Eastern Woodrat Surveys PENNSYLVANIA GAME COMMISSION BUREAU OF WILDLIFE MANAGEMENT RESEARCH DIVISION PROJECT ANNUAL JOB REPORT PROJECT CODE NO.: 06718 TITLE: Eastern Woodrat Research/Management JOB CODE NO.: 71801 TITLE: Eastern Woodrat Surveys PERIOD COVERED: July 1,1999 to June 30, 2000 COOPERATING AGENCIES: PA Biological Survey Mammal Technical Committee; Department of Biology, Dickinson College; U.S. Fish and Wildlife Service, Division of Federal Aid WORK LOCATION: Statewide PREPARED BY: Jerry Hassinger and Calvin Butchkoski DATE: June 30, 2000 Abstract: Woodrats (Neotoma magister) are classified as a threatened species in Pennsylvania. This determination was based on widespread declines of this species across the northern one third of its range. Numerous islands and corridors of rock in eastern, central and northwestern Pennsylvania that had supported woodrats no longer do so. This report includes working definitions for: suitable habitat, den site, survey site, rock island (habitat patch), colony area (patch cluster), and metapopulation area. Between 18 June 1999 and 15 June 2000, 74 potential woodrat sites (rocky islands) were surveyed for the presence or absence of woodrat signs. Of these sites, 60 had no evidence of use by woodrats, 8 had been used but are now inactive, and 10 were active with recent evidence of use by woodrats. Currently, the Game Commission woodrat database contains 950 records comprising 686 sites. Through 18 June 1999, PGC surveyors visited 431 sites with evidence of current (263 sites) or past (168 sites) woodrat use. These sites belong to 47 active and 55 inactive (locally extinct) colony areas. Based largely on topography and spatially related colony areas, 21 metapopulation areas have been designated. Six of these large areas no longer support woodrats. Six more, represented by one or two small (<6 sites) colony areas are endangered. OBJECTIVES To complete an inventory of all woodrat habitats in Pennsylvania by the year 2005; 2) to inventory all woodrat colony areas by 2005; 3) to delineate the boundaries of woodrat metapopulations; and 4) to protect known woodrat colony areas and the surrounding, forested matrix from further habitat degradation. PROCEDURES Definitions The following definitions and survey protocol have evolved as a result of extensive (1982-2000) experience surveying file:///C|/Game/pgc/reports/wildlife_rep/99wmar/71801-99.htm (1 of 7) [10/29/2003 11:18:47 AM] Eastern Woodrat Surveys woodrats in Pennsylvania. Area-related definitions, indicated by an asterisk, are arranged hierarchically from small (survey site) to large (metapopulation area). Suitable Habitat --In Pennsylvania Neotoma magister is perforce a forest interior species.Sufficient "overhead shelter" (rock overhangs, vegetative cover) is consistently mentioned as a habitat requirement for woodrats (Fitch and Rainey 1956). Allegheny woodrats inhabit rocky islands embedded in a forested matrix. Their habitat in Pennsylvania can be categorized as 1) den sites consisting primarily of an island and/or corridor of rocks surrounded and typically overtopped by tree canopy; 2) foraging habitat that may extend >100m beyond rocks (Wright and Hall 1996); and 3)forested dispersal habitat (between colony areas) that is often absent surface rocks. Den Site -- a core area(s) within a rocky island (patch) characterized by tree cover, and rocks and boulders with an abundance of large, deep crevices and galleries. Exceptions to this are a few river valley shale outcrops where crevices are scarce but deep. This basic physical habitat is influenced positively by the following features: 1) a southerly exposure (Hassinger 1992, Balcom and Yahner 1996), 2) many large, flat rock overhangs, 3) subsurface rocks with some deep (below the frost-line) rat-accessible crevices, 4) the presence of caves, outcrops, talus and complex cliffs (with ledges and crevices), and 5) a hectare or more of rocks and boulders. The quality of den sites is not equal and they are usually not distributed evenly on a rock island. A cave or deep galleries are the core of prime den sites. Superimposed on and adjacent to this physical structure is extensive (radii: >2 km desirable) forest and at least intermittent, herbaceous ground cover. A mix of trees, vines, shrubs herbs and fungi are desirable from the standpoint of the woodrat's catholic diet, opportunistic foraging strategy (McMurray et al. 1993) and the year-round presence of a stable food source. Survey Site -- A survey site is anchored to a den site(s) or potential den site(s); it is a 1 hectare site (least rectangle) that normally will encompass at least one woodrat's home range (Goertz 1970, Wright and Hall 1996). Surveyors minimally sample one site per colony area plus one site for every additional 10 hectares of petrous habitat (surface rock) within the colony area. Because most colony areas and rock islands are linear (e.g., ridge crests and valley sides), survey sites are distributed along the long axis of colony areas as follows: 1 