Drift Fence Arrays Research Articles

Relationship between Cheatgrass Coverage and the Relative Abundance of Snakes on Antelope Island, Utah

ABSTRACT. Cheatgrass (Bromus tectorum) is an invasive annual known to negatively impact many shrub-dependent organisms; however, relatively little research has examined how it affects snake communities. Bromus tectorum is abundant at Antelope Island State Park, Davis County, Utah, and could be a possible threat to snake populations. Study sites representing different B. tectorum coverage percentages were established to measure relative abundance of snakes. Snakes were captured from June to September 2005 primarily by using funnel traps attached to drift-fence arrays. Linear regression revealed a negative relationship between B. tectontm coverage (%) and the relative abundance of the Great Basin gopher snake (Pituophis catenifer deserticola) and the western racer (Coluber mormon). These results (1) suggest that B. tectorum invasions result in reduced snake abundance in shrubsteppe habitat on Antelope Island and (2) add to our understanding of the relationships between B. tectorum and native fauna.

Capture Rates of Reptiles and Amphibians on Black-Tailed Prairie Dog (Cynomys ludovicianus) Colonies and on Uncolonized Prairie in Colorado

Prairie dog eradication negatively affects dependent wildlife. Assessing the effects of prairie dog activities on reptiles and amphibians may depend upon the efficacy of trapping designs. We compared capture rates of reptiles and amphibians on black-tailed prairie dog (Cynomys ludovicianus) colonies and on adjacent uncolonized short-grass prairie, using funnel traps and pitfall traps with drift fences, as well as ground captures. We captured 152 reptiles and amphibians representing 10 species. We captured 51.3% of all reptiles and amphibians on colonies, compared to 48.7% from uncolonized sites. Overall, captures of reptiles and amphibians were similar on colonies and uncolonized sites for all capture methods combined. We achieved higher capture rates on uncolonized sites using funnel traps and pitfall traps but higher capture rates on colonies for ground captures. For all years on all sites combined, we captured significantly more animals in funnel traps (52.6%), surpassing pitfall trap captures (23.0%) and ground captures (24.3%). We recommend using multiple Y-shaped drift fence arrays ≥ 7.6 m in length, funnel traps with double-ended openings, and black-colored pitfall traps with opening diameters ≥ 30 cm.

Short-term response of reptiles and amphibians to prescribed fire and mechanical fuel reduction in a southern Appalachian upland hardwood forest

We compared the effects of three fuel reduction techniques and a control on the relative abundance and richness of reptiles and amphibians using drift fence arrays with pitfall and funnel traps. Three replicate blocks were established at the Green River Game Land, Polk County, North Carolina. Each replicate block contained four experimental units that were each approximately 14 ha in size. Treatments were prescribed burn (B); mechanical understory reduction (M); mechanical + burn (MB); and controls (C). Mechanical treatments were conducted in winter 2001–2002, and prescribed burns in March 2003. Hot fires in MB killed about 25% of the trees, increasing canopy openness relative to controls. Leaf litter depth was reduced in B and MB after burning, but increased in M due to the addition of dead leaves during understory felling. The pre-treatment trapping period was short (15 August–10 October 2001) but established a baseline for post-treatment comparison. Post-treatment (2002–2004), traps were open nearly continuously May–September. We captured a total of 1308 species of 13 amphibians, and 335 reptiles of 13 species. The relative abundance of total salamanders, common salamander species, and total amphibians was not changed by the fuel reduction treatments. Total frogs and toads (anurans) and Bufo americanus were most abundant in B and MB; however, the proximity of breeding sites likely affected our results. Total reptile abundance and Sceloporus undulatus abundance were highest in MB after burning, but differed significantly only from B. Mean lizard abundance in MB was highest in 2004 and higher than in other treatments, but differences were not statistically significant. Our results indicate that a single application of the fuel reduction methods studied will not negatively affect amphibian or reptile abundance or diversity in southern Appalachian upland hardwood forest. Our study further suggests that high-intensity burning with heavy tree-kill, as in MB, can be used as a management tool to increase reptile abundance – particularly lizards – with no negative impact on amphibians, at least in the short-term.

