Anthropogenic/artificial light at night (ALAN) may have detrimental effects on individual organisms, ecosystem structure and integrity, and human sleep and circadian rhythms. The wavelength dependence of diverse biological photosensory systems is thus an appropriate consideration when quantifying ALAN. We propose spectral weighting functions for biological detection in animals (BA(λ)) and all organisms (BE(λ)) based on established features of biological spectral sensitivity. Light metrics employing B(λ) provide a biologically relevant way to measure ALAN and evaluate solutions to reduce it through spectral tuning.

Light pollution, an increasingly recognized environmental hazard, disrupts urban ecosystems, including plant phenology, such as leaf-out and senescence. In recent years, municipalities have enacted legislation to reduce artificial light at night (ALAN) at city levels. However, the effectiveness of these mitigation strategies on reducing ALAN and their impacts on urban ecosystems remain underexplored. Here, we present a proof of concept analysis to explore the potential of ALAN-mitigation policies on changes in intensity and spectrum composition of ALAN and consequent changes in plant phenology using Sustainable Development Science Satellite 1 data for 2022-2024 in paired US cities-one with mitigation policies and one without. Results suggest that ALAN declined in cities with ALAN-mitigation policies (New York City and Washington DC), with the largest decline in blue band. In contrast, ALAN increased in cities without policies (Newark and Philadelphia). The reduction in shifts of spring and autumn phenology observed in cities with mitigation was consistent with declines in ALAN exposure. These findings highlight the potential of multispectral nighttime light data in quantitatively assessing the efficacy of ALAN-mitigation policies in reducing light pollution and its ecological impacts.

Predicting the adverse effects of light at night is necessary to ensure compliance with laws and regulations that protect species. Using two case studies, we developed a method to map the impacts of roadway lighting on two endangered species using software widely available and used in lighting engineering and conservation planning. We calculated vertical and horizontal illuminance at each site and converted the values based on the spectral sensitivity of the species and the spectral composition of the lamps. We mapped illumination in equivalent moonlight illuminance (lux), meaning the illumination is as bright as the same amount of moonlight would appear to the organism, once the spectral sensitivity of the organism is considered, proposing a threshold for adverse impacts at 0.01 and 0.1 moonlight equivalent illuminance. Finally, we compared as-built lamps to lamps with other spectral compositions and calculated illumination that would result from use of commercially available shields. Although this workflow was feasible, improvements in software and characterization of species spectral responses is needed. Nevertheless, spectral tuning reduced the impact area for both species (8-19% and 21-25%). Shielding reduced the impact area for one case study by focusing light more closely on the roadways, but for the other site the available shields increased high-angle forward light emissions. The results demonstrate an approach to calculate the effects of new lights and to analyze benefits of spectral tuning, shielding, or reduction in light intensity that could be further refined through both basic ecological research and software development.

A complete genome assembly for the endangered Apodemia mormo langei (Lange’s Metalmark Butterfly) (Comstock, J.A. 1938) is reported here. Illumina short-read sequencing was performed using tissue from a single deceased individual. The selected specimen was a foundress individual collected directly from the wild population prior to captive propagation, minimizing the potential influence of captive breeding, genetic drift, or artificial selection on genomic patterns. This reference genome is an important resource for studying this presumably extinct dune-endemic butterfly.

Domestic cats (Felis catus) kill an estimated 1.3–4.0 billion birds annually in the United States and are a major source of mortality for urban birds. While their lethal impacts are well documented, fewer studies address sublethal effects such as changes in avian risk assessment. We analyzed a dataset of 1,120 experimental approaches by human observers on 48 bird species across 11 sites in the Los Angeles metropolitan area, which varied in free-roaming cat and human population densities. Using Bayesian mixed models, we examined ecological and intrinsic predictors of avian flight initiation distance (FID). At the community scale, cat and human population densities had no significant effects on FID, suggesting that predator and human presence may already exceed a threshold across the urban landscape beyond which additional variation does not produce detectable changes in avian escape behavior. Species-specific analyses revealed that black phoebe (Sayornis nigricans) FID increased with human population density. We found no community-level interaction effect of human density and cat density, but house finches (Carpodacus mexicanus) and rock pigeons (Columba livia) tolerated closer approaches in areas with both high human and cat density, suggesting that habituation to humans may lower perceived predation risk for some urban species. Heavier species, ground-foraging individuals, and actively foraging birds had shorter FIDs. Birds also flushed at greater distances as the time of day progressed. These results highlight the complex interplay of intrinsic and environmental factors shaping avian escape behavior and underscore how behavioral adaptation in megacities may alter predator–prey dynamics in urban landscapes.

