Bed Sites Research Articles

HABITAT RELATIONSHIPS BETWEEN SYMPATRIC MULE DEER AND WHITE-TAILED DEER IN TEXAS

Desert mule deer (Odocoileus hemionus eremicus) and Texas white-tailed deer (O. virginianus texanus) are sympatric in west-central Texas. During winter, spring, and summer 1999 and 2000, we recorded locations of sympatric mule and white-tailed deer to determine habitat-use differences between species. We measured 379 mule deer and white-tailed deer locations for biotic and abiotic landscape parameters. Slope and percent shrub cover explained most variation in distributions of the 2 species. Locations of bedded deer were the most discriminated behavior type for all models. Density of shrubs and slope were the most important variables used to describe habitat preference by either deer species. Mean shrub cover used by mule and white-tailed deer at bed sites was 37.7% and 53.9%, respectively. Mean percent slopes used by mule and white-tailed deer for bed sites were 9.2 and 2.9, respectively. To a lesser extent, the same habitat parameters discriminated locations between deer species for moving and browsing for 1999 and 2000. If land managers want to maintain both deer species, several land management actions might be necessary. For mule deer on relatively steep slopes, managers should maintain lower percent woody cover and encourage native forb growth. For white-tailed deer in lower drainages, managers should maintain >50% woody species cover and encourage intermittent grass growth in the remaining areas.

24 Diversity of macroalgal epiphytes on Thalassia and Syringodium in tampa bay, florida

Blooms of seagrass epiphytes have potentially important economic and ecological consequences in Tampa Bay, one of the Gulf of Mexico's largest estuaries. As part of a Tampa Bay Study to monitor the impact of environmental stresses, we are characterizing epiphyte diversity for efficient management of affected resources for assessment of ecosystem health. We have collected green, brown an red algal epiphytes on Thalassia testudinum and Syringodium filiforme from fixed monitoring sites at Bishop Harbor, Cockroach Bay, Feather Sound, and from dense and sparse Thalassia testudinum and Syringodium filiforme seagrass bed sites at Mariposa Key and north of Port Manatee. A main goal of this ongoing study is the determination of indicator species for both healthy and stressed seagrass bed environments.

Reindeer avoidance of pasture contaminated with sheep and reindeer faeces

Contamination by excrements will increase in areas with high animal densities, such as snow free patches with accessible forage in winter and holding paddocks. Avoidance of faeces dropped by other grazers may result in interference competition by reducing optimal forage intake, or offer protection from the transfer of parasites or disease. We conducted two enclosure experiments investigating reindeer (Rangifer tarandus) reactions towards faeces. The first experiment tested whether reindeer avoid pasture contaminated with faeces from reindeer or sheep (Ovis aries). Both high (0.5 kg/m2) and low (0.05 kg/m2) concentrations of faeces reduced reindeer grazing compared to no faeces. Reindeer grazed significantly less in areas with high concentration of faeces compared to areas with low concentrations, with equally strong avoidance regardless of faeces source. The second experiment analysed the defecation pattern (random or not) of reindeer in a 50 m x 40 m enclosure to investigate how this pattern might change following the introduction of female sheep or additional female reindeer. Both reindeer and sheep defecated in a non-random pattern that was related to their preferred bedding sites. When sheep visited reindeer, the species' faeces distributions were positively correlated, indicating that reindeer and sheep had an overlap in area utilization, at least while bedding. When additional reindeer were introduced and then removed, the combined resident and visiting reindeers' faeces distributions were negatively correlated with the resident reindeers' faeces distribution following the removal of the visiting reindeer. This suggested that resident reindeer avoided the visiting reindeers' faeces. Resident reindeer also produced fewer total droppings when visited by new reindeer, while the number of droppings did not change when visited by sheep. Thus, resident reindeer were more adversely affected by the introduction of new reindeer even after their removal than by the introduction of sheep. In conclusion, the amount and distribution of excrements will play an important role in reindeer grazing and area use in pastures maintaining high densities of reindeer or reindeer and sheep.

