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Aulsebrook, A. E., Connelly, F., Johnsson, R. D., Jones, T. M., Mulder, R. A., Hall, M. L., et al. (2020). White and Amber Light at Night Disrupt Sleep Physiology in Birds. Curr Biol, in press.
Abstract: Artificial light at night can disrupt sleep in humans [1-4] and other animals [5-10]. A key mechanism for light to affect sleep is via non-visual photoreceptors that are most sensitive to short-wavelength (blue) light [11]. To minimize effects of artificial light on sleep, many electronic devices shift from white (blue-rich) to amber (blue-reduced) light in the evening. Switching outdoor lighting from white to amber might also benefit wildlife [12]. However, whether these two colors of light affect sleep similarly in different animals remains poorly understood. Here we show, by measuring brain activity, that both white and amber lighting disrupt sleep in birds but that the magnitude of these effects differs between species. When experimentally exposed to light at night at intensities typical of urban areas, domestic pigeons (Columba livia) and wild-caught Australian magpies (Cracticus tibicen tyrannica) slept less, favored non-rapid eye movement (NREM) sleep over REM sleep, slept less intensely, and had more fragmented sleep compared to when lights were switched off. In pigeons, these disruptive effects on sleep were similar for white and amber lighting. For magpies, however, amber light had less impact on sleep. Our results demonstrate that amber lighting can minimize sleep disruption in some birds but that this benefit may not be universal.
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Becker, D. J., Singh, D., Pan, Q., Montoure, J. D., Talbott, K. M., Wanamaker, S. M., et al. (2020). Artificial light at night amplifies seasonal relapse of haemosporidian parasites in a widespread songbird. Proc Biol Sci, 287(1935), 20201831.
Abstract: Urban habitats can shape interactions between hosts and parasites by altering not only exposure rates but also within-host processes. Artificial light at night (ALAN) is common in urban environments, and chronic exposure can impair host immunity in ways that may increase infection. However, studies of causal links between this stressor, immunity, and infection dynamics are rare, particularly in migratory animals. Here, we experimentally tested how ALAN affects cellular immunity and haemosporidian parasite intensity across the annual cycle of migrant and resident subspecies of the dark-eyed junco (Junco hyemalis). We monitored an experimental group exposed to light at night and a control group under natural light/dark cycles as they passed through short days simulating early spring to longer days simulating the breeding season, followed by autumn migration. Using generalized additive mixed models, we show that ALAN increased inflammation, and leucocyte counts were greatest in early spring and autumn. At the start of the experiment, few birds had active infections based on microscopy, but PCR revealed many birds had chronic infections. ALAN increased parasitaemia across the annual cycle, with strong peaks in spring and autumn that were largely absent in control birds. As birds were kept in indoor aviaries to prevent vector exposure, this increased parasitaemia indicates relapse of chronic infection during costly life-history stages (i.e. reproduction). Although the immunological and parasitological time series were in phase for control birds, cross-correlation analyses also revealed ALAN desynchronized leucocyte profiles and parasitaemia, which could suggest a general exaggerated inflammatory response. Our study shows how a common anthropogenic influence can shape within-host processes to affect infection dynamics.
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Dwyer, J. F., Pandey, A. K., McHale, L. A., & Harness, R. E. (2019). Near-ultraviolet light reduced Sandhill Crane collisions with a power line by 98%. Condor, 121(2), duz008.
Abstract: Midflight collisions with power lines impact 12 of the world’s 15 crane species, including 1 critically endangered species, 3 endangered species, and 5 vulnerable species. Power lines can be fitted with line markers to increase the visibility of wires to reduce collisions, but collisions can persist on marked power lines. For example, hundreds of Sandhill Cranes (Antigone canadensis) die annually in collisions with marked power lines at the Iain Nicolson Audubon Center at Rowe Sanctuary (Rowe), a major migratory stopover location near Gibbon, Nebraska. Mitigation success has been limited because most collisions occur nocturnally when line markers are least visible, even though roughly half the line markers present include glow-in-the-dark stickers. To evaluate an alternative mitigation strategy at Rowe, we used a randomized design to test collision mitigation effects of a pole-mounted near-ultraviolet light (UV-A; 380–395 nm) Avian Collision Avoidance System (ACAS) to illuminate a 258-m power line span crossing the Central Platte River. We observed 48 Sandhill Crane collisions and 217 dangerous flights of Sandhill Crane flocks during 19 nights when the ACAS was off, but just 1 collision and 39 dangerous flights during 19 nights when the ACAS was on. Thus, we documented a 98% decrease in collisions and an 82% decrease in dangerous flights when the ACAS was on. We also found a 32% decrease in the number of evasive maneuvers initiated within 25 m of the power line along the river, and a 71% increase in the number of evasive maneuvers initiated beyond 25 m when the ACAS was on. Sandhill Cranes reacted sooner and with more control, and experienced substantially fewer collisions, when the ACAS was on. Installation of the ACAS on other high-risk spans, and perhaps on other anthropogenic obstacles where birds collide, may offer a new solution to a long-running conservation dilemma.
