Canada's common nighthawk (Chordeiles minor) populations are in decline, but the cause is unknown. Some experts suggest these declines may be a result of the depletion of the nighthawk's primary food source, flying insects. If accurate, supplying artificial light to nighthawk habitats could support dwindling populations by attracting prey and extending their temporal foraging window. This project utilized autonomic recording units (ARUs), automated signal recognition software, and satellite infrared detection to assess the intensity of nighthawk habitat use with and without artificial light. This project compared the frequency and timing of nighthawk activity, obtained from 817 one-minute audio recordings, between lit (n=7) and unlit (n=9) habitats in Alberta's boreal forest. Lit habitats saw a significantly higher maximum likelihood estimate (MLE) of vocal activity (associated with foraging behavior) but no difference in wing boom activity (associated with territorial and mating behavior). Higher vocalization rates may have resulted from denser foraging populations or a higher intensity of habitat use by the same individuals. No observable change in wing boom activity could suggest the latter or that nighthawks are traveling outside their nesting territories to utilize habitats with artificial light for foraging. These results suggest that the depletion of nesting habitat may be contributing to population declines. Vocalization rates also extended beyond the typical foraging period in illuminated habitats, confirming that artificial light can aid nighthawks in obtaining additional resources. However, latitude significantly influenced these results. Further research is required to understand the applicability of artificial light as recovery measure for the common nighthawk across a broader landscape.
Disclaimer
This website was created as a credit requirement for the University of Alberta's REN R 480 Applied Statistics course taught by Dr. Andreas Hamann. The data used for this project was supplied by C. A. Adams on behalf of Alberta's Bioacoustic Unit, a collaborative effort between the Alberta Biodiversity Monitoring Institute (ABMI) and the Bayne Lab at the University of Alberta.