Evaluation of a Winter Habitat Suitability Index Model for Elk in West-Central Alberta

Abstract We evaluated a habitat suitability index (HSI) model developed to assess impacts of forestry on elk (Cervus elaphus) winter range in west-central Alberta. The HSI model consisted of 3 submodels that collectively utilized 14 habitat variables to represent the life requisites of food, thermal cover, and hiding cover. We assessed the performance of each submodel by determining if there was a positive correlation between a preference index (PI) and HSI classes and by determining if there was a significant difference in mean HSI for sites selected by elk versus mean HSI for available habitat sites. We used stepwise logistic regression to determine which habitat variables significantly differentiated used and available habitat sites. All 3 submodels in the original model performed poorly. Of the 20 habitat variables entered, stepwise logistic regression identified only 3 as important in differentiating elk feeding sites from available sites: tree height, stem density, and distance to unimproved access. Performance of the food submodel was improved when these 3 habitat variables and their logistic relationships were applied. Only stem density significantly differentiated elk bedding sites from available sites, but using only stem density and its logistic relationship did not improve performance of the cover submodels. Our approach to testing the model involved separating HSI scores for used and available sites, and is an alternative method to using population data. FOR. SCI. 48(2):417–425.

Molecular diversity of diazotrophs in oligotrophic tropical seagrass bed communities

Denaturing gradient gel electrophoresis (DGGE) was employed to resolve PCR-amplified nifH sequences from vegetated and unvegetated sediments from two oligotrophic seagrass bed sites on San Salvador Island, Bahamas, in order to assess diazotroph species composition. All DGGE profiles from these sites showed the same prominent bands. These bands were sequenced, yielding 67 different nifH sequences, which were used in phylogenetic reconstructions. Most sequences were from anaerobes, but some were affiliated with the alpha- and (gamma-+beta-) Proteobacteria. Several NifH sequences were nearly identical to those from Azospirillum brasilense and Vibrio diazotrophicus. These seagrass bed sediments support a diverse diazotroph assemblage that is, at least superficially, similar to that associated with an intertidal grass (Spartina alterniflora).

Molecular diversity of diazotrophs in oligotrophic tropical seagrass bed communities

Denaturing gradient gel electrophoresis (DGGE) was employed to resolve PCR-amplified nifH sequences from vegetated and unvegetated sediments from two oligotrophic seagrass bed sites on San Salvador Island, Bahamas, in order to assess diazotroph species composition. All DGGE profiles from these sites showed the same prominent bands. These bands were sequenced, yielding 67 different nifH sequences, which were used in phylogenetic reconstructions. Most sequences were from anaerobes, but some were affiliated with the α- and (γ-+β-) Proteobacteria. Several NifH sequences were nearly identical to those from Azospirillum brasilense and Vibrio diazotrophicus. These seagrass bed sediments support a diverse diazotroph assemblage that is, at least superficially, similar to that associated with an intertidal grass ( Spartina alterniflora).

Bed-Site Selection by Desert Mule Deer in Southern Arizona

Bed-Site Selection by Desert Mule Deer in Southern Arizona

Influence of reach geomorphology on hyporheic communities in a gravel‐bed stream

The surface sediment, subsurface sediment, and hyporheos were sampled by freeze‐coring at three sites of contrasting geomorphology in a New Zealand gravel‐bed stream. No differences in size class composition were detected among the subsurface sediments of the three sites but the forced pool‐riffle (a stretch of stream where the sequence of pool and riffles is controlled by in‐channel bedrock outcrops) had significantly finer surface sediments than the other sites. The hyporheos of all sites was dominated numerically by insects, including nymphs of Deleatidium and Oniscigaster, and chironomid larvae. Of the non‐insect taxa, Isopoda, Oligochaeta, and Acari were most common. No significant differences existed between total invertebrate density or taxon richness at the sites. Aoteapsyche was found only in the plane bed site, whereas Nesameletus was found only in the forced pool‐riffle. Psilochorema and Nematoda occurred at significantly lower densities in the forced pool‐riffle than in the plane bed or floodplain sites. For most taxa, local variation within a site was greater than that between sites. Total invertebrate density was highest near the sediment surface but no significant differences were found between the three sites in this or any other depth layer. Significant site‐depth interactions were obtained for three taxa (Zelandobius, Ostracoda, and Oligochaeta) indicating that local geomorphology may result in differential depth distributions of hyporheic species.

