Amphibians and Reptiles

Abstract

Amphibians and reptiles are a diverse group of ectothermic vertebrates that occupy a variety of habitats in rangelands of North America, from wetlands to the driest deserts. These two classes of vertebrates are often referred to as herpetofauna and are studied under the field of herpetology. In U.S. rangelands, there are approximately 66 species of frogs and toads, 58 salamanders, 98 lizards, 111 snakes, and 27 turtles and tortoises. Herpetofauna tend to be poorly studied compared with other vertebrates, which creates a challenge for biologists and landowners who are trying to manage rangeland activities for this diverse group of animals and their habitats. Degradation of habitats from human land use and alteration of natural processes, like wildfire, are primary threats to herpetofauna populations. Disease, non-native predators, collection for the pet trade, and persecution are also conservation concerns for some species. Properly managed livestock grazing is generally compatible with herpetofauna conservation, and private and public rangelands provide crucial habitat for many species. Climate change also poses a threat to herpetofauna, but we have an incomplete understanding of the potential effects on species. Dispersal and adaptation could provide some capacity for species to persist on rangelands as climates, disturbance regimes, and habitats change. However, inadequate information and considerable uncertainty will make climate mitigation planning difficult for the foreseeable future. Planning for and mitigating effects of climate change, and interactions with other stressors, is an urgent area for research. Maintaining large, heterogeneous land areas as rangelands will certainly be an important part of the conservation strategy for herpetofauna in North America.

1 General Life History and Population Dynamics

Amphibians and reptiles are diverse classes of vertebrates. Amphibia are organized taxonomically into three orders: Anura (frogs and toads); Caudata or Urodela (salamanders); and Apoda or Gymnophiona (caecilians). Reptilia are organized into four orders: Squamata (lizards and snakes); Testudines (turtles and tortoises); Crocodylia (alligators and their allies); and Rhynchocephalia (tuatara). Amphibians and reptiles were combined historically and studied in the field of herpetology, but their evolutionary history is not so tidy. Modern cladistics even abandons the term reptile in favor of the clade Sauropsida, which includes birds. This chapter, however, follows a traditional taxonomy of amphibians and non-avian reptiles. North America is home to more than 733 amphibian and reptile species (Crother 2017). According to our analyses, there are about 124 amphibian species, composed of frogs and toads (N = 66) and salamanders (N = 58), whose distributions overlap by at least 10% with the rangeland ecoregions described in this book (Table 25.1). The United States (U.S.) is a global hotspot of salamander diversity, but salamanders are much less common in U.S. rangelands. About 89% of U.S. rangeland reptile species are lizards (N = 98) and snakes (N = 111), with the remaining diversity composed of turtles and tortoises (N = 27) (Table 25.2). One crocodilian, the American alligator (Alligator mississippiensis), occurs on the periphery of southeastern U.S. rangelands, but its distribution was below the 10% threshold for inclusion in this chapter. Keep in mind that diversity estimates of herpetofauna are dynamic as new species continue to be discovered or described. For example, using molecular and morphological evidence, two new toad species were described in central Nevada in 2019 (Gordon et al. 2020). Taxonomy of amphibians and reptiles is somewhat unresolved and often disputed, which creates challenges for communication in conservation. In this chapter, we use taxonomy from Crother (2017) and the Integrated Taxonomic Information System (ITIS; www.itis.gov, accessed 13 July 2021). Species counts, however, were generated from distribution maps in the USGS Gap Analysis Project (USGS GAP 2018a), which used an older taxonomy (Crother et al. 2003). Crother (2017) is currently the most widely accepted taxonomy for North America and thus we recommend checking this reference and consulting with state herpetologists for the latest taxonomic information about species in your area.

Table 25.1 Count of amphibian species within U.S. rangelands grouped by family

Table 25.2 Count of reptile species within U.S. rangelands grouped by family

Some life history characteristics are shared by amphibians and reptiles and these are important to consider when characterizing their ecology and understanding their habitat use patterns in rangelands. First, amphibians and reptiles are both ectothermic, meaning they cannot regulate body temperatures through metabolism. Instead, their body temperature tracks the environmental temperatures of their surroundings, although they can influence this process behaviorally. For example, amphibians and reptiles raise their body temperatures by exposure to solar or thermal radiation. This is accomplished by a variety of mechanisms, especially darkening their skin through pigmentation, basking, and pressing their bodies against warm surfaces. This process, known as behavioral thermoregulation, explains why lizards are frequently seen basking in morning sunlight or hugging rocks on a cool day. This also explains why snakes are often encountered (and unfortunately killed) on asphalt roads. Behavioral thermoregulation allows herpetofauna to accelerate temperature increases for activity and maintain optimal body temperatures for more hours of the day, including into the night. Amphibians and reptiles can also lower their body temperatures by evaporative cooling or re-radiating body heat into a cooler surrounding environment, such as water, shade, or burrows (Figs. 25.1 and 25.2). Spadefoot toads (Spea and Scaphiopus spp.), for example, are some of the most widespread amphibian inhabitants of U.S. rangelands and use a hardened skin spur on their hind feet to dig burrows into sandy soils to escape dangerously hot, dry surface conditions. Thus, amphibians also select specific microsites to maintain preferred body temperatures, but at the expense of water loss and thus strike a fine balance between temperature regulation and dehydration (Bartelt et al. 2010). Scales, shells, and thickened skin protect reptiles from dehydration. These and other anatomical features, traits, and adaptations enable reptiles to use a wider range of terrestrial locations than amphibians to optimize body temperatures to meet physiological needs.

Reproduction and development are life history characteristics where amphibians and reptiles diverge (Pough et al. 1998). Amphibians produce eggs that are not protected by shells and thus must be deposited in water or very moist environments. Like fishes, most frogs and toads fertilize their eggs externally whereby a female deposits her eggs directly into the water and the male releases sperm onto them. Most amphibian embryos develop gills and become free-swimming tadpoles (frogs and toads) or larvae (salamanders). Some terrestrial species of lungless salamanders (family Plethodontidae) skip the larval stage and embryos develop directly into the adult body form, albeit a tiny version. Most tadpoles and larvae go through metamorphosis, which is the developmental transformation from an aquatic, gilled life stage to terrestrial juveniles that have the adult body form and use lungs for respiration. Amphibians are among only a handful of vertebrates that go through metamorphosis (Laudet 2011). The duration of the larval stage and timing of metamorphosis varies considerably by species and is dependent on both genetic and environmental factors. A few salamander species, including tiger salamanders (Ambystoma spp.) which are common in U.S. rangelands (Fig. 25.1), can retain their gills and remain aquatic as sexually mature adults. Finally, all amphibians have retained some capacity to respire through their skin, although this inefficient form of respiration usually only occurs for animals overwintering under water and obligatorily among the lungless salamanders, which lack both lungs and gills.

