Occurrence of Ord's kangaroo rat ( Dipodomys ordii ) along its eastern distributional limit in Nebraska

Changes in land use continue to alter habitats throughout Nebraska, and few studies have examined how such changes affect distributional limits of mammals. The distribution of Ord’s kangaroo rat ( Dipodomys ordii ) was last examined in eastern Nebraska about 4 decades ago. We examined the current eastern distributional limits of D. ordii to see whether its range had expanded, contracted, or remained constant in the state since the 1960s. Based on our study, kangaroo rats have experienced little change in distribution during recent decades. Herein, we report on data for 8 counties without prior records and a marginal range extension, as well as comment on habitat, reproduction, and taxonomic status of kangaroo rats in eastern Nebraska. Los cambios en el uso del suelo siguen modificando los hábitats a lo largo del estado de Nebraska, y pocos estudios han examinado cómo estos cambios afectan los límites de distribución de los mamíferos. La última evaluación de la distribución de la rata canguro de Ord ( Dipodomys ordii ) en el este de Nebraska se llevó a cabo hace 4 décadas. Examinamos los límites orientales actuales de la distribución de D. ordii para ver si su área de distribución se ha expandido, contraído o permanecido igual en el estado desde los años 1960. Con base en nuestra investigación, es posible decir que la distribución de las ratas canguro ha cambiado poco en décadas recientes. Aquí reportamos datos para 8 condados para los cuales no existían registros anteriores e informamos sobre una pequeña expansión de su área de distribución. También comentamos sobre el hábitat, la reproducción y la situación taxonómica de las ratas canguro en el este de Nebraska.     

Growth of Dipodomys ordii (Rodentia: Heteromyidae)

Growth rates were determined for laboratory - reared Dipodomys ordii pallidus Durrant & Setzer. Instantaneous growth rates were used to express increase of body weight, total length, tail length, ear length and hind foot length as rates between times of measurements and the instantaneous percentage of maximum size. Data were analyzed for growth periods of 1 – 3, 4 – 15, 16 – 29 and 30 – 70 days. All five parameters provided significant correlations of growth with age during all growth periods. Even though all of the growth parameters correlate with age, these parameters cannot be reliably used to predict age.     

Summer food habits of coyotes in Idaho's River of No Return Wilderness Area

Summer food habits of coyotes ( Canis latrans )in the River of No Return Wilderness Area, Idaho, were determined. Analysis of 51 scats (fecal samples) revealed that Columbian ground squirrels ( Spermophilus columbianus ), mule deer ( Odocoileus hemionus ), and deer mice ( Peromyscus manniculatus ) exhibited the greatest frequency of occurrence for identified food items, being detected in 57%, 27%, and 16%, respectively, of scats examined.     

Whipworm ( Trichuris dipodomys ) infection in kangaroo rats ( Dipodomys spp.): effects on digestive efficiency

To determine whether infections by whipworms ( Trichuris dipodomys [Nematoda: Trichurata: Trichuridae]) might affect digestive efficiency and therefore energy budgets of two species of kangaroo rats ( Dipodomys microps and Dipodomys ordii [Rodentia: Heteromyidae]), we compared the apparent dry matter digestibility of tree groups of hosts: those naturally infected with whipworms, those naturally uninfected with whipworm, and those originally naturally infected but later deinfected by treatment with the anthelminthic Ivermectin. Prevalence of T. dipodomys was higher in D. microps (53%) than in D. ordii (14%). Apparent dry matter digestibility was reduced by whipworm infection in D. microps but not in D. ordii . Although a statistically significant effect was shown, its small magnitude indicates that whipworm infection is unlikely to have a biologically significant impact on the energy budgets of host kangaroo rats.     

Taphonomy and significance of Jefferson's ground sloth (Xenarthra: Megalonychidae) from Utah

While a variety of mammalian megafauna have been recovered from sediments associated with Lake Bonneville, Utah, sloths have been notably rare. Three species of ground sloth, Megalonyx jeffersonii, Paramylodon harlani, and Nothrotheriops shastensis , are known from the western United States during the Pleistocene. Yet all 3 are rare in the Great Basin, and the few existing records are from localities on the basin margin. The recent discovery of a partial skeleton of Megalonyx jeffersonii at Point-of-the-Mountain, Salt Lake County, Utah, fits this pattern and adds to our understanding of the distribution and ecology of this extinct species. Its occurrence in Lake Bonneville shoreline deposits permits a reasonable age determination of between 22 and 13 ka.     

Dorsal hair length and coat color in Abert's squirrel ( Sciurus aberti )

Sciurus aberti, like many other sciurids including Sciurus vulgaris and Sciurus carolinensis, shows a coat color polymorphism. Like Sciurus vulgaris, Sciurus aberti shows a correlation between coat color phase and dorsal hair length. Both squirrels show an increased frequency of dark morphs in the northern portions of their respective ranges.     

