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At least 757 records · Page 42Linked to original sources
USGS2008

Post-breeding habitat use by adult Boreal Toads (Bufo boreas) after wildfire in Glacier National Park, USA

Effects of wildfire on amphibians are complex, and some species may benefit from the severe disturbance of stand-replacing fire. Boreal Toads (Bufo boreas boreas) in Glacier National Park, Montana, USA increased in occurrence after fires in 2001 and 2003. We used radio telemetry to track adult B. boreas in a mosaic of terrestrial habitats with different burn severities to better understand factors related to the post-fire pulse in breeding activity. Toads used severely burned habitats more than expected and partially burned habitats less than expected. No toads were relocated in unburned habitat, but little of the study area was unburned and the expected number of observations in unburned habitat was < 3. High vagility of B. boreas and preference for open habitats may predispose this species to exploit recently disturbed landscapes. The long-term consequences of fire suppression likely have had different effects in different parts of the range of B. boreas. More information is needed, particularly in the northern Rocky Mountains, where toads are more likely to occupy habitats that have diverged from historic fire return intervals. Copyright ?? 2008. C. Gregory Guscio. All rights reserved.

Herpetological Conservation and Biology↗
USGS2008

Wildfire effects on water temperature and selection of breeding sites by the Boreal Toad (Bufo boreas) in seasonal wetlands

Disturbances can significantly affect the thermal regime and community structure of wetlands. We investigated the effect of a wildfire on water temperature of seasonal, montane wetlands after documenting the colonization of recently burned wetlands by the Boreal Toad (Bufo boreas boreas). We compared the daily mean temperature, daily maximum temperature, and accumulated growing degree days measured on the north shore of three classes of wetlands: unburned wetlands, burned wetlands that were colonized by breeding toads, and burned wetlands that were not colonized. We hypothesized that toads colonized burned wetlands because they were warmer than unburned wetlands and selected specific burned wetlands because they were warmer than neighboring burned sites. There was weak evidence that toads selected burned wetlands with higher temperature maxima; however, the differences were small (???1??C) and were not supported when accounting for geography and wetland features. We also found no evidence that burning the forest around wetlands increased water temperatures two and three years after the fire. Unburned wetlands had higher daily mean and maximum temperatures and accrued more growing degree days than either class of burned wetlands. Temperature differences among groups of wetlands seemed to be driven by subtle differences in geography. We suspect we did not find warmer temperatures in burned wetlands because all of the wetlands we monitored already had open canopies and the fire likely resulted in only small increases in incident radiation. Copyright ?? 2008. Blake R. Hossack. All rights reserved.

Herpetological Conservation and Biology↗
USGS2011

Herpetofauna of the cedar glades and associated habitats of the Inner Central Basin of middle Tennessee

The cedar glades and barrens of the Inner Central Basin (ICB) of middle Tennessee support a unique and diverse flora and fauna and represent some of the state's most valued natural areas. We conducted herpetofaunal inventories of the cedar glades, associated barrens, cedar-hardwood forest, and adjacent aquatic habitats of the Stones River drainage of Middle Tennessee, focusing our sampling effort primarily at seven state- or federally owned properties in Rutherford and Wilson counties. These properties included Stones River National Battlefield (SRNB), Flat Rock State Natural Area (FRSNA), Vesta Cedar Glade State Natural Area (VSNA), Fall Creek Recreation Area (FCRA) on J. Percy Priest Wildlife Management Area, Cedars of Lebanon State Forest (CLSF), Cedars of Lebanon State Forest Natural Area (CLSNA), and Cedars of Lebanon State Park (CLSP). We used a variety of inventory techniques in terrestrial, aquatic, and subterranean habitats to survey these properties periodically from 1989 to 2010. We documented 49 species (22 amphibian and 27 reptile) accounting for 75.4% of the 65 herpetofaunal species thought to occur in the ICB, including records for Cemophora coccinea, Aneides aeneus, Gyrinophilus palleucus, Ambystoma barbouri, and Pseudotriton montanus. We found differences in alpha and beta diversity between sites, with the CLSF complex containing a high of 41 herpetofaunal species and FRSNA containing a low of 23 species. Beta diversity comparisons indicated similarity in amphibian species composition between FRSNA and CLSF and between SRNB and CLSF (9 shared species), and in reptile species composition between VSNA and the CLSF complex (16 shared species). We compare the results of our inventory with two previous studies conducted in the area and discuss the relative abundance, conservation, and threats to the herpetofaunal community of these habitats.

