Research interests

My research mainly focusses on the effects of urbanisation on wildlife from an ecophysiological and evolutionary point of view. 

Since 2019, I am Principal Investigator in the Applied Animal Ecology group at the University of Innsbruck. My research aims at understanding the role that plays food availability (both natural and voluntarily provided by humans) on bird diet, nutritional status, seasonal movements and evolution. How food availability for birds vary within urban ladnscapes? How birds respond to such spatial and temporal variations in food availability? To answer these questions, I study great tit and blue tit populations within an urbanised landscape in North Tyrol (Austria).

Within a first project, I assessed the spatial and temporal variation in arthropod prey availability in trees and bushes. I showed that arthropod prey in trees and bushes are available in different amount within the urban mosaic: while web spiders and springtails occur less and are less abundant in more urbanised areas, such areas offer more aphids, crab spiders, barklice and dipterans (Chatelain et al. 2023, Frontiers in Ecology and Evolution). By shaping the availability of arthropod prey, urbanization is expected to have consequences on bird foraging behaviour, nutritional status but also reproduction success, survival and distribution within the urban landscape. As expected, analyses of great tit and blue tit diet, based on prey DNA extracted from droppings, revealed clear species- and season-specific patterns shaped by urbanisation. Urban great tits showed greater dietary diversity and frequently consumed sunflower seeds from bird feeders, but relied less on arthropods such as moths, spiders, and weevils, likely contributing to their lower reproductive success. By contrast, urban blue tits replaced moth intake with more frequent consumption of crab spiders and aphids. These dietary shifts reflect changes in prey availability, vegetation composition, and bird feeding practices, and highlight how urbanisation alters nutrient intake with potential fitness consequences (Chatelain et al. 2025, BioRxiv).

This project was funded by a Lise Meitner grant from the Austrian Science fund. Updates on the project can be found at: https://bit.ly/bird_diet

Arthropods are far to be the only food available for birds like great tits and blue tits. Actually, the meta-barcoding analyses realised on more than 450 birds caught all over the urban landscape showed that more than 60% of the birds ate sunflower seeds and almost 30% ate peanuts. Such food items were very likely collected from bird feeders. Bird feeding is a widespread and extremely popular practice in urban areas throughout Europe. As such, it drastically alters the type, the quantity and the spatial and temporal distribution of food available for birds within the urban space. By modifying bird foraging behaviour, bird feeding is likely to have consequences for the evolution of birds in urban environments, especially by exerting selective pressures (e.g. on beak morphology, behaviour, etc.) and/or by shaping gene flow within the urban landscape. In this second project, I am measuring gene flow and selection using an individual-based assessment of fine-scale genetic structure. The sampling of great tits and blue tits took place from Marsh 2023 to 2025 and data are currently being analyzed. 

This project is funded by an Elise Richter grant from the Austrian Science fund. Updates on the project can be found at: https://bit.ly/bird_feeding

During more than two years, I have been working at the Wild Urban Evolutionary & Ecology Lab (Center of New Technologies; University of Warsaw).

Chemical pollution such as trace metals are of particularly timely concern given their implication in several human diseases and their noxious effect on wildlife. However, we know little about the exposure of urban wildlife to trace metals and how it affects their fitness. I studied whether trace metal exposure in urban environments 1) covaries with urbanisation level (see DSM grant), 2) is associated with oxidative stress and 3) influences the quality of nestlings - including their telomere length - in great tits and blue tits. During this project, I showed that great tit and blue tit exposure to zinc, copper and lead increases with increasing habitat urbanization level (i.e. with increasing the percentage of impervious surface area or decreasing the percentage of tree cover) and this whatever the city. This result strongly suggests that urban metal pollution is likely to trigger the emergence of parallel responses at the phenotypic and/or genotypic level between urban environments worldwide (Chatelain et al. 2021 Sceintific Reports). Moreover, I demonstrated consistent negative effects of copper and arsenic exposure on fledging success and nestling mass in both great tits and blue tits (Chatelain et al. 2021 Science of the Total Environment). Those results suggest that urban metal pollution likely contributes to the differences in reproductive outputs observed between bird populations living in urban and rural environments, including the poorer development and lower survival of nestlings in more urbanized habitats (Corsini et al. 2020 Evolutionary Applications).

In parallel, my collaborators and I conducted a meta-analysis to understand how well telomere length and shortening reflect animal exposure to different stressors (e.g. harsh environmental conditions). By analysing 109  studies, we showed that, overall, the exposure to possible stressors was associated with shorter telomeres or higher telomere shortening rate (average effect size = −0.16 ± 0.03). This relationship was consistent for all phylogenetic classes and for all a priori-selected stressor categories. It was stronger in the case of pathogen infection, competition, reproductive effort and high activity level, which emphasises their importance in explaining intraspecific telomere length variability and, potentially, lifespan variability. Interestingly, the association between stressor exposure and telomeres in one hand, and oxidative stress in the other hand, covaried, suggesting the implication of oxidative stress in telomere dynamics (Chatelain et al. 2019 Ecology Letters). 

I also co-wrote a book chapter on mammals in urban environments in which I described the phenotypic characteristics that allow species to thrive in cities (Chatelain & Szulkin 2020 The Routledge Handbook of Urban Ecology). 

This project was funded by a Polonez grant (Marie Curie cofund). 

Between 2015-2016, I had an assistant lecturer position at the Pierre & Marie Curie University. My research in the Institute of Ecology and Environmental Sciences aimed at investigating dispersal, habitat choice and community composition in earthworm in a context of urbanisation.

