![]() ![]() We found that the intensity of road use by nightjars was affected by ambient temperature, amount of moonlight, and wind conditions – all factors known to influence their foraging efficiency and thermoregulatory requirements. Here, we use road transect counts conducted once a week for 9 consecutive years (2009-2017) to investigate environmental factors influencing road use in the red-necked nightjar (Caprimulgus ruficollis), a nocturnal insectivorous bird that frequents roads to forage and thermoregulate. Understanding the factors that influence the intensity of road use by these species can help understand temporal patterns of road mortality and thereby maximize the cost-effectiveness of mitigation measures. Many animals avoid roads due to traffic disturbance, but there are also some species that use roads in their everyday life and even obtain resources from them. Our results suggest that nightjars use roads either to minimize their thermal needs under poor foraging conditions or to maximize food intake rates under optimal foraging conditions, most likely in response to common fluctuations in insect availability. Nightjar use of roads is therefore jointly determined by ambient temperature, amount of moonlight, and wind conditions-factors that all affect the thermal needs and foraging efficiency of nightjars. Being its abundances negatively affected by wind speed and increasing in nights warmer than the monthly average. We found that nightjars are most abundant on roads in either cold, dark nights or warm, bright nights. Additionally, we included the week to account for seasonality, and year as a random factor. To assess changes in nightjar abundance (birds/km), we fitted a LMM including a set of 16 environmental variables as explanatory factors. Here we investigate nightjar use of roads in relation to environmental variables known to influence insect availability and the thermal requirements and foraging efficiency of nightjars.īetween April and October 2009-2017, we carried out weekly counts of red-necked nightjars (Caprimulgus ruficollis) along a 24-km road network crossing the Doñana Natural Park, SW Spain. Foraging decisions are made to maximize energy gain by increasing food intake and decreasing the energy costs of movement and thermoregulation.Īmong nightjars, it has been suggested that they use roads at night as an open observation platform to forage for flying insects and to thermoregulate on a surface that absorbs heat during the day and attracts insects at night. ![]()
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June 2023
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