Herpetological Conservation and Biology↗
USGS2011

The effects of isolation on the demography and genetic diversity of long-lived species: Implications for conservation and management of the gopher tortoise (Gopherus polyphemus)

In the southeastern United States, habitat loss has fragmented the landscape and isolated many populations of this region's flora and fauna, which has presumably resulted in smaller population sizes and reduced levels of genetic diversity. For example, forestry practices and anthropogenic disturbances are both cited as factors fragmenting the once extensive range of Gopherus polyphemus. One localized, but extreme, source of fragmentation was the impoundment of the Chattahoochee River in 1963 to form Walter F. George Reservoir along the border of Georgia and Alabama. The formation of this reservoir isolated populations of G. polyphemus on two newly created islands providing a natural laboratory to explore the demographics and genetic effects of fragmentation on a long-lived species. These populations were first surveyed in 1984 and, 21 years later, we revisited them to collect demographic data and tissue samples for genetic analysis. We genotyped all individuals for 10 microsatellite loci, and we tested these data for bottlenecks and compared them to levels of genetic diversity for populations from other portions of the range. We found 45 and two individuals on the larger and smaller islands, respectively. On the large island, however, the population size was identical to the 1984 survey. Only the population structure based on estimated age differed between the 1984 and 2004 surveys, while population size structure based on carapace length, sex ratio, and sex-specific growth rates did not differ. The population of the large island showed genetic evidence of a past bottleneck. The genetic diversity indices from the population of the large island, however, were comparable to or greater than those found at mainland sites, in particular from western populations.

Herpetological Conservation and Biology↗
USGS2011

Effects of wind energy production on growth, demography, and survivorship of a Desert Tortoise (Gopherus agassizii) population in Southern California with comparisons to natural populations

We studied a Desert Tortoise (Gopherus agassizii) population at a large wind energy generation facility near Palm Springs, California over six field seasons from 1997 to 2010. We compared growth and demographic parameters to populations living in less disturbed areas; as well as populations of the closely-related and newly-described G. morafkai elsewhere in the Sonoran Desert of Arizona. We marked 69 individuals of all size classes and estimated a population size of 96 tortoises, or about 15.4/km 2 . Growth rates for males were lower than reported elsewhere, although maximum body size was larger. The smallest female with shelled eggs was 221 mm and males mature at over 200 mm. Mean male size was greater than that of females. The adult sex ratio was not significantly different from unity. Size frequency histograms were similar over time and when compared to most, but not all, G. morafkai populations in the Sonoran Desert. For a cohort of adult females, we estimated mortality at 8.4% annually due, in part, to site operations. This value was low in comparison to many other populations during the same time period. Other than possible differences in growth rate of males and the high survivorship of females, there appear to be few differences between this population and those in more natural areas. The high productivity of food plants at the site and its limited public access may contribute to the overall stability of the population. However, the effects of utility-scale renewable energy development on tortoises in other, less productive, areas are unknown. Additional research (especially controlled and replicated before and after studies) is urgently needed to address this deficiency because of forecasted expansion of utility-scale renewable energy development in the future.

California↗
USGS2011

Using spatiotemporal models and distance sampling to map the space use and abundance of newly metamorphosed Western Toads (Anaxyrus boreas)

High variability in abundance, cryptic coloration, and small body size of newly metamorphosed anurans have limited demographic studies of this life-history stage. We used line-transect distance sampling and Bayesian methods to estimate the abundance and spatial distribution of newly metamorphosed Western Toads (Anaxyrus boreas) in terrestrial habitat surrounding a montane lake in central Washington, USA. We completed 154 line-transect surveys from the commencement of metamorphosis (15 September 2009) to the date of first snow accumulation in fall (1 October 2009), and located 543 newly metamorphosed toads. After accounting for variable detection probability associated with the extent of barren habitats, estimates of total surface abundance ranged from a posterior median of 3,880 (95% credible intervals from 2,235 to 12,600) in the first week of sampling to 12,150 (5,543 to 51,670) during the second week of sampling. Numbers of newly metamorphosed toads dropped quickly with increasing distance from the lakeshore in a pattern that differed over the three weeks of the study and contradicted our original hypotheses. Though we hypothesized that the spatial distribution of toads would initially be concentrated near the lake shore and then spread outward from the lake over time, we observed the opposite. Ninety-five percent of individuals occurred within 20, 16, and 15 m of shore during weeks one, two, and three respectively, probably reflecting continued emergence of newly metamorphosed toads from the lake and mortality or burrow use of dispersed individuals. Numbers of toads were highest near the inlet stream of the lake. Distance sampling may provide a useful method for estimating the surface abundance of newly metamorphosed toads and relating their space use to landscape variables despite uncertain and variable probability of detection. We discuss means of improving the precision of estimates of total abundance.