Dispersal is an ecological process that enables organisms to colonize new habitats and have access to resources which availability differ with time and space. Therefore, dispersal capacity shapes the capacity of an individual to escape a low quality habitat. Investigating dispersal behaviour is necessary to understand population dynamics and community structures. I experimentally demonstrated the importance of habitat quality and population density in the departure choice of epigeic earthworms (Chatelain & Mathieu 2017 Soil Biology and Biochemistry). My results also show that dispersal behaviour is highly variable between species, suggesting different evolutionary histories between species (for example due to different degrees of exposure to environmental disturbances).

In response to long-lasting high levels of metallic trace elements (MTEs) in urban soils, we expect soil invertebrates inhabiting urban environments to have evolved detection and avoidance and/or tolerance mechanisms to MTE pollution. To test this, I used artificial soils with concentrations of lead, zinc, copper, chromium and nickel that reflect pollution levels in the soils of Parisian lawns. Using choice experiments, I compared habitat preference (i.e., the occurrence of individuals in the polluted vs. unpolluted soil) and health status (i.e., body mass maintenance, mobility, mortality) between three species of endogeic earthworms—Aporrectodea caliginosa, Aporrectodea icterica and Allolobophora chlorotica—originating either from urban or rural grasslands. This study highlights a clear avoidance of MTE-polluted soils in all three species, as well as MTE-induced health impairments, especially in A. chlorotica. Interestingly, earthworm response to MTE exposure only slightly differed between earthworms of urban and rural origin, suggesting the absence of widespread acclimatization or adaptation mechanisms to MTE pollution in cities (Chatelain 2023 Sustainability).

Earthworm avoidance to soil polluted with MTEs suggests that MTE pollution levels in urban soils structure earthworm communities. To test this hypothesis, I investigated the impact of MTE pollution on earthworm communities in lawns within the city of Paris. In this study, we sampled a comprehensive selection of earthworm communities, comprising a total 965 individuals from 13 distinct species. These communities were obtained from three different locations within 18 parks. At these locations, we assessed the concentrations of eight metals and metalloids in the soil, along with selenium concentrations and eight fundamental soil parameters, to examine the association between earthworm communities and soil attributes. MTE median concentrations surpassed recommended statutory limit values by approximately 20% (Cd), 30% (Cu), 40% (Zn), and as much as 90% (Hg and Pb). Nevertheless, these concentrations exhibited considerable variability both between and within parks, correlating with the variations in earthworm community structures. Specifically, our results highlight that Cu concentrations in the soil have the most significant influence on the assemblage of earthworm species. Our findings underscore the importance of considering MTE pollution levels to enhance our comprehension of earthworm distribution in urban environments and its effects on the ecosystem services provided by urban lawns (Chatelain et al. 2024 STOTEN).  

During my PhD (2012-2015), my research aimed at explaining melanin-based plumage polymorphism. More specifically, I tested the beneficial role of melanism in coping with high levels of trace metals.

Lead and zinc are the most abundant metal in urban areas. Understanding their effects on wildlife is a main challenge of the 21st century. I experimentally showed that lead exposure has consistent negative effects on the reproduction success (Chatelain et al. 2015 Global Change Biology, independently of parental hormones Chatelain et al. 2018 Ecotoxicology & Environmental safety), on some parameters of the immune response (Chatelain et al. 2016 Ecotoxicology) and on the transfer of antibodies into the eggs (Chatelain et al. 2016 Physiological and Biochemial Zoology) in the feral pigeon. On the contrary, zinc has positive effects on bird reproduction and physiology, and also compensates lead detrimental effects.

Interestingly, I found that zinc and lead concentrations in the feathers of the feral pigeon (Columba livia) increase with increasing plumage darkness. This result suggests that eumelanin, the pigment responsible for the black colouration of plumage, coat and skin in numerous animals, could allow animals to detoxify themselves by transferring a part of the metals circulating in their bloodstream in their feathers (Chatelain et al. 2014 Biology letters, Chatelain et al. 2015 Global Change Biology). Accordingly, juveniles exposed to lead are darker than  their counterparts raised in a metal-free environment, suggesting a higher survival of dark pigeons compared to pale pigeons (Chatelain et al. 2015 Global Change Biology). 

Altogether, those results suggest that melanism could be selected in urban area because of the higher ability of melanistic birds to cope with the deleterious effects of some trace metals. Thus, this mechnism could explain the higher frequency of dark pigeons in cities than in rural environments. 

In parallel, I showed that lead and zinc exposure also affect the plumage microbiome (Chatelain et al. 2016 Journal of Avian Biology), which could explain the effect of those two metals on plumage colouration (Chatelain, Pessato et al. 2017 Oikos) and odor composition (Leclaire et al. 2018 Ecotoxicology). Therefore, those results suggest that metal exposure may affect social interactions including mate choice.  

During my master's internship (2012) in the Center for Behaviour and Evolution (Institute of Neuroscience, Newcastle University), supervised by Candy Rowe, I identified some parameters influencing predators' motivation to consume  aposematic* and mimetic** prey. To do so, I carried out experimental studies on starlings (Sturnus vulgaris). First we showed that predation pressure on aposematic prey increases when decreasing temperature (Chatelain et al. 2013). This study gives an interesting answer to the temporal and geographical distribution of aposematic species. Second, we showed that predation pressure on the aposematic-mimic pair increases with increasing the nutrious content of the mimic. This result highlights the parasitic interaction between an aposematic species and its mimic when the two species have different nutritional values. 

*aposematism is a defensive strategy that associates a conspicuous phenotype and the production of toxic compounds.

** a mimetic species is a species displaying a similar phenotype (i.e. shape, colouration or behaviour) as another species. In this case, the mimetic species exhibits the same conspicious phenotype as the aposematic species bus does not produce any toxic compounds.