Terrestrial Habitat Use Research Articles

Great Lakes wetlands as amphibian habitats: A review

Amphibians are highly adapted for life in wetland habitats. They form a major component of wetland faunas, and being both prey and predator, they are important in ecosystem functioning. Wetlands provide aquatic habitats that amphibians require for breeding, development, foraging, hibernation and refuge, and they form an interface with essential adjacent upland habitat. The size and type of wetlands as well as their spatial configuration and local structural characteristics are important features of these habitats for amphibian use. Because of their dependence on water, use of both aquatic and terrestrial habitat, permeable skin, and other biological characteristics, amphibians are considered to be excellent indicators of ecosystem health. Amphibians have a tremendous diversity of natural history characteristics and species differ in their patterns of habitat and microhabitat selection. Over 30 species of amphibians occur in wetlands within the Great Lakes Basin and an increasing trend in species richness exists from north to south across the region. Since European settlement, this region has lost over 50% of its wetlands. Loss rates of coastal and inland wetlands exceed 90% in some areas. Many restoration efforts are underway across the region but losses still exceed gains. No species have been extirpated from the entire basin but numerous local extirpations have occurred. However, nearly half of the species are officially designated as being of conservation concern somewhere in the basin. A more realistic estimate suggests that at least 2/3 of species are of concern. Habitat loss is reported as the primary cause of decline for 60% of species and habitat degradation by pollution is cited for 43% of the fauna. Considering the extent of wetland loss across the basin it seems reasonable to assume a similar magnitude of amphibian population loss. The current conservation status of amphibians indicates that Great Lakes wetlands are unhealthy ecosystems.

Biological Criteria for Buffer Zones around Wetlands and Riparian Habitats for Amphibians and Reptiles

Abstract: Terrestrial habitats surrounding wetlands are critical to the management of natural resources. Although the protection of water resources from human activities such as agriculture, silviculture, and urban development is obvious, it is also apparent that terrestrial areas surrounding wetlands are core habitats for many semiaquatic species that depend on mesic ecotones to complete their life cycle. For purposes of conservation and management, it is important to define core habitats used by local breeding populations surrounding wetlands. Our objective was to provide an estimate of the biologically relevant size of core habitats surrounding wetlands for amphibians and reptiles. We summarize data from the literature on the use of terrestrial habitats by amphibians and reptiles associated with wetlands ( 19 frog and 13 salamander species representing 1363 individuals; 5 snake and 28 turtle species representing more than 2245 individuals ). Core terrestrial habitat ranged from 159 to 290 m for amphibians and from 127 to 289 m for reptiles from the edge of the aquatic site. Data from these studies also indicated the importance of terrestrial habitats for feeding, overwintering, and nesting, and, thus, the biological interdependence between aquatic and terrestrial habitats that is essential for the persistence of populations. The minimum and maximum values for core habitats, depending on the level of protection needed, can be used to set biologically meaningful buffers for wetland and riparian habitats. These results indicate that large areas of terrestrial habitat surrounding wetlands are critical for maintaining biodiversity.

Postbreeding Emigration and Habitat Use by Jefferson and Spotted Salamanders in Vermont

Abstract In New England, temporary pool-breeding salamanders inhabit terrestrial forested habitats for the majority of the year. Wetland regulations and forestry Best Management Practices rarely consider the upland areas surrounding breeding pools for protection. Those that do, generally establish buffer zones that are insufficient to protect salamander populations. A better understanding of the area requirements and upland habitat preferences of pool-breeding salamanders is needed to develop biologically relevant buffers for conservation. I used radiotelemetry to investigate the postbreeding emigration and terrestrial habitat use of two syntopic mole salamander species. Sixteen adult salamanders (eight Ambystoma jeffersonianum, and eight Ambystoma maculatum) were radiotracked for a mean of 164 days (SE = 5.1). Eleven individuals were tracked to overwintering sites (five A. jeffersonianum, and six A. maculatum). Emigration distances from breeding pool edge varied widely (range = 30–219 m) with a mean of 1...

