Do wildlife corridors make for bigger and better predators? The effect of habitat connectivity on spider body condition

Background/Question/Methods

 Wildlife corridors are a primary conservation method to facilitate species movement by increasing connectivity between fragmented habitats. In a successful corridor, ecological processes such as predator-prey dynamics should be maintained in otherwise isolated populations by providing food web subsidies. Without maintaining these ecological processes, corridors are destined to reduce diet breadth and trophic stability. Yet, the main focus of corridor research has resided within the movement of single species and not on the factors that affect trophic dynamics. Here, we test if corridors improve body condition of green lynx spiders (Peucetia viridans), a generalist ambush predator whose body condition and fecundity are inextricably linked to prey availability. If corridors facilitate prey movement, then spider body condition should be higher than those found in isolated habitats. We used experimental landscapes at the Savannah River Site in Aiken, SC, designed to isolate the effect of connectivity by controlling for distance, area, and edge effects. We collected green lynx spiders within connected and unconnected patches to test the effect of connectivity on body condition. 

Results/Conclusions

We found that spider mass relative to body size increased with connectivity (t₇ = 2.631; P = 0.0339). Spiders collected from high-core patches had similar body condition to those collected in high edge patches, suggesting that the connectivity of the corridors, not the linear shape or area, facilitated in the increase in relative mass. Corridors may provide food web subsidies to connected patches, thus likely providing spiders the highest prey availability. Further research in prey subsidies from connected and unconnected patches is necessary as reproductive success, and therefore the overall benefit of a corridor for conservation, can be influenced by a multitude of factors other than patch shape and connectivity.