Using cloud radar polarization measurements to evaluate stratus cloud and insect echoes

Suspended insects and other nonhydrometeor particulates are commonly detected in and near the planetary boundary layer by high‐sensitivity millimeter‐wave cloud radars. Radar reflectivity patterns of these targets are difficult to discern from those of stratus clouds, and therefore these particles represent undesirable contaminants for automated cloud‐detection algorithms. Radar polarization measurements, however, offer a means of distinguishing between cloud droplets and these contaminants, based on the shape information contained in depolarization ratio observations. A procedure is presented which allows dual‐polarization cloud radar data and simultaneous lidar and laser ceilometer data to determine the presence of cloud droplets alone, insects alone, and mixtures of the two at the Atmospheric Radiation Measurement program's Cloud and Radiation Test bed sites. Theory is also developed for estimating the contribution of cloud droplets to the observed reflectivity of an insect plus droplet mixture using dual‐polarization cloud radar data. Preliminary data indicate that the method provides more accurate estimates if the radar transmits circular rather than linear polarization because the effects of target orientation are minimized.

Diurnal Bed-Site Selection of Urban-Dwelling Javelina in Prescott, Arizona

Javelina (Tayassu tajacu) are an economically important big game species in the southwestern United States, but are considered nuisance wildlife in urban areas. We radiotracked individuals from 6 herds to identify diurnal bed sites of urban-dwelling javelina in 1992-93. We compared microsite habitat characteristics at 46 diurnal javelina bed sites with the same characteristics at 49 random plots. Characteristics of bed sites included south- and east-facing sites with >20% slope, >50% shrub cover, and chaparral habitat with >75 cm dbh trees, javelina also selected sites where visibility was completely obstructed by dense vegetation and-or rocks within 3-4 m.

Ranging behaviour and habitat usage in black rhinoceros, Diceros bicornis, in a Kenyan sanctuary

Home range area and habitat utilization by translocated black rhinoceros Diceros bicornis were studied at Sweetwaters Rhino Sanctuary in the Laikipia district of Kenya. Home ranges were estimated from sightings and tracking data; home range area was very variable between individuals (range 2.25–14.39km2, minimum convex polygons), and was independent of age or sex. Groups of rhinoceros shared common home ranges, with little or no overlap between groups; each group consisted of one adult male, one or more adult females and their calves, and sometimes immature animals. Rhinoceros utilize a variety of habitats, but within these show positive selection for certain habitats. Home ranges generally included more Euclea bush, and less grassland and Acacia bush than expected. Rhinoceros make use of regular resting places, or bedding sites, generally situated in bushland in secluded areas, often in dense thickets. Rhinoceros defaecate at dung piles or middens. Middens are located throughout the range not just on the boundaries; the highest density of middens was found in riverine woodland, and the lowest density in grassland and Acacia bush.

Objective Determination of Cloud Heights and Radar Reflectivities Using a Combination of Active Remote Sensors at the ARM CART Sites

Abstract The U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) Program is deploying sensitive, millimeter-wave cloud radars at its Cloud and Radiation Test Bed (CART) sites in Oklahoma, Alaska, and the tropical western Pacific Ocean. The radars complement optical devices, including a Belfort or Vaisala laser ceilometer and a micropulse lidar, in providing a comprehensive source of information on the vertical distribution of hydrometeors overhead at the sites. An algorithm is described that combines data from these active remote sensors to produce an objective determination of hydrometeor height distributions and estimates of their radar reflectivities, vertical velocities, and Doppler spectral widths, which are optimized for accuracy. These data provide fundamental information for retrieving cloud microphysical properties and assessing the radiative effects of clouds on climate. The algorithm is applied to nine months of data from the CART site in Oklahoma for initial evaluation. Much of...

Documentation of intertidal mussel bed (Mytilus edulis) sites at the coast of Lower Saxony

Surveys and aerial photograph series were evaluated to show the temporal development of the blue mussel (Mytilus edulis) stock in Lower Saxony. The data, which include the interpretations of aerial photographs (material back to 1966) and surveys (back to 1950/51) in irregular intervals, form the base for the construction of maps which represent the intertidal blue mussel stock locations at the Lower Saxonian coast. These maps contain information about the existence/absence of blue mussel beds for selected periods.

Winter bed-site selection by red deer Cervus elaphus xanthopygus and roe deer Capreolus capreolus bedfordi in forests of northeastern China

Winter bedding sites used by red deer Cervus elaphus xanthopygus Milne-Edwards, 1867 and roe deer Capreolus capreolus bedfordi Thomas, 1908 were studied in the forests of northeastern China from 1991 to 1992.

