Nocturnal flight-calling behaviour predicts vulnerability to artificial light in migratory birds

Abstract

Understanding interactions between biota and the built environment is increasingly important as human modification of the landscape expands in extent and intensity. For migratory birds, collisions with lighted structures are a major cause of mortality, but the mechanisms behind these collisions are poorly understood. Using 40 years of collision records of passerine birds, we investigated the importance of species' behavioural ecologies in predicting rates of building collisions during nocturnal migration through Chicago, IL and Cleveland, OH, USA. We found that the use of nocturnal flight calls is an important predictor of collision risk in nocturnally migrating passerine birds. Species that produce flight calls during nocturnal migration tended to collide with buildings more than expected given their local abundance, whereas those that do not use such communication collided much less frequently. Our results suggest that a stronger attraction response to artificial light at night in species that produce flight calls may mediate these differences in collision rates. Nocturnal flight calls probably evolved to facilitate collective decision-making during navigation, but this same social behaviour may now exacerbate vulnerability to a widespread anthropogenic disturbance. Our results also suggest that social behaviour during migration may reflect poorly understood differences in navigational mechanisms across lineages of birds.

Zebra finches show spatial avoidance of near but not far distance traffic noise

“…This experiment convincingly demonstrated an impact of road noise (rather than the road itself) on the usage of a migratory stop-over site. However, for both of the aforementioned field playback studies different mechanisms could have been underlying the reductions in birds attending the sites: the noise itself could have kept the birds away and/or the noise masked the vocalizations of the birds already on site and thereby prevented the phonotactic aggregation of more birds (Mönkkönen & Forsman, 2002;Winger et al, 2019), a phenomenon that has been demonstrated experimentally (Schepers & Proppe, 2017).…”

How lovebirds maneuver through lateral gusts with minimal visual information

“…Our model could also give mechanistic insight into why birds fly toward and crash into artificial light sources at night. These sources, which can be lighthouses (40), monuments (41), or skyscrapers (42), are estimated to lead to billions of bird deaths a year (43). Steady lights-like the one in our study-can be particularly attractive and thus disorienting for migrating birds (44).…”

Flight morphology and visual obstruction predict collision risk in birds

“…Building collisions are the second leading source of direct, human-caused bird mortality in North America, and are estimated to cause between 365-988 million deaths annually in the US [1] and between 16-42 million deaths annually in Canada [2]. Birds are attracted to lighted structures at night [3] or attempt to fly through windows in the daytime [4], only to collide and die upon impact or from injuries later on. Migratory species are especially at risk; the majority of collisions occur during migration, particularly in areas with strong levels of artificial light [3,5].…”

“…Birds are attracted to lighted structures at night [3] or attempt to fly through windows in the daytime [4], only to collide and die upon impact or from injuries later on. Migratory species are especially at risk; the majority of collisions occur during migration, particularly in areas with strong levels of artificial light [3,5].…”