Urbanization and artificial light at night reduce the functional connectivity of migratory aerial habitat

Authors: Alicia M. Korpach, Colin J. Garroway, Alex M. Mills, Valerie von Zuben, Christina M. Davy and Kevin C. Fraser

Year: 2022

Publication: Ecography

Publication Link: https://onlinelibrary.wiley.com/doi/full/10.1111/ecog.05581

Keywords: aerial habitat, artificial light at night, functional connectivity, GPS tracking, nightjar, nocturnal bird migration, resource selection, whip-poor-will

Abstract: Flying animals use aerial habitats to forage, communicate and travel. However, human
activities that fragment aerial habitat with built structures, noise, and chemical or light
pollution, may limit the ability of wildlife to use airspace efficiently. Applying landscape
connectivity theory to aerial habitats could reveal how long-distance migrants respond
to sources of aerial habitat fragmentation along their migratory routes. Artificial
light at night is a major component of urbanization that fragments dark skies across
North America. Attraction of nocturnal migrants to urban light is well documented,
but species-specific responses, especially throughout a full migration from breeding
to wintering grounds, are not. We tested hypotheses about long-distance migratory
movements in relation to artificial light using a highly nocturnal, Nearctic-Neotropical
avian migrant (Eastern whip-poor-will Antrostomus vociferus). We applied a resource
selection framework at multiple spatial scales to explore whether GPS-tracked birds
(n = 10) responded to urbanization in general, or artificial light specifically, during
migratory flights. We found little evidence of attraction to artificial light during
nocturnal flights. Artificial light and urbanization were highly correlated and difficult
to disentangle, but the birds generally avoided urban areas and selected dark-connected
skies for travel. Migratory stopovers (locations where GPS-tracked birds (n = 20)
paused for at least one night), were located almost exclusively in dark, rural areas. Our
results illustrate that considering how nocturnal aerial migrants respond to both aerial
and terrestrial habitat elements can improve our understanding of what may facilitate
their long-distance movements.

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