Climate change, combined with the Urban Heat Island effect, will generate more frequent, intense extreme heat events. These events can induce heat stroke, organ damage, and death, especially in lower-income communities, communities of color, and people with chronic health conditions. Research demonstrates parks mitigate extreme heat and combat Urban Heat Island effects locally. To investigate how parks provide heat relief in Los Angeles County, California, we compared park use on extreme heat and control days from the summer of 2017. Our research uses big spatial datasets from smartphone devices to describe broad park use. We intersected anonymous smartphone geolocation data with county parks and census tract layers, then analyzed how the time of day, day of week, and park amenities influenced visitation. Then, we assigned users location-based social sensitivity indices using nighttime locations to explore demographic influence on park use. We found 1) park attendance decreased during extreme heat, 2) temporal convenience, rather than cooling amenities, influenced park use, and 3) users were more likely to visit parks with similar social sensitivity scores as their residence. Our results highlight the influence of social factors above extreme heat on park user behavior. We recommend that city planners focus on equitably and creatively distributing blue and green cooling amenities to communities (i.e. areas of convenience, common daily routes), rather than enhancing parks specifically.

Vulnerability to environmental hazards is spatially heterogeneous and dynamic. Static measures that are used to determine spatial heterogeneity in vulnerability are unable to capture temporal dynamics. To complement research on vulnerability to extreme heat, we investigated temporal and spatial trends in availability and use of shade by pedestrians during extreme heat events in a vulnerable neighborhood. Shade from trees and buildings calculated from LiDAR were paired with smartphone locations filtered to include outdoor pedestrians on an hourly basis for control and extreme heat days to study behavioral patterns for neighborhood residents, non-residents, and the unhoused population. High-use pedestrian locations showed little difference in activity between control and extreme heat days, especially during weekdays, but with greater variation on weekends. The results indicate inflexibility in space use, even during extreme heat. Outdoor heat mitigation strategies should consider bringing shade to the people in heavily used locations, as pedestrian behavior is inelastic.

Numerous declines have been documented across insect groups, and the potential consequences of insect losses are dire. Butterflies are the most surveyed insect taxa, yet analyses have been limited in geographic scale or rely on data from a single monitoring program. Using records of 12.6 million individual butterflies from >76,000 surveys across 35 monitoring programs, we characterized overall and species-specific butterfly abundance trends across the contiguous United States. Between 2000 and 2020, total butterfly abundance fell by 22% across the 554 recorded species. Species-level declines were widespread, with 13 times as many species declining as increasing. The prevalence of declines throughout all regions in the United States highlights an urgent need to protect butterflies from further losses.

Plant growing seasons are largely regulated by light and temperature. Cities are increasingly hot (higher air temperature), from the urban heat island effect, and bright (artificial light at night, ALAN). However, the relative effect of heat and light on the timing of plant growth events, called phenology, is unclear, limiting our understanding under climate change and urbanization. Here we used multiple satellite observations of 428 Northern Hemisphere cities from 2014 to 2020 to analyze phenological patterns along a gradient from rural to urban. We found that ALAN increased exponentially toward urban centers, and exerted stronger influence than air temperature in lengthening the urban growing season, especially by delaying its end, although the effects varied across climate zones. Our findings demonstrate that ALAN is a critical driver of vegetation dynamics in cities, one we should consider during urban management and development.

