This is the third of a series of interviews made by Andrea Giacomelli to experts in the field of artificial light at night and light pollution. The ideas was originally proposed in the context of the Loss of the Night Network, but it is open to anybody active in this field.
The interview to Clémentine Azam was made in August 2015 and is translated into Italian by Alessia Carrara.
AG: Clémentine, will you give us a brief introduction of yourself and of your organization?
CA: I am a PhD student working on the effect Artificial Light At Night on bats. More specifically, I am interested in how ALAN influences the spatial distribution and movements of bats at different spatial scales.
My lab, the Center for Ecology and Conservation Science of the National Natural History Museum in Paris is focused on biodiversity conservation issues, and aims at characterizing how anthropogenic disturbances such as intensive farming and urbanization affect biodiversity, and how public policies can impedes biodiversity erosion. We are a team of 7 people working on bats.
AG: Did you first become interested in research on ALAN, or on bats?
CA: I first got interested in bats, as they are really fascinating species, full of mystery! In particular, I worked on habitat selection patterns and how human activities could modify the availability of foraging patches for bats in the landscape. Quickly, the question of light pollution came out, if working on bats, landscape at night is of major importance.
AG: Is part-night lighting an effective measure to limit the impacts of artificial lighting on bats?
CA: Yes, part-night lighting can be an efficient measure for bats; however, the way it is done in many localities (turning off streetlight from midnight to 05AM) is not optimal. These schemes have been set up by local authorities mostly to save energy and money, and also to achieve sustainable development goals by limiting CO2 emissions. They have not really been designed for biodiversity in the first place. Yet, with such lighting schemes, there could be a potential to meet economic, energetic and biodiversity goals.
Last year, we intended to characterize how 8 species of bats responded to such schemes in an area located 60 km south from Paris. Half of the localities were practicing part-night lighting for at least 2 years, and half had standard full-night lighting regimes. It appears that bats adapted their foraging behavior to part-night lighting schemes. Two light-sensitive taxa presented higher level of activity on part-night lighting sites compared to full-night lighting sites, suggesting they can exploit these sites once streetlights are turned off. Nevertheless, for one of them, the level of activity on part-night lighting sites was still much lower than on control unlit sites, suggesting that current part-night lighting schemes fail catching an important part of the range of the nightly activity of the genus.
This is consistent with another study made by Julie Day and collaborators in the UK, in which they simulated different part-night lighting scenarios on the activity of another light-sensitive bat species, and concluded that such schemes should start before 23h to catch more than 50% of its nightly activity. Therefore, part-night lighting schemes can become an efficient mitigation measure for light-sensitive species if implemented earlier at night.
Such a schedule would likely face resistance from the local inhabitants if implemented in an entire city, but this could be a valuable strategy along ecological corridors, such as urban parks and river banks, and would allow light-sensitive species to persist in urban and peri-urban environments.
AG: From your perspective as a PhD Student in France, where do you see yourself in five years?
CA: That is a hard question! I would like to keep working on light pollution and nightscape conservation issues and maybe broaden the perspective into urban ecology and sustainable land-use planning; probably as a post-doc in France or elsewhere…
AG: are you aware of the legislative development in France concerning light pollution mitigation, how are these working in the areas you live and work in?
CA: In France, since 2013, offices in buildings have to be switched off one hour after last occupation, and shops displays and public buildings front have to be switched off before 1AM (or 1 hour after last occupation of this occurs after 1AM). In Paris, officially, all buildings and monuments managed by the city have to be switched off at midnight during the week, 1AM during weekends and during summer (touristic season). However, there are a lot of buildings that are still illuminated after midnight, and it is hard to know if this is an infraction or if there was derogation for this particular building. However, we see a real mobilization from local administrations to change and ameliorate lighting management. This is likely due to the fact that ALAN represents an important part of localities electric bills; and also that lighting equipment is becoming old and has to be replaced in the coming decade. There is a real demand from people to set up sustainable lighting infrastructure that are energy-saving, and that also meets social needs, and health and environmental issues.