Daily and yearly movement of the Devil's Hole pupfish Cyprinodon diabolis Wales in Devil's Hole, Nevada

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Ground nesting and aggressive behavior by the Swainson's Hawk ( Buteo swainsoni )

A successful ground nesting by Swainson’s Hawks, Buteo swainsoni, is reported for central Utah. Unusual aggressive nest defense behavior is described for this ground nesting pair.     

Reproduction and seasonal activity of silver-haired bats ( Lasionycteris noctivagans ) in western Nebraska

Silver-haired bats ( Lasionycteris noctivagans ) were thought only to migrate through Nebraska; however, recent surveys in eastern Nebraska report summer records of females and their young. Our study in western Nebraska also shows that silver-haired bats are summer residents. We discovered the 1st reproductively active L. noctivagans in this part of the state. We caught lactating females and volant young in riparian forests along the North Platte River and in forested areas of the Pine Ridge. Previously, adult males were not known from Nebraska in summer, and only 4 records of L. noctivagans were known from western Nebraska during migration. On 28 July we captured an adult male in a coniferous forest of the Wildcat Hills, and we have more than 100 records of migrating individuals. Lastly, an obese L. noctivagans captured on 4 November may represent an individual preparing to hibernate in the state.     

Habitat and spatial relationships of nesting Swainson's Hawks ( Buteo swainsoni ) and Red-tailed Hawks ( B. jamaicensis ) in northern Utah

A total of 28 Swainson's Hawk ( Buteo swainsoni ) and 30 Red-tailed Hawk ( B. jamaicensis ) nests were found in Cache Valley, Utah, during the summers of 1992 and 1993. All nests were in trees, but only Red-tailed Hawks nested in dead trees (30%). In the intensive study area, nesting densities were 0.10 nests/km 2 for Swainson's Hawk and 0.08 nests/km 2 for Red-tailed Hawk. Nearest-neighbor nest distances were significantly shorter among Swainson's Hawks (1.74 km) than among Red-tailed Hawks (2.83 km). Congeneric nearest-neighbor distances were significantly shorter than conspecific distances for Red-tailed Hawks (1.59 vs 2.83 km) but not for Swainson's Hawks (1.52 vs. 1.74). GIS analysis of habitat types was made for 2-km radii around nest sites. Cropland was the dominant land cover type at nest sites of both species and no significant difference was found between species. Swainson's Hawk nest sites contained significantly more pasture, whereas Red-tailed Hawk nest sites contained significantly more juniper, maple, and sagebrush. Only Red-tailed Hawk nests ( n = 8; 27%) were found on the periphery of the valley at the base of foothills of the Cache Mountains. This preference resulted in a significantly higher elevation for Red-tailed Hawk nest sites. Swainson's Hawk nests occurred only on the valley floor on level terrain. Distance to the nearest paved road and building was very similar for both species, implying that little difference exists in tolerance levels for human activities. Overall, multivariate niche overlap for habitat was high (0.89), indicating a lack of habitat partitioning between these 2 Buteos in Cache Valley.     

Captures of Crawford's gray shrews ( Notiosorex crawfordi ) along the Rio Grande in central New Mexico

We captured >2000 Crawford’s gray shrews ( Notiosorex crawfordi ) in a riparian forest mainly consisting of cottonwoods ( Populus deltoides ) along the Rio Grande in central New Mexico. Little has been published about abundance and habitat of Crawford’s gray shrew throughout its distributional range. During 7 summers, we captured shrews in pitfall traps at 13 study sites in Bernalillo, Valencia, and Socorro counties. Capture rates of shrews were greatest in August and September, and we did not detect a response of shrews to restoration treatments that removed nonnative plants from riparian forests. Results from our study indicate that (1) Crawford’s gray shrews are more abundant in riparian habitats than historically presumed and (2) pitfall traps with drift fences are an effective means to capture shrews.     

The short song of Brewer's Sparrow: individual and geographic variation in southern Idaho

Brewer's Sparrows ( Spizella breweri ) have two song types--a ""short"" song that has 1 to 3 trill types and a ""long"" song that has 5 to 10 or more trill types. I describe the short song and examine patterns of individual and geographic song variation from 15 sites on the Snake River Plain in southern Idaho. Territorial males sang the short song regularly during the breeding season. Two-trill song types comprised 72.9% of all song types, with 3-trill types (18.8%) and 1-trill types (8.2%) less frequent. Over 90% of the males sang their song type(s) essentially without variation. Many trill types appeared most often in only 1 of 3 possible song positions, i.e., 1st, 2nd, or 3rd trill. Trill types that occurred in different song positions differed in syllables per second, trill and syllable duration, and frequency variables. First trill types were more variable than 2nd or 3rd trill types. There was no evidence that birds at sites closer together shared more trill types or pairs of trill types than those farther apart. There was no tendency for territorial neighbors to sing similar song types. Brewer's Sparrows' small territories, dense populations, and apparently high rate of annual turnover may mediate against the evolution of song sharing or vocal dialects.     

