Abstract
While road-side productivity attracts wildlife, roads are also a major cause of mortality. Thus, roads are potentially an attractive sink. We investigated whether roads in a desert environment in southern Israel act as an ecological trap for the territorial mourning wheatear (Oenanthe lugens). We applied an individual-based mechanistic approach to compare the apparent survival of individually-marked wheatears between roadside territories and territories in natural habitats farther away from the road, and determined directionality in territorial shifting to and from the road. Analysis was based on mark-resight techniques and multi-model inference in a multi-strata approach (program MARK). Wheatear survival in road-side territories was too low to be compensated by the maximum possible recruitment, but shifted territories from natural habitat toward the roadside habitat as these territories were vacated by mortality. Vacated territories along the road were re-occupied faster than vacated territories in natural habitat. Thus, the roadside habitat in our study area fulfilled all conditions for an ecological trap. Roads may act as widespread ecological traps and their impact, therefore, may extend well-beyond the existing perception of narrow dissecting elements causing local mortality and/or animal avoidance. In species where habitat selection is based on contest competition (e.g., territorial species) and contest success has a genetically heritable component, ecological traps will induce a paradoxical selection process.
Highlights
Roads cover only a small fraction of the planet’s land surface (∼0.5%), yet exert a considerable impact on biodiversity due to fragmentation, road-kills, contamination and habitat modification (Brady and Richardson, 2017)
Following Robertson and Hutto (2006) we addressed the three basic questions necessary to determine the existence of an ecological trap: (1) Do the wheatears prefer the roadside habitat over natural habitats farther away from the road? (2) Does a reliable surrogate of fitness differ between the roadside habitats and the natural habitats? (3) Is the fitness outcome of settling along the road lower than in the natural habitats and does it indicate a negative population growth rate? We addressed these questions by tracking individual birds over time and in doing so elucidating the behavioral mechanisms underlying the process of entrapment
In each section we identified and delineated wheatear territories and classified them as either: roadside habitat (RSH)—territories traversed by the road, or territories in “natural habitat” (NH)—territories located within a dry riverbed 300–1,200 m away from the road
Summary
Roads cover only a small fraction of the planet’s land surface (∼0.5%), yet exert a considerable impact on biodiversity due to fragmentation, road-kills, contamination and habitat modification (Brady and Richardson, 2017). Many studies demonstrate that road-side productivity and plant diversity attracts wildlife while at the same time inflicting mortality (Coffin, 2007). If mortality rates in populations inhabiting roadside habitats are not compensated by improved recruitment stemming from the high roadside productivity, roadside habitats become attractive sinks—i.e., ecological traps (Coffin, 2007). Considering the abundance of roads and the evidence regarding their attractiveness and impact on survival to wildlife only few empirical studies have focused on roads as ecological traps (Norris et al, 2013; Egri et al, 2017), many studies speculate they may act as such
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