Management of Amphibians, Reptiles, and Small Mammals in North America

Abstract.-Between 1977 and 198 1, the Bureau of Distribution and Habitat Land Manaaement conducted extensive surveys of Associations of Herpetofauna Arizona's h&petofauna in 16 different habitat types on approximately 8.5 million acres of public lands. This paper describes results of one of the most exten- in Arizona: Corn~arisonsI by sive surveys ever conducted on amphibian and rep- Habitat Type1 tile communities in North America. K. Bruce Jones2 With the passage of the Federal Land tats and are often good indicators of Policy and Management Act in 1976, habitat conditions (Jones 1981a). the Bureau of Land Management Therefore, in order to obtain infor- (BLM) was mandated to keep an in- mation on these animals, principally ventory of resources on public lands. for land-use planning, the BLM con- Information collected during inven- ducted extensive inventories of am- tories or surveys was then to be used phibians and reptiles by habitat type. to identify issues for land use plan- This inventory included a scheme ning and opportunities for land man- whereby associations between am- agement. The BLM made a decision phibians and reptiles and certain rni- to collect data on all major wildlife crohabitats could be determined. The groups and their habitats inventory, conducted between 1977 Early in the development of its in- and 1981, was one of the most com- ventory program, the BLM recog- prehensive surveys of herpetological nized a need to devise a strategy that communities ever conducted in would compare animal distributions North America (27,885 array-nights and abundance to habitats. This in 16 habitat types over a five-year strategy was important since the period). It also represents the first BLM manages wildlife habitats and large-scale effort to quantitatively not wildlife populations. compare herpetofaunas associated In 1977 the BLM initiated invento- with ecosystems. This paper reports ries of wildlife resources on public the results of these surveys, includ- lands. At that time, considerable in- ing species distributions and associa- formation was already available on tions with microhabita ts and habitat Figure 1 .-The study area. game species. However, data on types (plant communities). nongame species were mostly lack- ing. As a result, priority was given to those presented by Brown et al. collecting data on nongame species STUDY AREA (1979). For example, because of the and their habitats. scale of their map, Brown et al. (1979) Amphibians and reptiles are im- The study area consisted of approxi- failed to recognize several small, rel- portant members of the nongame mately 3,441,296 ha (8.5 million ict stands of chaparral woodland, fauna. They use a wide range of habi- acres) of public lands located in cen- although Brown (1978) had noted the tral, west-central, southwestern, and presence of chaparral woodland 'Paper presented at symposium, Man- northwestern Arizona (fig. 1). Sixteen vegetation at several small sites (see agemen t of Amphibians, Reptiles, and different habitat types were deline- Jones et al. 1985 for the importance of Small Mammals in North America. (Flag- staff, Arizona, July 1 9-2 ?, 1 988). a ted within this area, primarily from small woodland stands to certain 2K. Bruce Jones is a Research Ecologist an existing map of vegetation asso- herpetofauna). Therefore, the habitat with the Environmental Protection Agency, ciations (Brown et al. 1979). Field re- type map used to allocate samples in Environmental Monitoring Systems Labora- connaissance allowed more local as- this study drew upon the Brown tory, Las Vegas, Nevada 89193. sociations to be recognized within (1978) and Brown et al. (1979) maps, and results of field reconnaissance. of 18.3 1 (5 gal) plastic containers bur- mary of sampling effort in each habi- For detailed descriptions of these ied in the ground and connected by tat type). Arrays were placed so that habitat types see Jones (1981b) and 0.41 m (8 inches) high aluminum microhabitat variability within each Buse (1981). drift fence; one trap was located in habitat type was sampled. The num- the center with three evenly dis- ber of arrays used to sample habitat persed (120") peripheral traps 7.14 m types was par tially influenced by the SAMPLING METHODS (25 ft) from the center (Jones 1981a, size of habitats; generally, more ex- Jones 1986).This modified array tensive habitats received proportion- Amphibian and reptile distribution method was designed specifically for ally larger samples. However, certain and abundance by habitat type were sampling amphibians and reptiles in habitats (e.g., riparian) were known determined by on-the-ground Sam- desert habitats (see Jones 1986 for a to be great sources of diversity pling efforts between October, 1977, comparison of this procedure with within desert regions; therefore, pri- and July, 1981. Samples were ob- the original array trapping scheme ority was