Terrestrial activity and conservation of adult California red-legged frogs Rana aurora draytonii in coastal forests and grasslands

The federally threatened California red-legged frog Rana aurora draytonii occupies both aquatic and terrestrial habitats in its adult life stage. The terrestrial activities of this species are not well known and require documentation to assist in the development of appropriate levels of protection under the US Endangered Species Act. We studied the terrestrial activities of radio-tagged red-legged frogs ( n=8–26) inhabiting a coastal watershed in Santa Cruz County, California, during 1997–1998. In particular, we investigated (1) the use of terrestrial habitats by non-migrating adults in relation to season, breeding chronology, and precipitation, and (2) adult migration behavior, including seasonal timing, duration, distances traveled, and the use of corridors. Non-migrating red-legged frogs occupied terrestrial habitats briefly (median=4–6 days) following infrequent summer rains, but resided nearly continuously on land (median=20–30 days) from the onset of the winter wet-season until breeding activities commenced 1–2 months later. All of the non-migrating frogs remained within 130 m of their aquatic site of residence (median <25 m). Intervals spent on land were again brief during mid/late winter (median=1–4 days), despite frequent and copious rainfall. Adult migration to and from breeding sites occurred from late October through mid-May (wet season). We monitored 25 migration events between aquatic sites that were 200–2800 m apart. Short distance movements (<300 m) were completed in 1–3 days, longer movements required up to 2 months. Most migrating frogs moved overland in approximately straight lines to target sites without apparent regard to vegetation type or topography. Riparian corridors were neither essential nor preferred as migration routes. Frogs traveling overland occurred in upland habitats as far as 500 m from water. Approximately 11–22% of the adult population was estimated to migrate to and from breeding sites annually, whereas the bulk of the adult population was resident at these sites. Adequate protection of red-legged frog populations inhabiting relatively undeveloped landscapes is liable to be achieved by retaining an array of suitable habitat elements within at least 100 m of occupied aquatic sites, and by imposing seasonal limitations on detrimental human activities occurring within this zone. Specific protections for migrating frogs are probably unwarranted in forest and rangeland environments because dispersal habitat is ubiquitous and migrating frogs are widely distributed across the landscape in space and time.

Terrestrial Habitat Use by Pacific Pond Turtles in a Mediterranean Climate

The Pacific pond turtle (Clemmys marmorata) is a widespread aquatic turtle in the Pacific states, yet relatively little is known about its ecology. We radio-tracked 34 individuals during an 8 year period in 4 small coastal creeks in central California to determine their use of terrestrial upland habitats. Most of our turtles left the drying arroyos during late summer and returned after winter floods. Turtles spent an average of 111 days at these land refuges, which were located in woodland and coastal sage scrub habitats an average of 50 m from arroyos. Most gravid females left the creeks during June to oviposit in sunny upland habitats with low vegetation structure, such as grazed pastures. Nest sites were an average of 28 m from creeks. Terrestrial basking sites averaged 4.5 m from streams, but were only used for a few days. We believe the use of terrestrial upland sites was related to the Mediterranean climate and the resulting unique hydrodynamics of the small coastal arroyos (dry in summer and flooding in winter).

Status, Appropriate Sampling Scheme, and Movement in the Tiger Salamander (Ambystoma tigrinum) in Yellowstone National Park

Due to the current trend of amphibian declines (Wake 1998, Alford and Richards 1999, Semlitsch 2000), the monitoring and study of amphibian populations has become increasingly necessary. To properly do such studies, we must consider several issues. Some of these include the detectability of the species at a site, current status of the population, and the spatial scale for sampling of a population. Determining the detectability of a species is important to consider because some amphibian species may have different difficulties of detection. Therefore, if a species is difficult to observe, it may occupy a greater number of sites than a survey indicates (MacKenzie et al. 2002). The appropriate spatial scale is also important for monitoring studies. For example, in a pond breeding amphibian, do one or two breeding ponds with the appropriate terrestrial habitat constitute the correct sampling area for a population, or does a population utilize multiple ponds within a larger terrestrial area? If the sampling scale is not appropriate, then any conclusions made may be inaccurate (Wiens 1989). In addition, understanding the terrestrial habitat use of pond breeding amphibians is important for both monitoring and conservation reasons. Many pond-breeding amphibians use the ponds for breeding and then utilize terrestrial zones around the pond for the rest of the year. The total area that is encompassed by these terrestrial zones is known as the terrestrial "buffer zone" or core habitat area for that population (Semlitsch 1998). To identify these core habitat areas, we must know not only the distance that the amphibians physically move from the breeding pond, but also the type of habitat that they will use. For example, short, steep slopes or rivers can serve as a barrier to amphibian movement (Laan and Verboom 1990, Storfer 1999), even if they are within the movement range of a population. Understanding individual movement may also give insights into the spatial population structure of the species. If we can identify the average distance of movement, we can then extrapolate if a breeding pond is likely to have an isolated subpopulation based on its distance from other ponds.

Spatial and temporal use of floodplain habitats by lentic and lotic species of aquatic turtles.

