groups are more successful in innovative problem solving in house sparrows

“…This finding is in accordance with the common notion that behavioral flexibility and adopting novel behaviors may be especially adaptive in urban habitats (10,43), although this assumption has not yet been tested within any species to our knowledge. In an interspecific aspect, Sasvári (44) showed that more urbanized species learn faster, whereas Kark et al (45) found no association between the degree of urbanization and innovativeness. Clearly this topic needs more attention.…”