Distribution, foraging behaviour, and capture results of the spotted bat ( Euderma maculatum ) in central Oregon

The spotted bat ( Euderma maculatum ) has been virtually unknown in Oregon despite the existence of potential habitat in many areas of the state. In 2002 and 2003 we searched for spotted bats along the John Day, Deschutes, and Crooked Rivers and at a remote dry canyon southeast of the city of Bend in central Oregon. The species was documented through the use of mist-nets, a bat detector, and recognition of audible spotted bat calls. Spotted bats were found at 11 locations in 6 Oregon counties. Nightly activity patterns of spotted bats were unpredictable. Spotted bats were found in 78% of search areas but on only 48% of survey nights. We observed spotted bats foraging above fields and low upland slopes adjacent to rivers and creeks and along the rims of cliffs. Estimated flying heights of spotted bats ranged from 3 m to 50 m aboveground. The species was difficult to capture and was captured only after considerable experimentation with methods and materials. Three spotted bats were captured toward the end of the project in 2003 and accounted for only 0.5% of all bats captured during the study. Although we attached radio transmitters to 2 spotted bats, we found no roost locations. We believe additional spotted bat surveys in Oregon are warranted, especially in higher-elevation habitats, but recommend that to increase their effectiveness, surveys accommodate the unique foraging behavior of the species.     

Hatching chronology of Blue Grouse in northeastern Oregon

Hatching chronology of Blue Grouse ( Dendragapus obscurus ) in northeastern Oregon was determined from 431 immatures examined from 1981 to 1985. Young hatched from 1 May through 8 July; median hatching dates for the five years ranged from 27 May to 5 June. Peak hatching in Oregon occurred from one to four weeks earlier than in most portions of the range of Blue Grouse but were similar to north central Washington and Idaho. Variations in hatching dates possibly were related to rainfall.       

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.     

Spotted bats ( Euderma maculatum ) from Mt. Taylor, New Mexico

The spotted bat ( Euderma maculatum ) is an elusive and rarely captured species in western North America. In the United States, it is known from 12 western states. In New Mexico, few individuals have been reported in recent years, and multiple individuals are known from 9 of 12 capture sites. This study reports on additional captures of E. maculatum from Mt. Taylor (Cibola County) for 2 consecutive summers and includes evidence of a reproducing population in the area. On 30 June/1 July 2006, I captured 4 individuals of E. maculatum , including a lactating female, and on 5 June 2007, I captured a nonreproductive female. The flight of this species was directional and deliberate; I captured 5 of 6 spotted bats that came low over the earthen pond. This study demonstrates how human-made sources of water in an arid region provide opportunities for many species of bats to drink.     

Breeding populations of Swainson's Hawks, Red-Tailed Hawks, and Golden Eagles in north central Oregon: 1975-1982 and 1999

Populations of breeding Swainson's Hawks ( Buteo swainsoni ), Red-tailed Hawks ( B. jamaicensis ), and Golden Eagles ( Aquila chrysaetos ) present in 1999 were compared with populations present between 1975 and 1982 at a 129-km 2 site in north central Oregon. Populations of Red-tailed Hawks and Golden Eagles remained unchanged, but the number of Swainson's Hawks pairs increased from 15 to 17. In 1999 Golden Eagles used nests occupied between 1975 and 1982, and 7 of 31 pairs of Red-tailed Hawks used nests occupied in earlier years. No Swainson's Hawks nested in trees occupied earlier. Few changes in territorial boundaries were detected.     

Capture rates of reptiles and amphibians on black-tailed prairie dog ( Cynomys ludovicianus ) colonies and on uncolonized prairie in Colorado

Prairie dog eradication negatively affects dependent wildlife. Assessing the effects of prairie dog activities on reptiles and amphibians may depend upon the efficacy of trapping designs. We compared capture rates of reptiles and amphibians on black-tailed prairie dog ( Cynomys ludovicianus ) colonies and on adjacent uncolonized short-grass prairie, using funnel traps and pitfall traps with drift fences, as well as ground captures. We captured 152 reptiles and amphibians representing 10 species. We captured 51.3% of all reptiles and amphibians on colonies, compared to 48.7% from uncolonized sites. Overall, captures of reptiles and amphibians were similar on colonies and uncolonized sites for all capture methods combined. We achieved higher capture rates on uncolonized sites using funnel traps and pitfall traps but higher capture rates on colonies for ground captures. For all years on all sites combined, we captured significantly more animals in funnel traps (52.6%), surpassing pitfall trap captures (23.0%) and ground captures (24.3%). We recommend using multiple Y-shaped drift fence arrays ≥7.6 m in length, funnel traps with double-ended openings, and black-colored pitfall traps with opening diameters ≥30 cm.     

