Power lines rewire avian hormone.Birds roosting along high-power electric-transmission lines may get more than a lofty perch. A new study suggests they may also undergo a shift in biochemical signals controlled by melatonin melatonin: see pineal gland. melatonin Hormone secreted by the pineal gland of most vertebrates. It appears to be important in regulating sleeping cycles; more is produced at night, and test subjects injected with it become sleepy. , the nighttime hormone that sets their biological clocks Biological clocks Self-sustained circadian (approximately 24-hour) rhythms regulating daily activities such as sleep and wakefulness were described as early as 1729. . Kimberly J. Fernie of McGill University McGill University, at Montreal, Que., Canada; coeducational; chartered 1821, opened 1829. It was named for James McGill, who left a bequest to establish it. Its real development dates from 1855 when John W. Dawson became principal. in Quebec City observed that several conservation groups had begun providing platforms on transmission-line towers for roosting raptors. She and her colleagues duplicated the conditions on the platforms by exposing captured American kestrels to electromagnetic fields electromagnetic field Property of space caused by the motion of an electric charge. A stationary charge produces an electric field in the surrounding space. If the charge is moving, a magnetic field is also produced. A changing magnetic field also produces an electric field. (EMFs) of 30 microteslas throughout two breeding seasons Breeding season is the most suitable season usually with favorable conditions and abundant food and water when wild animals and birds (wildlife) have naturally evolved to breed to achieve the best reproductive success. . Ordinarily, the concentrations of melatonin in males' blood drop gradually during the roughly 70-day breeding season. However, a decline that normally takes 10 weeks in unexposed males happened in 6 weeks in the EMF-exposed birds, Fernie reports. Although adult females appeared unaffected by the fields, fledglings of pairs that had roosted for two breeding seasons in the EMFs also produced less melatonin than normal, her team reports in the November ENVIRONMENTAL HEALTH PERSPECTIVES. Fernie says her findings suggest that "the birds might be responding to the EMFs as if they were light." Although the degree of melatonin suppression was only moderate, she would like to investigate whether it's shifting the birds' calendar in ways that might affect migration or other seasonal changes. |
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