John A. Bissonette

Influence of Understory Characteristics on Snowshoe Hare Habitat Use and Density

The influence of forest understory characteristics on snowshoe hare (Lepus americanus) habitat use and density was studied in eastern (Cherryfield) and western (Pierce Pond) Maine during 1981-83. Fecal pellet counts indicated that hares at Cherryfield preferred hardwood and avoided mixedwood and open understories during the leaf-off season (Oct-May) (P < 0.05). At Pierce Pond, hares used softwood more and hardwood and open understories less than expected during leaf off (P < 0.05). Hardwood understories provided the densest cover at Cherryfield, whereas at Pierce Pond softwoods were the densest cover. Hares in both areas used dense understories less during the leaf-on season (Jun-Sep). Spring population densities (0.1-1.7/ha) were correlated with understory density (r = 0.94, P < 0.001). Overwinter survival also was associated with understory density (r = 0.74, P < 0.04). Dense understories provided escape and thermal

Bobcat Habitat Use and Home Range Size in Relation to Prey Density

Bobcat (Felis rufus) diet, habitat use, and home range size were studied in relation to snowshoe hare (Lepus americanus) density and distribution in 2 areas in Maine during 1979-84. Hare remains occurred in 63-76% of bobcat feces collected during all seasons in both areas. Habitat use patterns of 12 transmitter-equipped bobcats in eastern Maine indicated that they used hardwood understories more, and softwood and mixedwood understories less than expected (P 5* (P < 0.05). The average home range of resident male bobcats (95.7 kmn2) was 3 x as large as that of resident females (31.2 km2) (P < 0.05), and home range size was correlated with bobcat weight (r2 = 0.45, P < 0.002). Metabolic home range size (km2/kg075 body wt) of bobcats was inversely correlated with stem cover unit density and estimated hare density (r2 = 0.22, P < 0.05). Estimated hare density and average topographic slope within bobcat home ranges accounted for 50% of the variation in metabolic home range size (P < 0.006). J. WILDL. MANAGE. 50(1):110-117 Many factors influence vertebrate habitat use and home range size, including energy requirements, prey distribution and density, reproductive requirements, and intraand interspecific relations (Stenger 1958, McNab 1963, Schoener 1968, Smith 1968). Among these, prey density has been reported to be inversely correlated with home range size (Smith 1968, Holmes 1970, Mares et al. 1976). Large variation has been observed in bobcat home range sizes. Bailey (1974) reported bobcats in Idaho occupied ranges from 9 to 108 km , and bobcats in Alabama occupied ranges <4 km2 (Miller 1980). Buie (1980) observed a 4-fold increase in home range size in South Carolina 13 years after Marshall and Jenkins (1967) studied bobcats in the same area. Buie suggested that changes in land-use patterns caused declines in prey populations and resulted in decreased bobcat density and increased home range size. Snowshoe hares are the major prey of bobcats in Maine (May 1981, Major 1983). Therefore, bobcat habitat use within home ranges should be influenced by the distribution of hares. Bobcats occurring in areas with relatively dense hare populations may occupy smaller ranges than bobcat in areas with low hare densities. The objective of our study was to determine the relati nship between bobcat habitat use and home range s ze and snowshoe hare distribution and abundance in Maine. This research was supported by the Maine Coop. Wildl. Res. Unit, U.S. Fish and Wildl. Serv., Maine Dep. Inland Fish. and Wildl., Wildl. Manage. Inst., and the Univ. Maine, cooperating. A. G. Clark, J. H. Hunt, and L. Perry made valuable contributions in executing and funding this study. We thank students at the Coll. For. Resour., Univ. Maine, and Unity Coll. that provided field assistance. We also thank J. W. Ault III; J. R. Gilbert; G. L. Jacobson, Jr.; D. M. Leslie, Jr.; R. B. Owen, Jr.; and R. E. Rolley for reviewing this report. This is contribution 1078 from Maine Agric. Exp. Stn.

Marten Subnivean Access Point Use: Response to Subnivean Prey Levels

Because marten (Martes americana) require subnivean access for cover, prey access, and homeothermic reasons, we developed a predictive model to explain their differential use of subnivean access holes in Yellowstone National Park. We included prey biomass and percent ground cover of coarse woody debris (CWD) as explanatory variables in a logistic regression model because of their biological importance to marten in winter. Taken singly, relative prey biomass yielded the best univariate predictive model (P = 0.001). However, we included CWD in a multivariate model because of its biological significance. Coarse woody debris provides structure that intercepts snowfall, creating subnivean tunnels, interstitial spaces, and access holes, and was found at used and unused access points

Scale-Sensitive Ecological Properties: Historical Contest, Current Meaning

In landscape ecology, attention to scale is most important (Wiens 1989). Indeed Levin (1992)has argued that the “problem of pattern and scale is the central problem in ecology”. A Special Features section in the journal Ecologywith the title “Space: the final frontier for ecological theory” (Kareiva 1994) echoed the same theme. Clearly, the choice of appropriate time and space scales is important if understanding in ecology is to advance (Bissonette 1996). This issue is central to current dialog in landscape ecology (Golley 1989, Kareiva 1994) because different patterns and properties tend to emerge at different scales (May 1994).