Changes in phenology are a common response to climate change, but their impact on population dynamics is often ambiguous and at-risk species are omitted from most analyses. We assessed the relationship between change in abundance and change in phenology for 114 butterfly populations of 31 at-risk species from five families in 10 US states. We used data from Pollard-walk and similar monitoring programmes for which count data were collected on multiple occasions per year. We also collected information from managers on site-level management interventions. To estimate abundance, we first fit separate smoothing splines for each species at each site. Yearly abundance was estimated as the area under the activity curve for that year, and from this, we estimated abundance trends over the period for which we had population data. Phenological shifts were measured as the changes in median activity date, beginning of flight season, duration of flight season and phenological constancy (negative of the magnitude of trends in median activity date). We also evaluated the association of ecological traits (voltinism, diet breadth, position within geographic range, ecoregion, overwintering stage and seasonality) and management (proportion of years with interventions) with trends in abundance and in phenology. Across all populations, the estimated trend in abundance was -0.085, equivalent to an 8.1% decline/year. Positive trends in abundance were associated with smaller shifts in the median flight date (higher constancy). We also found strong associations between trends in abundance and management interventions, with increased management associated with increasing abundance trends. In general, ecological traits were not strongly associated with trends in phenology or trends in abundance. Synthesis and applications: Populations with less phenological constancy are more likely to be rapidly declining and populations with more frequent management interventions are increasing. These results suggest that one key outcome of management interventions may be to mitigate some of the impacts of climate change, which in turn may contribute to higher population growth. These results also imply that managers may need to alter the timing of appropriate management to synchronize with activities of at-risk species as species shift their phenology. Populations with less phenological constancy are more likely to be rapidly declining and populations with more frequent management interventions are increasing. These results suggest that one key outcome of management interventions may be to mitigate some of the impacts of climate change, which in turn may contribute to higher population growth. These results also imply that managers may need to alter the timing of appropriate management to synchronize with activities of at-risk species as species shift their phenology.image

Anthropogenic light at night disrupts natural patterns of light and darkness, and the color of light that have been reliable over geological time. Such changes in the environment result in nonadaptive responses from species and disruption of daily, lunar, and annual rhythms. The range of impacts of light pollution on biodiversity include interference with movement, interspecific interactions, sleep and daily rhythms, reproduction, development, gene expression, and stress and fear responses. Design principles are available to guide deployment of light at night to reduce, but not eliminate, adverse impacts on biodiversity arising from the human production of light at night.

ABSTRACT The influence of light spectral properties on circadian rhythms is of substantial interest to laboratory-based investigation of the circadian system and to field-based understanding of the effects of artificial light at night. The trade-offs between intensity and spectrum regarding masking behaviors are largely unknown, even for well-studied organisms. We used a custom LED illumination system to document the response of wild-type house mice (Mus musculus) to 1-h nocturnal exposure of all combinations of four intensity levels (0.01, 0.5, 5 and 50 lx) and three correlated color temperatures (CCT; 1750, 1950 and 3000 K). Higher intensities of light (50 lx) suppressed cage activity substantially, and consistently more for the higher CCT light (91% for 3000 K, 53% for 1750 K). At the lowest intensity (0.01 lx), mean activity was increased, with the greatest increases for the lowest CCT (12.3% increase at 1750 K, 3% increase at 3000 K). Multiple linear regression confirmed the influence of both CCT and intensity on changes in activity, with the scaled effect size of intensity 3.6 times greater than that of CCT. Activity suppression was significantly lower for male than for female mice. Assessment of light-evoked cFos expression in the suprachiasmatic nucleus at 50 lx showed no significant difference between high and low CCT exposure. The significant differences by spectral composition illustrate a need to account for light spectrum in circadian studies of behavior, and confirm that spectral controls can mitigate some, but certainly not all, of the effects of light pollution on species in the wild.

