Thomas E. Morrell

Characteristics of ponderosa pine snag roosts used by reproductive bats in northern Arizona

Little information exists on the roost habitat characteristics of reproductive forest bats; hence, we used radiotelemetry to locate 121 roosts of species of bats in 2 study areas on the Coconino National Forest (CNF), northern Arizona, during 1993-95. Only pregnant or lactating bats were examined in the study. Ninety-seven (80%) roosts were in ponderosa pine (Pinus ponderosa) snags. Snags used by bats were larger in diameter at breast height (dbh) and were more likely to have exfoliating bark (bark peeling away from the snag, thus creating space between the bark and the snag) than random snags in both areas. In both study areas, roost snags were surrounded by forest with higher tree densities, greater tree species diversity, and trees had larger basal areas than forest surrounding random snags. Forests immediately surrounding roost snags also had higher densities of snags and logs than random snag areas. In the southern study area, roost snags were located closer to water than random snags and were more likely near the tops of slopes. Roost snags in the northern study area were on steeper slopes and were less likely within a recently harvested area. Radiomarked bats frequently used multiple roosts: 37 of 76 (49%) bats used ≥2 snags during the study. We recommend preserving all large snags with exfoliating bark and suggest steps to ensure that sufficient numbers of such snags are maintained for roosting bats in the future.

The decline of fruit bats in American Samoa due to hurricanes and overhunting

Abstract Populations of the two fruit bat species in American Samoa Pteropus samoensis and P. tonganus have declined dramatically (80–90%) in the past five years due to hurricane losses and subsequent overhunting by villagers. Current estimates are that only 200–400 P. samoensis and 1500–2500 P. tonganus remain on Tutuila Island, which formerly supported the largest bat populations in the Territory. A three-year hunting ban was enacted in 1992, but modeling projections indicate that a much longer recovery period will be required.

Predictive Occurrence Models for Bat Species in California

Abstract The ability to accurately predict the potential occurrence of species of management concern is useful for wildlife managers, particularly for those whose management activities involve large areas where sampling is difficult due to logistical or financial constraints. During the summers of 2002 and 2003, we used mist nets to capture bats (Myotis yumanensis, M. californicus, M. evotis, M. thysanodes, Eptesicus fuscus, Lasionycteris noctivagans, Tadarida brasiliensis, Antrozous pallidus, Lasiurus borealis, and Lasiurus cinereus) in Whiskeytown National Recreation Area in north-central California, USA. We used landscape-scale variables, logistic regression, and Akaikes Information Criterion (AICc) to model species distributions and produce spatially discerning predictive occurrence maps. We developed a priori models that we used to determine which landscape-scale variables best discriminated between capture sites and non-capture sites. The odds of capturing a bat were 3.3 greater when total edge increased by 10,000 m, whereas for Yuma myotis (Myotis yumanensis), the odds of predicting presence were 0.2 greater when distance to lakes and ponds decreased by 2,000 m. Elevation was important in predicting the distribution of silver-haired bats (Lasionycteris noctivagans) and big brown bats (Eptesicus fuscus). Increasing elevation by 400 m decreased the odds of capturing a silver-haired bat by 0.1 and a big brown bat by 0.4. Classification accuracy for our models ranged from 80.9% for all bat species combined to 72.3% for Yuma myotis and silver-haired bats. Predictive occurrence models can be valuable to bat conservation efforts because they provide spatial data important for evaluating the effects of management activities on species distributions.

Habitat use and activity patterns of urban-dwelling javelina

In Arizona, conflicts between homeowners and urban-dwelling javelina (Tayassu tajacu) continued to increase. Human-javelina conflicts often occurred when javelina responded to urban attractants and destroyed ornamental landscapes, injured pets, and frightened homeowners. This prompted initiation of a study during 1992–93 to develop recommendations to alleviate these conflicts. We captured, radio-collared, and located eight javelina from six herds to determine home ranges, habitat use, and activity patterns in Prescott, Arizona. Urban-dwelling javelina adjusted their home ranges, habitat use, and activity patterns to best use human-provided urban food, water, and cover resources. The most conspicuous of these adjustments was the increased nocturnal activity of urban-dwelling javelina to avoid human disturbances. Undeveloped land within or adjacent to Prescott provided javelina with daytime bedding areas and nighttime travel corridors. We determined that this issue was more a people problem than it was a javelina problem. Thus, strategies to resolve the conflicts must target homeowners.

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.

NEST-SITE CHARACTERISTICS OF RED-TAILED TROPICBIRDS ON ROSE ATOLL, AMERICAN SAMOA

Abstract We examined nest sites of Red-tailed Tropicbirds (Phaethon rubricauda) on Rose Island of the Rose Atoll National Wildlife Refuge, American Samoa, to determine habitat features important for nest-site selection of this species. We quantified habitat characteristics at 27 nest sites and at 27 random sites during September 1991. All nests were located under beach heliotrope (Messerschmidia argentea) shrubs or pisonia (Pisonia grandis) trees. Nest sites were placed farther under the nest shrub, had more stems in the nest space, and greater percent shade cover than random sites. Nest sites averaged 24.9 m from their nearest neighbor, ≥20 m greater than has been reported elsewhere for this colonial species. We suggest that an overpopulation of Polynesian rats (Rattus exelans) may have influenced nest-site selection by Red-tailed Tropicbirds on Rose Island.