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taxonomy, behavior, ecology, and recovery The following text was taken from the Department of the Interior, Fish and Wildlife Service Federal Register dated November 17th, 2005, pertaining to the proposed delisting of the Yellowstone grizzly bear. For the full document pdf click here (800kb file). Species description Grizzly bears are generally larger and more heavily built than other bears (Craighead and Mitchell 1982; Schwartz et al. 2003a). Grizzly bears can be distinguished from black bears, which also occur in the lower 48 States, by longer, curved claws, humped shoulders, and a face that appears to be concave (Craighead and Mitchell 1982). A wide range of coloration from light brown to nearly black is common (LeFranc et al. 1987). Spring shedding, new growth, nutrition, and coat condition all affect coloration. Guard hairs (long, course outer hair forming a protective layer over the soft underfur) are often pale in color at the tips; hence the name ‘‘grizzly’’ (Craighead and Mitchell 1982). In the lower 48 States, the average weight of grizzly bears is generally 200 to 300 kilograms (kg) (400 to 600 pounds (lb)) for males and 110 to 160 kg (250 to 350 lb) for females (Craighead and Mitchell 1982). Grizzly bears are long-lived mammals, generally living to be around 25 years old (LeFranc et al. 1987). Taxonomy Grizzly bears (Ursus arctos horribilis) are vertebrates that belong to the Class Mammalia, Order Carnivora, and Family Ursidae. The grizzly bear is a member of the brown bear species (U. arctos) that occurs in North America, Europe, and Asia; the subspecies U. a. horribilis is limited to North America (Rausch 1963; Servheen 1999). Early taxonomic descriptions of U. arctos based primarily on skull measurements described more than 90 subspecies (Merriam 1918), but this was later revised to 2 subspecies in North America, U. a. middendorfi on the islands of the Kodiak archipelago and U. a. horribilis in the rest of North America (Rausch 1963). Subsequent analyses (Hall 1984) suggested seven North American subspecies. DNA analyses provide an additional tool for evaluating taxonomic classification. Using mitochondrial DNA (mtDNA) of brown bears across their worldwide range, five lineage groups or clades have been described: Clade I brown bears from Scandinavia and southern Europe; Clade II from Admiralty, Baronoff, and Chichagof islands in Alaska; Clade III from eastern Europe, Asia, and western Alaska; Clade IV from southern Canada and the lower 48 United States; and Clade V from eastern Alaska and northern Canada (Cronin et al. 1991; Taberlet and Bouvet 1994; Kohn et al. 1995; Randi et al. 1994; Taberlet et al. 1995; Talbot and Shields 1996; Waits et al. 1998a; Waits et al. 1999). The two North American subspecies approach of Rausch (1963) is generally accepted by most taxonomists today. Behavior Although adult bears are normally solitary (Nowak and Paradiso 1983), home ranges of adult bears frequently overlap (Schwartz et al. 2003a). Grizzly bears display a behavior called natal philopatry in which dispersing young establish home ranges within or overlapping their mother’s (Waser and Jones 1983; Schwartz et al. 2003a). This type of movement makes dispersal across landscapes a slow process. For instance, McLellan and Hovey (2001) documented male and female dispersal over 20 years and found that grizzly bears gradually move farther from the center of their mother’s home range over the course of 1 to 4 years. Females established home ranges an average of 9.8 kilometers (km) (6.1 miles (mi)) away from the center of their mother’s home range, whereas males generally strayed further, establishing home ranges roughly 29.9 km (18.6 mi) away from their mother’s (McLellan and Hovey 2001). Similarly, Proctor et al. (2004) used genetic analyses to find that, on average, females disperse only 14.3 km (8.9 mi) and males disperse 42.0 km (26.0 mi) from the center of their mother’s home range. The home range of adult male grizzly bears is typically 3 to 5 times the size of an adult female’s home range (LeFranc et al. 1987). The large home ranges of grizzly bears, particularly males, enhance genetic diversity in the population by enabling males to mate with numerous females (Blanchard and Knight 1991; Craighead et al. 1995). Grizzly bear population densities of 1 bear per 20 sq km (8 sq mi) have been reported in Glacier National Park (Martinka 1976), but most populations in the lower 48 States are much less dense (LeFranc et al. 1987). For example, estimates of grizzly bear densities in the Yellowstone area range from one bear per 50 sq km (20 sq mi) to one bear per 80 sq km (30 sq mi) (Blanchard and Knight 1980; Craighead and Mitchell 1982). Grizzly bears