Burrowing Owl nest success and burrow longevity in north central Oregon

We studied nest success, burrow longevity, and rates of burrow reuse for a migratory population of Burrowing Owl ( Athene cunicularia ) in north central Oregon from 1995 to 1997. Nest success varied annually from 50% to 67%. Principal causes of nest failure were desertion (26%) and depredation by badgers ( Taxidea taxus ; 13%). Reuse of available nest and satellite burrows in subsequent years was 87% in 1996 and 57% in 1997. Reuse was highest at burrows in sandy soils, which may indicate that nest-site availability is a limiting factor in sandier soil types. Trampling by livestock resulted in the loss of 24% of all burrows between one season and the next, and natural erosion resulted in closure of 17%. Both causes of burrow failure occurred more frequently in soils with a sand component due to their friable nature. We recommend that habitat used by livestock be evaluated for use by Burrowing Owls, that occupied areas be managed to minimize destruction of burrows by livestock, and that predator-control efforts be revised to exclude mortality of badgers.     

Abundance and condition indices of coyotes on Hart Mountain National Antelope Refuge, Oregon

U.S. Fish and Wildlife Service staff at Hart Mountain National Antelope Refuge (HMNAR), southeastern Oregon, documented high pronghorn ( Antilocapra americana ) fawn mortality, subsequent low fawn recruitment, and declining pronghorn numbers from 1996 to 1999. Coyote ( Canis latrans ) predation was the primary cause, accounting for 60-85% of fawn mortalities each year, and fawns were not physiologically predisposed to predation. Therefore, we investigated certain coyote population parameters (age structure, survival, density, physiology) to evaluate how or if these factors influence coyote predation rates on pronghorn fawns. We captured 11 coyotes (5 male and 6 female) in December 1998. Age of captured animals ranged from 1.7 to 10.7 yrs (￣x = 5.0 years), and all coyotes appeared healthy upon capture. There were no known mortalities through December 1999. We estimated pre-whelping (December through February 1997-1999) density from howling surveys conducted within HMNAR to be 0.40-0.53 km -2 . Compared to other published studies, we found significant ( P ≤ 0.05) differences in selected blood parameters (e.g., blood urea nitrogen, total protein, white blood cell counts), indicating coyote nutrition may be marginal to deficient during winter at HMNAR. A high percentage of coyotes (91%) tested positive for serum-neutralizing antibodies to canine parvovirus. We judged that parasite ( Toxascaris spp., Alaria spp., Sarcocystis spp., and Isospora spp.) prevalence and intensity were not high enough to influence coyote condition. Based on our data, the coyote population at HMNAR is old aged, at a relatively high density, and stable, but their nutrition may be marginal to deficient during winter. Presently, we are unable to draw direct conclusions relating the parameters we sampled with predation rates by this unexploited coyote population.     

Bat distribution and hibernacula use in west central Nevada

We captured 299 individuals of 11 bat species in mist-nets at 18 water sources in west central Nevada from June through August 1994. Myotis ciliolubrum, Pipistrellus hesperus, M. californicus , and Corynorhinus townsendii were the most common species captured. These species are apparently broadly distributed throughout west central Nevada, occurring in a variety of habitat types. We captured Euderma maculatum at 2 localities. These represent the 1st known records of this species in Esmeralda County, Nevada. Mine adits were surveyed for hibernating bats from December 1994 through February 1995. We determined the presence of 3 hibernating species: C. townsendii, M. ciliolabrum and P. hesperus . Bats were present in 19 of 70 mines (27%) we surveyed at elevations ranging from 1500 m to 2460 m. C. townsendii was the most common species encountered. Our study provides some much-needed baseline data on bat distribution and use of mines for hibernacula in west central Nevada.     

