Geology topics

Douglas W. Smith

Publications and source records attributed to Douglas W. Smith.

28 records · Page 2Linked to original sources

USGS2016

Territoriality and inter-pack aggression in gray wolves: shaping a social carnivore's life history

When Rudyard Kipling wrote The Jungle Book in 1894 and included the famous line "For the strength of the Wolf is the Pack, and the strength of the Pack is the Wolf," he would have had no idea that over a century later, scientific research would back up his poetic phrase. Recent studies in Yellowstone have found that both the individual wolf and the collective pack rely on each other and play important roles in territoriality. At a time when most fairy tales and fables were portraying wolves as demonic killers or, at best, slapstick gluttons, Kipling seemed to have a respect or even reverence for the wolf. Wolves in The Jungle Book raise and mentor the main character Mowgli, with the pack's leader eventually dying to save the "man-cub" from a pack of wolves. Kipling may have extended intra- pack benevolence to a human boy for literary sake, but he was clearly enthralled with how pack members treat each other. As wolf packs are almost always family units, most commonly comprised of a breeding pair and their offspring from several years, amiable behavior within the pack is unsurprising. By contrast, wolf packs are fiercely intolerant of their neighbors, their rivals. And this competition is proving to be an important facet in the life of a wolf and its pack.

Yellowstone Science↗

USGS2016

Infectious diseases of wolves in Yellowstone

The summer of 2005 began with such promise for wolves in Yellowstone. The population had been at an all-time high the last few years, and the wolves appeared to be in good condition. Several packs had been particularly busy during the breeding season, and early summer pup counts suggested another healthy crop of new wolves rising through the ranks.

Colorado↗

USGS2015

Group composition effects on aggressive interpack interactions of gray wolves in Yellowstone National Park

Knowledge of characteristics that promote group success during intraspecific encounters is key to understanding the adaptive advantages of sociality for many group-living species. In addition, some individuals in a group may be more likely than others to influence intergroup conflicts, a relatively neglected idea in research on social animals. Here we use observations of aggressive interactions between wolf ( Canis lupus ) packs over an extended period and use pack characteristics to determine which groups had an advantage over their opponents. During 16 years of observation in Yellowstone National Park from 1995 to 2010, we documented 121 interpack aggressive interactions. We recorded pack sizes, compositions, and spatial orientation related to residency to determine their effects on the outcomes of interactions between packs. Relative pack size (RPS) improved the odds of a pack displacing its opponent. However, pack composition moderated the effect of RPS as packs with relatively more old members (>6.0 years old) or adult males had higher odds of winning despite a numerical disadvantage. The location of the interaction with respect to pack territories had no effect on the outcome of interpack interactions. Although the importance of RPS in successful territorial defense suggests the evolution and maintenance of group living may be at least partly due to larger packs’ success during interpack interactions, group composition is also an important factor, highlighting that some individuals are more valuable than others during interpack conflicts.

Wyoming↗

USGS2015

Social living mitigates the costs of a chronic illness in a cooperative carnivore

Infection risk is assumed to increase with social group size, and thus be a cost of group living. We assess infection risk and costs with respect to group size using data from an epidemic of sarcoptic mange ( Sarcoptes scabiei ) among grey wolves ( Canis lupus ). We demonstrate that group size does not predict infection risk and that individual costs of infection, in terms of reduced survival, can be entirely offset by having sufficient numbers of pack-mates. Infected individuals experience increased mortality hazards with increasing proportions of infected pack-mates, but healthy individuals remain unaffected. The social support of group hunting and territory defence are two possible mechanisms mediating infection costs. This is likely a common phenomenon among other social species and chronic infections, but difficult to detect in systems where infection status cannot be measured continuously over time.

