Effect of Weekend Road Traffic on the Use of Space by Raptors

Abstract

The traffic load near large cities may show dramatic cyclical changes induced by weekend tourism, and this could induce cyclical changes in the activity patterns of wildlife. We studied a 19-km-long section of a road that crossed a high-use raptor area near a large city in Spain. We observed 18 raptor species along this segment of the road, including some threatened species, such as the Spanish Imperial Eagle (Aquila adalberti). The number of cars increased dramatically on Saturdays and Sundays, so we assessed the effect of varying traffic loads on raptor behavior by recording all birds of prey as close or distant to the road during working days and weekend days. On weekends, the occurrence of Spanish Imperial Eagles and vultures decreased near the road. The occurrence of other species did not change between working days and weekend days. The activity decrease on weekends by Imperial Eagles and other large raptors suggests that there are weekly cycles in raptor activity. Weekly cycles in wildlife caused by human activity are a source of concern in conservation biology. Efecto del Tráfico de Fin de Semana sobre el Uso de Espacio por Rapaces Resumen: El tráfico en carreteras cercanas a las grandes urbes muestra incrementos cíclicos debidos al turismo de fin de semana, lo que podría inducir ciclos semanales en los patrones de actividad de las aves de presa. Cerca de una gran ciudad estudiamos una sección de 19 Km en una carretera que cruza una de las mejoresáreas para las rapaces de toda España. Observamos 18 especies de rapaces en elárea de estudio, incluyendo varias en peligro de extinción, como eláguila imperial ibérica (Aquila adalberti), una de las rapaces en mayor peligro de extinción del mundo. Registramos los movimientos de todas las rapaces observadas en una malla de cuadrículas UTM clasificadas como cercanas o lejanas a la carretera para estudiar si las observaciones de rapaces eran diferentes en días de semana y en fines de semana, dado que hubo un incremento muy marcado en la intensidad de tráfico los fines de semana. Comprobamos que eláguila imperial y los buitres utilizaban con menor frecuencia las inmediaciones de la carretera durante los fines de semana, restringiendo su actividad a lasáreas remotas y poco transitadas. Los cambios cíclicos en actividad humana durante los fines de semana podrían por tanto inducir también cambios cíclicos en los patrones de actividad † †Current address: Instituto de Agrobiotecnología y Recursos Naturales, Consejo Superior de Investigaciones Cientificas, Carretera Disturbance of Raptors by Road Traffic 727de especies amenazadas como eláguila imperial. Los ciclos semanales de actividad en la fauna tienen mucho interés para la biología de la conservación, ya que son consecuencia de la actividad humana.

Anthropogenic activities influence the abandonment of Bearded Vulture (Gypaetus barbatus) territories in southern Africa

“…Similarly, non-natural mortalities attributed to illegal poisoning were the main mortality factors in other Bearded Vulture populations (Margalida et al 2008) and other large raptor populations (Whitfield et al 2004, Smart et al 2010, and collisions with power lines are known to threaten other vulture species in Africa (Smallie andVirani 2010, Boshoff et al 2011). Impacts related to human disturbance were also found to limit the distribution patterns of Bearded Vulture and other large raptor breeding ranges, densities, and foraging areas (Brown 1988, Herremans and Herremans-Tonnoeyr 2000, Donázar et al 2002, Bautista et al 2004, Gavashelishivili and McGrady 2006, Margalida et al 2007). …”

Evidence that a Highway Reduces Apparent Survival Rates of Squirrel Gliders

“…Higher predation rates along the freeway due, for example, to reduced concealment from potential predators and higher predator densities may also contribute to higher mortality rates along the freeway. Studies of predator densities along large roads have found inconsistent responses among species, with examples of positive, negative, and neutral population responses all seemingly evident (Meunier et al 2000, Bautista et al 2004, Fahrig and Rytwinski 2009. Whether predator populations are at higher densities along the Hume Freeway than populations at control sites is yet to be determined, as is qualification of whether this translates into higher predation rates of squirrel gliders along the freeway.…”

Assessing large-scale wildlife responses to human infrastructure development

“…We overlaid distance maps to transportation infrastructure with distribution maps (10 × 10-km cells) (44) of six emblematic species of the Iberian fauna known to be negatively affected by roads at local scales: Strix aluco (Tawny owl), Otis tarda (Great bustard), Aquila adalberti (Spanish imperial eagle), Canis lupus (Gray wolf), Lynx pardinus (Iberian lynx), and Ursus arctos (Brown bear) (28,29,38,(45)(46)(47). For each species, we quantified the median distance to transport infrastructure in presence cells and classified resulting distances by bands of 500 m from the nearest infrastructure for graphical representation as a normalized histogram.…”