Hybridization between a rare and introduced Oenothera along the north Pacific Coast

Interspecific hybridization has increasingly become regarded as a serious threat to the genetic integrity and persistence of rare plants. Oenothera glazioviana (Onagraceae) is a horticultural species that has escaped cultivation and now threatens the narrow Pacific coastal endemic O. wolfii with hybridization. Reports of morphologically intermediate and ecologically aggressive forms prompted this investigation into the extent of hybridization over the range of O. wolfii . In particular, this study identifies populations of pure and hybrid origins. We used multivariate methods to characterize the morphological variation of Oregon and northern California coastal Oenothera populations. Putatively pure O. wolfii and O. glazioviana individuals do not overlap in many floral characteristics. We found morphologies ranging between the 2 species in northern California populations, however, supporting the inference of hybridization. Remote O. wolfii populations in Oregon were smaller in almost all characters, and discriminant analysis was able to distinguish the rare species from both hybrids and O. glazioviana . However, 5 of 10 O. wolfii populations overlapped significantly with hybrid populations for individual traits and composite morphology, and trait values outside the range of O. wolfii were discovered in 2 populations previously considered to be pure. We also discuss the morphological evidence in light of these species’ chromosomal complexes and environmental factors.     

Brood-rearing habitat use by Rio Grande Wild Turkeys in Oregon

Wild turkey ( Meleagris gallopavo ) brood-rearing sites have been described for portions of their range, but brood-rearing habitat use and characteristics of brood-rearing sites used by Rio Grande Wild Turkeys ( M. g. intermedia ) in the Pacific Northwest were unknown. We described cover types at 362 brood-rearing sites and measured habitat characteristics at 64 of these sites used by a recently established Rio Grande Wild Turkey population in southwestern Oregon during May-September 1989 and 1990. Hens with broods used 9 of 10 available cover types. Meadows, mixed hardwood/conifer woodlands, and savannas were used more often than expected (47% of observations, P ≤ 0.05). Broods used mature mixed conifer and dense sapling/pole mixed conifer cover types less than expected and did not use brush-fields. Many brood-rearing sites were characterized by a parklike appearance. Understory vegetation averaged P ≤ 0.05). We suggest that land managers maintain mixed hardwood/conifer woodland and savanna cover types adjacent to meadows on south slopes to provide brood-rearing habitat for Rio Grande Wild Turkeys in southwestern Oregon.     

Redescription of the Tyee Sucker, Catostomus tsiltcoosensis (Catostomidae)

We resurrect Catostomus tsiltcoosensis, the Tyee sucker of Oregon coastal rivers, from the synonymy of Catostomus macrocheilus and compare it with its congeners. Catostomus tsiltcoosensis is superficially similar to disjunctly distributed Catostomus occidentalis of the Sacramento drainage and Catostomus ardens of the Upper Snake River and Bonneville Basin. However, the gill raker structure, wide frontoparietal fontanelle, location of the ninth cranial foramen, scale radii patterns, and cytochrome b sequences clearly align C. tsiltcoosensis with C. macrocheilus rather than C. occidentalis. Differences in counts of infraorbital pores and dorsal fin rays, in body depth proportions, and in cytochrome b sequences distinguish C. tsiltcoosensis and C. macrocheilus. Within C. tsiltcoosensis, specimens from each of the 4 main drainages (north to south—Siuslaw, Umpqua, Coos, and Coquille) were reciprocally monophyletic based on cytochrome b data but showed no differences in the morphological features examined. Both C. tsiltcoosensis and another Oregon coastal taxon Catostomus rimiculus were paraphyletic based on cytochrome b. Although such discordant mitochondria results can be due to introgression, incomplete lineage sorting, and paralogy, other evidence suggests that introgression and lateral transfer of mitochondria explains the cytochrome b pattern in C. rimiculus. We speculate that lateral transfer might also be responsible for the pattern in C. tsiltcoosensis, except that the Coquille River population appears not to have been included in recent transfers.     