The Home Owners' Loan Corporation (HOLC) was a U.S. government-sponsored program initiated in the 1930s to evaluate mortgage lending risk. The program resulted in hand-drawn "security risk" maps intended to grade sections of cities where investment should be focused (greenlined areas) or limited (redlined zones). The security maps have since been widely criticized as being inherently racist and have been associated with high levels of segregation and lower levels of green amenities in cities across the country. Our goal was to explore the potential legacy effects of the HOLC grading practice on birds, their habitat, and the people who may experience them throughout a metropolis where the security risk maps were widely applied, Greater Los Angeles, California (L.A.). We used ground-collected, remotely sensed, and census data and descriptive and predictive modeling approaches to address our goal. Patterns of bird habitat and avian communities strongly aligned with the luxury-effect phenomenon, where green amenities were more robust, and bird communities were more diverse and abundant in the wealthiest parts of L.A. Our analysis also revealed potential legacy effects from the HOLC grading practice. Associations between bird habitat features and avian communities in redlined and greenlined zones were generally stronger than in areas of L.A. that did not experience the HOLC grading, in part because redlined zones, which included some of the poorest locations of L.A., had the highest levels of dense urban conditions (e.g., impervious surface cover), whereas greenlined zones, which included some of the wealthiest areas of the city, had the highest levels of green amenities (e.g., tree canopy cover). The White population of L.A., which constitutes the highest percentage of a racial or ethnic group in greenlined areas, was aligned with a considerably greater abundance of birds affiliated with natural habitat features (e.g., trees and shrubs). Conversely, the Hispanic or Latino population, which is dominant in redlined zones, was positively related to a significantly greater abundance of synanthropic birds, which are species associated with dense urban conditions. Our results suggest that historical redlining and contemporary patterns of income inequality are associated with distinct avifaunal communities and their habitat, which potentially influence the human experience of these components of biodiversity throughout L.A. Redlined zones and low-income residential areas that were not graded by the HOLC can particularly benefit from deliberate urban greening and habitat enhancement projects, which would likely carry over to benefit birds and humans. center dot Redlining was a racially biased investment and lending practice established in the 1930s and applied in 239 cities across the United States.center dot The program was terminated in 1968 but has since been linked with strong segregation of human communities, wealth, and green amenities in cities nationwide.center dot In Greater Los Angeles, California, redlining continues to be negatively related to avian community patterns, their habitat and the people who may experience them.center dot Luxury-effect patterns, where biodiversity is positively associated with affluence, largely predicted avifaunal patterns in Greater Los Angeles center dot Legacy-effect patterns due to historical redlining also showed strong relationships and patterns of bird habitat and community composition, suggesting the practice is potentially a powerful force structuring contemporary urban avifauna and human communities.center dot Careful yet deliberate action in urban greening could likely benefit birds and humans in redlined zones and other low-income areas of Greater Los Angeles. La Corporacion de Prestamos para Propietarios de Hogares (HOLC, por sus siglas en ingles) fue un programa patrocinado por el gobierno de EEUU, iniciado en la decada de 1930, para evaluar el riesgo en la concesion de hipotecas. El programa resulto en la creacion de mapas de "riesgo de seguridad" dibujados a mano, destinados a clasificar secciones de ciudades donde la inversion deberia centrarse (areas resaltadas en verde) o limitarse (zonas marcadas en rojo). Los mapas de seguridad han sido ampliamente criticados posteriormente por ser inherentemente racistas y se han asociado con altos niveles de segregacion y niveles mas bajos de comodidades verdes en ciudades de todo el pais. Nuestro objetivo fue explorar los posibles efectos heredados de la practica de calificacion de HOLC en las aves, su habitat y en las personas que podrian experimentarlos, en toda una metropolis donde los mapas de riesgo de seguridad se aplicaron ampliamente, el Gran Los angeles, California (L.A.). Utilizamos datos recopilados en el terreno, obtenidos de forma remota y censales, junto con enfoques descriptivos y de modelado predictivo, para abordar nuestro objetivo. Los patrones de habitat de las aves y de las comunidades de aves se alinearon fuertemente con el fenomeno del efecto de lujo, en el que las comodidades verdes fueron mas solidas y las comunidades de aves fueron mas diversas y abundantes en las partes mas ricas de L.A. Nuestro analisis tambien revelo posibles efectos heredados de la practica de calificacion de HOLC. Las asociaciones entre las caracteristicas del habitat de las aves y las comunidades de aves en las zonas marcadas en rojo y verde fueron generalmente mas fuertes que en las areas de L.A. que no experimentaron la calificacion de HOLC, en parte porque las zonas marcadas en rojo, que incluian algunas de las ubicaciones mas pobres de L.A., tuvieron los niveles mas altos de condiciones urbanas densas, como la cobertura de superficie impermeable, mientras que las zonas marcadas en verde, que incluian algunas de las areas mas ricas de la ciudad, tuvieron los niveles mas altos de comodidades verdes, como la cobertura de dosel arboreo. La poblacion blanca de L.A., que constituye el mayor porcentaje de un grupo racial o etnico en las areas resaltadas en verde, se correspondio con una abundancia considerablemente mayor de aves afiliadas a caracteristicas de habitat natural (e.g., arboles y arbustos). Por el contrario, la poblacion hispana o latina, que es dominante en las zonas marcadas en rojo, estuvo relacionada positivamente con una abundancia significativamente mayor de aves sinantropicas, que son especies asociadas con condiciones urbanas densas. Nuestros resultados sugieren que la discriminacion historica en la delimitacion de zonas y los patrones contemporaneos de desigualdad de ingresos estan asociados con comunidades de avifauna distintas y con sus habitats, lo que potencialmente influye en la experiencia humana de estos componentes de la biodiversidad en todo L.A. La delimitacion de zonas marcadas en rojo y las areas residenciales de bajos ingresos que no fueron calificadas por HOLC pueden beneficiarse especialmente de proyectos dirigidos al enverdecimiento urbano y a la mejora de habitat, que probablemente a su vez beneficiaran a las aves y los humanos.

