Sampling Methods and Habitat Selection by the Western Slender Glass Lizard (Ophisaurus attenuatus) at Fort McCoy, Wisconsin

Abstract

Because of conservation concerns regarding the Wisconsin state endangered Western Slender Glass Lizard, Ophisaurus attenuatus, a study was undertaken to: (1) determine the most effective protocol for sampling O. attenuatus in Wisconsin; and to (2) identify habitat variables associated with sites occupied by O. attenuatus. Success of three sampling methods (active search, cover-board arrays, and drift fences) were compared between 23 May – 20 June 2007 at ten sampling plots within the Fort McCoy military installation, Monroe County, Wisconsin. Each of the ten sampling plots was visited twenty times with only eleven O. attenuatus being encountered. Hand-sampling was significantly the most productive method (n=7) and also by far the most efficient method in terms of time and cost. Assessment of habitat use was performed during May and June of 2008 by measuring a total of fifteen habitat variables at nineteen pairs of occupied and random sites. The variables included nine percent cover variables, four distance variables, and two other variables. Canopy closure, leaf/needle litter, woody debris, and woody vegetation were all significantly lower in occupied sites than random sites, whereas thatch cover and grass cover were significantly higher in occupied sites than random. The results of this study are consistent with those of other studies in indicating a preference by O. attenuatus for more open areas (less trees and thus lower values of variables associated with trees), having more coverage associated with open areas such as grass and thatch. Additionally the results suggest a preference for proximity to an edge and for large woody debris, the latter known to be important nesting structures in open areas.