Interpreting Catch in a Single Trap

Abstract

Trap findability × efficiency × retention averaged across the set of animals populating a trapping area can be abbreviated as T fer . Then, catch per trapping area is given simply as T fer multiplied by animals per trapping area. We call the proportion of movers originating at a specified distance from the trap specific Tfer and abbreviate it as spTfer. T fer has apparently not yet been measured directly for any animal. But, it can be calculated from spT fer values arising from a single-trap, multiple-release experiment. A simple way to calculate T fer when the trapping area is comprised of annuli bounded by the release distances is to sum the values for spT fer × respective annulus area and then divide this sum by total annulus area. Once T fer and trapping area are known, organisms per trapping area can be calculated as catch divided by T fer . The precision of abundance estimates and mover density derived from a catch number rises in accordance with plume reach. This chapter details four specific examples of how spT fer data from field experiments on invertebrates can best be analyzed for plume reach, trapping area, and T fer , and how these values can then be translated into estimates of absolute animal density for sharpening pest management decisions.