Newswise — Light pollution is on everyone’s minds in Reno, Nevada, a city famous for its bright lights and nightlife. Nighttime light pollution is a growing concern for cities worldwide. Artificial light at night has been found to cause serious health effects including disrupting our sleep-wake cycle –our circadian rhythm.
Our local wildlife and their circadian rhythms are affected by light pollution just like humans. Valentina Alaasam, a graduate student in Dr. Jenny Ouyang’s lab at University of Nevada, Reno, is studying a small bird, the zebra finch, to better understand how cities affect the biology of urban wildlife. Their findings suggest that light pollution changes everything from the bird’s behavior to its underlying physiology. In the most scientifically precise meaning of the term, the birds are stressed out. Their results of their research will be presented at the annual meeting of the Society for Integrative and Comparative Biology in Tampa, FL.
Take a step back from birds for a moment and imaging yourself in the lighting isle of your local hardware store. There is a plethora of lights of different sizes, brightness, and “temperatures,” or whiteness to choose from. Because of their lower energy requirements and longevity, LED bulbs are filling more shelf space than they once did. With such a selection there is much to learn about the ways different lighting options affect wildlife. Alaasam’s study found that different temperatures of commercially available LEDs affect wildlife differently – cooler temperature lights, those that best replicate natural light, are more stressful to birds. Nighttime exposure to cooler temperature LEDs caused birds to have increased levels of nighttime activity and trigged their physiological stress response, raising levels stress hormones in their blood.
Precise regulation of stress hormones is critical for an animal’s survival. When a bird is captured, its stress hormones rapidly increase to give them energy to attempt escape – the famous fight-or-flight response. Stress hormones normally follow a circadian rhythm and only peak during active periods of the day. Thus, excess stress hormones in birds indicate that their normal schedule is disrupted and may affect their metabolism and behavior. The long-term physiological and behavioral effects of these elevated stress hormones on wildlife is not fully understood. However, in humans elevated stress hormones can challenge fundamental physiological process such as blood sugar regulation, inflammation, and fatigue.
Analyzing the effects of light on the stress response of urban birds required an interdisciplinary experiment that brought together members of Dr. Ouyang’s lab, an electrical engineer to design and build new instruments, a neuroscientist who played a role in analyzing bird behavior, and a team of students that helped care for the birds. Such diversity in experiences led to unexpected challenges throughout the experiments. The birds behavior was to be recorded using specially designed perches. However, the researchers quickly realized that the bird’s weight, – about as much as a pencil– was not enough to activate the perch correctly. They had to adjust each perch to work for its intended bird’s weight. Relying on new technology is never an easy task. Alaasam remarked that there were several sleepless nights troubleshooting glitches, “I always joke about how my circadian rhythm and stress hormones were off the charts doing this experiment on circadian rhythms and stress on birds.”
“Understanding how populations can acclimate to urban areas and whether or not that is genetically controlled – who can acclimate the best and who can’t – is a really interesting question.” Alaasam notes. Her findings could improve out understanding of the way wildlife are challenged in today’s cities. Over time, research like Alaasam’s could inform the way environmentally conscious urban planners light their cities. When talking to the citizens of Reno about her research, Alaasam described the potential the benefit of changing out cooler temperature LED’s in outdoor lights to warmer LED’s Alaasam also wants the public to know that “we might be experiencing the same stressors birds are experiencing in a less obvious way. Bird behavior has obvious changes, humans are complicated. The more we ameliorate stressors for our wildlife, the better our conservation and policies will be in the long run.”
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