Fig. 25.1

Photographs of some of the amphibian species found in rangelands. Photographs by Alan St. John, Ryan Hagerty, Mindy Meade, Chad Mellison, Charles R. Peterson, and Alan Schmierer

Like birds and a few mammals, reptiles produce eggs that have multiple membranes external to the embryo and a protective outer shell that is either parchment-like and leathery, or hard and calcified similar to a chicken egg. Reptiles use one of three strategies for reproduction: ovipary, vivipary, and ovovivipary. In ovipary, the egg must be fertilized internally by copulation between the male and female prior to eggshell formation. Oviparous embryos partially develop inside the female and eggs are laid in microsites with specific soil substrate and moisture and temperature conditions for development and hatching. Oviparous reptiles hatch fully formed as miniature adults, although they may carry the remainder of the egg yolk as a ‘sack-lunch’ during their first season. In ovovivipary, embryos may acquire their sustenance from a yolk that remains inside the female during development, or embryos may be connected to the female by a placenta (i.e., true vivipary). Rattlesnakes (Crotalus spp.), boas (Charina spp.), and gartersnakes (Thamnophis spp.) are all ovoviviparous species from U.S. rangelands (Fig. 25.2).

Fig. 25.2

Photographs of some of the reptile species found in rangelands. Photographs by Patrick Alexander, Courtney Celley, Michelle Jeffries, Jerry Kirkhart, Gavin O’Leary, Peter Paplanus, and Charles R. Peterson

2 Species Status

2.1 Historical Versus Current Distributions

The diversity of rangeland herpetofauna presently found across North America can be linked to the environments their ancestors experienced and numerous vicariance events (Pyron 2014; Modesto et al. 2015; Wollenberg Valero et al. 2019). Over the eons, the configurations, sizes, and positions of drifting continents shaped the habitats available to herpetofauna with changes in latitude (i.e., tropical versus polar conditions), climates, sea levels, and formations of lava flows, mountain ranges, deserts, and inland seas. The uplift of mountain ranges in western North America (e.g., most recently the Cascade Range and Sierra Nevada around 4–7 mya) produced rain shadows that drastically altered the climates and vegetation of western rangelands. These deserts influenced the evolution, speciation, and adaptations of modern rangeland herpetofauna (Bryson et al. 2012; Bouzid et al. 2021). Glacial cycles and the formation and draining of inland lakes (e.g., Bonneville, Missoula) during the past 15,000–25,000 yrs also influenced diversification of the species we know today (Thompson and Russell 2005; Funk et al. 2008; Kimberly and Fender 2020). Vicariance and introgression of rangeland species is ongoing with modern processes like anthropogenically induced climate change and fragmentation of habitat.

Amphibians and reptiles are generally understudied, even in rangelands where diversity is comparable to, or higher than, other vertebrate groups (Qian 2009). Therefore, information about historical distribution is severely lacking. A logical assumption is that the historical distribution of amphibians in rangelands was probably determined by the availability of surface water and we know surface waters have changed dramatically over contemporary times (Qian 2010). Part of that change is attributed to intensive trapping of North American beaver (Castor canadensis) for pelts and draining of wetlands for cropland agriculture and pasture (Gibson and Olden 2014; Grudzinski et al. 2020; Wohl 2021). We suspect that loss of amphibian habitat must have been enormous because beaver activity in the western U.S. today is strongly associated with amphibian occupancy patterns, especially for frogs and toads (Arkle and Pilliod 2015; Hossack et al. 2015; Zero and Murphy 2016). Other novel water sources were American bison (Bison bison) wallows, which must have once been numerous and extensive across the Great Plains (Meagher 1986). Remnant wallows were still found during the 1940s in grasslands where wallows had not been destroyed by cultivation. Some of those remnant wallows were about 6 m (20 ft) wide and 2.5 m (8 ft) deep and were used as breeding sites by Great Plains toads (Anaxyrus cognatus; Bragg 1940). Western chorus frogs (Pseudacris triseriata) and northern cricket frogs (Acris crepitans) started using bison wallows for breeding at the Konza Prairie in Kansas after bison were reintroduced in 1987 (Gerlanc and Kaufman 2003). Similarly, western chorus frog choruses can be heard from bison wallows at Theodore Roosevelt National Park, North Dakota where bison were reintroduced in 1956 (Hossack et al. 2005). Hence, evidence suggests that bison wallows were once important breeding sites for prairie amphibians, even though successful metamorphosis may have only occurred in wetter years that provided sustained surface water, or what is often referred to as hydroperiods that are long enough for successful reproduction (Gerlanc and Kaufman 2003). Bison wallow abundance and distributions in rangelands are certainly much reduced today and we know little about the consequences for prairie amphibians.

Between 1780 and 1980, an estimated 53% of 894,355 km² (221 million acres) of wetlands were intentionally or unintentionally drained in the contiguous United States, especially freshwater emergent marshes that are so important to wildlife (Dahl 1990). In Nevada, for example, over half of its original 1971 km² (487,000 acres) of wetlands were lost in that 200-yr span. These losses were partially offset by the creation of water impoundments, such as stock ponds and reservoirs, which are common in rangelands. For example, a state-wide inventory in the early twenty-first century found that more than 70% of lentic wetlands in eastern Montana were human-created (Maxell 2009). Both the loss and creation of wetlands has influenced the contemporary distribution of herpetofauna across U.S. rangelands. Species such as the painted turtle (Chrysemys picta; Fig. 25.2), Woodhouse’s toad (Anaxyrus woodhousii), and tiger salamander (Ambystoma spp.) may have increased their distribution in some places because of water impoundments. In other cases, stock ponds may be the only habitat remaining in otherwise cropland-dominated landscapes (Knutson et al. 2004). Regardless, anthropogenic changes in the type, size, and depth of wetlands in rangelands has influenced herpetofauna distributions in all likelihood, and this may have implications for persistence as climates change. The Great Basin, for example, has been getting warmer and drier in the last century resulting in increased isolation of amphibian populations as detectable in the genetic structure of Columbia spotted frogs (Rana luteiventris; Fig. 25.1; Pilliod et al. 2015; Robertson et al. 2018). In the Great Plains, connectivity among > 80,000 playas from Nebraska to Texas may have been reduced beyond levels needed to support movements for many amphibian species (Heintzman and McIntyre 2021). Except for a few aquatic species, such as the painted turtle and common water snake (Nerodia sipedon), that require surface water to meet their life history needs, reptile distributions and threats are more subtle with regard to water.

