NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 31 Many migrating birds seem more disoriented by steady burning rather than flashing or strobe lights (Gehring et al. 2009). The exact mechanism by which certain types of lighting disorient birds is uncertain but is believed to involve interference in magnetoreception and celestial navigation mechanisms birds use to orient themselves in unfamiliar locations (Gaston et al. 2013). Changing obstruction lighting to flashing red lights, in accordance with Federal Aviation Administration (FAA) guidance, has been found to significantly reduce mortality of migratory birds at communication towers (Gehring et al. 2009; FAA 2015). Birds may avoid areas lit at night (e.g., godwits choose nesting sites away from lighted roadways) (de Molenaar et al. 2006). Wading birds foraging and hunting at night have exhibited enhanced success along shorelines where there is lighting (Santos et al. 2010), but this may raise the bird’s exposure to predators. 3.5.1.4 Effects on Reptiles The detrimental effects of artificial light on various species of sea turtles are well documented (Salmon 2003). Sea turtles hatch from clutches of eggs laid on ocean beaches and emerge en masse at night. Under natural lighting, newly hatched sea turtles immediately crawl to the ocean and then swim to deeper waters where they are less subject to predation. The hatchlings crawl away from the darkest part of the horizon and toward the lighter part of the horizon. Under natural lighting, because of an absence of shadows and the presence of light reflected from water, the ocean horizon is lighter than the land horizon. In the presence of shorter wavelength artificial light near the beach, the hatchlings do not crawl toward the ocean but rather either wander erratically or crawl toward the light sources, and many die as a result from exhaustion, predators, or accidents. Disorientation in sea turtle hatchlings is dramatically reduced where lights are retrofitted to warmer temperature “wildlife friendly” fixtures and lighting design (Shudes et al. 2013). In a multidecade effort, the staff and volunteers at Cape Hatteras National Seashore have worked to identify and protect sea turtle nests. This black fabric barrier flanks a sea turtle nest to block artificial light from the nearby development and help hatchlings navigate to the light produced by moon on water.
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