Le Quilliec, P. | bioRxiv Science

bioRxiv2021

Global change affects differently at local scales animal populations: why Starlings still expands to the south while other temperate species go to the north?

Global change, which regroups global warming, landscape transformations and other anthropic modifications of ecosystems, has effects on populations and communities and produces modifications in the expansion area of species. While some species disappear, other ones are beneficiated by the new conditions and some of them evolve in new adapted forms or leave their ancient distribution area. As climate change tends to increase the temperature in several regions of the world, some species have been seen to leave areas in equatorial regions in order to join colder areas either towards the north of the northern hemisphere or towards the south of the southern one. Many birds as have moved geographically in direction to the poles and in many cases they have anticipated their laying dates. Actually, two tit species that use to lay their eggs in a period that their fledging dates synchronize with the emerging dates of caterpillars are now evolving to reproductive in periods earlier than before the climate change. Several species are reacting like that and other ones are moving to the north in Europe for example. Nevertheless, and very curiously, European starling, Sturnus vulgaris, populations are behaving on the contrary: their laying dates are moving towards later spring and their distribution area is moving towards the south. In this study we explore and discuss about different factors that may explain this difference from other birds.

ecology↗

bioRxiv2021

Population colonization history influences behavioral responses of European starlings in personality tests

To understand the processes involved in biological invasions, the genetic, morphological, physiological and behavioral characteristics of invasive populations need to be understood. Many invasive species have been reported to be flying species. In birds, both invaders and migrants encounter novel situations, therefore one could expect that both groups might react similarly to novelty. Here we analyzed the behavioral responses of individuals from three populations of European starling Sturnus vulgaris: a population settled for centuries in a rural region, a population that recently colonized an urban area, and a population of winter migrant birds. We conducted a social isolation test, a novel environment test, a novel food test and a novel object test to explore their reactions towards novelty. We identified and characterized different behavioral profiles for each test. The group of migratory adults appeared to be less anxious in social isolation than the group of urban young. Urban and migrant groups entered the novel environment sooner than rural birds. Shy, bold and intermediate individuals were observed in all three groups when presented with novel food. Finally, the proportion of shy individuals which did not touch the novel object was higher than the proportion of bold individuals in the rural group. Our study emphasizes that neophilia or boldness present in migrant and invasive populations may facilitate the occupation of novel habitats. Our analysis also suggests that mixed reactions of neophobia ensure behavioral flexibility in a gregarious invasive species. Significant statementIn this paper, we show that an invasive species like European starling, Sturnus vulgaris, presents an important flexibility in neophobia and in reaction towards social isolation. These variations depend on the settlement history of populationseven when the birds had been wild-caught as nestlings and hand-raised in standard conditions. This is significant because it highlights possible scenarios of colonization processes. We believe that this manuscript is appropriate for publication by Behavioral Ecology and Sociobiology because it places individuals behavior in the core mechanisms of an ecological phenomenom as biological invasions. Our manuscript enlarges the paradigms related to the ways of coping with novelty in animals. This manuscript has not been published and is not under consideration for publication elsewhere.

animal behavior and cognition↗