Intercomparison of cloud liquid water path derived from the GOES 9 imager and ground based microwave radiometers for continental stratocumulus

Solar reflectance measurements (0.6 and 3.9 μm) from 15‐min Geostationary Operational Environmental Satellite (GOES) 9 imager data were used to estimate cloud liquid water path (LWP) for an extensive stratocumulus system over Oklahoma on May 2, 1996. The objective was to determine the consistency between these satellite estimates and retrievals from high temporal resolution (20 s) surface microwave radiometer (SMWR) measurements. The SMWRs were located at the Atmospheric Radiation Measurement (ARM) program cloud and radiation test bed (CART) sites at Morris and Purcell in Oklahoma. Results show that while the comparisons are in favorable agreement at both sites in the morning and early afternoon (root‐mean‐square difference of 17 g m−2 and correlation of 0.94), large cloud LWP maxima in the midafternoon as measured by the SMWR at the Morris site are not captured by the satellite retrievals. On the basis of indirect evidence (in situ microphysical measurements were unavailable), it is hypothesized that the discrepancies may be the result of the formation of light drizzle in the middle to lower portions of the cloud, unseen at visible and near‐infrared wavelengths from space but easily sensed by microwave radiometry. These results demonstrate that extra care must be taken in future efforts to validate satellite derived cloud properties on a routine basis using SMWR data. Additional information about the cloud microphysical properties may also be required to help properly interpret the comparisons, particularly in the later stages of development of stratocumulus.

Summer Bed Sites of Elk (Cervus elaphus) in the Black Hills, South Dakota: Considerations for Thermal Cover Management

Abstract We characterized 131 summer, diurnal bed sites of 26 elk (11 bulls and 15 cows) in Custer State Park, South Dakota, from 5 June–30 August 1994, 1995 and 1996. Overstory canopy closure, number and basal area of trees, percent litter and bare ground were greater (P 0.05). Trees were present at 128/131 (97.7%) of bed sites (0.01 ha square plot), but occurred on only 41.2% (54/131) of random plots. An average summer, diurnal elk bed site had basal area >12.4 m2/ha, >110 trees/ha, >54% canopy closure on N aspects. Overstory canopy closure, tree basal area and microsite temperature correctl...

Bed-Site Characteristics of Pronghorn Fawns

We examined microhabitat factors associated with bedding sites of pronghorn fawns in the Trans-Pecos Region of Texas. We marked 101 fawns during 3 consecutive fawning seasons, April-June 1990-92. We measured and compared 11 microhabitat characteristics of 127 and 489 bed sites from surviving (n = 11) and non-surviving (n = 89) fawns and compared these characteristics to 225 sites we selected randomly. Differences occurred between fawn-selected bed sites and random sites for shrub cover (P = 0.04), shrub density (P = 0.01), grass cover (P = 0.03), nearest concealing cover (NCC; P = 0.0001), rock cover (P = 0.008), and bed slope (P = 0.0001). Shrub cover, shrub density, and grass cover at bed sites of surviving fawns were more similar to that found at random sites than to bed sites of non-surviving fawns. Bed sites of survivors and non-survivors differed in rock cover (P = 0.03), slope (P = 0.008), and bed slope (P = 0.001) characteristics. Fawn age class appeared to influence preference for particular microhabitat characteristics; shrub density was greater (P = 0.027) and grass cover less (P = 0.0001) in young-age fawn bed sites. Environmental features that provided adequate concealment, but that also provided increased long-range visibility of the area surrounding the bed site, appeared to be favored for bedding. Overall, important microhabitat variables were shrub cover, shrub density, grass cover, NCC, and bed slope, and to a lesser extent rock cover, terrain slope, overstory height, and understory height. Management that encourages increased grass and forb production will provide necessary hiding cover for fawns.