INTRODUCTION:Several frameworks exist to measure vulnerability to extreme heat events using a health equity approach, but little evidence validates these measures and their applications. We investigated the degree to which social vulnerability measures and their constituent elements correlate with excess emergency room visits as an outcome measure. METHODS:The relationship between six commonly used social vulnerability indicators and measured excess emergency room visit rates (processed by including heat-related illnesses and all-internal causes diagnosis, with considerations for age and heat days) was tested through geospatial analytics and statistical regressions, for both California and Los Angeles County. RESULTS:The vulnerability indicators and the outcome measure were significantly positively associated at the census tract-level but weaker (∼0.2 rs) at the scale of California and stronger (∼0.6 rs) at the scale of Los Angeles County. Hazard-specific vulnerability indicators showed stronger relationships with outcome measures regardless of scale. A Poisson regression model showed a significant inter-county variation, indicating the importance of localized assessments for equitable environmental policies. CONCLUSION:The findings identify communities that are overburdened by heat and pollution and highlight the need for use of both social vulnerability and indicators of adverse outcomes from excessive heat. Patterns are found across all measures that suggest that populations facing accessibility barriers may be less likely to visit emergency rooms. This suggestion needs to be tested in other environmental settings to draw broader conclusions but has direct implications for environmental scientists and mitigation planners who use these methods.

Previous articleNext article No AccessConservation BiologyThe Hidden Universe: Adventures in Biodiversity. By Alexandre Antonelli. Chicago (Illinois): University of Chicago Press. $22.00. xi + 276 p.; ill.; index. ISBN: 978-0-226-82187-0 (hc); 978-0-226-82188-7 (eb). 2022.Travis LongcoreTravis LongcoreInstitute of the Environment & Sustainability, University of California, Los Angeles, California Search for more articles by this author PDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmailPrint SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 98, Number 3September 2023 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/726478 Views: 7Total views on this site For permission to reuse, please contact [email protected].PDF download Crossref reports no articles citing this article.

The presence and proportions of photopigments, which are responsible for the visual and physiological effects of light, vary between taxonomic groups. This leads to differing wavelength sensitivities ranging from ultraviolet (UV; <400 nm) to infrared (IR; >780 nm) and complicates the balancing of spectra used for outdoor lighting to maximize human visual performance while mitigating light pollution effects on wildlife. I developed a database of spectral response information for terrestrial wildlife to create generalized spectral response curves by taxonomic phylum, class, and order. Existing data on species visual sensitivity were collected from previously published research that used behavioral responses, electroretinograms (ERGs), and reflectance within the eye. Resulting summaries of photopigment peak sensitivities (n=968) and sensitivity curves (n=177) allow for general observations. Overall, longer wavelengths provide the highest possibility for supporting human visual performance at night while reducing intrusive overlap with the vision of other species, because many taxonomic groups are sensitive to light in the blue and into the ultraviolet. Comparison of average response curves at the class level and the spectral power distribution of lamps suggests that spectral tuning might reduce the apparency of the lowest correlated color temperature (CCT) lamps to insects, spiders, and non-human mammals the most, with substantial but smaller reductions for reptiles, birds, and amphibians. Spectral tuning, most simply by reducing CCT, should be considered an additional benefit to be used in concert with other mitigation measures such as dimming, shielding, and part-night lighting.

