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US Fish & Wildlife Service FieldNotes

Leslie Canyon NWR Reptile Monitoring Completes 13th Year 

Region 2, October 31, 2012
Mexican hognosed snake, the first capture in the course of this study.
Mexican hognosed snake, the first capture in the course of this study. - Photo Credit: n/a
Sonoran desert toad, one of the few amphibians captured this year, and by far the largest.
Sonoran desert toad, one of the few amphibians captured this year, and by far the largest. - Photo Credit: n/a

This completes the thirteenth year that refuge staff has been conducting herpetological monitoring on Leslie Canyon NWR. The information gathered from this monitoring allows refuge staff to better understand ecological trends, investigate population dynamics and the roles of rare species, and helps justify resource management decisions. While the emphasis of this monitoring is on terrestrial reptiles and amphibians, information is also gathered from the incidental captures of other organisms. This year had the lowest capture total since 2006 (234), but had the second highest species total, with thirty-three different species captured (2007 had thirty-six different species). The composition of reptile, amphibian, and mammal captures was 155 (55.56%), 76 (27.28%), and 48 (17.20%), respectively. This compares with the 12-year average (2000-2012) composition of 149.62 (51.46%) reptiles, 90.46 (25.67%) amphibians, and 79.85 (22.65%) mammals.There were two new species documented in the trap arrays this year, desert pocket mouse (Chaetodipus penicillatus) and Mexican hognosed snake (Heterodon nasicus). Other noteworthy captures were a canyon spotted whiptail (Aspidoscelis burti), a grassland whiptail (A. uniparens), a juvenile green rat snake (Senticolis triaspis), and a Sonoran coral snake (Micruroides euryxanthus). Some species that are regularly encountered were captured in numbers far greater than what the 12-year average is. These were green toad, 39 captured in 2012, average 18.91; Great Plains Skink, 19, avg. 5.9; Smith’s black-headed snake (Tantilla hobartsmithi), 6, avg. 1.46; green rat snake, 4, avg. 0.55. There were also some species that were well below their 12-year average: Madrean alligator lizard (Elgaria kingii), 5, avg. 15.36; Mexican spadefoot toad, 17, avg. 24.55; Couch’s spadefoot toad (Scaphiopus couchii), 16, avg. 23.09.The year saw the continuing trend of below average rainfall, with 9.78 inches for the year through November 7, and 7.16 inches during the period when the traps were open, which is the lowest amount during the trapping period since 2005 (6.50 inches). With continuing drought, Leslie Creek did not flow for the third consecutive year, aside from floods in 2010 and this year.

Contact Info: Christopher Lohrengel, 520-364-2104 x.106, chris_lohrengel@fws.gov