site/1000m of rock by £50m (average width); 2-3 sites/1000m by 50-250m; and 3-5 sites/1000m by >250m. For example, a colony area with rock islands aggregating to 55 hectares will have 5 sample survey sites scattered from end to end. Rock Island (or Patch) or Habitat Site -- Sample survey sites will be nested in a "patch" or island of surface rocks. Researchers often refer to these insular patches of habitat as "rock piles." Best rock islands include foraging areas between rocks and around the perimeter. An edge-to-edge gap, ³100m, in the surface rock delineates island boundaries and size. In accordance with the protocol for choosing "survey sites," some small (<10 ha) islands will not be surveyed. Colony Area (or Patch-cluster) -- A colony area, composed of one rock island or a cluster (archipelago) of islands, is defined by the extent of relatively contiguous (without a break:³5 km), suitable habitat. Rocky ridges or valley sides often form long colony areas. Edge-to-edge, adjacent colony areas are separated by ³5 km of unsuitable denning habitat, a significant break in the topography, or a filter-barrier to dispersal (e.g.,a river, major highway, or nonforest). The possibility of inter-island exchange of woodrats is greater within colony areas than between colony areas. The inhabitants of each colonyarea can be called a subpopulation (Hunter 1996). Records of long-distance woodrat dispersal movements are rare. Movements of about 1-2 km (Madej and Johnson 1993) and 1-4 km (McGowen 1993, Myers and Michael, 1997) have been documented. Metapopulation Area -- A metapopulation is a set of subpopulations distributed over a number of colony areas connected (at least historically) by dispersal movements .A metapopulation area is pragmatically defined as a ridge or valley, or a series of adjacent ridges and valleys wherein the movement (immigration and emigration) of woodrats between colony areas is possible if not likely. In effect a metapopulation is a topographically related set of subpopulations. Metapopulation areas are surrounded by expanses of non-habitat, dispersal barriers, and/or inhospitable anthropogenic habitat. While possible, successful inter-metapopulation area dispersals are unlikely and rare. file:///C|/Game/pgc/reports/wildlife_rep/99wmar/71801-99.htm (2 of 7) [10/29/2003 11:18:47 AM] Eastern Woodrat Surveys Survey Procedures A habitat and den site search image has been developed as a result of past experience. Basically, surveyors find potential den sites, then look for woodrat toilet areas and food caches. When found, these "signs" are characterized as old (dried, faded, disintegrated) or recent (intact, dark colored, not faded). A woodrat survey form, PGC06718-1 (5-90) (see Project Report 06718, 1992, Appendix 1) is completed for each site visited. This form was revised in 1994 and 1995. All data from these site records are entered into a comprehensive woodrat database. FINDINGS Between 6 June 1999 and 15 June 2000, 74 sites were surveyed (see Table 1); 56 sites fit our search image but had no sign that woodrats had been or were now using the habitat; 8 sites had old sign, but we could find no evidence that woodrats were still using these sites; and 10 active woodrat sites were found. Surveys were distributed in 8 counties; active colonies were found in 3: Blair, Dauphin and Lebanon. The Game Commission woodrat data base has 950 records (representing one or more visits to a site) comprising 686 sites within metapopulation areas. Most sites were visited since 1985. Sixteen sites are beyond delineated metapopulation areas, and 22 historical sites either have not been revisited or, insufficient data precludes their relocation. These 38 sites are not included in Table 2. Table 2 is a compilation of Game Commission woodrat habitat survey results (data base records) through 15 June 2000 by metapopulation area. These areas are illustrated in Figure 1. Of a total of 686 eligible sites, 263 were active when last surveyed, 168 previously occupied sites were inactive, and 255 sites had no recent evidence or record of use by woodrats. RECOMMENDATIONS The Game Commission should continue to pursue the objectives of this project by cooperating with the PABS Mammal Technical Committee's "Woodrat Subcommittee," and the regional NE Woodrat Recovery Group. Two wage employees should be used to continue field surveys. Excluding continuing work in Dauphin County, survey 30 or more colony areas in 10 counties during 2000 to 2001. Attempts should be made to find additional colony area and den sites within imperiled metapopulation areas. Develop and test a procedure for monitoring winkout and recolonization rates of rocky islands and colony areas. Locate, delineate, and map all colony areas within the Stony/Sharp/ Peters Mountain metapopulation, preliminary to designating this as a special woodrat management area. Keep the Game Commission woodrat database current. Sample raccoon scats in terms of scat prevalence and Baylisascaris procyonis egg prevalence (in scats).