Nearby night lighting, rather than sky glow, is associated with habitat selection by a top predator in human-dominated landscapes

Abstract

Artificial light at night (ALAN) is increasing in extent and intensity across the globe. It has been shown to interfere with animal sensory systems, orientation and distribution, with the potential to cause significant ecological impacts. We analysed the locations of 102 mountain lions ( Puma concolor ) in a light-polluted region in California. We modelled their distribution relative to environmental and human-disturbance variables, including upward radiance (nearby lights), zenith brightness (sky glow) and natural illumination from moonlight. We found that mountain lion probability of presence was highly related to upward radiance, that is, related to lights within approximately 500 m. Despite a general pattern of avoidance of locations with high upward radiance, there were large differences in degree of avoidance among individuals. The amount of light from artificial sky glow was not influential when included together with upward radiance in the models, and illumination from moonlight was not influential at all. Our results suggest that changes in visibility associated with lunar cycles and sky glow are less important for mountain lions in their selection of light landscapes than avoiding potential interactions with humans represented by the presence of nearby lights on the ground. This article is part of the theme issue ‘Light pollution in complex ecological systems’.

Light pollution in complex ecological systems

“…However, Grenis et al [37] reveal contrasting effects on community composition of moths in response to skyglow and point-light sources. Moreover, Barrientos et al [38] show that mountain lions are affected by direct light sources rather than skyglow, suggesting that avoiding potential interactions with humans is important for these animals in their selection of light landscapes. Overall, these findings underscore the necessity of differentiating between skyglow and point-light sources in future research endeavours.…”

“…R. Soc. B 378: 20220351 [52], plant production [34], soil respiration [36] and movement activity and space use [35,38]. Such changes in processes and functions can have strong consequences for species interactions and ecological networks that constitute entire communities [53].…”

“…Notably, alterations in both physiology and behaviour can exert significant influence on fundamental ecological processes and functions [ 39 ]. Research in this issue reveals significant effects on growth and development of marine invertebrates [ 52 ], plant production [ 34 ], soil respiration [ 36 ] and movement activity and space use [ 35 , 38 ]. Such changes in processes and functions can have strong consequences for species interactions and ecological networks that constitute entire communities [ 53 ].…”