Birds in the city: Stress and the city?

Population projections predict that by 2050, 70% of the human population will live in urban areas and cities are rightly considered one of the environments where global change is most rapid and intense. In this context, URBASTRESS aims to assess the costs and benefits of urbanisation for urban vertebrates, focusing on passerines, such as sparrows, chickadees, or blackbirds.

ECOPHY team : Frédéric AngelierFrançois Brischoux
Funding: ANR, Departmental Council 79, Région Nouvel-Aquitaine, Niort Town Hall, CPER Collaborators MNHN, Sorbonne University,
LPO Students involved : Alizée Meillère, Erika Beaugeard, Bertille Mohring

In the course of this project, we were able to:

Get a clear picture of the demographics of the house sparrow in urban and rural areas. Analyses carried out have shown, for example, the massive decline in urban sparrow populations in Paris (e.g. ~90% decline in Parisian sparrows in 15 years).

Describe the parasite levels of urban and rural sparrows. In particular, we showed that ticks were less present in urban areas and that avian malaria was not specifically associated with the city.

Describe the contamination of species in urban environments by various pollutants (pesticides, heavy metals). We have been able to show that heavy metal contamination can reach significant levels, even in medium-sized cities.

Using morphological and physiological markers, we were also able to assess the consequences of urbanization on sparrows and chickadees, and thus better understand the physiological disturbances associated with an urban lifestyle. We were thus able to :

Evidence that urban sparrows most certainly suffered from significant nutritional constraints (small size and poor quality plumage in urban areas, and high levels of stress hormones. These results are particularly apparent in young sparrows, demonstrating that the constraints are accentuated during development.

By studying another urban species, we were also able to generalize these results by showing that the urban environment was associated with nutritional constraints (carotenoids, an antioxidant) during development.

Obtain results suggesting that urban food is unsuitable for the proper development of young urban sparrows.

Enfin, nous avons utilisé des approches expérimentales pour évaluer l’impact de contraintes urbaines spécifiques sur les oiseaux. Nous avons ainsi pu montrer que :

Le bruit urbain induisait un vieillissement accéléré des moineaux domestiques et modifiait de manière subtile le fonctionnement physiologiques des organismes, notamment leur métabolisme

La pollution lumineuse induisait également un stress physiologique important aux poussins en cours de développement

Le bruit urbain et la pollution lumineuse pouvaient affecter le comportement des individus, et notamment leur vigilance et leurs rythmes d’activité

Le manque de cavités en milieu urbain ne semble pas être responsable du déclin des populations de moineaux domestiques en ville