Snake species distributions and temperate grasslands: A case study from the American tallgrass prairie

Many snake species are declining globally, yet data unavailability in temperate grasslands hinders snake conservation in one of the world’s most endangered biomes. To encourage and inform the conservation of snakes in these regions, I examined snake species diversity and abundance during 2 years of a mark-recapture study at 22 sites located in six American tallgrass prairie preserves in northern Illinois, USA. I emphasized landscape-scale relationships after accounting for covariance with environmental factors at both finer (microhabitat) and broader (regional) scales. A total of 120 snakes representing seven species was captured using drift fence arrays associated with funnel traps and sheet metal cover. The low numbers and diversity of snakes captured, when compared to historic evidence, indicate that since the 1930s Midwestern snake populations have declined. Non-metric multidimensional scaling and Mantel tests demonstrate that differences in snake species composition in remnant and degraded prairies are discernable along gradients of urban and agricultural land cover. However, different patterns of abundance for individual snake species indicate that the relative importance of specific landscape factors differ among species, which has significant conservation implications. Here, I recommend that conservationists use a species-specific approach to manage snake populations. I also stress the need for thorough inventory of snake populations and studies of snake–habitat relationships to advance our understanding of snake ecology and conservation within the little studied temperate grassland habitats of South America and eastern Eurasia.

Limitations of regulated “buffer zones” for the conservation of marbled salamanders

Most amphibians that breed in seasonal wetlands are predominantly terrestrial animals that require “upland” habitats for the majority of their life cycles. However, wetland regulations aimed partially at protecting wildlife values are often limited to the wetland basins and small terrestrial “buffer zones” that typically extend 30 m or less from the wetland edge. In this study, we assessed whether a common buffer zone (i.e., 30 m) is sufficient for the conservation of marbled salamanders (Ambystoma opacum). We installed and monitored two concentric and continuous drift fence arrays (3 m and 30 m from the pond margin) around each of three seasonal ponds in western Massachusetts, USA. We quantified the numbers and percentages of breeding adults and emerging juvenile salamanders that immigrated from and/or emigrated beyond the 30-m fences. In addition, we recorded incidental year-of-emergence captures of juveniles at more distant drift fences that were in place for a broader study. Of the breeding adults captured immigrating to the basins at 3-m fences, 84–96% were first captured at 30-m fences, and corrections for capture probabilities suggested that nearly 100% of these individuals originated beyond 30 m from their breeding sites. Of the newly emerging juveniles captured emigrating from the basins at 3-m fences, 58–85% were subsequently captured at 30-m fences and 284 juvenile captures were recorded at distances between 111 and 1,230 m (median = 269.2 m) from natal ponds. Our findings highlight the dramatic limitations of existing wetland regulations with regard to upland habitat use by mole salamanders (family Ambystomatidae) and the need to approach conservation of these animals both at broader scales and with more comprehensive and innovative strategies.

Movement patterns and relative abundance of coastal tailed frogs in clearcuts and mature forest stands

Age-specific movements, abundance, and capture rates of coastal tailed frogs (Ascaphus truei Stejneger) were compared between clearcuts and mature forests in southwestern British Columbia, Canada, during 1998 and 1999 using pitfall traps and drift-fence arrays. Total frog abundance was similar in both habitat types. More adults were caught in mature stands than in clearcuts, but there was no significant difference for immatures. Analysis of numbers of frogs captured indicated that the direction of movement did not differ between habitat types for any age-class. Frogs were captured at similar frequencies across distance from stream in both habitats. These findings suggest that there are age-specific differences in tailed frog abundance in clearcuts along streams without riparian reserves relative to mature forests. Variation among sites had a greater influence than habitat type on the number of immatures. Low proportions of adults in clearcuts suggested that immatures may be transient or that they incurred high rates of mortality. Age-specific differences in habitat use by tailed frogs indicated that total numbers alone are insufficient to determine the effect of forest management on habitat suitability for tailed frogs.

