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Twenty species of bats (Molossidae, Vespertilionidae) were collected from California, New Mexico, Oregon, South Carolina, Utah, and Baja California Norte (Mexico), and 29 of 404 (7%) animals, including Antrozous pallidus, Eptesicus fuscus, Myotis auriculus, Myotis californicus, Myotis ciliolabrum, Myotis evotis, Myotis lucifugus, Myotis thysanodes, Myotis vivesi, Myotis volans, Myotis yumanensis, and Nycticeius humeralis were infected with Eimeria spp., which represent 6 new species. Sporulated oocysts of a new species from A. pallidus are subspheroidal, 24.8 x 21.6 (22-27 x 19-24) microm with a polar granule and a large globular residuum. The oocyst wall is sculptured, with 2 layers, approximately 1.5 thick. Ovoidal sporocysts are 11.5 x 7.8 (9-13 x 7-10) microm, with Stieda body and residuum of many large granules. Sporulated oocysts of a new species from M. californicus are subspheroidal, 20.7 x 18.2 (19-23 x 16-20) microm, with 1-7 tiny polar granules, but without oocyst residuum. The oocyst wall is rough, with 2 layers, approximately 1.4 thick. Ovoidal sporocysts are 11.2 x 7.3 (10-12 x 7-8) microm, with Stieda body and a globular residuum. Sporulated oocysts of a second new species from M. californicus are subspheroidal, 23.1 x 20.7 (20-26 x 19-23) microm, with residuum and 1 polar granule, but a micropyle is absent. The oocyst wall is rough with 2 layers, approximately 1.5 thick. Ovoidal sporocysts are 12.5 x 7.2 (11-14 x 7-8) microm, with a Stieda body and residuum. Sporulated oocysts of a new species from M. ciliolabrum are subspheroidal, 24.9 x 20.1 (18-27 x 17-23) microm, with 1-2 polar granules, but without micropyle and residuum. The oocyst wall is rough with 2 layers, approximately 1.5 thick. Ellipsoidal sporocysts are 12.5 x 9.0 (8-14 x 7-10) microm, with Stieda and substieda bodies and residuum. Sporulated oocysts of a new species from M. evotis are subspheroidal, 21.3 x 18.6 (20-24 x 15-20) microm, with a prominent polar granule, but without micropyle and residuum. The oocyst wall is smooth with 2 layers, approximately 1.0 thick. Ovoidal sporocysts are 12.2 x 8.0 (11-13 x 7.5-9) microm, with Stieda and substieda bodies and residuum. Sporulated oocysts of the new species from N. humeralis are subspheroidal, 22.4 x 18 (21-24 x 17-20) microm, with 1-3 polar granules, but residuum and micropyle are absent. The oocyst wall is lightly sculptured with 2 layers, approximately 1.4 thick. Ovoidal sporocysts are 10.9 x 7.7 (9-12 x 6-8) microm, with Stieda body and residuum. Sporulated oocysts of E. pilarensis Scott and Duszynski, 1997 and those of at least 12 other morphological forms were seen in the other infected bats; these latter forms were seen in too few numbers to be adequately described as new species.

Winter records of bats in the Pacific Northwest are extremely limited (Barbour and Davis 1969). Of the 15 bat species other than Plecotus townsendii in Oregon and Washington, at least two are considered migratory. Five species (Eptesicus fuscus, Myotis californicus, M. Iucifugus, M. volans, Antrozous pallidus) are known to hibernate in the eastern portion of their ranges (Barbour and Davis 1969; Twente 1960). Marcot (1984) reported records for hibernating Myotis evotis in northern California, Senger et al. (1974) noted five species of hibernating myotids (M. californicus, M. evotis, M. Iucifugus, M. volans and M. yumanensis) in Washington, Genter (1986) observed hibernating M. Ie.;bii in Idaho, and Jewett (1955) recorded Tadarida brasiliensis from buildings in southwestern Oregon. Most hibernacula contained relatively few bats (range = 1-41) when compared with those of the eastern United States (Barbour and Davis 1969). The reports were from studies concentrated in small geographical areas and involved a small number of caves. Twente (1960), who investigated over 600 potential hibernacula in Utah, speculated few hibernating bats were noted because of warm temperatures in the caves. Results of Genter (1986), Marcot (1984), and Senger et al. (1974) suggest that hibernacula in the Pacific Northwest may contain larger bat populations than reported by Twente (1960). This prompted us to conduct a more extensive search that included most of Oregon and Washington. We defined winter as the period from 1 November to 1 April. During winters of 1982-1989, we searched more than 650 caves and mines and 70 buildings in Oregon and Washington. Seven of the caves were previously surveyed by Senger et al. (1974). Most bats were easily identified from observable external characters (Hall 1981). Closely related species (M. Iucifugus, M. yomRnensis; and M. thysanodes, M. evotis) were collected if positive identification could not be made in the field. In addition, we obtained winter records of museum specimens collected in Oregon and Washington from American Museum of Natural History (AMNH), the National Museum (USNM), the University of Puget Sound (PSMNH), the University of Washington (UW), Southern Oregon State College (SOSC), the San Diego Museum of Natural History (SDMNH), Oregon State University (OSUFW), the University of Michigan (UMMZ), and Walla Walla College (WWC). We located 174 bats of seven species at 26 sites (Table 1). M. volans (124) and M. Ieibii (36) were encountered more than any other species. Numbers of bats were