Reptiles are much more tolerant of aridity than other vertebrates, enabling them to inhabit a diversity of upland habitats (Fig. 25.3) as long as temperatures are not too cold (Qian 2010). In the last several hundred years, however, reptiles and amphibians have been subjected to large scale land use changes, such as cropland agriculture, livestock production, timber harvest, and urbanization, all of which have influenced species distributions to varying extents (Cordier et al. 2021). Conversion of rangelands to hayfields or irrigated croplands is a major modification to potential habitats from the perspective of local herpetofauna (Fig. 25.3). In rangeland landscapes, the interdigitation of cropland fields, right-of-ways, hedgerows, and fencelines alter herpetofauna communities as these modified areas are frequently only inhabited by the more common and adaptable species (Pulsford et al. 2017). Obviously human features on the landscape that destroy habitat for herpetofauna, such as buildings, parking lots, solar installations, roads, railways, and so forth, also have cumulatively large footprints, and their effects extend into surrounding habitats (Averill-Murray et al. 2021).

Fig. 25.3

The frequency distribution of predicted richness for amphibians and reptiles across different land cover types in rangelands of the U.S. Cropland and urban are embedded within rangelands and likely represent conversion of former rangelands. Richness data are from GAP predicted species distributions (USGS GAP 2018a). The vegetation cover types come from the North American Atlas Land Cover 2010 Mapping Project (data grain is 250 × 250 m). Metadata about these cover types can be found at: http://www.cec.org/north-american-environmental-atlas/land-cover-2010-modis-250m/. The y-axis is a count of 30-m pixels for each category and group. The pixel count (y-axis) of the top four land cover types (Cropland, Grassland, Shrubland, Forest) have a different range than the three less common land cover types (Barren, Urban, Water)

Species richness of both amphibians and reptiles tends to be higher in the south than the north (Fig. 25.4). Reptile diversity is greatest below the 37th parallel, which is highlighted by the state boundaries between Colorado and New Mexico as well as Utah and Arizona. This latitude coincidentally defines the average solar insolation on earth: below this line and toward the equator solar insolation is greater than average incoming solar radiation, whereas above the 37th parallel, toward the poles, solar insolation decreases. Below the 37th parallel, there are hotspots of reptile diversity in central and eastern Texas, with over 70 species found there. Moving northward, reptile diversity tapers off in a steady gradient (Kiester 1971). Amphibian diversity also decreases from the equator northward (Wiens 2007), but the Pacific Northwest has an unusually high diversity of salamanders. Similar to reptiles, the Texas–Mexico border area is also a hotspot of amphibian diversity (Fig. 25.4). The warm, dry conditions in the desert regions of the southwestern U.S. are ideal for reptiles, whereas this region has strikingly low amphibian diversity. Utah, for example, may only have one native salamander species, the western tiger salamander (Fig. 25.1; Ambystoma mavortium). The species was thought to also occur in Nevada, but molecular evidence suggests the only salamander populations in Nevada may be the eastern tiger salamander (Ambystoma tigrinum), introduced as bait by fisherman (Johnson et al. 2011). Introduced populations of eastern tiger salamanders have been discovered in other western states as well.

Fig. 25.4

Map of predicted amphibian (upper panel) and reptile (lower panel) species richness in the United States with rangelands delineated based on ecoregions derived from The Nature Conservancy’s Geospatial Conservation Atlas (geospatial.tnc.org), modified using ecotype layers downloaded from the EPA Level III ecoregions in the Central Mixed—Grass Prairie region in Nebraska and Texas. The amphibian and reptile richness data came from the Gap Analysis Project (USGS GAP 2018b, c)

The elevational range of amphibians and reptiles is broad. For example, the sidewinder rattlesnake (Crotalus cerastes) and western threadsnake (Leptotyphlops humilis) are found below sea level in Death Valley, California whereas western fence lizards (Sceloporus occidentalis: Fig. 25.2) and mountain yellow-legged frogs (Rana muscosa) can be found above 3300 m (10,827 ft) in the Sierra Nevada of central California (Stebbins 2003). About the only areas devoid of herpetofauna in rangelands are alkali flats (dry desert lake beds) and alpine zones.

2.2 Population Monitoring

Population monitoring of herpetofauna species is mostly conducted by state and federal agencies, and is usually associated with species listed or petitioned under the Endangered Species Act or those listed as species of greatest conservation need in State Wildlife Action Plans. For amphibians, monitoring focuses almost exclusively on individual breeding sites or groups of sites in a landscape for species that tend to form metapopulations. The gold standard for population monitoring is mark-recapture. Mark-recapture studies involve marking individual animals with a unique identifier so that they can be identified if captured again in subsequent surveys or trapping efforts (Buckland et al. 2000). Common ways of marking animals are with passive integrated transponder (PIT) tags (Fig. 25.5), scale clips, shell notching, and colored paints, inks, and elastomers (Silvy et al. 2012). When conducted over at least three or more years, mark-recapture data can provide valuable estimates of population size and demographic rates. Population demography includes measures of natality or reproduction, recruitment, survival, senescence, and mortality. Demography data can provide more robust measures of trends and responses to environmental stressors or management compared with simple counts of individuals observed (Schmidt 2003). Indirect measures of populations, such as egg mass counts or enumeration of calling frogs and toads (such as with call recorders; Fig. 25.5), can also provide useful information for tracking population trends (Heyer et al. 1994).

Fig. 25.5

Photographs of common field methods used in herpetological field studies, including: a Drift fences with funnel traps; b Line transect surveys, including distance sampling; c Hand capturing (in this case tubing a Great Basin rattlesnake (Crotalus oreganus lutosus) to allow for safe handling; d Radio-telemetry; e Marking individuals for mark-recapture studies (in this case inserting a passive integrative transponder (PIT) tag); f Call recorder for frogs and toads during the breeding season; g Environmental DNA sampling for species detection; and h PIT tag antenna to record the timing and direction of animal movement. Photographs by Todd Esque, Matthew Laramie, Chad Mellison, Amelia Orton-Palmer, Charles R. Peterson, and David Pilliod

Unlike amphibians or turtles that may congregate at water bodies to breed or forage, or snakes that may congregate to breed and overwinter at hibernacula, lizards and tortoises do not congregate and thus must be surveyed intensively over areas spanning hectares to square kilometers. Therefore, for most reptiles, optimal sampling designs include many plots or trapping locations distributed over large areas representing a range or variety of habitats used by a particular species. Search methods and effort must be consistent, or at least accounted for, among surveys and through time. Capture methods vary depending on the target species and include active sampling, such as noosing lizards or visual searching and capturing animals (Fig. 25.5). Sometimes capturing lizards and snakes involves wild chases and long arms to reach animals under rocks or in burrows, while other times it simply involves picking them up, as with tortoises. Passive sampling devices, such as drift fences, pitfall trap arrays, camera traps, or cover boards, are also commonly used and may be necessary for rare, cryptic, or fossorial species. Each method has some sampling bias because of activity patterns and size of target animals and life stages. Many studies are plagued by small sample sizes or high inter-annual variability in capture rates because of strong environmental associations, such as seasonal or annual weather. For community studies, oftentimes one or a few species dominate the capture tally whereas other species are captured too infrequently to even model.

