Field Notes
U.S. Fish & Wildlife Service
Field Notes Entry   
Herpetological and Small Mammal Trappingon Leslie Canyon NWR
Southwest Region, November 1, 2006
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Refuge staff recently concluded herpetological and small mammal monitoring in Leslie Canyon NWR.  This monitoring has been conducted since 2000.  Basic long-term reptile and amphibian population monitoring is generally lacking on National Wildlife Refuges, yet information gained from such work is important in documenting species richness, understanding ecological trends, investigating population dynamics and the roles of rare species, and in justifying resource management decisions.  For these reasons, intensive sampling with trap arrays composed of pitfalls, funnels, and drift fences was initiated in Leslie Canyon NWR during April 2000 and is ongoing. While the emphasis of this monitoring is on terrestrial reptiles and amphibians, information is also gathered from the incidental captures of other organisms.

Trap arrays were located at an elevation of 1,419 meters in various micro habitats within the canyon’s riparian corridor.  Each array consisted of pitfalls (19-liter capacity buckets buried in the ground to the rim) at the ends of 7.6 meter sections of tan-painted, metal drift fences 36 cm high having 2-compartmented funnel traps located at the center of the fence.  The funnel traps were boxes 1.2 m long, 0.6 m wide, and 0.3 m high and constructed of 2.3 mm (1/8 inch) hardware cloth, separated longitudinally by a piece of plywood so that they essentially functioned as two parallel traps.  Funnels with 5 cm entrance holes led into these traps from each end.  Funnels and pitfalls were shaded from the sun with plywood coverings, and plywood bucket trap covers were elevated approximately 4 cm from ground level to provide access to reptiles, amphibians, and invertebrates.  About 5 cm of loose soil served as a substrate in pitfalls and funnels traps.   During 2000, four trap arrays were in operation April 5 to December 7; during 2001, eight trap arrays were in operation March 29 to December 6; during 2002, eight trap arrays were in operation April 1 to November 22; during 2003, eight trap arrays were in operation March 27 to November 24; during 2004, eight trap arrays were in operation March 26 to October 25; during 2005, eight trap arrays were in operation March 21 to October 31; and during 2006, eight trap arrays were in operation March 31 to October 30.  Throughout these time periods, traps were checked approximately every other day to remove and record the vertebrates and invertebrates captured.

Individuals captured in the traps are identified, aged, sexed, measured, weighed, and PIT-tagged or otherwise marked to allow identification of individuals or recaptures.  Date, precipitation, trap array location, and trap type are also recorded for each individual, along with disposition and other comments.

A total of 48,272 trap days worth of effort have resulted during seven field seasons of effort (3,952 trap days in 2000; 8,096 trap days in 2001; 7,552 trap days in 2002; 7,776 trap days in 2003; 6,848 trap days in 2004, 7,200 trap days in 2005, and 6,848 trap days in 2006), with a total of 1,568 individual vertebrate captures (260 in 2000; 298 in 2001; 248 in 2002; 328 in 2003; 95 in 2004; 101 in 2005; and 234 in 2006) composed of 30 reptile and amphibian species, 19 mammal species, 1 fish species, and 2 bird species documented. The eleven most common species captured during the seven year period were the Sonoran spotted whiptail lizard (Aspidoscelis sonorae)-(299), desert/Cockrum’s shrew (Notiosorex crawfordi/cockrumi)-(220), Mexican spadefoot toad (Spea multiplicata)-(170), Clark’s spiny lizard (Sceloporus clarkii)-(105), Madrean alligator lizard (Elgaria kingii)-(103), tree lizard (Urosaurus ornatus)-(93), Sonoran whipsnake (Masticophis bilineatus)-(87), Great Plains toad (Bufo cognatus)-(55), Couch’s spadefoot toad (Scaphiopus couchii)-(58),  black-necked gartersnake (Thamnophis cyrtopsis)-(40), and Great Plains skink (Eumeces obsoletes)-(37).  These are preliminary results from only the first seven years of a long-term study.  Learning more about the varied life forms on the refuges being managed and protected is expected to increase the validity of our decision making abilities. 

Contact Info: Martin Valdez, 505-248-6599, martin_valdez@fws.gov
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