We investigated the use of aquatic and terrestrial floodplain habitats by lentic and lotic turtles inhabiting the Missouri River, a contemporary, regulated large river. Specifically, we tested whether habitats were used differentially by turtle species, sexes, and life stages over biologically determined spatial and temporal scales. We monitored female and male false map turtles (Graptemys pseudogeographica) and slider turtles (Trachemys scripta) for 14 months, using radiotelemetry. In addition, over a 3-year period we trapped G. pseudogeographica (n=591) and T. scripta (n=129) to supplement data on habitat use. Movements based on radiotelemetry and recaptures were summarized for each individual. Both species of turtles displayed dynamic annual activity patterns and used diverse habitats including those typically considered terrestrial. Although G. pseudogeographica and T. scripta spent a substantial portion of the year in the Missouri River (primarily in the cool months), newly created scour habitats also appeared to attract turtles during the cool season. However, in the warm months, habitat use became much more diverse, with turtles occupying all identified habitats including flooded agriculture and forest. Relative to their proportions, slough and scour habitats appeared to be highly favored while forests older than 4 years and agricultural habitats were proportionally less favored. We found few differences between species. However, males of both species were consistently more sedentary, used half as many habitats, and moved half as far from the river as did females, especially during May through July. Juveniles of both species were captured on average farther from the river than were adults, perhaps reflecting the close proximity of both nesting areas and shallow, productive habitats free of aquatic predators. We estimate a riparian zone of 449 m that encompasses 95% of the population movements away from the river and discuss the quality of habitats important to reproduction and survival of lentic and lotic floodplain turtles. These spatial and temporal movement patterns, in light of their potential adaptive costs and benefits to G. pseudogeographica and T. scripta, are critical to understanding the ecology of long-lived vertebrates that depend on contemporary large rivers.

Pup density related to terrestrial habitat use by New Zealand fur seals

Features of the terrain are important in the selection of terrestrial habitat by otariid seals. Fur seals use rocky shorelines where terrain features such as crevices and ledges may provide shelter for pups. New Zealand fur seals (Arctocephalus forsteri) are increasing in number and expanding their range, requiring them to select new habitat for breeding. Predicting population expansion is important for assessing potential conflicts with commercial fisheries. We quantified terrain features at 25 breeding colonies and 8 nonbreeding colonies around South Island. Univariate tests demonstrated some differences in terrain between breeding and nonbreeding colonies, although principal components analysis (PCA) did not reveal any obvious differences. We suggest that the power to detect differences is reduced by the tendency for nonbreeding colonies to become breeding colonies over time as the population increases. We found a significant relationship between pup density and terrain (i.e., PCA variables) within breeding colonies. The terrain occupied by high-density colonies contained more and smaller rocks, more crevices and ledges, less-pronounced slopes, higher cliffs, and a more westerly exposure than that occupied by low-density colonies. Smaller rocks may provide more spaces in which pups can find shelter; less-pronounced slopes may facilitate pup mobility and higher cliffs may increase shading. We suggest that in addition to terrain features, other phenomena are also involved in breeding-site selection.

Pup density related to terrestrial habitat use by New Zealand fur seals

Pup density related to terrestrial habitat use by New Zealand fur seals

Evaluating the Biotic Integrity of Watersheds in the Sierra Nevada, California

We developed a watershed index of biotic integrity that used whole watershed variables for metrics rather than site‐specific variables. We used the index to evaluate the biological health of 100 watersheds in the Sierra Nevada of California. The index scores, which were based on various measures of distribution and abundance of native fish and frogs, indicated that 7 of the watersheds were in excellent condition (high biotic health), 36 were in good to very good condition, 48 were in fair condition, and 9 were in poor condition. The biggest factors contributing to low index scores were large dams and introduced fishes, although measures of road density and indicators of intensity of use of terrestrial habitats were also important. Large areas of the Sierra Nevada that were once fishless now contain trout in most waters, anadromous fishes are excluded from many streams from which they were once abundant, assemblages of native fishes have been disrupted, and ranid frogs have been extirpated from many areas. All watersheds in the Sierra Nevada have thus experienced loss of biotic integrity, but some have suffered much less than others. Evaluations of the biotic integrity of watersheds over wide regions can help managers set priorities for watershed‐oriented systems of aquatic conservation and provide starting places for more‐intensive studies.Evaluación de la Integridad Biótica de Cuencas Acuíferas en la Sierra Nevada, CaliforniaUn indice de cuencas de integridad biótica fue desarrollado, el cual utilizó variables paramétricas en vez de variables de lugar específico. El índice fue utilizado para evaluar la salud biológica de cien cuencas en la Sierra Nevada de California. El muestreo, el cual fue basado en varias medidas de disribución y abundancia de peces nativos y ranas indicaron que siete de las cuencas estaban en excelente condición (salud biótica), treinta y seis estaban de buena a muy buena condición, cuarenta y ocho estaban en favorable condición y nueve estaban en mala condición. Los factores más grandes que contribuyeron al bajo muestreo fueron represas grandes y peces introducidos, aunque medidas de densidad de carreteras, indicadores de intensidad del uso de comunidades terrestres, fueron también importantes. Grandes areas de la Sierra Nevada que no tenían peces ahora contienen trucha en la mayoria de sus aguas, peces anadromos están excluidos de muchos arroyos, en los cuales ellos fueron una vez abundantes; comunidades de peces nativos han sido interrumpidas, y ranas de la familia ranidae han sido exterminadas de muchas areas. Todas las cuencas en la Sierra Nevada, por lo tanto, han experimentado pérdida de integridad biótica, pero algunas han experimentado menos pérdida que otras. Evaluaciones de la integridad biótica de cuencas sobre regiones extensas pueden ayudar a establecer prioridades para un sistema de conservación acuática y proveer información básica para estudios más intensos.

