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Geology topics

S.H. Anderson

Publications and source records attributed to S.H. Anderson.

At least 19 recordsLinked to original sources
USGS2007

Ecology and behavior of the Midget Faded Rattlesnake (Crotalus oreganus concolor) in Wyoming

We conducted a three-year study to describe the ecology and behavior of the Midget Faded Rattlesnake, Crotalus organus concolor. We encountered 426 and telemetered 50 C. o. concolor between 2000 and 2002. We found that their primary diet was lizards (associated with rock outcrops), though they will consume small mammals and birds. They den in aggregations, although in low numbers when compared to other subspecies. Movements and activity ranges were among the largest reported for rattlesnakes. Minimum convex polygon area was 117.8 ha for males, 63.9 ha for nongravid females, and 4.8 ha for gravid females. Mean distances traveled per year were 2122.0 m for males, 1956.0 m for nongravid females, and 296.7 m for gravid and postpartum females. Following emergence from hibernation, they spent several weeks shedding, often in aggregations before migration, and migrations occurred in early summer. Most snakes made straight-line movements to and from discrete summer activity ranges where short, multidirectional movements ensued, although others made multidirectional movements throughout the active season. We observed mating behavior between 21 July and 12 August. Gravid females gave birth during the third week of August. Mean clutch size was 4.17 (range 2-7). We found that the sex ratio was skewed favoring females 1:1.24, and they were sexually dimorphic in size (males SVL = 44.1 cm; females SVL = 40.8 cm). Our data further illustrate the diversity within the large group of Western Rattlesnakes (Crotalus viridis). Copyright 2007 Society for the Study of Amphibians and Reptiles.

Journal of Herpetology↗
USGS2004

Comparative habitat use in a juniper woodland bird community

We compared vegetation structure used by 14 bird species during the 1998 and 1999 breeding seasons to determine what habitat features best accounted for habitat division and community organization in Utah juniper (Juniperus osteosperma) woodlands of southwestern Wyoming. Habitat use was quantified by measuring 24 habitat variables in 461 bird-centered quadrats, each 0.04 ha in size. Using discriminant function analysis, we differentiated between habitat used by 14 bird species along 3 habitat dimensions: (1) variation in shrub cover, overstory juniper cover, mature tree density, understory height, and decadent tree density; (2) a gradient composed of elevation and forb cover; and (3) variation in grass cover, tree height, seedling/sapling cover, and bare ground/rock cover. Of 14 species considered, 9 exhibited substantial habitat partitioning: Mourning Dove (Zenaida macroura), Bewick's Wren (Thryomanes bewickii), Blue-gray Gnatcatcher (Polioptila caerulea), Mountain Bluebird (Sialia currucoides), Plumbeous Vireo (Vireo plumbeus), Green-tailed Towhee (Pipilo chlorurus), Brewer's Sparrow (Spizella breweri), Dark-eyed Junco (Junco hyemalis), and Cassin's Finch (Carpodacus cassinii). Our results indicate juniper bird communities of southwestern Wyoming are organized along a 3-dimensional habitat gradient composed of woodland maturity, elevation, and juniper recruitment. Because juniper birds partition habitat along successional and altitudinal gradients, indiscriminate woodland clearing as well as continued fire suppression will alter species composition. Restoration efforts should ensure that all successional stages of juniper woodland are present on the landscape.

Western North American Naturalist↗
USGS2003

Habitat use and movements of repatriated Wyoming toads

We studied habitat use and movements of a repatriated population of federally endangered Wyoming toads (Bufo baxteri) after the breeding season at Mortenson Lake, Albany County, Wyoming , USA. We followed 8 adult toads using telemetry (n = 68 relocations) during periods of activity and observed 59 post-metamorphic juvenile toads (n = 59 locations). Adult toads used habitat with a greater mean vegetation canopy cover (mean = 52.6%) than juveniles (mean = 39.20%). We found adults farther from the shoreline (mean = 1.32 m) than juveniles (mean = 1.04 m). Substrates used by toads had a mean surface temperature of 20.31°C for adults and 23.05°C for juveniles. We found most adult and juvenile toads on saturated substrates. All adult toads sampled did not move outside of a 30 x 500 m area along the east-to-south shore where they were captured. Toads were active diurnally through the end of October. We found toads torpid at night. We compared our results to a similar study of the historic population and found that adult toads of the current population used denser vegetation than those of the historic population. Unlike many bufonids, terrestrial stages of the Wyoming toad appear to depend on saturated substrates. The best logistic regression predictors of adult and juvenile toad presence were surface temperature and distance to shore. Survey transects within the moist margin of the lake (≤10 m from water) and after substrates have reached temperatures ≥20°C will likely yield more detections.

