PARENT SESSION
Poster Session # 21: Biogeography, Biodiversity, Populations, and Genetics.
Thursday, August 7 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
For camouflaged and elusive species, the concept of Detection Space. Example: midsize predators.
Meyer, Eugene*,1, 1 Loyola College, Baltimore, Maryland, Baltimore, MD, USA
ABSTRACT- It is easy to miss the largest predators in an animal community if the predators are well camouflaged and elusive. Such is the case with snapping turtles in my field searches, and I suggest for other midsize predators in the eastern US. The evidence: I recorded parallel searches for living amphibians and reptiles by experienced observers. I compared the results to my field experiments for non-living non-moving animal replicas. I found that a few species are so close to the threshold of detection that they are entirely missed by some observers and by generalized search methods. The most-missed taxa range from the smallest or most specialized salamander and frog species, to the largest reptile present. I introduce the concept of Detection Space to clarify detection effort and results. Detection Space is shown simply on transparencies upon conventional graphs of community structure. The use of Detection Space clarifies which species and life stages have received suitable field effort so that a zero record represents a true current absence. The wider utility of this approach is to behavior and camouflage that strongly reduce conspicuousness. Specific applications are to impacts of midsize predators in the eastern US suburbs. The depauperate condition of those communities is variously ascribed to one of three factors: roads, habitat fragmentation, and farm loss. We can take the biological step of asking if those three factors also increase the local densities of a handful of common midsize predators, reptile and mammalian. What that trophic level has in common is elusiveness as individuals and their impacts by generalized field methods. As an indication of density and potential impacts, I return to the snapping turtle example because they, once found, could equal the density of all the amphibians at a site combined.
Key words: mesocarnivore, suburbs, detection, depauperate