Efficacy of sampling techniques for inventorying herpetofaunal species

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					                     Efficacy of sampling techniques for surveying the community of
                              reptiles and amphibians in a pocosin wetland
                    Stan J. Hutchens*, Christopher S. DePerno, and Kenneth H. Pollock, North Carolina State University, Fisheries and Wildlife
                                                        Sciences Program, Box 7646, Raleigh, NC 27695


 Introduction                                                                                                                                                                                                                                                                                         Results/Discussion
                                                                                                    Table 1. Species composition based on capture data for all techniques,
                                                                                                                         May-August 2005-2006.
 Concern about reptile and amphibian population declines                                                                                                                                                                                                                                              • During 2005-2006, 32 species were recorded in
 has increased globally. These taxa occupy vital positions                                                                                                                                                                                                                                             BNS. Numbers of species and individual captures
                                                                                                  Taxon                                                                                    # Species                                                      # Individuals
 in ecosystems and concern over population declines has                                                                                                                                                                                                                                                varied between taxa (Table 1).
                                                                                                  Salamanders                                                                                               2                                                           13
 prompted new efforts to measure species richness.
                                                                                                                                                                                                                                                                                                      • Capture numbers varied by sampling technique
 However, inventory research frequently employs only two                                          Lizards                                                                                                   3                                                           13
                                                                                                                                                                                                                                                                                                        (Fig. 1).
 or three different sampling techniques. Consequently,                                            Turtles                                                                                                   9                                                           98
 certain species may be missed depending on the                                                   Snakes                                                                                                   10                                                         153                             • Subsequently, additional techniques added new,
 techniques used and species behavior.                                                            Frogs/Toads                                                                                               8                                                        1308                               “unique” species not previously recorded (Fig. 2).
                                                                                                  Totals                                                                                                   32                                                        1585
                                                                                                                                                                                                                                                                                                        Three techniques contributed 1 additional species,
 Objective                                                                                                                                                                                                                                                                                              whereas 1 technique captured 8 species not
 To evaluate the efficacy of multiple sampling techniques                                                                                                                                                                                                                                               sampled by another technique.




                                                                Number Individuals Captured
                                                                                                                                   957
 for surveying the reptile and amphibian community in a                                                     1000                                                                                                                                                                                      • Primary methods for reptile and amphibian sampling
                                                                                                               800
 pocosin wetland.                                                                                              600
                                                                                                                                                                                                                                                                                                        (i.e., drift fence arrays; VES; and coverboards)
                                                                                                               400
                                                                                                                                                                                                                         164                       187
                                                                                                                                                                                                                                                                                                        captured many individuals of the most common
                                                                                                               200                               96                                                                                    76
                                                                                                                                                                         16            31                    5                                                   38          22             0           species (Figs. 1, 2).
                                                                                                                       0
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                                                                                                                                                                                                                         tr a                                                                         • Secondary sampling techniques (i.e., aquatic funnel
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                                                                                                                                                                                     tic         Cr                                                                                                     traps, line transects, and opportunistic capture)
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                                                                                                                                                              po                                                                                                                                        provided a more robust sample of species diversity.
                                                                                                                                                                                                Capture Technique
                                                                                                                                                                                                                                                                                                      •Also, secondary techniques:
                                                                                                   Figure 1. Number of individuals captured by sampling techniques                                                                                                                                        • Are less expensive
                                                                                                   during May - August 2005-2006. VES = visual encounter survey.

                                                                                                                                                                                                                                                                                                          • Require less effort
                                                                                                                                                                                                                                                                                                          • Are reasonable alternatives for measures of
                                                               N u m b er S p ecies C ap tu red




                                                                                                                                                                                                                                                                                                            species richness
                                                                                                             25                                                                                                                                                   20
                                                                                                             20                                                                                                                                     16                                                • Opportunistic captures afforded a greater knowledge
                                                                                                             15          10                                                      11                                                                                             10
                                                                                                             10                              7
                                                                                                                                                                4
                                                                                                                                                                                                                         8             7                  8                                             of the reptile and amphibian community than any
                                                                                                                                                 1                       1                 3           11                    3             2                           2
                                                                                                              5                    0                                                                                                                                                 0          00      standardized technique used.
Study Area/Methods                                                                                            0

                                                                                                                              ys            ES                       s                 s                   ids             ts            ys             s             s            ps        tr a
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                                                                                                                                                                                                                                                                                                          • For example, road cruises contributed 38% of the
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                                                                                                                ce                                   rd                  se                                      tr a            su           dc           ne          yfi            sk
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• The study was conducted at Bull Neck Swamp (BNS), a                                                ift
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                                                                                                                                                                                                                                                       fu n C r a                                           unique species sampled on BNS.
                                                                                                  Dr                               C   ov                                                                                        Op             ua
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  24.3 km2 pocosin wetland in Washington County, NC                                                                                                                                                   Capture Technique                                                                               • Future studies surveying reptile and amphibian
  owned and managed by the Fisheries and Wildlife Sciences                                                                                                                                                                                                                                              communities should incorporate as many techniques
                                                                                                                                                                     Total Species                                Added Species
  Program at North Carolina State University.                                                                                                                                                                                                                                                           as economically and spatially possible to determine
• All techniques were designed as simple or systematic                                             Figure 2. Total and unique species captured by sampling techniques,                                                                                                                                  species diversity.
                                                                                                         May-August, 2005-2006. VES = visual encounter survey.
  random distributions and implemented from May to August,
  2005 and 2006.




                                                                                                                                                                                                                                                                                                      *Contact Info: Stan Hutchens, sjhutchi@ncsu.edu, (919) 513-7558.