|
|
Cabrera-Cruz, S. A., Smolinsky, J. A., McCarthy, K. P., & Buler, J. J. (2019). Urban areas affect flight altitudes of nocturnally migrating birds. J Anim Ecol, in press.
Abstract: 1.Urban areas affect terrestrial ecological processes and local weather, but we know little about their effect on aerial ecological processes. 2.Here, we identify urban from non-urban areas based on the intensity of artificial light at night (ALAN) in the landscape, and, along with weather covariates, evaluate the effect of urbanization on flight altitudes of nocturnally migrating birds. 3.Birds are attracted to ALAN, hence we predicted that altitudes would be lower over urban than over non-urban areas. However, other factors associated with urbanization may also affect flight altitudes. For example, surface temperature and terrain roughness are higher in urban areas, increasing air turbulence, height of the boundary layer, and affecting local winds. 4.We used data from nine weather surveillance radars in the eastern US to estimate altitudes at five quantiles of the vertical distribution of birds migrating at night over urban and non-urban areas during five consecutive spring and autumn migration seasons. We fit generalized linear mixed models by season for each of the five quantiles of bird flight altitude and their differences between urban and non-urban areas. 5.After controlling for other environmental variables and contrary to our prediction, we found that birds generally fly higher over urban areas compared to rural areas in spring, and marginally higher at the mid layers of the vertical distribution in autumn. We also identified a small interaction effect between urbanization and crosswind speed, and between urbanization and surface air temperature, on flight altitudes. We also found that the difference in flight altitudes of nocturnally migrating birds between urban and non-urban areas varied among radars and seasons, but were consistently higher over urban areas throughout the years sampled. 6.Our results suggest that the effects of urbanization on wildlife extend into the aerosphere, and are complex, stressing the need of understanding the influence of anthropogenic factors on airspace habitat. This article is protected by copyright. All rights reserved.
|
|
|
|
Clewley, G. D., Plummer, K. E., Robinson, R. A., Simm, C. H., & Toms, M. P. (2015). The effect of artificial lighting on the arrival time of birds using garden feeding stations in winter: A missed opportunity? Urban Ecosystems, 19(2), 535–546.
Abstract: The proliferation of artificial lighting at night is one of the key anthropogenic changes associated with urbanised areas as well as some non-urban areas. Disruption to natural light/dark regimes can have considerable effects on the timing of different behaviours of birds, particularly during the breeding season. However, the effect of artificial lights on the timing of behaviours during winter has received relatively little attention, despite the fact that time partitioning of foraging can have implications for avian winter survival. In this study, we assess at a landscape scale during winter, whether birds arrive at feeding stations earlier in areas with increased levels of artificial lighting using data from a citizen science project. Arrival times of the ten most commonly recorded species were associated with a combination of the density of artificial lights, temperature, rainfall and urban land cover. We found no evidence that birds advance the onset of foraging in gardens with more artificial lights nearby; contrary to our prediction, birds generally arrived later into these areas. This is possibly a response to differences in food availability or predation risk in areas with more artificial lights. We conclude that artificial light at night may not be as important for driving the timing of foraging behaviour in winter as previously thought, but it remains to be seen whether this represents a missed opportunity to extend the foraging period or an adaptive response.
|
|
|
|
Dominoni, D. M., & Partecke, J. (2015). Does light pollution alter daylength? A test using light loggers on free-ranging European blackbirds (Turdus merula). Philos Trans R Soc Lond B Biol Sci, 370, 20140118.
Abstract: Artificial light at night is one of the most apparent environmental changes accompanying anthropogenic habitat change. The global increase in light pollution poses new challenges to wild species, but we still have limited understanding of the temporal and spatial pattern of exposure to light at night. In particular, it has been suggested by several studies that animals exposed to light pollution, such as songbirds, perceive a longer daylength compared with conspecifics living in natural darker areas, but direct tests of such a hypothesis are still lacking. Here, we use a combination of light loggers deployed on individual European blackbirds, as well as automated radiotelemetry,to examine whether urban birds are exposed to a longer daylength than forest counterparts. We first used activity data from forest birds to determine the level of light intensity which defines the onset and offset of daily activity in rural areas. We then used this value as threshold to calculate the subjective perceived daylength of both forest and urban blackbirds. In March, when reproductive growth occurs, urban birds were exposed on average to a 49-min longer subjective perceived daylength than forest ones, which corresponds to a 19-day difference in photoperiod at this time of the year. In the field, urban blackbirds reached reproductive maturity 19 day earlier than rural birds, suggesting that light pollution could be responsible of most of the variation in reproductive timing found between urban and rural dwellers. We conclude that light at night is the most relevant change in ambient light affecting biological rhythms in avian urban-dwellers, most likely via a modification of the perceived photoperiod.
|
|
|
|
Dominoni, D. M., Helm, B., Lehmann, M., Dowse, H. B., & Partecke, J. (2013). Clocks for the city: circadian differences between forest and city songbirds. Proc Biol Sci, 280(1763), 20130593.
Abstract: To keep pace with progressing urbanization organisms must cope with extensive habitat change. Anthropogenic light and noise have modified differences between day and night, and may thereby interfere with circadian clocks. Urbanized species, such as birds, are known to advance their activity to early morning and night hours. We hypothesized that such modified activity patterns are reflected by properties of the endogenous circadian clock. Using automatic radio-telemetry, we tested this idea by comparing activity patterns of free-living forest and city European blackbirds (Turdus merula). We then recaptured the same individuals and recorded their activity under constant conditions. City birds started their activity earlier and had faster but less robust circadian oscillation of locomotor activity than forest conspecifics. Circadian period length predicted start of activity in the field, and this relationship was mainly explained by fast-paced and early-rising city birds. Although based on only two populations, our findings point to links between city life, chronotype and circadian phenotype in songbirds, and potentially in other organisms that colonize urban habitats, and highlight that urban environments can significantly modify biologically important rhythms in wild organisms.
|
|
|
|
Dunnett, O.,. (2014). Contested landscapes: the moral geographies of light pollution in Britain. Cultural Geographies, 22(4). Retrieved October 15, 2019, from http://cgj.sagepub.com/content/early/2014/07/17/1474474014542746.abstract
Abstract: This paper considers the concept of light pollution and its connections to moral geographies of landscape in Britain. The paper aims to provide a greater understanding of light pollution in the present day, where the issue connects to policy debates about energy efficiency, crime, health, ecology and night time aesthetics, whilst also engaging with new areas of research in cultural geography. The main sources of investigation are the Campaign to Protect Rural England and the British Astronomical Association’s Campaign for Dark Skies (est. 1990). Using interviews, archival and textual analysis, the paper examines this anti-light-pollution lobby, looking at the lead-up to the formation of the Campaign as well as its ongoing influence. A moral geography of light pollution is identified, drawing on two interconnected discourses – a notion of the ‘astronomical sublime’ and the problem of urbanization. Whilst the former is often invoked, both through visual and linguistic means, by anti-light pollution campaigners, the latter is characterized as a threat to clear night skies, echoing earlier protests against urban sprawl. Complementing a growing area of research, the geographies of light and darkness, this paper considers the light pollution lobby as a way of investigating the fundamental relationship between humankind and the cosmos in the modern age.
|
|