Distance-sampling methods provide population estimates of species over large areas using standardized linear transects traveled by observers (Fig. 25.5; Buckland et al. 2000). This method was adopted to monitor Mojave desert tortoise (Gopherus agassizii; Fig. 25.2) population trends across its range since 1999 and continues today (USFWS 2011). Field teams are tested with tortoise models to calculate their ability to detect tortoises at various distances from the transect line and these correction factors are used to reduce error and improve estimates. Radio-tagged tortoises have also been used for this purpose and for validation of population estimates. Distance-sampling estimates of population size and trends, usually averaged over extensive areas, have provided important contributions to population management of the Mojave desert tortoise in Arizona, California, and Utah.

There are other monitoring approaches that are useful for herpetofauna that involve only presence/non-detection data and some of these methods have become quite sophisticated. Occupancy modeling has proven useful for herpetofauna (Bailey et al. 2014), including indirect measures of species occurrence such as environmental DNA (Fig. 25.5; Burian et al. 2021) and open drift-fences with cameras instead of traps (Martin et al. 2017). Occupancy modeling accounts for imperfect detection, which is important for herpetofauna that are often rare, cryptic, fossorial, or otherwise difficult to detect. After accounting for detection probabilities and measured environmental variables, presence and non-detection data from repeated visits are used to create occupancy probabilities for an area or site.

Studies of herpetofauna movements have revealed the complexity of diel, seasonal, and interannual habitat use patterns and the role of migration and dispersal in population dynamics and gene flow (Cayuela et al. 2020). Understanding movement ecology of herpetofauna is crucial for their conservation (Bailey and Muths 2019; Joly 2019). Juveniles are particularly understudied, although, as in other vertebrates, juveniles may represent one of the most important life stages for dispersal, colonization, and gene flow (Petrovan and Schmidt 2019). Movement studies generally involve tagging or marking individual animals and tracking their locations actively using radio-transmitters, passively using trapping, or opportunistically with surveys (Fig. 25.5). Radio-telemetry can also increase the certainty of population and demographic estimations (e.g., Mitchell et al. 2021). Twenty years of monitoring amphibians across the U.S. by the U.S. Geological Survey’s Amphibian Research and Monitoring Initiative (ARMI) has provided robust evidence that many amphibian populations are at risk of decline or extinction. An analysis of 83 species revealed that amphibian populations are disappearing from 3.7 to 3.8% of formerly occupied sites annually (Adams et al. 2013; Grant et al. 2016). At this rate, by 2035 many amphibian species will be gone from half of the places where they occurred in 2015 (Grant et al. 2016). These declines are due to a combination of factors driven by habitat loss, invasive predators, disease, and climate change. However, the status and trends of individual amphibian populations depend on many factors and not all species are necessarily at risk (Muths et al. 2018). Monitoring of 14 species of frogs and toads in the southeastern U.S. concluded that seven species were increasing (especially the green treefrog, Hyla cinerea, and spring peeper, Pseudacris crucifer; Fig. 25.1), while eight species showed a declining trend between 2001 and 2013 (Villena et al. 2016). Comparable regional or national monitoring programs do not exist for reptiles, except for a few species of highest conservation concern, such as the Mojave desert tortoise. Recent analyses showed only one of five of the recovery areas for Mojave desert tortoises had positive population growth after ~ 15 yr of monitoring, and juvenile tortoise numbers were declining (Allison and McLuckie 2018). These results are mostly inconsistent with recovery goals (USFWS 2011).

3 Habitat Associations

As ectotherms, climate plays an overarching role in the distribution and habitat associations of herpetofauna. In general, amphibians are limited by environmental temperature and precipitation, whereas reptiles are strongly associated with temperature (Buckley and Jetz 2007; Qian 2010). This explains why we see amphibians and reptiles in specific locations or habitats, including relative to seasons and times of day. As previously described, thermoregulation is crucial for physiological functions (e.g., digestion, metabolism) and performance (locomotion) of herpetofauna. Water balance, or hydroregulation, is also a key process underlying physiological and ecological responses. As might be expected, thermoregulation and hydroregulation are closely linked and thus these physiological and behavioral mechanisms often represent decisions or tradeoffs between optimal body temperature and water loss (Rozen-Rechels et al. 2019). A toad or lizard, for example, may tolerate some dehydration when selecting a warm, dry microsite needed to maintain a higher body temperature necessary for dispersal, digestion, or, in the case of a gravid (pregnant) female, embryonic development.

At the regional or landscape level, availability of freshwater is paramount for amphibians and some reptiles, and species assemblages depend on characteristics of wetland habitats and the spatial distribution and configuration of those wetlands (Mushet et al. 2012). Wetland amphibian habitats in rangelands and croplands are often characterized by the amount and complexity of shoreline, depth of water and availability of shallows, solar insolation, water chemistry, hydrology and hydroperiods, amount of emergent vegetation, and characteristics of riparian and floodplain vegetation (Knutson et al. 2004; Swartz and Miller 2019). Depending upon these habitat characteristics, amphibian communities can also be strongly influenced by predation, especially by salmonids (i.e., trout, char), centrarchids (e.g., bass, bluegill, pumpkinseed, sunfish), gartersnakes (Thamnophis spp.), American bullfrogs (Lithobates catesbeianus) and various birds (Pilliod et al. 2012; Ford et al. 2013; Rowe et al. 2019). In terrestrial environments, the structure and composition of vegetation have strong influences on herpetofauna habitats, especially related to the thermal environment, food resources, and cover (Fischer et al. 2004). In general, heterogeneous habitats provide more niches and microsites than homogeneous habitats (Fuhlendorf et al. 2017; Londe et al. 2020). Finally, contextual location is important, such as past land uses, elevation, landform, soils, surrounding habitat, and distance to nearest habitat suitable for survival, reproduction, or development (Kay et al. 2017; Sawatzky et al. 2019).

The majority of reptiles are not similarly constrained by water requirements. Although most temperate reptiles drink surface water, they also can temporarily tolerate hyperosmotic states of dehydration, which often occurs seasonally in arid and semi-arid rangelands. Some water can be obtained from food, but reptiles also have several physiological adaptations and behaviors that limit water loss (Dupoué et al. 2017). Furthermore, the diversity of body forms, low energy requirements, and behavioral adaptations to inclement weather and seasons enables reptiles to inhabit nearly all rangeland habitat types including most mesic and aquatic sites, prairies, shrub steppes and shrublands, savannahs, woodlands, and forest (Fig. 25.3). Thus, reptile habitat associations are incredibly varied. Because most species are ground-dwellers, understory vegetation and leaf litter (or inversely, bare ground) are often cited as important variables predicting reptile species occurrence across rangelands (e.g., Lindenmayer et al. 2018). Shrubs and trees are important for some reptile species and these species may disappear if these habitat elements are removed or lost to wildfire (Cossel 2003; James and M’Closkey 2003).

