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Dominoni, D. M., Carmona-Wagner, E. O., Hofmann, M., Kranstauber, B., & Partecke, J. (2014). Individual-based measurements of light intensity provide new insights into the effects of artificial light at night on daily rhythms of urban-dwelling songbirds. J Anim Ecol, 83(3), 681–692.
Abstract: Summary
The growing interest in the effects of light pollution on daily and seasonal cycles of animals has led to a boost of research in recent years. In birds, it has been hypothesized that artificial light at night can affect daily aspects of behaviour, but one caveat is the lack of knowledge about the light intensity that wild animals, such as birds, are exposed to during the night. Organisms have naturally evolved daily rhythms to adapt to the 24-h cycle of day and night, thus, it is important to investigate the potential shifts in daily cycles due to global anthropogenic processes such as urbanization. We captured adult male European blackbirds (Turdus merula) in one rural forest and two urban sites differing in the degree of anthropogenic disturbance. We tagged these birds with light loggers and simultaneously recorded changes in activity status (active/non-active) through an automated telemetry system. We first analysed the relationship between light at night, weather conditions and date with daily activity onset and end. We then compared activity, light at night exposure and noise levels between weekdays and weekends. Onset of daily activity was significantly advanced in both urban sites compared to the rural population, while end of daily activity did not vary either among sites. Birds exposed to higher amounts of light in the late night showed earlier onset of activity in the morning, but light at night did not influence end of daily activity. Light exposure at night and onset/end of daily activity timing was not different between weekdays and weekends, but all noise variables were. A strong seasonal effect was detected in both urban and rural populations, such as birds tended to be active earlier in the morning and later in the evening (relative to civil twilight) in the early breeding season than at later stages. Our results point at artificial light at night as a major driver of change in timing of daily activity. Future research should focus on the costs and benefits of altered daily rhythmicity in birds thriving in urban areas. |
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Grenis, K., Tjossem, B., & Murphy, S. (2015). Predation of larval Lepidoptera in habitat fragments varies spatially and temporally but is not affected by light pollution. J. of Insect Cons., 19(3), 559–566.
Abstract: As human populations continue to expand, many more species are affected by habitat fragmentation and urbanization. One of the most common themes in studies of fragmented habitats is finding higher rates of predation along habitat edges. However, field studies supporting this pattern are heavily influenced by avian literature and may not apply similarly to other organisms, such as invertebrates. Field studies of predation are typically performed during the day or do not distinguish between day and night; these studies therefore overlook daily fluctuations in predation and may miss important effects that occur solely at night, such as light pollution from streetlights. We tested whether predation of larval Lepidoptera differed between edge and core habitats and also whether predation along the habitat edge varied in response to light pollution from streetlights. We placed larvae in the core of suburban habitat patches and along the habitat edge, both under streetlights as well as between streetlights where it was dark. We found that predation rate increased in both edge and core habitats over the summer. Early season, we found daily fluctuations in predation dynamics with greater predation along the habitat edge than in the habitat core during the day, but not at night. Additionally, we found that streetlights did not affect predation rate along the habitat edge. Our results suggest that increased predation along habitat edges may be a diurnal effect.
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Kamrowski, R. L., Limpus, C., Jones, R., Anderson, S., & Hamann, M. (2013). Temporal changes in artificial light exposure of marine turtle nesting areas. Glob Chang Biol, 20(8), 2437–2449.
Abstract: Artificial light at night poses a significant threat to multiple taxa across the globe. In coastal regions, artificial lighting close to marine turtle nesting beaches is disruptive to their breeding success. Prioritizing effective management of light pollution requires an understanding of how the light exposure of nesting areas changes over time in response to changing temporal and spatial distributions of coastal development. We analyzed multitemporal, satellite night-light data, in combination with linear mixed model analysis, to determine broadscale changes in artificial light exposure at Australian marine turtle nesting areas between 1993 and 2010. We found seven marine turtle management units (MU), from five species, have experienced significant increases in light exposure over time, with flatback turtles nesting in east Australia experiencing the fastest increases. The remaining 12 MUs showed no significant change in light exposure. Unchanging MUs included those previously identified as having high exposure to light pollution (located in western Australia and southern Queensland), indicating that turtles in these areas have been potentially exposed to high light levels since at least the early nineties. At a finer geographic scale (within-MU), nine MUs contained nesting areas with significant increases in light exposure. These nesting areas predominantly occurred close to heavily industrialized coastal areas, thus emphasizing the importance of rigorous light management in industry. Within all MUs, nesting areas existed where light levels were extremely low and/or had not significantly increased since 1993. With continued coastal development, nesting females may shift to these darker/unchanging 'buffer' areas in the future. This is valuable information that informs our understanding of the capacity and resilience of marine turtles faced with coastal development: an understanding that is essential for effective marine turtle conservation.
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Zele, A. J., & Cao, D. (2014). Vision under mesopic and scotopic illumination. Front Psychol, 5, 1594.
Abstract: Evidence has accumulated that rod activation under mesopic and scotopic light levels alters visual perception and performance. Here we review the most recent developments in the measurement of rod and cone contributions to mesopic color perception and temporal processing, with a focus on data measured using a four-primary photostimulator method that independently controls rod and cone excitations. We discuss the findings in the context of rod inputs to the three primary retinogeniculate pathways to understand rod contributions to mesopic vision. Additionally, we present evidence that hue perception is possible under scotopic, pure rod-mediated conditions that involves cortical mechanisms.
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