Washington↗
USGS2012

An experimental evaluation of potential scavenger effects on snake road mortality detections

As road networks expand and collisions between vehicles and wildlife become more common, accurately quantifying mortality rates for the taxa that are most impacted will be critical. Snakes are especially vulnerable to collisions with vehicles because of their physiology and behavior. Reptile road mortality is typically quantified using driving or walking surveys; however, scavengers can rapidly remove carcasses from the road and cause underestimation of mortality. Our objective was to determine the effect that scavengers might have had on our ability to accurately detect reptile road mortality during over 150 h and 4,000 km of driving surveys through arid shrublands in southwest Wyoming, which resulted in only two observations of mortality. We developed unique simulated snake carcasses out of Burbot (Lota lota), a locally invasive fish species, and examined removal rates across three different road types at three study sites. Carcass size was not a significant predictor of time of removal, and carcass removal was comparable during the daytime and nighttime hours. However, removal of simulated carcasses was higher on paved roads than unpaved or two-track roads at all study sites, with an average of 75% of the carcasses missing within 60 h compared to 34% and 31%, respectively. Scavengers may therefore negatively impact the ability of researchers to accurately detect herpetofaunal road mortality, especially for paved roads where road mortality is likely the most prevalent.

Wyoming↗
USGS2012

The shallow-water fish assemblage of Isla del Coco National Park, Costa Rica: Structure and patterns in an isolated, predator-dominated ecosystem

Fishes at Isla del Coco National Park, Costa Rica, were surveyed as part of a larger scientific expedition to the area in September 2009. The average total biomass of nearshore fishes was 7.8 tonnes per ha, among the largest observed in the tropics, with apex predators such as sharks, jacks, and groupers accounting for nearly 40% of the total biomass. The abundance of reef and pelagic sharks, particularly large aggregations of threatened species such as the scalloped hammerhead shark (up to 42 hammerheads ha-1) and large schools of jacks and snappers show the capacity for high biomass in unfished ecosystems in the Eastern Tropical Pacific. However, the abundance of hammerhead and reef whitetip sharks appears to have been declining since the late 1990s, and likely causes may include increasing fishing pressure on sharks in the region and illegal fishing inside the Park. One Galapagos shark tagged on September 20, 2009 in the Isla del Coco National Park moved 255km southeast towards Malpelo Island in Colombia, when it stopped transmitting. These results contribute to the evidence that sharks conduct large-scale movements between marine protected areas (Isla del Coco, Malpelo, Galápagos) in the Eastern tropical Pacific and emphasize the need for regional-scale management. More than half of the species and 90% of the individuals observed were endemic to the tropical eastern Pacific. These high biomass and endemicity values highlight the uniqueness of the fish assemblage at Isla del Coco and its importance as a global biodiversity hotspot.

Cocos Island, Isla Del Coco↗
USGS2013

Efficacy of trap modifications for increasing capture rates of aquatic snakes in floating aquatic funnel traps

Increasing detection and capture probabilities of rare or elusive herpetofauna of conservation concern is important to inform the scientific basis for their management and recovery. The Giant Gartersnake (Thamnophis gigas) is an example of a secretive, wary, and generally difficult-to-sample species about which little is known regarding its patterns of occurrence and demography. We therefore evaluated modifications to existing traps to increase the detection and capture probabilities of the Giant Gartersnake to improve the precision with which occurrence, abundance, survival, and other demographic parameters are estimated. We found that adding a one-way valve constructed of cable ties to the small funnel opening of traps and adding hardware cloth extensions to the wide end of funnels increased capture rates of the Giant Gartersnake by 5.55 times (95% credible interval = 2.45–10.51) relative to unmodified traps. The effectiveness of these modifications was insensitive to the aquatic habitat type in which they were deployed. The snout-vent length of the smallest and largest captured snakes did not vary among trap modifications. These trap modifications are expected to increase detection and capture probabilities of the Giant Gartersnake, and show promise for increasing the precision with which demographic parameters can be estimated for this species. We anticipate that the trap modifications found effective in this study will be applicable to a variety of aquatic and semi-aquatic reptiles and amphibians and improve conservation efforts for these species.