Some habitat selection by herpetofauna is associated with foraging behavior and mate finding. Some species will travel to and forage in locations with higher amounts of food resources, which often varies seasonally. Snakes and lizards can be classified as either active foragers that seek, and sometimes chase, their prey or sit-and-wait predators that opportunistically grab prey that comes close enough. The diet of snakes varies by species and habitat preferences, but can include small mammals, birds, fish, lizards, amphibians, and some invertebrates. A few snakes eat other snakes. Lizards and adult amphibians generally feed on arthropods (insects and spiders), annelids (segmented worms), and gastropods (slugs). Turtles are omnivorous, eating a variety of invertebrates, amphibians, fish, algae, and plants, whereas tortoises are strictly herbivorous.

4 Rangeland Management

4.1 Livestock Grazing

Excessive livestock grazing can affect amphibians through multiple pathways. First, overgrazing of grasses and forbs during the spring and summer can expose terrestrial amphibians to predators and desiccation in meadows and wetlands by reducing cover and allowing soils to dry (Canals et al. 2011; Pulsford et al. 2019). Second, excessive livestock use in aquatic habitats can increase turbidity and alter water chemistry via deposition of urine and feces (Schmutzer et al. 2008; Smalling et al. 2021). Negative impacts to water quality may affect larval development of amphibians but likely has fewer effects on amphibians compared with other factors such as hydroperiod and predators (Canals et al. 2011; Cole et al. 2016). Larval developmental issues associated with poor water quality, however, may be sublethal and have delayed effects that are only potentially problematic later in an animal’s life (Gray and Smith 2005; Chelgren et al. 2006). These time-lagged and carryover effects are particularly difficult to observe or measure but can have consequences at the population level (Babini et al. 2015; Bionda et al. 2018). And, finally, livestock may cause some direct mortality of individuals from trampling, although this is probably not a major source of mortality at the population level.

Despite these possible impacts from excessive livestock grazing, few studies have documented consistent negative effects of livestock grazing on amphibians and many amphibians breed successfully in stock ponds, even with heavy livestock use. Effects appear to be species-specific and depend upon habitat preferences (Burton et al. 2010). Some of this variability, however, may also be associated with variation in the type of grazers (e.g., cattle, sheep, goats), stocking rates, and timing and duration of grazing. One review of 46 published studies found only 22% demonstrated negative effects on amphibian communities and the remainder had either positive, neutral, or mixed effects (Howell et al. 2019). This meta-analysis indicated that most of the negative consequences of livestock grazing on amphibians occur in closed-canopy habitats whereas well-managed grazing in open habitats is compatible with amphibian conservation objectives. For example, some species, such as tiger salamanders, American toads (Anaxyrus americana), and western toads (A. boreas), thrive in open, shallow water environments even if used by grazing animals (Pyke and Marty 2005; Burton et al. 2010; Barrile et al. 2021a). A study of livestock-grazed meadows on the western slope of the Sierra Nevada Mountains, California found that Yosemite toads (Bufo canorus; Fig. 25.1) occupied pools that tended to be shallower, warmer, and more nitrogen enriched than unoccupied pools, regardless of livestock grazing intensity ranging from heavy to none (Roche et al. 2012). Similarly, Columbia spotted frog populations also do not appear to be impacted by use of breeding ponds by livestock (Adams et al. 2018), even though studies have found that frog survival, recruitment, and reproduction may increase in the first year or two after livestock are fenced out of breeding ponds (Pilliod and Scherer 2015). These short-term benefits to frogs, however, also are known to disappear from ponds as emergent vegetation becomes tall and dense in the absence of any livestock grazing (Pilliod and Scherer 2015).

Livestock may affect reptiles in both negative and positive ways through changes in grazed vegetation, nutrient redistribution, and physical impact of trampling to habitat components (soil, burrows, vegetation). Some research suggests, however, that livestock do not commonly crush reptiles or damage burrows by trampling (Nicholson and Humphreys 1981). In Australia, light to moderate livestock grazing intensities with a wet-season rest supported the most abundant reptile community, but only when compared with heavy, prolonged livestock grazing treatments (Neilly et al. 2018b). Other studies have found that reptile species richness is lower in grazed areas compared with areas where livestock are absent or where livestock have been removed or excluded with fencing (Hellgren et al. 2010; Read and Cunningham 2010). These responses are not universal and depend upon environmental conditions and habitat requirements of species present (Castellano and Valone 2006; Neilly et al. 2021).

Lizards can benefit from habitats opened up by livestock, as they sprint after prey and toward cover from predators, especially when grazing is managed carefully or used to reduce dense stands of invasive annual grasses that dominate formerly open areas and increase fire risk (Barry and Huntsinger 2021). The federally protected blunt-nosed leopard lizard (Gambelia sila; Fig. 25.2), for example, increased 500% in areas grazed by cattle in comparison with ungrazed areas dominated by invasive annual grasses in the San Joaquin Desert of southern California (Germano et al. 2012). Furthermore, the benefit of increased solar insolation for thermoregulation of reptiles and their egg temperatures in grazed habitats may confer benefits to reptiles from livestock grazing (Fabricius et al. 2003). The volume of rangeland research on herpetofauna in the last two decades has helped advance livestock grazing strategies that are compatible with reptile conservation. While more research is needed, we have sufficient credible, defensible information to move forward constructively (Barry and Huntsinger 2021).

4.2 Other Rangeland Management Actions

Water development, especially in arid and semi-arid environments, has likely influenced the distribution of amphibians. The development of springs, such as installing pipes and pumps, to provide livestock drinking water and other uses may alter the spring such that it no longer provides suitable overwintering habitat for some amphibians. Stock ponds and leaky or overflowing troughs, however, also create surface water in locations that may not have had surface water prior to development. Amphibians may use these artificial sources of water on the landscape to hydrate and occasionally breed (Alvarez et al. 2021). Chorus frogs, tiger salamanders, and other species can be found in water troughs or in their spillage areas in some otherwise dry shrublands and grasslands (Scott 1996). These oases also draw in amphibian predators like gartersnakes (Thamnophis spp.). Efforts are underway to help make water developments for livestock more compatible with amphibian and reptile use (Canals et al. 2011).

Vegetation treatments are common throughout rangelands of the western U.S., to improve forage quantity or quality, but also to control or remove non-native plant species, to stabilize soils and reduce erosion, and to rehabilitate recently burned areas, among other intentions (Pilliod et al. 2017). Many of these land treatments have the potential to affect herpetofauna, either positively or negatively (Pilliod et al. 2020). Research on this topic, however, is lacking and thus there are few guidelines to help resource managers design herp-friendly land treatments (but see Pilliod and Wind 2008; Kingsbury and Gibson 2012; Jones et al. 2016).