have a promiscuous mating system (Hornocker 1962; Craighead and Mitchell 1982; Schwartz et al. 2003a) with genetic studies confirming that cubs from the same litter can have different fathers (Craighead et al. 1998). Mating occurs from May through July with a peak in mid-June (Craighead and Mitchell 1982; Nowak and Paradiso 1983). Age of first reproduction and litter size may be related to nutritional state (Stringham 1990; McLellan 1994; Hilderbrand et al.1999). Age of first reproduction varies from 3 to 8 years of age, and litter size varies from one to four cubs (Schwartz et al. 2003a). The average age of first reproduction is approximately 6 years old, and the average litter size is 2.04 cubs. Cubs re born in a den in late January or early February and remain with the female for 2 to 3 years before the mother will again mate and produce another litter (Schwartz et al. 2003a). Grizzly bears have one of the slowest reproductive rates among terrestrial mammals, resulting primarily from the late age of first reproduction, small average litter size, and the long interval between litters (Nowak and Paradiso 1983; Schwartz et al. 2003a). Given the above factors and natural mortality, it may take a single female 10 years to replace herself in a population (Service 1993). Grizzly bear females cease breeding successfully some time in their mid-to late 20s (Schwartz et al. 2003b). For 3 to 6 months during winter, grizzly bears across their range enter dens in an adaptive behavior which increases survival during periods of low food availability, deep snow, and low air temperature (Craighead and Craighead 1972). Grizzly bears in the lower 48 States spend up to 4 to 6 months in dens beginning in October or November (Linnell et al. 2000). During this period, they do not eat, drink, urinate, or defecate (Folk et al. 1976; Nelson 1980). Hibernating grizzly bears exhibit a marked decline in heart and respiration rate, but only a slight drop in body temperature (Nowak and Paradiso 1983). Due to their relatively constant body temperature in the den, hibernating grizzly bears can be easily aroused and have been known to exit dens when disturbed by seismic or mining activity (Harding and Nagy 1980) or by human activity (Swenson et al. 1997). Both males and females have a tendency to use the same general area year after year but the same exact den is rarely used twice by an individual (Schoen et al. 1987; Linnell et al. 2000). Females display stronger area fidelity than males and generally stay in their dens longer, depending on reproductive status (Judd et al. 1986; Schoen et al. 1987; Linnell et al. 2000). In preparation for hibernation, bears increase their food intake dramatically during a stage called hyperphagia. Hyperphagia is defined simply as overeating (in excess of daily metabolic demands) and occurs throughout the 2 to 4 months prior to den entry. During hyperphagia, excess food is deposited as fat, and grizzly bears may gain as much as 1.65 kg/day (3.64 lb/day) (Craighead and Mitchell 1982). Grizzly bears must consume foods rich in protein and carbohydrates in order to build up fat reserves to survive denning and post- denning periods (Rode and Robbins 2000). These layers of fat are crucial to the hibernating bear as they provide a source of energy and insulate the bear from cold temperatures and are equally important in providing energy to the bear upon emergence from the den when food is still sparse relative to metabolic requirements. Although the digestive system of bears is essentially that of a carnivore, bears are successful omnivores, and in some areas may be almost entirely herbivorous (Jacoby et al. 1999; Schwartz et al. 2003a). Grizzly bears are opportunistic feeders and will consume almost any available food including living or dead mammals or fish, and, sometimes, garbage (Knight et al. 1988; Mattson et al. 1991a; Schwartz et al. 2003a). In areas where animal matter is less available, grasses, roots, bulbs, tubers, and fungi may be important in meeting protein requirements (LeFranc et al. 1987). High-quality foods such as berries, nuts, insects, and fish are important in some areas (Schwartz et al. 2003a). The search for food has a prime influence on grizzly bear movements. In the Yellowstone area, four food sources have been identified as important to grizzly bear survival and reproductive success (Mattson et al. 2002). Winter- killed ungulates serve as an important food source in early spring before most vegetation is available (Greene et al.1997; Mattson 1997). During early summer, spawning cutthroat trout (Oncorhynchus clarki) are a source of nutrition for grizzly bears in the Yellowstone population (Mattson et al. 1991a; Mattson and Reinhart 1995; Felicetti et al. 2004). Grizzly