Road zone effects in small-mammal communities

This study focused on the putative effects of roads on small-mammal communities in a high desert region of southern Utah. Specifically, the authors tested whether or not roads create adjacent zones characterized by lower small-mammal densities, abundance, and diversity. They sampled an abundance of small mammals at increasing distances from Interstate 15 during two summers. They recorded 11 genera and 13 species. The authors detected no clear abundance, density, or diversity effects relative to distance from the road. Only two of 13 species were never captured near roads. The abundance of the remaining 11 small mammal species was either similar at different distances from the road or higher closer to the road. The authors conclude that although roads may act as barriers and possible sources of mortality, adjacent zones of vegetation often provide favorable microhabitat in the desert landscape for many small mammals.

Ranking the risk of wildlife species hazardous to military aircraft

Abstract Collisions between birds and aircraft (birdstrikes) pose a major threat to aviation safety. Different species pose different levels of threat; thus, identification of the most hazardous species can help managers identify the level of hazard and prioritize mitigation efforts. Dolbeer et al. (2000) assessed the hazard posed by birds to civilian aircraft by analyzing data from the Federal Aviation Administrations (FAA) Wildlife Strike Database to rank the hazardous species and species groups. A similar analysis has not been done for the military but would be useful and necessary. Military flight characteristics differ from those of civilian flights. During the period 1985–1998, birdstrikes cost the United States Air Force (USAF) an average of

Understanding Measures of Landscape Pattern

35 million/year in damage. Using the USAF Birdstrike Database, we selected and evaluated each species or species group by the number of strikes recorded in each of 3 damage categories. We weighted damage categories to reflect extent and cost of damage. The USAF Birdstrike Database contained 25,519 records of wildlife strikes in the United States. During the period 1985–1998, 22 (mean =1.6/year) Class-A birdstrikes (>

Do Well Connected Landscapes Promote Road-Related Mortality

1,000,000 damage, loss of aircraft, loss of life, or permanent total disability) were sustained, accounting for 80% of total monetary losses caused by birds. Vultures (Cathartes aura, Coragyps atratus, Caracara cheriway) were ranked the most hazardous species group (Hazard Index Rank [HIR]=127) to USAF aircraft, followed by geese (Branta canadensis, Chen caerulescens, HIR = 76), pelicans (Pelecanus erythrorhynchos, P. occidentalis, HIR=47), and buteos (Buteo sp., HIR=30). Of the smaller flocking birds, blackbirds and starlings (mostly Agelaius phoeniceus, Euphagus cyanocephalus, Molothrus ater, Sturnus vulgaris, HIR = 46), horned larks (Eremophila alpestris, HIR=24), and swallows (Families Hirundinidae, Apodidae, HIR= 23) were species groups ranked highest. Coupling these results with local bird census data to adjust hazard rank indices to specific locations can facilitate hazard management and lead to meaningful reductions in hazards and costs associated with birdstrikes.

Evaluation of the Use and Effectiveness of Wildlife Crossings

A major emphasis in landscape ecology is the study of landscape pattern, including pattern dynamics, ecological processes that influence pattern, and effects of pattern on organisms. In order to investigate relationships between landscape pattern and ecological processes, it is often helpful to describe the patterns in quantifiable terms, and a variety of spatial metrics have been developed for this purpose (Whitcomb et al. 1981 Forman and Godron 1986 O’Neill et al. 1988 Turner 1990 Milne 1991 Gustafson and Parker 1992] Li and Reynolds 1993 Plotnick et al. 1993 McGarigal and Marks 1995). Although these metrics enable ecologists to address landscape-level questions in a more rigorous fashion, they often are applied without a clear understanding of the strengths and limitations of each measure or how various measures are interrelated.

Scaling roads and wildlife: the Cinderella principle

Cost surface (CS) models have emerged as a useful tool to examine the interactions between landscapes patterns and wildlife at large-scale extents. This approach is particularly relevant to guide conservation planning for species that show vulnerability to road networks in human-dominated landscapes. In this study, we measured the functional connectivity of the landscape in southern Portugal and examined how it may be related to stone marten road mortality risk. We addressed three questions: (1) How different levels of landscape connectivity influence stone marten occurrence in montado patches? (2) Is there any relation between montado patches connectivity and stone marten road mortality risk? (3) If so, which road-related features might be responsible for the species’ high road mortality? We developed a series of connectivity models using CS scenarios with different resistance values given to each vegetation cover type to reflect different resistance to species movement. Our models showed that the likelihood of occurrence of stone marten decreased with distance to source areas, meaning continuous montado. Open areas and riparian areas within open area matrices entailed increased costs. We found higher stone marten mortality on roads in well-connected areas. Road sinuosity was an important factor influencing the mortality in those areas. This result challenges the way that connectivity and its relation to mortality has been generally regarded. Clearly, landscape connectivity and road-related mortality are not independent.