Herpetological Conservation and Biology↗
USGS2013

Complex spatial dynamics maintain northern leopard frog (Lithobates pipiens) genetic diversity in a temporally varying landscape

In contrast to most local amphibian populations, northeastern populations of the Northern Leopard Frog (Lithobates pipiens) have displayed uncharacteristically high levels of genetic diversity that have been attributed to large, stable populations. However, this widely distributed species also occurs in areas known for great climatic fluctuations that should be reflected in corresponding fluctuations in population sizes and reduced genetic diversity. To test our hypothesis that Northern Leopard Frog genetic diversity would be reduced in areas subjected to significant climate variability, we examined the genetic diversity of L. pipiens collected from 12 sites within the Prairie Pothole Region of North Dakota. Despite the region's fluctuating climate that includes periods of recurring drought and deluge, we found unexpectedly high levels of genetic diversity approaching that of northeastern populations. Further, genetic structure at a landscape scale was strikingly homogeneous; genetic differentiation estimates (D est ) averaged 0.10 (SD = 0.036) across the six microsatellite loci we studied, and two Bayesian assignment tests (STRUCTURE and BAPS) failed to reveal the development of significant population structure across the 68 km breadth of our study area. These results suggest that L. pipiens in the Prairie Pothole Region consists of a large, panmictic population capable of maintaining high genetic diversity in the face of marked climate variability.

North Dakota↗
USGS2013

Terrestrial movement patterns of western pond turtles (Actinemys marmorata) in central California

We used radio telemetry to track the terrestrial movements and seasonal habitat use patterns of Western Pond Turtles (Actinemys marmorata) near two ponds in the Carrizo Plain Ecological Reserve, California, USA. We captured 93 turtles in September 2005 and, of these, we tagged three males and six females(weighing > 300 g) with external transmitters. Tagged turtles traveled from 255–1,096 m over the 448-day study, and we found none further than 343 m from ponds. All turtles moved away from the ponds as water levels receded in the fall, resulting in periods of terrestrial overwintering ranging from 10–30 weeks (74–202 d). We found no evidence for group migrations as turtles departed ponds over 2–8 week periods, moved in different directions from their ponds, and used different habitats. Turtles overwintered mainly in oak and chaparral vegetation communities, which constituted most of the local vegetation. We found overwintering turtles in a variety of microhabitats, but all turtles were on the surface with their carapace just visible amongst the duff layer. Turtles returned to ponds over several weeks, sometimes months after they refilled with winter rains. In the winter of 2006–2007, no turtles returned to terrestrial overwintering sites used the previous year. Most of the turtles we tracked spent over half of each year on land, demonstrating the importance of terrestrial habitats around these seasonal ponds. This pattern is similar to pond turtles living in streams (overwinter on land), as compared to permanent ponds (turtles often remain in water).

California↗
USGS2013

Comparative microhabitat characteristics at oviposition sites of the California red-legged frog ( Rana draytonii )

We studied the microhabitat characteristics of 747 egg masses of the federally-threatened Rana draytonii (California red-legged frog) at eight sites in California. our study showed that a broad range of aquatic habitats are utilized by ovipositing R. draytonii , including sites with perennial and ephemeral water sources, natural and constructed wetlands, lentic and lotic hydrology, and sites surrounded by protected lands and nested within modified urban areas. We recorded 45 different egg mass attachment types, although the use of only a few types was common at each site. These attachment types ranged from branches and roots of riparian trees, emergent and submergent wetland vegetation, flooded upland grassland/ruderal vegetation, and debris. eggs were deposited in relatively shallow water (mean 39.7 cm) when compared to maximum site depths. We found that most frogs in artificial pond, natural creek, and artificial channel habitats deposited egg masses within one meter of the shore, while egg masses in a seasonal marsh averaged 27.3 m from the shore due to extensive emergent vegetation. Rana draytonii appeared to delay breeding in lotic habitats and in more inland sites compared to lentic habitats and coastal sites. eggs occurred as early as mid-december at a coastal artificial pond and as late as mid-April in an inland natural creek. We speculate that this delay in breeding may represent a method of avoiding high-flow events and/or freezing temperatures. Understanding the factors related to the reproductive needs of this species can contribute to creating, managing, or preserving appropriate habitat, and promoting species recovery.