Wyoming↗
USGS2001

Distributions of roosting sandhill cranes as identified by aerial thermography

We used aerial thermography to determine the location of sandhill crane ( Grus canadensis ) roosting sites during a single night over a 142-km reach of the Platte River, Nebraska. We assessed the influences of human disturbance features, screening of disturbance features by woody vegetation, distance to surrounding cropland of various types and channel width on distribution patterns of sandhill crane roosting sites with the aid of a geographic information system (GIS). We found that roosting sites were farther from bridges and paved roads than random points along the river channel; a visual woody screen mitigated the effect of bridges on locations of roosting sites; and roosting sites were in wider river channels than were observed at random points.

Prairie Naturalist↗
USGS1999

Influence of prerelease experience on reintroduced black-footed ferrets (Mustela nigripes)

Captive breeding is increasingly being used to create supplies of endangered animals for release into natural habitats, but rearing strategies vary and debates arise over which methods are most efficient. We assessed postrelease behaviors and survival of three groups of black-footed ferrets, each with different prerelease experience. Eighteen ferret kits ???60 days of age were moved with their dams from cages to 80-m2 outdoor pens with prairie dog burrows. These animals were compared to animals reared in standard cages (n = 72), some of which were given experience killing prairie dogs (n = 32). Ferrets were released onto white-tailed prairie dog (Cynomys leucurus) colonies in Wyoming, USA, in fall, 1992. Radio-tagged cage-reared ferrets made longer nightly moves and dispersed further from release sites than their pen-reared counterparts. The band return rate was 4-fold higher for pen-reared animals than for cage-reared animals during surveys conducted about 1 month after release. We recommend routine use of quasi-natural outdoor pens for prerelease conditioning of black-footed ferrets.

Biological Conservation↗
USGS1998

Waterfowl management on grass-sage stock ponds

We studied waterfowl use of grass-sage stock ponds in north-central Wyoming during the 1988 and 1989 breeding seasons. Dabbling ducks, particularly mallards, were the most common breeders. Indicated breeding pair density averaged 2.7 pairs/ha of wetland surface, while brood density averaged 1.0 brood/ha of wetland surface. Waterfowl use and productivity were greatest on large (> 3 ha), clear, deep ponds with grass shorelines and abundant submergent macrophytes. Pair use was positively correlated with water clarity, pond area, and macroinvertebrate diversity. Brood use was related to macroinvertebrate diversity, pond depth, and Shoreline Development Index. We recommend management priority be given to ponds that are deeper than 1 m to provide more water that is clear so macrophytes can be established. Macroivertebrates should be artificially introduced into ponds. Fencing should be used to improve ponds for waterfowl use and brood rearing.

Wyoming↗
USGS1981

Habitat size and bird community management

The purpose of this paper is to review the results in the literature that show the effect of area of forest on nesting migratory bird species, and to present the results of additional field work that we have conducted in forest habitats in western Maryland. These results indicate the area sensitivity of many long distance migrants. Because 80 to 95 percent of the breeding birds in the northeastern deciduous forest are neotropical migrants, the changes in bird species composition as a result of forest fragmentation can be immense. Management strategies based on habitat size are suggested to assist in maintaining communities of nesting migratory birds.

Transactions of the North American Wildlife and Na↗
USGS1980

Consistency in habitat preference of forest bird species

The important management conclusion that follows from our results is that the habitat requirements of most forest bird species, although quite specific for each species, apply generally throughout their breeding ranges. Thus a habitat management program that proves beneficial in one part of the breeding range of a species has a high likelihood of success in an area hundreds of kilometers away. Site-specific programs may be necessary for successful management of species whose habitat preferences change across their range. Alternatively, geographical variation in habitat use may indicate that a species' habitat requirements are easily met and that effective management for the species is more readily attained. Close monitoring of a species' response to specific management programs will be required to resolve whether species showing geographic variation in habitat preference are habitat specialists or simply habitat generalists with varying responses to habitat structure

Transactions of the North American Wildlife and Na↗
USGS1980

Coastal and Marine Bird Data Base

Summary: This report discusses the development of a coastal and marine bird data base at the Migratory Bird and Habitat Research Laboratory. The system is compared with other data bases, and suggestions for future development, such as possible adaptations for other taxonomic groups, are included. The data base is based on the Statistical Analysis System but includes extensions programmed in PL/I. The Appendix shows how the system evolved. Output examples are given for heron data and pelagic bird data which indicate the types of analyses that can be conducted and output figures. The Appendixes include a retrieval language user's guide and description of the retrieval process and listing of translator program.

FWS/OBS↗