Size and Overlap of Townsend Ground Squirrel Home Ranges

We evaluated movement distance (an index of home range size) based on capture histories of 32 postbreeding Townsend ground squirrels ( Spermophilus townsendii ) on a 15 × 15 trap grid in southwestern Idaho. Capture frequencies and movement distances of adult males were significantly greater than those of other sex/age groups. Members of the same sex/age group were rarely captured at the same grid location, evidence of mutual avoidance within sex/age groups. These results are compared with those for other species of ground squirrels.     

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.     

Historical fire frequency on contrasting slope facets along the McKenzie River, western Oregon Cascades

Fire has been a critical influence on forest dynamics over much of western North America, and knowledge of historical fire regimes provides a valuable reference point for guiding ecosystem management. Spatial and temporal variations in historical (1550–1997) fire frequency were quantified for a 145-km 2 area straddling the McKenzie River in the central western Cascades of Oregon. Fire-scar and tree-origin years estimated from cut stumps in 63 clearcut sites were used to approximately date fires. The estimated natural fire rotation was 162 years for the presettlement period (1550–1849). Natural fire rotation varied considerably over the period of record, ranging from 40 years for the Euro-American settlement period (1850–1924) to 504 years for the recent (1925–1997) fire-suppression period. Such temporal variation in fire regime may be attributed to a combination of climatic and anthropogenic influences. The study area also experienced 2 periods of widespread fire recorded at a majority of sample sites: one in the mid-1500s and the other from 1850 to 1925. Historical fire frequency has also varied spatially over at least 2 distinct scales. At the slope-facet scale, fire frequency was greatest on the generally south-facing slope to the north of the McKenzie River. At the finer scale of individual 4-ha sites, local topographic influences varied according to a site’s broad geographical context north or south of the river. Results suggest that meaningful fire-regime characterization may require information derived from multiple spatial scales.     

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.     

Field identification of Myotis yumanensis and Myotis lucifugus: a morphological evaluation

Myotis lucifigus and Myotis yumanensis are 2 species of bats subject to potentially high rates of misidentification because they are often difficult to differentiate in the hand under field conditions. We tested the utility of a suite of external morphological characteristics frequently cited in regional keys to differentiate the 2 species in the field. Forearm length, dorsal pelage sheen, ear color, and forehead slope were examined from 101 bats captured in central Oregon during 2002–2003. Post hoc genetic analysis was performed on tissue samples collected from the 101 bats to confirm identification. Forearm lengths overlapped considerably between species. Only 18% of M. yumanensis and 17% of M. lucifugus were correctly identified with probability ≥95% using forearm length alone. Pelage sheen, ear color, and forehead slope successfully identified 96%, 82%, and 77% of individual bats, respectively. When forearm length was considered together with other traits, identification rates ranged from 92% to 20%. Ability to correctly identify M. yumanensis was 2–6 times greater than for M. lucifugus. Pelage sheen was useful in our study; however, using this character required a subjective decision from the observer, and the result often contradicted other characters for species identification stated in regional keys. For these reasons, we recommend that morphological features be used judiciously and only as supportive criteria for field identification in combination with voucher echolocation calls and genetic confirmation.     

Temporal variation in the diets of California Quail in western Oregon

This study was designed to describe dietary changes by comparison of information on long-term diet and plant food availability of California Quail ( Callipepla californica ) in western Oregon. We examined crops from 222 California Quail collected in 1976-78 and 1985-87. Diets included 14 key plant foods (annual frequency > 15%) among 53 taxa consumed; 10 of the 14 key foods were similar between time periods. Collectively, key foods contributed 87% of the diet by aggregate dry mass during 1985-87; six species of legumes (family Leguminosae) composed 67% of diet. Relative rankings of availabilities of key foods were similar between 1976-78 and 1985-87. This study revealed that quail were opportunistic within the group of key foods because 9 of the 14 key foods were consumed in different frequencies between the two periods. Legumes were an important dietary component in western Oregon because they composed the bulk of the diet, were among the most frequently consumed, and most were taken in substantially greater proportions than available.