Habitat Use during Breeding and Emigration in Radio-Implanted Tiger Salamanders, Ambystoma tigrinum

Twenty-seven adult radio-implanted Ambystoma tigrinum from four ponds in Long Island, New York, were tracked for up to a year to examine adaptive flexibility in aquatic and terrestrial habitat use. Adults in two exposed breeding ponds preferred deep, vegetated areas. In a heavily shaded pond, the males segregated from the females and preferred nonvegetated areas, and in a pond with bluegills, the adults preferred shallow zones. On land, most resident salamanders remained close to a breeding pond that was immediately surrounded by a steep bank and woods, whereas few stayed close to exposed ponds with little ground cover. Salamanders were facultative emigrators, making major emigratory movements during spring, fall, or both, or not migrating at all. Two displaced salamanders showed normal pond activity but atypical terrestrial movements. Frequent predation occurred in small-mammal runways, most likely by short-tailed shrews. Salamanders excavated tunnels for temporary refuge but used small-mammal runway systems for long-term refuge. These new observations for A. tigrinum show adaptability in movements and habitat use during breeding and emigration consistent with the species' wide distribution in eastern North America.

Phylogenetic Analysis of the Cuculidae (Aves, Cuculiformes) Using Behavioral and Ecological Characters

A cladistic analysis of 21 genera of cuckoos (Aves, Cuculidae) using 28 behav- ioral and ecological characters produces one shortest-length tree (L = 80 steps, CI = 0.52, RI = 0.79, RC = 0.42) that differs from traditional classifications of the Cuculidae. My results suggest that two cuculid subfamilies, the terrestrial Neomorphinae and the Phaenicophaeinae, are polyphyletic. The obligate brood parasite Tapera (Neomorphinae) and the facultative brood parasite Coccyzus (Phaenicophaeinae) are removed from otherwise nonparasitic sub- families and placed among the Old World obligate parasites in the Cuculinae. This suggests that: (1) brood parasitism arose only once in the Cuculidae rather than three times as pre- viously thought; and (2) that terrestrial habitat use in Tapera has evolved secondarily. The placement of Coccyzus among the obligate parasites implies that the immediate ancestor of this genus was an obligate brood parasite. Therefore, the facultative behavior of Coccyzus represents a loss of obligate parasitism, rather than the development of facultative parasitism from a nonparasitic ancestor. In life, Coccyzus shares a number of life-history traits with the obligate brood parasites that support this hypothesis. Based on my analysis, I propose changes to the classification of the cuckoos that are consistent with the opinions of many early systematists, and the results of an unpublished phylogeny of the cuckoos based on postcranial osteological characters. In addition, my findings suggest that the Hoatzin (Opisthocomus hoat- zin) is a cuckoo most closely related to the communally breeding anis (Crotophaginae). Received 12 May 1994, accepted 27 January 1995.

Terrestrial habitat use by frogs and toads, Rana temporaria L. and Bufo bufo (L.), in West Norway

Frogs and toads, Rana temporaria and Bufo bufo, are the most common amphibians in Norway, but little information is available on their distribution and numbers. We studied their habitat use during the terrestrial phase in West Norway (Rogaland to Møre and Romsdal counties) by examining all specimens in the collections of the Museum of Zoology, University of Bergen and by analyzing questionnaires. Frogs and toads were generally found at different sites, and both species were located together in only 10 sites (9.9 %). Differences in habitat use between the two species were mainly due to toads occupying coniferous forest or cultivated land below 200 m a.s.l. More frogs were found in deciduous forests and humid regions, at varying altitudes to above 1 000 m a.s.l.