bears feed on army cutworm moths (Euxoa auxiliaris) during late summer and early fall as they try to acquire sufficient fat levels for winter (Pritchard and Robbins 1990; Mattson et al. 1991b; French et al. 1994). Lastly, whitebark pine seeds (Pinus albicaulis) serve as a crucial fall food due to their high fat content and abundance as a pre-hibernation food (Mattson and Reinhart 1994). The distribution and abundance of these grizzly bear foods vary naturally among seasons and years. In some years, whitebark pine seeds are an important food and in other years, few seeds are available and bears switch to alternate foods. On average, approximately 79 percent of the diet of adult male and 45 percent of the diet of adult female grizzly bears in the Greater Yellowstone Area (GYA) is terrestrial meat (Jacoby et al. 1999). In contrast, in Glacier National Park, over 95 percent of the diets of both adult male and female grizzly bears is vegetation (Jacoby et al. 1999). Ungulates rank as the second highest source of net digestible energy available to grizzly bears in the GYA (Mealey 1975; Pritchard and Robbins 1990; Craighead et al. 1995). Ungulates provide a high-quality food source in early spring before most plant foods become available. Grizzly bears with home ranges in areas with few plant foods depend extensively on ungulate meat (Harting 1985). Grizzly bears in the Yellowstone area feed on ungulates primarily as winter-killed carrion from March through May although they also depredate elk calves for a short period in early June (Gunther and Renkin 1990; Green et al. 1997; Mattson 1997). Carcass availability fluctuates with winter severity because fewer ungulates die during mild winters. Due to their high digestibility and protein and lipid content, spawning cutthroat trout are one of the highest sources of digestible energy available to bears during early summer in Yellowstone National Park (Mealey 1975; Pritchard and Robbins 1990). Grizzly bears are known to prey on cutthroat trout in at least 36 different streams tributary to Yellowstone Lake (Reinhart and Mattson 1990). From 1997 to 1999, Haroldson et al. (2000) identified 85 different grizzly bears that had likely fished spawning streams tributary to Yellowstone Lake. While importance varies by season and year, few bears develop a dependence on this food source. Only four individuals visited spawning streams consistently every year, suggesting that this resource is used opportunistically. Fishing activity can occur any time during the spawning runs but generally coincides with peak spawning numbers in mid- June through mid-July. In contrast to earlier studies which used different assumptions and methods (Reinhart and Mattson 1990; Mattson and Reinhart 1995), Felicetti et al. (2004) showed that male grizzly bears are the primary consumers of cutthroat trout, accounting for 92 percent of all trout consumed by Yellowstone grizzly bears. Alpine moth aggregations are an important food source for a considerable portion of the Yellowstone grizzly bearpopulation (Mattson et al. 1991b). As many as 35 different grizzly bears with cubs-of-the-year have been observed feeding at moth sites in a single season (Ternent and Haroldson 2000). Some bears may feed almost exclusively on moths for a period of over 1 month (French et al. 1994). Moths have the highest caloric content per gram of any other bear food (French et al. 1994). Moths are available during late summer and early fall when bears consume large quantities of foods in order to acquire sufficient fat levels for winter (Mattson et al. 1991b). A grizzly bear feeding extensively on moths over a 30-day period may consume up to 47 percent of its annual energy budget of 960,000 calories (White et al. 1999). Moths are also valuable to bears because they are located in remote areas, thereby reducing the potential for grizzly bear/ human conflicts during the late-summer tourist months. Due to their high fat content and potential abundance as a pre- hibernation food, whitebark pine seeds are an important fall food for bears in the GYA (Mattson and Jonkel 1990; Mattson et al. 1991a). Yellowstone grizzly bears consume whitebark pine seeds extensively when whitebark cones are available. Bears may feed predominantly on whitebark pine seeds when production exceeds 22 cones per tree (Mattson et al. 1992). During years of low whitebark pine seed availability, grizzly bears often seek alternate foods at lower elevations in association with human activities (Mattson et al. 1992; Knight and Blanchard 1995; Gunther et al. 1997, 2004). The production and availability of these four major foods can have a positive effect on reproduction and survival rates of Yellowstone grizzly bears (Mattson et al. 2002). For example, during