Movement Patterns of Adult and Juvenile Rana sylvatica (LeConte) and Ambystoma maculatum (Shaw) in Three Restored Seasonal Pools in Maine

Research on amphibian movement patterns can aid in strengthening amphibian conservation strategies. Yet for many species, there remain substantial gaps in our knowledge of such movement patterns. From 1999–2002, we documented movement patterns to and from breeding pools of both adult and juvenile Rana sylvatica LeConte (Wood Frog) and Ambystoma maculatum Shaw (Spotted Salamander) by using drift fence arrays at three restored vernal pools in Maine to lend insight into conservation strategies for these two species. Adults and juveniles of both species exhibited nonrandom movement at breeding pools directed preferentially from and toward closed-canopy forested habitat. Marked male, female, and juvenile R. sylvatica were recaptured at 30 m, 150 m, and 300 m from the pool in the surrounding terrestrial environment. Most terrestrial recaptures occurred within the forested wetland habitat to the north of the pool. Median snout–vent lengths (SVL) of recaptured juvenile R. sylvatica were progressively larger at greater distances from the pool. Number of juveniles emerging from the pool was positively correlated with number of juveniles recaptured two days later at 30 m, four days later at 150 m, and six days later at 300 m. Male R. sylvatica were 98% faithful to their breeding pools from 2001–2002, whereas female R. sylvatica were 88% faithful. Male and female A. maculatum were 100% faithful to their breeding pools during the same period. Both species' (adult and juvenile) nonrandom movement toward forest upon leaving breeding pools suggests that quality of adjacent terrestrial habitat is relevant to both juvenile and adult pool-breeding amphibians. High levels of pool fidelity observed in these two species emphasize the importance of conserving vernal pools and mitigating for pool-losses on-site if the nonbreeding habitat is still available. Correlations between amphibian migrations and weather variables varied between years and species, suggesting emigration, immigration, and dispersal may be associated other environmental variables in conjunction with temperature and precipitation. However, heightened activity of both species (adults and juveniles) in response to temperature and precipitation can inform the timing of monitoring efforts and conservation strategies aimed at protecting migration routes.

Terrestrial movements of juvenile and adult tailed frogs in relation to timber harvest in coastal British Columbia

Tailed frog (Ascaphus truei Stejneger) populations are at risk in much of the Pacific Northwest, and recolonization of sites may be slow postlogging. To examine the terrestrial movements of Ascaphus in clearcuts and old growth, we employed pitfall traps and drift-fence arrays installed along streams and 100 m into upland habitat. In the fall, we captured frogs farther from streams in old growth than in clearcuts, and more frogs were captured ≤25 m from streams in clearcuts. Stronger stream affinity in clearcuts was most evident with juvenile frogs, which exhibited more upstream movements than adults. Compared with inland sites where frogs remained close to streams (e.g., 12 m), frogs at our coastal sites were captured at greater distances from streams (≥100 m), having lower stream affinity than frogs at inland sites. Long-distance overland movements appear more likely where forested stands are present. Aggregations of Ascaphus at individual streams may not represent distinct populations and should not be managed as distinct units. Preserving groups of interconnected streams within watersheds instead of individual streams will improve the conservation status of Ascaphus. Population monitoring can ensure conservation measures promote long-term persistence.