Fugitive dust emissions play an important role in urban air quality. Much research on fugitive dust's effects has focused on human health and societal impacts, with limited work investigating effects on other species. The endangered Apodemia mormo langei butterfly is endemic to the Antioch Dunes, a small area on the south bank of the San Joaquin River in northern California, largely protected as a National Wildlife Refuge. Between the two protected portions of the dunes is a gypsum processing facility. Deposition of gypsum dust may adversely affect endangered insects, especially in their vulnerable larval life stage. Persistent westerly winds blow from the western section of the refuge, across the industrial facility, to the eastern protected dune area. Ambient particulate matter (PM) was collected at 30 sites in both sections of the refuge using passive samplers deployed at times matching the butterfly life cycle. The prevailing wind maintained upwind-downwind sampling orientation throughout the study. PM samples were analyzed for total mass, and elemental composition via X-ray fluorescence. Downwind concentrations of gypsum-related elements were between 4 (strontium) and 12 (sulfur) times higher than upwind loadings, suggesting deposition of PM from the gypsum facility. The effect of fugitive emissions was strongest at the industrial facility's fenceline, closest to a conveyor belt that loads gypsum. Combined with documented reductions in insect larval longevity when exposed to gypsum dust, the results suggest that gypsum deposition may be affecting the ecosystem and endangered species in the downwind unit of the Antioch Dunes National Wildlife Refuge.Implications: Fugitive dust has impacts not only on humans, but on other organisms. The Antioch Dunes National Wildlife Refuge (ADNWR) in California, set aside to protect the endangered Apodemia mormo langei butterfly, consists of two land units separated by a gypsum processing facility in between them. In this study, we demonstrate fugitive gypsum dust deposition on the downwind unit of the ADNWR, which may impact the endangered butterfly and its ecosystem.

According to archaeological records, chickpea (Cicer arietinum) was first domesticated in the Fertile Crescent about 10,000 years BP. Its subsequent diversification in Middle East, South Asia, Ethiopia, and the Western Mediterranean, however, remains obscure and cannot be resolved using only archeological and historical evidence. Moreover, chickpea has two market types: "desi" and "kabuli," for which the geographic origin is a matter of debate. To decipher chickpea history, we took the genetic data from 421 chickpea landraces unaffected by the green revolution and tested complex historical hypotheses of chickpea migration and admixture on two hierarchical spatial levels: within and between major regions of cultivation. For chickpea migration within regions, we developed popdisp, a Bayesian model of population dispersal from a regional representative center toward the sampling sites that considers geographical proximities between sites. This method confirmed that chickpea spreads within each geographical region along optimal geographical routes rather than by simple diffusion and estimated representative allele frequencies for each region. For chickpea migration between regions, we developed another model, migadmi, that takes allele frequencies of populations and evaluates multiple and nested admixture events. Applying this model to desi populations, we found both Indian and Middle Eastern traces in Ethiopian chickpea, suggesting the presence of a seaway from South Asia to Ethiopia. As for the origin of kabuli chickpeas, we found significant evidence for its origin from Turkey rather than Central Asia.

Anthropogenic light at night (ALAN) has pervasive ecological effects on species, habitats, and ecosystems. Research into the impact of ALAN has increased dramatically in the past decade, however, we find (through a literature review of 341 publications) a troubling lack of consistency and conceptual organization in the measurement of night-time light and related organismal responses. To address this, we propose a holistic framework that considers space, time, taxonomic uniqueness, and the physics of light. Principally, we suggest that light measurements should both match the mechanism of influence and the unique photoreceptor system of the organism being studied. Anthropogenic light at night is continuing to increase globally, as are its impacts on organisms and biodiversity (from genes to ecosystems). A measurement framework for disentangling the loss of natural night-time darkness and disruption of ecological systems provides a deeper insight into the nature of these relationships and is important for establishing paths forward in the face of intensifying global change.

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'.