Herpetological Conservation and Biology↗
USGS2013

Effects of prescribed fire on Coluber constrictor Mormon in coastal San Mateo County, California

Although prescribed burns are used in many locations where reptiles are present, the effects of fire on reptiles are poorly understood. our objective was to determine the effects of prescribed fire on the Western yellow-bellied racer, Coluber constrictor mormon , at a study site in coastal san Mateo county, california. We sampled an unburned site and an adjacent prescribed burn site two to five years post fire in the spring and summer of 2007 through 2010. We found no differences in apparent survival or body condition of snakes between burned and unburned sites. the burned site had lower snake abundance than the unburned site in 2008 but we found no difference in abundance between sites in 2009 and 2010. We also found a difference in body condition across years and asymmetry in the probability of transition (movement between burned and unburned sites). Vegetation cover between the burned and unburned sites was similar. this study serves as a baseline for investigation of the effects of fire on Coluber constrictor mormon at our study site and provides further insight on the effects of prescribed fire on reptile species.

California↗
USGS2014

Northeast regional and state trends in anuran occupancy from calling survey data (2001-2011) from the North American Amphibian Monitoring Program

We present the first regional trends in anuran occupancy from North American Amphibian Monitoring Program (NAAMP) data from 11 northeastern states using an 11 years of data. NAAMP is a long-term monitoring program where observers collect data at assigned random roadside routes using a calling survey technique. We assessed occupancy trends for 17 species. Eight species had statistically significant regional trends, of these seven were negative (Anaxyrus fowleri, Acris crepitans, Pseudacris brachyphona, Pseudacris feriarum-kalmi complex, Lithobates palustris, Lithobates pipiens, and Lithobates sphenocephalus) and one was positive (Hyla versicolor-chrysoscelis complex). We also assessed state level trends for 101 species/state combinations, of these 29 showed a significant decline and nine showed a significant increase in occupancy.

Herpetological Conservation and Biology↗
USGS2014

A review of pipe and bamboo artificial refugia as sampling tools in anuran studies

Artificial pipe-like refugia have been used for more than 40 years in anuran studies, and have captured 28 species, primarily (82%) hylid treefrogs. Early pipe-like refugia were made using cut pieces of bamboo in the tropical forests of Puerto Rico, but most recent studies have used synthetic pipes and have occurred primarily in the southeastern United States. Characteristics of artificial refugia (e.g., color, length, and diameter), and their placement in the environment have varied greatly among studies, making comparisons difficult. Here, we summarize and evaluate different pipe designs and placement, address potential concerns when using artificial pipe-like refugia, and suggest studies necessary to better interpret the data gained from this technique in anuran studies.

Herpetological Conservation and Biology↗
USGS2015

Spatial requirements of different life-stages of the loggerhead turtle ( Caretta caretta ) from a distinct population segment in the northern Gulf of Mexico

Many marine species have complex life histories that involve disparate developmental, foraging and reproductive habitats and a holistic assessment of the spatial requirements for different life stages is a challenge that greatly complicates their management. Here, we combined data from oceanographic modeling, nesting surveys, and satellite tracking to examine the spatial requirements of different life stages of Loggerhead Turtles (Caretta caretta) from a distinct population segment in the northern Gulf of Mexico. Our findings indicate that after emerging from nesting beaches in Alabama and Northwest Florida, hatchlings disperse widely and the proportion of turtles following a given route varies substantially through time, with the majority (mean of 74.4%) projected to leave the Gulf of Mexico. Adult females use neritic habitat throughout the northern and eastern Gulf of Mexico both during the inter-nesting phase and as post-nesting foraging areas. Movements and habitat use of juveniles and adult males represent a large gap in our knowledge, but given the hatchling dispersal predictions and tracks of post-nesting females it is likely that some Loggerhead Turtles remain in the Gulf of Mexico throughout their life. More than two-thirds of the Gulf provides potential habitat for at least one life-stage of Loggerhead Turtles. These results demonstrate the importance of the Gulf of Mexico to this Distinct Population Segment of Loggerhead Turtles. It also highlights the benefits of undertaking comprehensive studies of multiple life stages simultaneously: loss of individual habitats have the potential to affect several life stages thereby having long-term consequences to population recovery.

Gulf of Mexico↗