The thinning and removal of pinyon and juniper trees is a common rangeland management practice in the western U.S., particularly lately in the name of habitat management for the greater sage-grouse (Centrocercus urophasianus). What are often called pinyon-juniper or P-J woodlands are a forest type composed of single leaf‐pinyon pine (Pinus monophylla), Colorado pinyon (P. edulis), western juniper (Juniperus occidentalis), and Utah juniper (J. osteosperma). In the absence of fire and under favorable climatic conditions, these species have expanded their range into grasslands and shrublands, resulting in changes in water availability, soil chemistry, understory vegetation, and animal communities (Miller et al. 2000; Leis et al. 2017). Several lizard species inhabit P-J woodlands and benefit from the woody structure (Morrison and Hall 1999; James and M’Closkey 2003). The lizards use the trees and downed logs for basking, except for the tree lizard (Urosaurus ornatus; Fig. 25.2), which is distinctly arboreal and perches at greater heights than the other species (James and M’Closkey 2002). Arboreality may protect some lizard species from typical effects of livestock grazing (Jones 1981; Neilly et al. 2018a). Felling or burning trees might benefit lizards, like the sagebrush lizard (Sceloporus graciosus), but removing the dead and downed wood as part of fire management, fuel reduction, or habitat management for shrubland and grassland wildlife species could have negative consequences for tree lizards (Morrison and Hall 1999; James and M’Closkey 2003; Evans et al. 2019). Other lizard species are unlikely to be affected by such activities and ground-dwelling lizard species may benefit from such practices (Radke et al. 2008).

Prescribed fire practices appear to have minimal effects on herpetofauna in rangelands where it is appropriate. Besides concern about causing mortality from combustion or heat stress (Smith et al. 2001), particularly for turtles and tortoises (Larson 2014), most interest in prescribed fire is related to the role of fire in creating or maintaining heterogeneity in vegetation structure and composition that can sustain or enhance herpetofauna diversity (Wilgers and Horne 2006; Larson 2014). In southern Texas, a short-term study concluded that dormant-season fires had little effect on diversity and abundance of herpetofauna, but growing-season fires tended to increase diversity and abundance of grassland species, such as the six-lined racerunner (Cnemidophorus sexlineatus; Fig. 25.2; Ruthven et al. 2008). Minimal effects of prescribed fire on herpetofauna also have been reported in other rangelands, including California oak woodlands (Vreeland and Tietje 2002). Prescribed fire, grazing, and herbicide treatments have been used for creating or maintaining habitat heterogeneity for herpetofauna in seasonal wetlands, grasslands, and some woodlands, with mixed success (Jones et al. 2000; Larson 2014; Mester et al. 2015; Wilgers et al. 2006). In general, effects seem to be short-lived as plant communities respond to the disturbance and associated changes in nutrients, light availability, and competition. Even where prescribed fire appears to have negative effects on herpetofauna (e.g., Wilgers et al. 2006; Larson 2014), these effects tend not to persist through time. To optimize diversity, management for habitat mosaics may need to involve rotational burning, sometimes coupled with low-intensity cattle-grazing or herbicide treatments (Mester et al. 2015). This approach may allow species-specific responses in relation to changes in vegetation structure and microhabitat conditions (e.g., temperature, moisture of soil or vegetation) that changes through time (Wilgers and Horne 2006). The winners and losers scenario of wildlife response to local rangeland management is a reasonable conservation strategy as long as massive areas are not managed uniformly.

5 Impacts of Disease

Several amphibian and reptile diseases may be influenced by human activities and management practices in rangelands (Gray et al. 2017). One of the most notable amphibian diseases is the amphibian chytrid fungus, Batrachochytrium dendrobatidis or Bd, which causes chytriodiomycosis and is associated with severe population declines in several North American species (Lips 2016; Scheele et al. 2019). In rangelands, Bd is now thought to have contributed to the near extirpation of two toad species in the mid-1970s: the Wyoming toad (Anaxyrus hemiophrys baxteri; Fig. 25.1) and the Yosemite Toad (Kagarise Sherman and Morton 1993; Green and Kagarise Sherman 2001; Fig. 25.1). The Wyoming toad became functionally extinct in the wild by the 1980s (Lewis et al. 1985) and is a case study of the challenges of captive rearing, reintroduction, and species recovery in amphibians (Dreitz 2006). Variants of Bd exist and their pathogenicity are still being studied because not all amphibians in the U.S. are susceptible to Bd, at least under current environmental conditions. Like all wildlife diseases, the contraction of Bd, its prevalence in populations, and its effects on survival and fitness depend on the ecology and evolutionary history of the species with the disease in relation to the environment (Russell et al. 2019). For example, a study of boreal toads (Anaxyrus boreas) in western Wyoming revealed that livestock grazing may influence toad-Bd dynamics by creating warmer microclimates from the reduction of vegetation that allow toads to bask and clear themselves of the disease (Barrile et al. 2021a, b). Batrachochytrium salamandrivorans (Bsal) is a recently discovered disease from Asia that also causes chytridiomycosis. It quickly spread across Europe but has yet to arrive in North America (Waddle et al. 2020). The high diversity of North American salamanders puts the U.S. at extreme risk but, like frogs and toads exposed to Bd, some species may have innate protection, such as skin peptide defenses (Pereira and Woodley 2021).

Besides Bd, ranavirus is a major cause of mortality in some populations of amphibians (and some reptiles and fishes) around the world (Brunner et al. 2015). Ranavirus is not a single virus, but instead a group of iridoviruses first discovered in the northern leopard frog (Lithobates pipiens; Fig. 25.1), a common inhabitant of North American rangelands. Besides leopard frogs, it is known to infect the American bullfrog (Lithobates catesbeianus) and the commercial sale of leopard frogs and bullfrogs to laboratories and schools across America likely contributed to the spread and continental distribution of the viruses. The most widely known member of this group of viruses is the Ambystoma Tigrinum Virus (ATV), which can cause mortality in three species of tiger salamanders found in U.S. rangelands (Picco et al. 2007; Price et al. 2017). Ranaviruses appear to proliferate under periods of stress for the animals, such as changes in water temperature (Brunner et al. 2015). Ranavirus also may be more prevalent in areas where cattle congregate, possibly due to poor water quality caused by elevated turbidity and ammonia which stresses amphibians, particularly tadpoles and larvae (Hoverman et al. 2012). The creation of permanent ponds as water sources for livestock may also attract American Bullfrogs, which are known vectors of amphibian diseases (Yap et al. 2018; Brunner et al. 2019).

