NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 27 3.4.5 Spatial Orientation and Navigation in Animals Almost all animal species use light detection and other visual cues to navigate the nighttime environment (Longcore and Rich 2016). Therefore, illuminating environments that would otherwise be dark influences spatial orientation and navigation. Awareness is growing through research and media that lights in buildings and on structures may attract birds often with fatal results (USFWS 2016). Likewise, the attraction of sea turtle hatchlings to lights is also well documented (see Section 3.5.1.4.). Everyone likely has observed swarms of moths and other nocturnal insects attracted to lights at night. These swarms may alter navigation patterns as predators move to take advantage of the easy access to prey. Artificial light at night can influence predator-prey relationships, with possible effects on populations of the species involved. Artificial light can also influence reproductive behavior by affecting spatial orientation. For example, fireflies use bioluminescence to find mates under cover of night; these communications are best seen by potential mates in dark environments. Effects on spatial orientation and navigation depend in part on the spectral composition of the light. Research shows that most insects are more attracted to light sources that include blue or ultraviolet light (Poiani et al. 2014), whereas some birds are preferentially attracted to red lights (Poot et al. 2008). 3.4.6 Photosynthesis in Plants Lights of sufficient brightness can cause plants to photosynthesize when natural darkness would normally prevent it. Artificial light can potentially cause photosynthesis to occur at night, but this requires that the light source be extremely close to the affected plants. This situation would likely be very rare for BLM-managed lands, except in naturally dark cave environments, where even very low levels of light can support certain species of plants (Gaston et al. 2013). 3.5 Effects of Artificial Light at Night on Animals and Plants This section summarizes select research about plants and various types of animals that is most relevant to environments the BLM manages but is not specific to BLM-managed lands. The body of research is growing about darkness dependencies of plant and animal species. Research specific to BLM special status species represents a field for future study. The information presented focuses on taxonomic groupings that can be applied to the context of plants and animals common to BLM-managed lands. The information is intended to raise awareness and encourage education of local plant and animal darkness dependencies. 3.5.1 Effects of Artificial Light at Night on Animals General changes in natural darkness of the environment (ecological light pollution) may affect niche partitioning, photoperiodism and circadian rhythms, health as related to dark repair and recovery, enhanced/extended visual perception, and orientation and navigation behaviors in dark environments. Many animals also exhibit phototaxis, a behavioral response to light characterized by movement toward light sources (positive phototaxis) or away from light sources (negative phototaxis). For example, many flying insect species (e.g., moths) are attracted to artificial light sources (positive phototaxis). Cockroaches and some bat species avoid light sources (negative phototaxis). Phototaxis has various effects. For example, positive phototaxis in flying insects can lead to increased predation by bats, birds, and other predators, while negative phototaxis in mice can decrease their opportunities for foraging in illuminated areas.
RkJQdWJsaXNoZXIy NTkzMzk=