Preble's Shrew and Great Basin Pocket Mouse from the Centennial Valley Sandhills of Montana

tana sandhills habitat is poorly documented. During a 1999 faunal survey of the Centennial Valley Sandhills in Beaverhead County, extreme southwestern Montana, we captured specimens of Preble's shrew (Sorex preblei) and Great Basin pocket mouse (Perognathus parvus). Both are state Species of Concern (Montana Fish, Wildlife & Parks; Montana Natural Heritage Program) and are rarely collected in Montana. The Centennial Valley Sandhills are approximately 2 to 3 km wide and 14 km long (between 44'40'N, 111'42'W and 44'42'N, 111'49'W) at an average elevation of 2030 m; they are north of Lower and Upper Red Rock lakes near the east end of the Centennial Valley (Sonderegger and others 1982). The sandhills are small and generally stable dunes. Sandhills vegetation (Lesica and Cooper 1999) is a mixture of treeless successional types dominated by shrubs (Artemisia tridentata, A. tripartita, Chrysothamnus nauseosus, C. viscidiflorus, Tetradymia canescens), forbs (Lupinus argenteus, L. sericeus, Machaeranthera canescens, Opuntia fragilis, Phaecelia hastata, Psoralea tenuiflora) and grasses (Agropyron dasystachyum, Festuca idahoensis, Koeleria cristata, Poa nevadensis, Stipa comata). Standing water is absent within the sandhills proper, once winter snows melt in May, but is present south of the sandhills in nearby wetlands surrounding Upper and Lower Red Rock lakes. Shrews and pocket mice were collected from a series of 6 pitfall trap lines (10 stations, 30 m between stations, with a single can trap at each station; 60 cans total) and 3 drift-fence arrays (each with 4 pitfall can traps; 12 cans total). Pitfall lines were set 25 to 26 May 1999, and driftfence arrays were established on 25 May; each line and array was run continuously (except to clean and repair traps) until retrieved on 21 to 22 September (7000 trap-nights total on the pitfall lines and 1380 trap-nights total for the drift fence arrays). All pitfall can traps were in place for 115 to 117 nights of trapping. Traps were examined daily while we were at the sandhills (25 to 28 May, 28 June to 2 July, 28 to 30 July, 21 to 22 September), although no shrews or pocket mice were captured while we were present.

Stand age and habitat influences on salamanders in Appalachian cove hardwood forests

We surveyed cove hardwood stands aged 15, 25, 50, and ≥85 years following clearcutting in the southern Appalachian Mountains of northern Georgia to assess the effects of stand age and stand habitat characteristics on salamander communities using drift-fence array and pitfall methodologies from May 1994 to April 1995. Over a 60,060 pitfall trapnight effort, we collected 3937 salamanders represented by Desmognathus aeneus, Desmognathus monticola, Desmognathus ocoee, Desmognathus quadramaculatus, Eurycea bislineata, Gyrinophilus porphyriticus, Pseudotriton ruber, Plethodon glutinosus, Plethodon serratus, and Notophthalmus viridescens. Analysis of covariance with pitfall array to stream distance as the covariate showed that salamander species richness and diversity measures and numbers of Desmognathus aeneus and Desmognathus ocoee were highest in stands ≥85 years. Eurycea bislineata and Plethodon glutinosus were more abundant in stands ≤50 years old than in stands ≥85 years. Within cove hardwood stands, species richness and diversity measures and relative abundances of Desmognathus spp. and Gyrinophilus porphyriticus were negatively correlated with distance to stream. Species richness and diversity were positively correlated to amounts of emergent rock. Species richness, diversity and relative abundances of Desmognathus spp. were correlated with basal area within stands and extent of connected mesic, cove hardwood habitat and amount of cove habitat within 1 km radius among stands. Eurycea bislineata was negatively correlated with landform index, a measure of surrounding landform sheltering, and Plethodon glutinosus was positively correlated with elevation in cove hardwood stands. Our research indicates stand age is an important factor in explaining the abundance and community composition of salamanders in southern Appalachian cove hardwood communities. Because southern Appalachian woodland salamander communities are slow to recover and are substantially changed following disturbances such as clearcutting, populations in small, isolated cove hardwood stands might be more vulnerable to extirpation or may require longer recovery times than those in larger coves. Managers may need to assess habitat features such as cove extent and habitat connectivity to minimize impacts on these taxa by forest management activities in southern Appalachian cove hardwood communities.