Disease in rangeland reptiles is a growing conservation concern (Fitzgerald et al. 2018; Mendoza-Roldan et al. 2021). Disease agents include microscopic bacteria, viruses, protozoans, and mycoses (fungi), frequently called zoonoses (or zoonotic) when they cause disease in humans and livestock (Mendoza-Roldan et al. 2021). Upper Respiratory Tract Disease Syndrome (URTDS), which causes inflammation and erosion of the nasal cavity and sometimes death, was first described in Mojave desert tortoises in California (Jacobson et al. 1991). The discovery of the disease agents of URTDS, Mycoplasma agassizii (Myag) and M. testudineum (Myte), was influential in the listing of the Mojave desert tortoises as Threatened under the Endangered Species Act (Brown et al. 2004; USFWS 2011). Myag and Myte are also found in Texas tortoises (G. berlandieri), gopher tortoises (G. polyphemus), and Sonoran desert tortoises (G. morafkai; Weitzman et al. 2017). Snake Fungal Disease is a rapidly emerging mycosis (Ophidiomyces ophiodiicola) that has now been found throughout the eastern U.S., and in several rangeland reptile species west of the Mississippi River (Lorch et al. 2016; Allender et al. 2020).

Many macroscopic parasites are also disease agents for reptiles, the most well-known including Arachnida (e.g., ticks, mites) and Diptera (flies and mosquitoes). Ticks are known globally as vectors for diseases hosted by reptiles, other wildlife, livestock, and humans. Borrelia spp. are spirochete bacteria carried by ticks and transmitted through the blood of vertebrate hosts. Borrelia spp. are causative agents for Lyme disease (Jacobson 2007; Swei et al. 2011) and Tick-Borne Relapsing Fever (TBRF; Forrester et al. 2015; Bechtel et al. 2021). Lyme disease (B. burgdorfii—Bobu) is the most common vector-born disease in the United States (CDC 2008). In California, western black-legged ticks (Ixodes pacificus) are vectors for Bobu among > 55 vertebrate hosts, including nine lizard species (Swei et al. 2011). About 90% of hosts for nymphal and larval ticks are western fence lizards, but the lizards are not very competent hosts because their blood includes borreliacidal components (i.e., when the lizard blood enters the tick during a meal it kills the Bobu). Regions with abundant lizards may have a lower proportion of Borrelia-infected tick nymphs and larvae (Ginsberg et al. 2021).

6 Ecosystem Threats

6.1 General

Some threats to amphibians, such as wetland habitat loss and degradation, non-native predators, and disease, are common to amphibians around the world (Lemckert et al. 2012; Pilliod et al. 2012; Wake and Koo 2018). Much less is known about specific threats to rangeland-associated amphibians, but several warrant consideration even if scientific evidence for their impacts is ambiguous or lacking (Mims et al. 2020). First, changes to hydrology or hydroperiod associated with water pumping, diversions, and dams are concerns. Stable, predictable water levels and flow rates are crucial for the development of amphibian tadpoles and larvae and the survival of post-metamorphic animals during the dry season and drought (Pilliod et al. 2021). Second, intensive human land use puts amphibians at risk because of clearing of vegetation, road construction, culvert installation, wastewater discharge (e.g., from hydrocarbon extraction, concentrated animal feeding operations), and construction of impervious surfaces (i.e., cement, asphalt). Crop production also is an intensive land use, although amphibian responses can be mixed. Some amphibians will venture into fields during pivot and flood irrigation and be attracted to lights when foraging for insects (Hansen et al. 2019) but, in general, homogenization of vegetation and application of chemicals (i.e., fertilizers, herbicides, insecticides) can be detrimental to amphibians or their habitats. Amphibians that forage in moist crop fields may then avoid these same areas after harvest. Fire and its relationship with changes in climate and invasive plant species is also potentially important, but in need of additional study (Mims et al. 2020).

Reptiles face many of the same threats as amphibians in rangelands, especially loss and isolation of suitable habitats, disease, and pollution from animal wastes and agrichemicals (Fitzgerald et al. 2018). A meta-analysis of 56 studies that reported on how habitat modification affected the abundance of 376 reptile species concluded that mining had the most negative impacts, followed by farming, livestock grazing, and tree plantations (Doherty et al. 2020). The mean effect of logging was neutral. Because of their tendency to bask and forage in areas of human use, reptiles may be more prone to direct mortality from human activities than other animals, although this has been difficult to quantify. A study using carcass detection dogs found that 57% of animals killed during typical agricultural mowing were reptiles, especially lizards (Deak et al. 2021). Invasive plants, especially dense annual grasses that cover open areas of bare ground, are known to interfere with lizard and snake movements and foraging ability in desert rangelands (Rieder et al. 2010; Blakemore 2018). The increased frequency of wildfire caused by these grasses also appears to have negative consequences for some reptile species, either through direct mortality (Jolly et al. 2022) or changes in habitat (Woinarski et al. 1999; Cossel 2003). Some species are also the target of exploitation, such as collection and sale in the illicit internet pet trade, whereas others are simply persecuted because of general fear or hatred of snakes, especially rattlesnakes and other pit vipers (Katzner et al. 2020).

The proliferation of transportation and energy infrastructure across rangeland landscapes further increases herpetofauna road mortality, creates barriers to migration and dispersal, and fragments once continuous habitats (Doherty et al. 2021). Road mortality is considered the leading cause of reptile mortality, especially for snakes (Hill et al. 2019). Roads provide attractive surfaces for thermoregulation and movement and collisions with vehicles are rampant, even on rural rangeland roads (Jochimsen et al. 2014; Hubbard et al. 2016). A study in southeastern Ohio found that the amount of pasture within a 100 m buffer of a roadkill was the strongest predictor of road mortality for 14 snake species (Wagner et al 2021). Fencing reptiles out of roadways comes with its own costs for snakes and turtles, including restricting access to seasonal resources and reducing gene flow among populations (Markle et al. 2017). Newly applied genetic tools and analyses provide insight to the influence of geographic factors like roads and railways on reptiles and amphibians. For example, a railway constructed some 120 yr ago bisected a population of Mojave desert tortoises resulting in differences in genetic diversity on either side of the railway after only about eight generations of tortoises (Dutcher et al. 2020). Roads and other human development certainly continue to play a role in shaping the population genetic structure of herpetofauna through reduced movement of individuals and reduced exchange of genes among populations. More research is needed on appropriate methods to avoid herpetofauna mortality and barriers to movement using overpasses or culverts to provide safe passage routes across roads and railways.