Various aspects of night roosting behavior were observed for four species of desert bats. Variability in night roost utilization was found for those species for which adequate observations were available. Myotis californicus roosted primarily in desert shrubs or trees, depending on availability. Pipistrellus hesperus utilized rock, rock crevices, and desert shrubs as primary roosting sites, rock being preferred when in close proximity to water. Antrozous pallidus was more flexible in roosting behavior, utilizing small trees, rock crevices, and an abandoned shed. In contrast, Tadarida brasiliensis roosted in a bridge expansionjoint where they were also found during daylight hours. Night roosting for digestion and subsequent weight loss reduces wing loading, thereby allowing considerable energy conservation in further foraging activity or long flights back to day roosts. During daylight hours, bats seek shelter in a wide variety of habitats. Day roosts have been described in numerous previous studies. Existing data on night roosts, however, are limited and have resulted mainly from accidental encounters in buildings, bridges, mines, caves, and rock crevices (Barbour and Davis 1969). In desert areas bat activity is concentrated near free water, which may be located at a considerable distance from roosting sites. There are, however, numerous isolated mountain ranges and adequate vegetation which could provide suitable night shelter. Where typical roosting sites occur adjacent to a water source, night roosts for some species of desert bats have been described (Dalquest 1953; Krutzsch 1954; Orr 1954; Cross 1965; Barbour and Davis 1969; Poche and Ruffner 1975). In this study we attempted to locate and describe night roosts in areas of the Mojave Desert where night roosts have not previously been identified. MATERIALS AND METHODS. Bats used for roosting behavior observations were collected at various locations in southern Nevada and northern Arizona (600-1480 m elevation) during the period July-September 1975. Roosting behavior observations were made on 34 Myotis californicus, 32 Pipistrellus hesperus, 26 Antrozous pallidus, and 24 Tadarida brasiliensis.

During the period between August 13 and 24, 1938, the writer collected fourteen Myotis californicus caurinus Miller and four Myotis evotis evotis (A. Allen) at Nelscott, Oregon, and a single Myotis californicus caurinus near McMinnville, Oregon. Nelscott is a seashore resort and the bats obtained there were taken from their daytime hiding places in the coniferous forest about one mile from the village. Small streams and a nearby freshwater lake might serve for the development of probable arthropod intermediate hosts of the trematodes found.

Bats were captured in a mist net at White Spot Spring, Desert Game Range, Clark County, Nevada during the months September through May for a total of 21 mist net nights. Time of capture, air temperature, and wind conditions are given for each species. Two species, Pipistrellus hesperus and Myotis californicus were active throughout the fall and winter. Pipistrellus was netted at air tempera- tures ranging from 10 to 310 C. Myotis californicus was netted at air temperatures of 20 to 270 C. Approximately 48% of the Myotis were taken at air temperatures be- tween 2o and 60 C. and approximately 11% of the Pipistrellus were netted at air temperatures of 50 C. or below. A third species Antrozous pallidus was netted in low numbers at air temperatures as low as 20 C. Studies of bat activity have usually been conducted during the spring, summer, and early fall months when bat activity is highest. Since bat activity is low or non-existent in temperate areas during the fall and winter, few data on activity are available for these seasons. The present study provides some indications of fall and winter activity for certain species found to be active at these seasons in southern Nevada. DESCRIPTION OF THE STUDY AREA. White Spot Spring is lo- cated at 4460 feet elevation, on the north-facing slope of the Las Vegas Range, Desert Game Range, Clark County, Nevada. The spring flow is contained within a stone tank which is approximately 11.5 feet square by 2 feet deep. The tank was usually full of water. It is bordered on one side by Tamarix spp. and Phragmites communis. The surrounding area consisting or rolling hills is covered by various desert shrubs in- cluding Coleogyne ramosissima, Larrea divaricata, Yucca schidigera, and Atriplex canescens.