Artificial light more harmful to great tits than blue tits

Date: 27 September 2017

Introduction: UAntwerp researchers find that the impact of light pollution varies between species.

Scientists have known for some time that artificial light affects our sleep – and that of animals. Research by the University of Antwerp has now established that the negative effects vary from species to species, even when they are closely related. Great tits, for example, appear to feel the effects of light pollution much more severely than blue tits do.

With levels of light pollution on the increase all over the world, scientists fear that it may impact the survival chances of some animal species. Previous research has already shown that exposure to artificial light has an effect on animals’ behaviour and physiology. 

Ecologist Thomas Raap and his colleagues at the University of Antwerp recently investigated the effects of light pollution on two closely related bird species: the great tit (Parus major) and the blue tit (Cyanistes caeruleus). “We first compared the two birds’ sleep behaviour in dark conditions”, explains Raap. “In that phase, no differences were observed.”

Falling asleep later

In the following phase, the nest boxes of both species were exposed to artificial light under identical conditions. Raap: “As you would expect, the light disturbed the sleep of both the great tits and the blue tits. But the negative effects of the light were much clearer among the great tits. They entered their nest boxes later, fell asleep later, woke up earlier the next day and also went back outside earlier. The total amount of sleep they got was much lower.”

The Antwerp researchers’ work, which has been published in the journal Environmental Pollution, demonstrates conclusively that findings on the impact of light pollution cannot be generalised to all animal species. Raap: “That conclusion is important, because the species-specific effects of light pollution may have an impact on the birds’ group dynamics.

The study was carried out as part of long-term urban-ecological research being conducted in the Behavioural Ecology and Ecophysiology research group, led by professors Marcel Eens and Rianne Pinxten. Ongoing and future research will focus on how a range of urban stressors (light, sound, air pollution, etc.) affect the behaviour and health of birds.