6.2 Climate Change

Changes in climate across U.S. rangelands may alter environmental conditions to such an extent that many, if not all, aspects of herpetofauna ecology will be affected. Observed changes in climate over the last several decades depend on location, especially latitude and elevation, but also continental position relative to mountain ranges (e.g., rain shadows) and the Pacific coast. Depending upon location, rangelands are experiencing warmer winters, shallower snowpacks, earlier springs, warmer nighttime (i.e., minimum) temperatures, longer and warmer growing seasons, shifts in summer monsoons, and longer, more frequent and severe heat waves and droughts (Polley et al. 2013; McCollum et al. 2017). All of these factors tend to be more variable year to year, and less predictable. These environmental changes will affect herpetofauna reproduction, development, and survival. Changes in wetland hydroperiods, earlier peak flows and more variable intermittency in streams, changes in the insulating capacity of snow in winter, changes in the thermal environment during the active season, and changes in the phenology of plants and prey (insects, small mammals) are most worrisome. Animals will adjust their diel and seasonal activity patterns to a point, but not without consequences. For example, some amphibians are breeding earlier and at smaller body sizes compared with a few decades ago (Li et al. 2013), which may expose some populations to higher mortality and stress (e.g., heightened disease risk) and result in population declines (Miller et al. 2018; Muths et al. 2018). Spiny lizards (Sceloporus spp.), which are common in rangelands, may have already experienced widespread population declines associated with climate change. Revisits of 200 sites in Mexico revealed 12% of local populations may have gone extinct since 1975. Using physiological models, the research suggests that thermal niches at these locations may have been altered to the point where lizards can no longer forage adequately to permit viable embryo development (Sinervo et al. 2010). Lizards may be particularly vulnerable to climate change because of their close affiliation with specific soil substrates for thermoregulation and reproduction and relatively limited dispersal abilities, often resulting in small or patchy distributions. Thermal niche modeling suggests that local extinction of lizard populations could reach 39% worldwide and 20% of species may be at risk of extinction by 2080 (Sinervo et al. 2010). Unfortunately, few lizard populations or species are being monitored in rangelands and thus many extinctions may occur quickly and without notice.

Adaptive behavior may enable herpetofauna to cope with climate changes. For example, herpetofauna may find microhabitats that allow them to maintain preferred body temperatures and moisture levels (Long and Prepas 2012). Phenotypic plasticity and genetic adaptation among herpetofauna also may mitigate some of the effects of climate change (Urban et al. 2013) but also may create new challenges. There is concern, for example, that, as temperatures increase, amphibians who rely on terrestrial foraging may need to change their foraging strategies because of the risk of dehydration (Lertzman‐Lepofsky et al. 2020). This effect could be worsened in heavily grazed areas where vegetative cover is reduced (Bartelt et al. 2010). A study in California, however, found that vernal pools that were grazed by livestock dried an average of 50 days per year later than ungrazed pools, probably because of increased evapotranspiration from the abundant vegetation in the ungrazed wetlands (Pyke and Marty 2005). This study demonstrates the complex interactions between grazing and climate change and, in this case, climate mitigation strategies for species like the endangered California tiger salamander (Ambystoma californiense; Pyke and Marty 2005). Predictions for reptiles are no simpler, because we know little about how these animals are able to adjust their basking and foraging behavior or take advantage of microhabitats. Further, livestock grazing in rangelands may ameliorate or exacerbate the effects of climate change in unforeseen ways, including potential changes in the availability and distribution of thermal refuges (Clayton and Bull 2015; Rutschmann et al. 2016).

7 Conservation and Management Actions

Concerns about herpetofauna in the U.S. have stimulated an active community of diverse partners, including federal, state, tribal, NGOs, private landowners, and concerned citizens. These groups and partnerships take many forms. Formal working groups, such as those involved in endangered species conservation, tend to work on single species issues. Examples from U.S. rangelands include the Columbia spotted frog in Nevada and other states (Pilliod, in press). In Nevada, interagency technical teams have met since 1999 and helped the U.S. Fish and Wildlife Service write a conservation plan for this species that balanced species conservation with other rangeland issues. This led to a Conservation Agreement and Strategy for two distinct population segments (Northeast Nevada and Toiyabe subpopulations) that were first implemented in 2003 and then renewed for another 10 yr in 2015 (McAdoo and Mellison 2016). The technical team helps coordinate and implement the conservation plan, recruit assistance from scientists and other stakeholders to evaluate the effectiveness of conservation actions, status, and trends, and change the plan as necessary to meet the stated goals.

Partners in Amphibian and Reptile Conservation (www.parcplace.org, accessed 14 July 2021) is another organization that is bringing conservation issues to the forefront and facilitating creative solutions to pressing conservation challenges in rangelands and elsewhere. PARC is an open conservation community with participation, partnerships, and directions determined by current members at state, regional, and national levels. Most importantly, biologists, natural resource specialists, and land managers from public agencies meet with private landowners, concerned citizens, and industry to foster and implement conservation efforts. Simply put, the group forges proactive partnerships to conserve amphibians, reptiles, and the places they live. This inclusive approach to conservation has proven highly successful because it brings diverse perspectives to the table and garners ownership of conservation approaches. An important set of publications produced by PARC is the habitat management guidelines (HMG’s). Each volume covers a specific region of the country with rangelands mostly represented in the Northwest and Western Canada (Pilliod and Wind 2008), Midwest (Kingsbury and Gibson 2012), and Southwest (Jones et al. 2016). The HMG’s are designed to help managers think about herpetofauna habitat needs from the perspective of specific vegetation types. The guidelines include examples for “maximizing compatibility” whereby landowners and resource managers can contribute to the conservation and stewardship of these animals while managing their land primarily for other uses, such as livestock grazing or farming.

Habitat management guidelines for livestock grazing suggest landowners and managers consider: (1) controlling timing and extent of livestock access to wetlands and streams through fencing, restricted access points, and seasonal use, (2) establishing alternative water sources such as water troughs, (3) carefully developing springs to serve as a source for livestock water without interfering with the spring’s ability to provide water to wildlife and hibernacula for amphibians, and (4) managing grazing to maintain a higher stubble height of herbaceous vegetation that could preserve forage quality while maintaining cover from predators and desiccating conditions. More detailed recommendations can be found in the HMGs and other guidelines that are available for specific species or locations (e.g., Ford et al. 2013).

8 Research/Management Needs

The research and management needs of herpetofauna in rangelands are considerable because they are some of the least-studied vertebrates and many species lack sufficient information to make informed conclusions about status, trends, and threats, much less decisions about effective management and conservation strategies. Throughout this chapter we have highlighted areas of needed research. We encourage researchers and managers to work together to identify the most pressing and relevant issues to improve conservation actions and outcomes for rangeland amphibians and reptiles. Efficient, timely, co-production of scientific information is urgently needed given the current and forthcoming threats to herpetofauna and rangelands. Public–private engagement and diverse stakeholder partnerships may be the best way to incorporate this information effectively into conservation planning and decision making for herpetofauna and other wildlife across our nation’s rangelands.