Bristlecone pine and Clark's Nutcracker: probable interaction in the White Mountains, California

Many bristlecone pines in the White Mountains, California, are members of multistem clumps. We propose that these clumps have arisen by multiple germinations from seed caches of Clark’s Nutcracker, as occurs in several other pine species. The commonness of nutcrackers and their caching of singleleaf pinyon seeds in the study area provide supporting evidence. Other vertebrates appear unlikely to be responsible for the stem clumps. Seed burial may be required to establish regeneration on these adverse sites where bristlecone pine attains great longevity.        

Springtime movements, boost Use, and foraging activity of Townsend's big-eared bat ( Plecotus townsendii ) in central Oregon

Seasonal movements, roost-site fidelity, and foraging activity patterns are largely unknown for western populations of Townsend's big-eared bat ( Plecotus townsendii ). We used miniature radiotelemetry units to track springtime movements of six bats inhabiting forested lava flows in central Oregon, and found that bats moved up to 24 km from hibernacula to foraging areas. Individual bats returned to the same foraging area on successive nights but shifted to different areas in presumed response to changes in insect availability. Both sexes apparently use a series of interim roost sites between emergence from hibernation and the time females enter into maternity colonies, with little individual fidelity to these sites. In regions characterized by extensive lava-flow topography, suitable daytime roosts are numerous and dispersed over a large area, allowing bats to move relatively great distances to locate foraging ranges. Hence, the actual area of concern for effective management of individual populations can be considerably larger than indicated solely by locations of hibernacula and maternity caves of this declining species.     

Habitat use and selection and home ranges of Merriam's Wild Turkey in Oregon

Habitat use and selection by Merriam's Wild Turkeys ( Meleagris gallopavo merriami ) in Wasco County, Oregon, was studied during 1981-82. This turkey population selectively used forested cover types (such as ponderosa pine-Douglas-fir-oak, ponderosa pine-oak) characterized by a variety of structural features, species, and age classes. The population used single species forested cover types (oak, ponderosa pine) less than expected, used nonforested cover types in proportion to their availability, and avoided forested cover types with structure simplified by logging activities. The four age and sex classes had large seasonal home ranges (￣x = 1,615 ha); the smallest home ranges were exhibited by adult males in winter and the largest were shown by subadult males in fall. In most instances, turkeys used cover types as they were available. We suggest that structural complexity of vegetation, both within and among cover types, is an important component of habitat for Merriam's Wild Turkeys that should be considered in the evaluation of potential release sites and in habitat management plans.     

Boggy meadows, livestock grazing, and interspecific interactions: influences on the insular distribution of montane Lincoln's Sparrows ( Melospiza lincolnii alticola )

I surveyed 34 meadows in California and Oregon to count Lincoln's Sparrows ( Melospiza lincolnii alticola ) and to identify habitat features that might influence their local, insular occurrence. Lincoln's Sparrows were most common in wet meadows with little damage by grazing. Singing males were concentrated in flooded or boggy areas near meadow edges, where pines ( Pinus sp.) provided elevated perches for singing and vigilance. Patches of willows ( Salix sp.) were often present nearby. Numbers of male Lincoln's Sparrows were strongly and negatively correlated with abundance of sympatric Song Sparrows ( M. melodia fisherella ). Lincoln's Sparrows breeding in montane meadows are potentially vulnerable to local extirpation because of their insular distribution, low population density, and fluctuating habitat conditions. Heavy damage from livestock grazing drastically increases the probability of local extirpation.     

Notes on the Swainson's Hawk in central Utah: insectivory, premigratory aggregations, and kleptoparasitism

A premigratory flock of Swainson's Hawks numbering at least 213 individuals was observed during July and August of 1984. Aerial feeding on grasshoppers was noted and kleptoparasitism was recorded between the Swainson's Hawk and the American Kestrel.     

New record and southern range extension for the Mearn's grasshopper mouse ( Onychomys arenicola Mearns, 1896) in Veracruz, Mexico

Mearn’s grasshopper mouse ( Onychomys arenicola ) in Mexico is found primarily in the central and northern states. This is the first report of the genus Onychomys in the state of Veracruz, based on 7 captured specimens (3 collected). This finding extends the species’ known distribution by approximately 470 km east-southeast. In addition, this record increases the alpha diversity of terrestrial mammals for the state of Veracruz to 192 species.