given to obtaining larger tained by three methods. The most designed by Christman and samples within these habitats. Once extensive sampling was accom- Campbell 1982). A total of 183 arrays placed into the ground, arrays were plished with a pit-fall trapping were used to sample 16 different continuously open for a minimum of method (array) consisting of a series habitat types (see table 1 for sum- 60 days. Some arrays (60) were open for 9 months. Generally, samples were taken during the spring, sum- mer, and fall. However, some arrays (17) were open only during spring months and others only in the fall (12). The opening of new arrays at different locations, and the closing of other arrays, were often dictated by BLM's predetermined resource planning schedule. Since some amphibians and many snakes could not be effectively sampled by pit-fall traps, it was nec- essary to use two other field tech- niques. Road riding, consisting of traveling roads from dusk to approximately 2300 h throughout de- lineated habitat types, was used to determine the occurrence of amphibians and medium and large snakes (see table 1 for sampling effort within each habitat type). Time-constraint searches (Bury and Raphael 19831, consisting of walking along permanent and tem- porary water sources (natural and man-made) at night, were used to verify the presence of frogs and toads at waters within habitat types (see table 1 for sampling effort within each habitat type). Finally, to get an idea of the known distribution of amphibians and reptiles within the study area, I obtained records from 7 museums known for their outstanding collec- tions of amphibians and reptiles from the Southwest: the University of Michigan, Arizona State University, the total number of any species lar to arrays, only array data were the University of New Mexico, caught during a 24-hour period (ar- used to calculate species diversity. Northern Arizona University, the ray-night). Relative abundance was Two types of cluster analysis were University of Arizona, the Los Ange- determined for each species on array used to determine similarities among les County Museum, and the Univer- sites by taking the greatest number of habitat types. The first cluster analy- sity of California at Berkeley. In addi- individuals of a species trapped dur- sis was performed only on array tion, these data wcre used to com- ing a 30-day period and dividing by data, and it was based on euclidean pare the past distribution of amphibi- the number of days. This calculation distances (Pimental 1979). Calcula- ans and reptiles within the study was used because of monthly differ- tion of euclidean distances between area with that obtained during the ences in species' activity patterns. hahitats wcre based on a combina- BLM's inventories. The number of arrays in which a spe- tion of species' presence or absence Microhabitat data were collected cies was trapped in each habitat type on a site and similarity in species' on each array site and along roads by also was compiled to determine how dominance (relative abundance) be- a modified point-intercept method widespread a species was within in- tween habitats. Since medium and consisting of 100 sample points sepa- dividual habitat types. large snakes (> 0.5 m or 1.5 ft) are not rated by 8 m (26 ft) along a randomly A principdl components analysis readily caught in pit-ball traps, their determined compass line; on array (Pimental 1979) was performed to relative abundances could not be cal- sites, the center of the line crossed compress microhabitat data into a culated accurately. To compare the over the array. At each point, the fol- smaller, depictable subset. Mean fac- overall herpetofaunas of habitat lowing measurements were taken: (1) tor scores of compressed microhabi- types, a second cluster analysis was vertical distribution of vegetation be- tat data were computed for each performed. This procedure involved tween 0-0.6 m (0-2 ft), 0.6-1.7 m (2-6 habitat type and plotted on a 3 vector calculation of Simpson similarity co- ft), 1.7-6.0 m (6-20 ft), and > 6 m (20 (axis) graph. Similarly, mean factor efficients (Pimental 1979). These coef- ft) (each time vegetation occurred in scores of compressed microhabita t ficients were then submitted to a a height class above the point, a con- data were computed for each am- cluster analysis. Unlike the analysis tact or "hit" was recorded); (2) pene- phibian and reptile species (turtles of array data via euclidean distances, tration to the nearest cm into the soil were excluded because aquatic mi- the use of Simpson similarity coeffi- by a pointed metal rod (1 cm in di- crohabitats were not measured). cients in a cluster analysis did not ameter); (3) depth of leaf litter (if These scores were calculated for each consider relative dominance in calcu- present); (4) depth of other litter such species by averaging mean factor lating distances between habitats.

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