Daytime Habitat Selection by Cottontails in Central Pennsylvania

Information on behavioral responses of wildlife to habitat alterations is needed to allow restoration and maintenance of suitable habitats for a variety of vertebrate species. We studied the use by radiotagged eastern cottontail rabbits (Sylvilagus floridanus) of habitats within a terrestrial ecosystem scheduled to be used for disposing secondarily-treated effluent (domestic wastewater) in central Pennsylvania. Cottontails selected old-fields and shrublands for daytime use, but croplands were used when oats and corn matured during summer and fall: Aboveground bedding sites (forms) were associated with relatively dense cover, indicating that cottontails recognized variations in microhabitat within habitat types. Females frequently used underground burrows when air temperature was less than 0 C, whereas males seldom used burrows except when air temperature was less than -5 C during winter. Cottontails encountered a wide range of microclimates at forms. Air temperature, net radiation, and wind speed extremes were -7.1 to 38 C, -21 to 70 W/ m 2 , and 0.0 to 11.3 cm/sec. Air temperature, net radiation, and wind speed were greater at open sites than those at forms used by cottontails during each season. Cottontails selected micro-environments in which the insulating effect of dense cover may allow conservation of metabolic energy or reduction of heat loss. Provision of dense herbaceous and shrub cover is essential to management of cottontail habitat because it allows the animal to maintain a positive energy balance as well as avoid predators. Typically, cottontails occupied a form from sunrise to sunset. Thus, the structure of vegetation associated with forms may be a key indicator of suitable cottontail habitat. Shrub-woodland habitat appeared to be especially important to cottontails during late winter and early spring because of increased cover associated with early leaf-out of shrubs.

Paleomagnetism of the Dockum Group (Upper Triassic), northwest Texas: Further evidence for the J‐1 cusp in the North America apparent polar wander path and implications for rate of Triassic apparent polar wander and Colorado plateau rotation

We report paleomagnetic data for 26 accepted sites collected in two sections of flat‐lying strata of the upper Carnian‐lower Norian (∼225 Ma) Dockum Group, northwest Texas. Six additional sites in coarse‐grained conglomeratic sandstones gave no usable results. The total assemblage of 26 VGPs is streaked along the Late Triassic ‐ earliest Jurassic track of the North America apparent polar wander path and their mean is inconsistent with the accepted upper Carnian‐lower Norian reference pole. In detail, 12 sites in grayish white (nonhematitic) sandstones have weak magnetizations (less than about 1 mA/m) carried by magnetite or maghemite that give a paleopole at 56.4°N–96.3°E (N=12 dual‐polarity VGPs; K=44.2; A95=6.6°) in close agreement with other results for upper Carnian‐lower Norian rocks in North America. The 14 remaining sites in tan and redcolored (hematitic) sandstones, siltstones, and claystones give high unblocking temperature characteristic magnetizations carried by hematite, with paleopoles at 59.0°N–53.8°E (normal; N=7 VGPs, K=62.4, A95=7.6°) and 59.3°N–77.8°E (reverse; N=7 VGPs, K=204.2, A95=4.2°). These poles fall along the younger track of poles and near the J‐I cusp of the North American APWP as defined by (unrotated) poles derived from Colorado plateau rocks. We suggest that the characteristic magnetization of the non‐hematitic sandstones is an “early” magnetization, acquired during or soon after deposition. However, the characteristic magnetization of the red bed sites is interpreted as a secondary magnetization, for which we infer an earliest Jurassic age. The secondary origin for this magnetization is supported by the observation of conflicting magnetostratigraphies. The extreme westward position of the poles derived from red bed sites, particularly those with normal polarity, confirms the general position of the J‐I cusp indicated by poles in the Piedmont province, the Newark basin, and the Colorado plateau; it also suggests that the magnitude of rotation of the Colorado plateau is no greater than about 5°. We compile an apparent polar wander path for North America, including Colorado plateau data, which suggests a fast rate of apparent polar wander throughout the Triassic period (about 0.8°/m.y.) with a gradual increase that preceded the opening of the Atlantic.

Summer Diurnal Bed Sites of Coues White-Tailed Deer

We radiotracked 22 Coues white-tailed deer (Odocoileus virginianus couesi) in 1989-90 to characterize summer (May-Aug) diurnal bed sites. Summer is the critical period for Coues white-tailed deer, and bed sites provide thermal cover, enabling deer to maintain body core temperature and water balance during high temperature-low water periods. Human activities cannot be mitigated without characterizing bed sites. Trees were present in 80.3% of bed sites (40-m 2 -circular plot), but occurred in only 33.8% of random plots. Tree density, tree species richness, and tree canopy cover were greater (P < 0.01) in bed sites than in random plots. Tree species were not used (P < 0.01) in proportion to availability for bedding. Distance to nearest tree from bed-site center was less (P < 0.01) than for random plots