Quantifying the erosion of natural darkness in the global protected area system

The nighttime light environment of much of the earth has been transformed by the introduction of electric lighting. This impact continues to spread with growth in the human population and extent of urbanization. This has profound consequences for organismal physiology and behavior and affects abundances and distributions of species, community structure, and likely ecosystem functions and processes. Protected areas play key roles in buffering biodiversity from a wide range of anthropogenic pressures. We used a calibration of a global satellite data set of nighttime lights to determine how well they are fulfilling this role with regard to artificial nighttime lighting. Globally, areas that are protected tend to be darker at night than those that are not, and, with the exception of Europe, recent regional declines in the proportion of the area that is protected and remains dark have been small. However, much of these effects result from the major contribution to overall protected area coverage by the small proportion of individual protected areas that are very large. Thus, in Europe and North America high proportions of individual protected areas (>17%) have exhibited high levels of nighttime lighting in all recent years, and in several regions (Europe, Asia, South and Central America) high proportions of protected areas (32–42%) have had recent significant increases in nighttime lighting. Limiting and reversing the erosion of nighttime darkness in protected areas will require routine consideration of nighttime conditions when designating and establishing new protected areas; establishment of appropriate buffer zones around protected areas where lighting is prohibited; and landscape level reductions in artificial nighttime lighting, which is being called for in general to reduce energy use and economic costs.     

A Habitat-Based Metapopulation Model of the California Gnatcatcher

We present an analysis of the metapopulation dynamics of the federally threatened coastal California Gnatcatcher (Polioptila c. californica) for an approximately 850 km² region of Orange County, California. We developed and validated a habitat suitability model for this species using data on topography, vegetation, and locations of gnatcatcher pair observations. Using this habitat model, we calculated the spatial structure of the metapopulation, including size and location of habitat patches and the distances among them. We used data based on field studies to estimate parameters such as survival, fecundity, dispersal, and catastrophes, and combined these parameters with the spatial structure to build a stage-structured, stochastic, spatially-explicit metapopulation model. The model predicted a fast decline and high risk of population extinction with most combinations of parameters. Results were most sensitive to density-dependent effects, the probability of weather-related catastrophes, adult survival, and adult fecundity. Based on data used in the model, the greatest difference in results was given when the simulation's time horizon was only a few decades, suggesting that modeling based on longer or shorter time horizons may underestimate the effects of alternative management actions.     

Flash competition in male Photinus macdermotti fireflies

Summary The courtship of Photinus macdermotti fireflies involves a flash code in which the male emits a pair of flashes about two seconds apart and the female responds with a flash about 1.2 s after the second flash of the male pair. The male repeats his pair of courting flashes at varying intervals of four seconds or more. Lloyd (1979, 1981 a, b) observed that rival males in Florida sometimes interject flashes between the courtship flashes of the courting male. We have found that the competitive behavior of males of the same species on Long Island, New York, was somewhat different. Rival males timed their competing flashes from either the first or second of the original males's courting flashes. When a competing flash from the rival male was timed from the first courting flash it was synchronized with the original male's second courting flash. When a competing flash was timed from the second courting flash, a delayed flash resulted which appeared after the female's response. In either case the male's display period was preserved, insuring that the female would continue to respond. Either of these rival male flashes could sometimes induce the female to respond in his direction.