Herpetofaunal Responses to Brush Management with Herbicide and Fire

We examined how native herpetofauna of the Cross Timbers in Oklahoma, USA, were influenced by vegetation types derived from combinations of herbicide applications and prescribed burning. Brush management treatments consisted of tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiazol-2-y-1] -N,N'-dimethylurea)-only, tebuthiuron + fire, and untreated pastures of mature hardwood forest (no herbicide or fire). A total of 292 individuals representing 30 species was captured in 1994 and 1995 using time-constrained searching and drift-fence arrays on 3 replicates of the 3 treatments. Relative total abundance and species richness of herpetofauna were similar on all 3 treatment types. However, differences were apparent by taxonomic group. In general, amphibians were most abundant in untreated and tebuthiuron-only pastures, lizards were most abundant on the untreated pastures, and snakes were most abundant on pastures treated with tebuthiuron + fire. Maintenance of a mosaic of habitats in the Cross Timbers may enhance diversity of the native herpetofauna. DOI:10.2458/azu_jrm_v53i2_jones

Herpetofaunal responses to brush management with herbicide and fire

We examined how native herpetofauna of the Cross Timbers in Oklahoma, USA, were influenced by vegetation types derived from combinations of herbicide applications and prescribed burning. Brush management treatments consisted of tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiazol-2-y-1] -N,N'-dimethylurea)-only, tebuthiuron + fire, and untreated pastures of mature hardwood forest (no herbicide or fire). A total of 292 individuals representing 30 species was captured in 1994 and 1995 using time-constrained searching and drift-fence arrays on 3 replicates of the 3 treatments. Relative total abundance and species richness of herpetofauna were similar on all 3 treatment types. However, differences were apparent by taxonomic group. In general, amphibians were most abundant in untreated and tebuthiuron-only pastures, lizards were most abundant on the untreated pastures, and snakes were most abundant on pastures treated with tebuthiuron + fire. Maintenance of a mosaic of habitats in the Cross Timbers may enhance diversity of the native herpetofauna.

Amphibian and Reptile Communities Associated with Beaver (Castor canadensis) Ponds and Unimpounded Streams in the Piedmont of South Carolina

ABSTRACT We used drift fence arrays with pitfall traps to compare amphibian and reptile assemblages at the peripheries of beaver (Castor canadensis) ponds of two age-classes (“new”: ≤ 5 yr old, and “old”: ≥ 10 yr old) and unimpounded streams in the Piedmont of South Carolina. The richness and total abundance of amphibians were not significantly different among new beaver ponds, old beaver ponds, and unimpounded streams, although several species of anurans were captured predominantly or exclusively at beaver ponds. Amphibian community overlap and diversity also were similar among the three habitats. In contrast, the richness and total abundance of reptiles were significantly higher at old beaver ponds when compared to new beaver ponds and unimpounded streams. The degree of reptile community overlap also was relatively low, with significant differences in diversity among all three habitats. Differences in amphibian and reptile community attributes between beaver ponds and unimpounded streams likely were related to the lentic or lotic habitat requirements of individual species and the effects of beaver impoundments on surrounding upland habitats.

Effects of a community restoration fire on small mammals and herpetofauna in the southern Appalachians

