Artificial lights often illuminate sport stadiums – putting a spotlight on your favorite sporting events. These floodlights are, however, a notorious contributor to light pollution. To figure out the impact of lights from sport stadiums, researchers analyzed the behavioral patterns of specific bat species. While floodlights gave some bat species an opportunity to feast to their heart's content, overall they posed a threat to biodiversity.
The conclusion of the new study published in the journal Animal Conservation could have implications for conservation policy. The problem with light pollution, defined as the inability to see the Milky Way with the naked eye, is global. It is estimated to impact 85.3% of the surface area in Europe, 61.8% in the United States (excluding Alaska and Hawaii) and 18.7% of emerging countries. Light pollution is already known to alter specific aspects of a species’ ecology, which includes communication, foraging and reproduction.
For the study, researchers set out to investigate the impact of light pollution on the fitness of bat species that are attracted to urban areas – known as “urban exploiters” – and bat species that aren’t likely to utilize urban areas, termed “urban avoiders.” The researchers looked at the seasonal activity and feeding attempts of these two bat groups at both lit and dark sport stadiums. The stadiums were at different distances from the urban center.
In lit stadiums, bat activity and feeding attempts where much higher than in dark stadiums. Urban exploiters were found to dominate both activity and feeding attempts. Researchers warn that the dominance of urban exploiter bats could lead to a homogenization of this group.
“My results show that bright, temporally variable light sources in landscapes with diverse human land-use patterns are important feeding grounds for urban exploiters,” Corrie Schoeman, an evolutionary ecologist at the University of KwaZulu-Natal, South Africa, noted in the study. “This could lead to biotic homogenization that may threaten native biodiversity."
Schoeman warns of a cascading effect on other organisms as light pollution could favor some species to persist in urban landscapes, pushing out other species such as avoider bats.