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Sepp, T., Webb, E., Simpson, R. K., Giraudeau, M., McGraw, K. J., & Hutton, P. (2021). Light at night reduces digestive efficiency of developing birds: an experiment with king quail. Naturwissenschaften, 108(1), 4.
Abstract: Artificial light at night (ALAN) exposes animals to a novel environmental stimulus, one that is generally thought to be maladaptive. ALAN-related health problems have received little attention in non-model species, and we generally know little about the nutritional-physiological impacts of ALAN, especially in young animals. Here, we use a novel application of the acid steatocrit method to experimentally assess changes in digestive efficiency of growing king quail (Excalfactoria chinensis) in response to ALAN. Two weeks after hatching, quail were split into two groups (n = 20-21 per group): overnight-light-treated vs. overnight-dark-treated. When the chicks were 3 weeks old, the experimental group was exposed to weak blue light (ca. 0.3 lux) throughout the entire night for 6 consecutive weeks, until all the chicks had achieved sexual maturation. Fecal samples for assessing digestive efficiency were collected every week. We found that digestive efficiency of quail was reduced by ALAN at two time points from weeks 4 to 9 after hatching (quail reach adulthood by week 9). The negative effect of ALAN on digestion coincided with the period of fastest skeletal growth, which suggests that ALAN may reduce digestive efficiency when energetic demands of growth are at their highest. Interestingly, growth rate was not influenced by ALAN. This suggests that either the negative physiological impacts of ALAN may be concealed when food is provided ad libitum, the observed changes in digestive efficiency were too small to affect growth or condition, or that ALAN-exposed birds had reduced energy expenditure. Our results illustrate that the health impacts of ALAN on wild animals should not be restricted to traditional markers like body mass or growth rate, but instead on a wide array of integrated physiological traits.
Keywords: Animals; Avian; Development; Digestion; Excalfactoria chinensis; Light pollution; Steatocrit
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Yang, Y., Liu, Q., Wang, T., & Pan, J. (2020). Wavelength-specific artificial light disrupts molecular clock in avian species: A power-calibrated statistical approach. Environ Pollut, 265(Pt B), 114206.
Abstract: Nighttime lighting is an increasingly important anthropogenic environmental stress on plants and animals. Exposure to unnatural lighting environments may disrupt the circadian rhythm of organisms. However, the sample size of relevant studies, e.g. disruption of the molecular circadian clock by light pollution, was small (<10), which led to low statistical power and difficulties in replicating prior results. Here, we developed a power-calibrated statistical approach to overcome these weaknesses. The results showed that the effect size of 2.48 in clock genes expression induced by artificial light would ensure the reproducibility of the results as high as 80%. Long-wavelength light (560-660nm) entrained expressions of the positive core clock genes (e.g. cClock) and negative core clock genes (e.g. cCry1, cPer2) in robust circadian rhythmicity, whereas those clock genes were arrhythmic in short-wavelength light (380-480nm). Further, we found artificial light could entrain the transcriptional-translational feedback loop of the molecular clock in a wavelength-dependent manner. The expression of the positive core clock genes (cBmal1, cBmal2 and cClock), cAanat gene and melatonin were the highest in short-wavelength light and lowest in long-wavelength light. For the negative regulators of the molecular clock (cCry1, cCry2, cPer2 and cPer3), the expression of which was the highest in long-wavelength light and lowest in short-wavelength light. Our statistical approach opens new opportunities to understand and strengthen conclusions, comparing with the studies with small sample sizes. We also provide comprehensive insight into the effect of wavelength-specific artificial light on the circadian rhythm of the molecular clock in avian species. Especially, the global lighting is shifting from “yellow” sodium lamps, which is more like the long-wavelength light, toward short-wavelength light (blue light)-enriched “white” light-emitting diodes (LEDs).
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