As part of the Wine Spring Creek ecosystem management project on the Nantahala National forest, North Carolina, we assessed effects of a community restoration fire on small mammals and herpetofauna in the upper slope pitch pine ( Pinus rigida) stands, neighboring midslope oak ( Quercus spp.) stands and rhododendron ( Rhododendron maximum) dominated riparian areas during 1995 and 1996. Using drift-fence arrays with pitfalls and snap-trapping, we collected these small mammals: masked shrew ( Sorex cinereus), smoky shrew ( S. fumeus), water shrew ( S. palustris), pygmy shrew ( S. hoyi), northern short-tailed shrew ( Blarina brevicauda), deer mouse ( Peromyscus maniculatus), white-footed mouse ( P. leucopus), golden mouse ( Ochrotomys nuttalli), southern red-backed vole ( Clethrionomys gapperi), pine vole ( Microtus pinetorum) and woodland jumping mouse ( Napaeozapus insignis). Herpetofauna collected from drift-fence arrays and time-constrained searches included: eastern newt ( Notophtalmus viridescens), seepage salamander ( Desmognathus aeneus), mountain dusky salamander ( D. ochrophaeus), Blue Ridge two-lined salamander ( Eurycea wilderae), spring salamander ( Gyrinophilus porphyriticus), Jordan's salamander ( Plethodon jordani), wood frog ( Rana sylvatica), five-lined skink ( Eumeces fasciatus), eastern garter snake ( Thamnophis sirtalis), and northern ringneck snake ( Diadophis punctatus). Prior to the prescribed community restoration fire in the spring of 1995, there were no significant differences in small mammal or herpetofauna collections between burned and control areas. Post-treatment in 1995 and 1996, showed no significant differences among collections of most species between burned and control areas. Slope position accounted for more variation among the species of greatest abundance than did burning. Concern for the effects of prescribed fire as a management tool on small mammals and herpetofauna in the southern Appalachians seems unwarranted.

A Comparison of Herpetofaunal Sampling Effectiveness of Pitfall, Single-Ended, and Double-Ended Funnel Traps Used with Drift Fences

We assessed the relative effectiveness of pitfalls, single-ended, and double-ended funnel traps at 12 replicate sites in sand pine scrub using drift fence arrays. Pitfalls captured fewer species but yielded more individuals of many species and higher average species richness than funnel traps. Pitfalls and funnel traps exhibited differential capture bias probably due to differences in behavior or morphology. More surface-active lizards, frogs, and small semifossorial herpetofaunal species were captured in pitfalls whereas captures of large snake species were restricted to funnel traps. Double-ended funnel traps captured twice as many large snakes as single-ended funnel traps. All three trap types yielded similar estimates of relative abundance of lizards and frogs but not snakes. Estimates of relative abundance of large snakes were higher for double-ended funnel traps than pitfalls or single-ended funnel traps. Pitfall and funnel traps yield complementary results, and choice of type(s) depends on target species and sampling goals.

Effects of clearcutting and site preparation on herpetofauna of a North Florida flatwoods

Drift-fence sampling for 1 year yielded information on effects of clearcutting and site-preparation intensity on flatwoods herpetofauna in northern Florida. Sampling occurred in a naturally regenerated 40-year-old slash pine forest and two adjacent 3–4-year-old clearcuts subjected to different site treatments. Four drift-fence array (16 fences) in the forest captured totals of 6266 amphibians (15 species) and 230 reptiles (21 species). From an equal number of arrays in both the minimum- and maximum-treatment clearcuts, amphibian captures totalled 592 (9 species) and 758 (11 species), respectively, and reptile captures totalled 196 (19 species) and 85 (14 species), respectively. Clearcutting and site-preparation treatments did not affect amphibian species richness, but reptile species richness was lower in the maximum-treatment clearcut, due to the absence of some arboreal lizard and snake species. Clearcutting reduced amphibian abundance tenfold by affecting reproductive success. Reptile abundance was reduced by maximum site preparation but not by minimum site preparation. Arboreal lizard populations were severely reduced by clearcutting. Herpetofaunal biomass was not affected by clearcutting and site preparation, but the biomass was apportioned differently among taxonomic groups. The minimum-treatment clearcut had higher snake biomass and lower anuran biomass than the other two sites, whereas the maximum-treatment clearcut had lower lizard biomass than the other two sites. Reptile communities in flatwoods would be favored by site-preparation practices that minimized site disturbances and maximized presence of logging debris. Responses of amphibian communities seemed to be dependent upon availability of water. Overall herpetofaunal diversity would be greatest in an area containing a mosaif of small clearcuts, cypress domes, and different-aged pine stands.