Résumé
Both natural and artificial light have proximate influences on many
aspects of avian biology, physiology and behaviour. To date artificial
light at night is mostly considered as being a nuisance disrupting for
instance sleep and reproduction of diurnal species. Here, we investigate
if lamppost night lighting affects cavity-nesting bird species inside
their breeding cavity. Nest height in secondary cavity-nesting species is
the result of trade-offs between several selective forces. Predation is
the prevailing force leading birds to build thin nests to increase the
distance towards the entrance hole. A thin nest may also limit artificial
light exposure at night. Yet, a minimum level of daylight inside nesting
cavities is necessary for adequate visual communication and/or offspring
development. Against this background, we hypothesised that avian
nest-building behaviour varies in response to a change in night lighting.
We monitored nest height of urban great tits (Parus major) during six
years and found that it varied with artificial light proximity. The birds
built thinner nests inside nestboxes of various sizes in response to
increasing lamppost night light availability at the nest. In large
nestboxes, the nests were also thinner when a lamppost was present in the
territory. Whether this relationship between artificial night lighting and
nest height reflects a positive or negative effect of urbanisation is
discussed in the light of recent experimental studies conducted in rural
populations by other research groups.