Nimpkish Black Bear Study: Habitat Analyses
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Nimpkish Black Bear Study: Habitat Analyses Prepared for: Canadian Forest Products Ltd. Woss, BC February 2003 This report has not been peer-reviewed and is not suitable for citation or distribution. Please refer to Davis et al. (in submission) for citation or distribution of the information contained in this report. Prepared by: Helen Davis, M.Sc., R.P.Bio. Richard D. Weir, M.Sc., R.P.Bio. Artemis Wildlife Consultants 4515 Hullcar Road Armstrong, BC V0E 1B4 (250) 546-0531 Final Report – Nimpkish Black Bear Habitat Analyses Executive Summary We examined habitat selectivity by American black bears (Ursus americanus) at 2 spatial scales (within home ranges and patches within stands) in coastal British Columbia, Canada from 1992–1995. We monitored 13 radio-collared males, but could only gather unbiased data for 4. We used information-theoretic inference to assess the effect of 18 habitat and spatial variables in 22 candidate models to explain selection of sites within home ranges. We examined patch scale selection within stands for 4 food and security variables by comparing the sites used by radio-collared males to typical stand conditions. Male black bears exhibited selectivity for a variety of resources that provided food and security at different spatial scales. The probability of use of sites by adult males increased with increasing values of berry-producing and succulent forage plants as well with increased security cover. Juvenile male black bears, however, did not make similar selections and may be relegated to using poor quality habitats with higher mortality risk because of social factors. The male black bears that we studied appeared to make the majority of their site selection decisions at the scale of the home range (i.e., for stands within their home ranges), although some selection was evident at the patch spatial scale. These results increase our understanding of the ecology of black bears and have several implications for the appropriate management of their habitats in coastal British Columbia. Data from 9 female bears were analysed and written as a scientific manuscript submitted for publication. This report has not been peer-reviewed and is not suitable for citation or distribution. Please refer to Davis et al. (in submission) for citation or distribution of the information contained in this report. ARTEMIS WILDLIFE CONSULTANTS i Final Report – Nimpkish Black Bear Habitat Analyses Acknowledgements Funding for the field portion of the study was provided by the Habitat Silviculture Protection Account of the joint Federal and Provincial Forest Resource Development Agreement, the Habitat Conservation Trust Fund, Canadian Forest Products Ltd., and Wildlife Habitat Canada. Assistance during the collection of the field data was provided by A. Friedman, A. Hahn, P. Kaczensky, M. Kellner, C. Mueller, R. Ramcharita, D. Wellwood, and numerous volunteers. Alton Harestad (SFU) also provided crucial support and helpful ideas during the execution of the study. The habitat analyses of the Nimpkish Black Bear Study data would not have been completed without the support of the Forest Investment Account through Canadian Forest Products Ltd.’s Recipient Agreement and the efforts of John Deal. Canadian Forest Products Ltd. supplied all the TEM and road data that made such a complex habitat analysis possible. Tony Hamilton (MWLAP) provided the radiotelemetry and patch-scale habitat data and played an instrumental role in the analyses by answering endless questions. Volker Michelfelder (SFU) entered the vegetation data. People who rounded up obscure information that helped with the analysis included Doug Janz of MWLAP, Karl Wilson of DFO, Bert Svanvik of the Gwanii Hatchery, and Pat Bryant and Bev Webber of Canfor. ARTEMIS WILDLIFE CONSULTANTS ii Final Report – Nimpkish Black Bear Habitat Analyses Table of Contents Executive Summary...................................................................................................... i Acknowledgements ..................................................................................................... ii Introduction .................................................................................................................. 1 Data Constraints........................................................................................................... 3 Study Area .................................................................................................................... 3 Methods.........................................................................................................................5 Radiotracking ........................................................................................................... 5 Within home range selection.................................................................................. 6 Habitat measurements ............................................................................................ 7 Data Analysis............................................................................................................ 8 Model parameterization.......................................................................................... 9 Model selection and averaging .............................................................................. 9 Patch (within-stand) selection.............................................................................. 10 Error Checking of Data ......................................................................................... 10 Results.......................................................................................................................... 12 Radiotelemetry monitoring .................................................................................. 12 Selection within home ranges .............................................................................. 12 Patch scale selection............................................................................................... 13 Discussion ................................................................................................................... 14 Management Implications ........................................................................................ 16 Modelling Non-denning Habitat Suitability.......................................................... 17 Female Best Model................................................................................................. 17 Adult Male Best Model ......................................................................................... 18 Literature Cited .......................................................................................................... 18 Appendix A: Variable definitions............................................................................ 33 Appendix B: Groupings of variants and site series............................................... 37 Appendix C: Excluded model variables................................................................. 40 Appendix D: Plant rankings for bear foods ........................................................... 41 Appendix E: Plant phenology curves ..................................................................... 44 Appendix F: Values of canopy closure, horizontal visibility and food values recorded at random locations within each stand type. ........................................ 46 ARTEMIS WILDLIFE CONSULTANTS iii Final Report – Nimpkish Black Bear Habitat Analyses Introduction From the dry pine forests of Arizona to wet temperate rainforests of western North America, American black bears (Ursus americanus) exploit a wide variety of different habitats for resources needed for survival and reproduction. Wet meadows (California; Kelleyhouse 1980), conifer stands and clearcuts (Washington State; Lindzey and Meslow 1977, Barber 1983), forests that produce hard mast (Powell et al. 1997), and aspen stands (Pelchat and Ruff 1986) are all habitats that black bears utilize successfully throughout their range. Site selection, the process by which bears choose a point in space at which to acquire resources, is affected by many factors, which can be grossly divided in to habitat and non-habitat factors. Habitat factors influence site selection through the distribution and abundance of resources, such as forage, needed by each individual. Non-habitat factors affect the probability of use of sites through the effects of either point or linear features, typically through either attraction or displacement. An example of a non-habitat factor that affects site selection may be heavily travelled roads (Brody and Pelton 1989). The influence of habitat factors on site selection is not limited to the distribution and abundance of resources. The effect of habitat on site selection is hierarchical; that is, bears make simultaneous decisions about habitat resources at several different “selection orders.” Johnson (1980) hypothesised that these selection orders occur at the geographic extent of the species (first order), the selection of a home range (second order), the selection of stands within the home range (third order), and the selection of particular sites for feeding or resting (fourth order). Lofroth (1993) identified an additional selection level between the third and fourth order: selection of patches within larger tracts of habitat that are homogeneous with regard to broad habitat characteristics (i.e., stands). Resources required by a species may be found at any or all of these scales. These habitat