years when these food sources are abundant, there are few grizzly bear/ human conflicts in the GYA (Mattson et al. 1992; Gunther et al. 1997; Gunther et al. 2004). Grizzly bear/human conflicts are incidents in which bears kill or injure people, damage property, kill or injure livestock, damage beehives, obtain anthropogenic foods, or damage or obtain garden and orchard fruits and vegetables (United States Department of Agriculture (USDA) 1986). In contrast, during years when there are shortages of natural food sources, grizzly bear/ human conflicts are more frequent, resulting in higher numbers of human- caused grizzly bear mortalities due to defense of life or property and management removals of nuisance bears (Mattson et al. 1992; Gunther et al. 2004). A nuisance bear is one that seeks human food in human use areas, kills lawfully present livestock, or displays unnatural aggressive behavior towards people (USDA 1986). Introduced organisms (e.g., white pine blister rust and lake trout), habitat loss, and other human activities can negatively impact the quantity and distribution of these four primary foods (Reinhart et al. 2001). The effects of invasive species on food supply and human/bear conflict are discussed in more detail in the five factor analysis. Recovery Prior to the arrival of Europeans, the grizzly bear occurred throughout the western half of the contiguous United States, central Mexico, western Canada, and most of Alaska (Roosevelt 1907; Wright 1909; Merriam 1922; Storer and Tevis 1955; Rausch 1963; Herrero 1972; Mattson et al. 1995; Schwartz et al. 2003a). Pre-settlement population levels for the western contiguous United States were believed to be in the range of 50,000 animals (Servheen 1999). With European settlement of the American west, grizzly bears were shot, poisoned, and trapped wherever they were found, and the resulting range and population declines were dramatic (Roosevelt 1907; Wright 1909; Storer and Tevis 1955; Leopold 1967; Koford 1969; Craighead and Mitchell 1982; Mattson et al. 1995). The range and numbers of grizzlies were reduced to less than 2 percent of their former range and numbers by the 1930s, approximately 125 years after first contact (Service 1993; Mattson et al. 1995; Servheen 1999). Of 37 grizzly populations present in 1922, 31 were extirpated by 1975 (Servheen 1999). In 1981, the Service hired a grizzly bear recovery coordinator to direct recovery efforts and to coordinate all agency efforts on research and management of grizzly bears in the lower 48 States. In 1982, the first Grizzly bear recovery plan was completed (Service 1982). The 1982 Grizzly Bear Recovery Plan identified five ecosystems within the conterminous United States thought to support grizzly bears. Today, grizzly bear distribution is primarily within, but not limited to, the areas identified as Recovery Zones (Service 1993), including the Yellowstone area in northwest Wyoming, eastern Idaho, and southwest Montana (24,000 sq km (9,200 sq mi)) at more than 580 bears (Interagency Grizzly Bear Study Team (Study Team) 2005); the Northern Continental Divide Ecosystem (NCDE) of north central Montana (25,000 sq km (9,600 sq mi)) at more than 400 bears (70 FR 24870; May 11, 2005); the North Cascades area of north central Washington (25,000 sq km (9,500 sq mi)) at less than 20 bears (Almack et al. 1993); the Selkirk Mountains area of north Idaho, northeast Washington, and southeast British Columbia (5,700 sq km (2,200 sq mi)) at approximately 40 to 50 bears (64 FR 26725, May 17, 1999; 70 FR 24870, May 11, 2005); and the Cabinet- Yaak area of northwest Montana and northern Idaho (6,700 sq km (2,600 sq mi)) at approximately 30 to 40 bears (Kasworm and Manley 1988; Kasworm et al. 2004). There is an additional Recovery Zone known as the Bitterroot Recovery Zone in the Bitterroot Mountains of east-central Idaho and western Montana (14,500 sq km (5,600 sq mi)), but this area does not contain any grizzly bears at this time (Service 1996; 65 FR 69624, November 17, 2000; Service 2000). The San Juan Mountains of Colorado also were identified as an area of possible grizzly bear occurrence (40 FR 31734, July 28, 1975; Service 1982, 1993), but no evidence of grizzly bears has been found in the San Juan Mountains since a bear was killed there in 1979 (Service 1993). In 1983, the Interagency Grizzly Bear Committee was created to coordinate management efforts and research actions across multiple Federal lands and States within the various Recovery Zones to recover the grizzly bear in the lower 48 States. Its objective was to change land management practices to more effectively provide security and maintain or improve habitat conditions for the grizzly bear. 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