Ecology Letters↗

USGS2015

Wolves on the hunt: The behavior of wolves hunting wild prey

The interactions between apex predators and their prey are some of the most awesome and meaningful in nature—displays of strength, endurance, and a deep coevolutionary history. And there is perhaps no apex predator more impressive and important in its hunting—or more infamous, more misjudged—than the wolf. Because of wolves’ habitat, speed, and general success at evading humans, researchers have faced great obstacles in studying their natural hunting behaviors. The first book to focus explicitly on wolf hunting of wild prey, Wolves on the Hunt seeks to fill these gaps in our knowledge and understanding. Combining behavioral data, thousands of hours of original field observations, research in the literature, a wealth of illustrations, and—in the e-book edition and online—video segments from cinematographer Robert K. Landis, the authors create a compelling and complex picture of these hunters. The wolf is indeed an adept killer, able to take down prey much larger than itself. While adapted to hunt primarily hoofed animals, a wolf—or especially a pack of wolves—can kill individuals of just about any species. But even as wolves help drive the underlying rhythms of the ecosystems they inhabit, their evolutionary prowess comes at a cost: wolves spend one-third of their time hunting—the most time consuming of all wolf activities—and success at the hunt only comes through traveling long distances, persisting in the face of regular failure, detecting and taking advantage of deficiencies in the physical condition of individual prey, and through ceaseless trial and error, all while risking injury or death. By describing and analyzing the behaviors wolves use to hunt and kill various wild prey—including deer, moose, caribou, elk, Dall sheep, mountain goats, bison, musk oxen, arctic hares, beavers, and others—Wolves on the Hunt provides a revelatory portrait of one of nature’s greatest hunters.

Book↗

USGS2012

Parasite invasion following host reintroduction: a case of Yellowstone’s wolves

Wildlife reintroductions select or treat individuals for good health with the expectation that these individuals will fare better than infected animals. However, these individuals, new to their environment, may also be particularly susceptible to circulating infections and this may result in high morbidity and mortality, potentially jeopardizing the goals of recovery. Here, using the reintroduction of the grey wolf (Canis lupus) into Yellowstone National Park as a case study, we address the question of how parasites invade a reintroduced population and consider the impact of these invasions on population performance. We find that several viral parasites rapidly invaded the population inside the park, likely via spillover from resident canid species, and we contrast these with the slower invasion of sarcoptic mange, caused by the mite Sarcoptes scabiei. The spatio-temporal patterns of mange invasion were largely consistent with patterns of host connectivity and density, and we demonstrate that the area of highest resource quality, supporting the greatest density of wolves, is also the region that appears most susceptible to repeated disease invasion and parasite-induced declines. The success of wolf reintroduction appears not to have been jeopardized by infectious disease, but now shows signs of regulation or limitation modulated by parasites.

Wyoming↗

USGS2011

Nonlinear effects of group size on the success of wolves hunting elk

Despite the popular view that social predators live in groups because group hunting facilitates prey capture, the apparent tendency for hunting success to peak at small group sizes suggests that the formation of large groups is unrelated to prey capture. Few empirical studies, however, have tested for nonlinear relationships between hunting success and group size, and none have demonstrated why success trails off after peaking. Here, we use a unique dataset of observations of individually known wolves ( Canis lupus ) hunting elk ( Cervus elaphus ) in Yellowstone National Park to show that the relationship between success and group size is indeed nonlinear and that individuals withholding effort (free riding) is why success does not increase across large group sizes. Beyond 4 wolves, hunting success leveled off, and individual performance (a measure of effort) decreased for reasons unrelated to interference from inept hunters, individual age, or size. But performance did drop faster among wolves with an incentive to hold back, i.e., nonbreeders with no dependent offspring, those performing dangerous predatory tasks, i.e., grabbing and restraining prey, and those in groups of proficient hunters. These results suggest that decreasing performance was free riding and that was why success leveled off in groups with >4 wolves that had superficially appeared to be cooperating. This is the first direct evidence that nonlinear trends in group hunting success reflect a switch from cooperation to free riding. It also highlights how hunting success per se is unlikely to promote formation and maintenance of large groups.

Behavioral Ecology↗

USGS2002

Leadership behavior in relation to dominance and reproductive status in gray wolves, Canis lupus

We analyzed the leadership behavior of breeding and nonbreeding gray wolves ( Canis lupus ) in three packs during winter in 19971999. Scent-marking, frontal leadership (time and frequency in the lead while traveling), initiation of activity, and nonfrontal leadership were recorded during 499 h of ground-based observations in Yellowstone National Park. All observed scent-marking ( N = 158) was done by breeding wolves, primarily dominant individuals. Dominant breeding pairs provided most leadership, consistent with a trend in social mammals for leadership to correlate with dominance. Dominant breeding wolves led traveling packs during 64% of recorded behavior bouts ( N = 591) and 71% of observed travel time ( N = 64 h). During travel, breeding males and females led packs approximately equally, which probably reflects high parental investment by both breeding male and female wolves. Newly initiated behaviors ( N = 104) were prompted almost 3 times more often by dominant breeders (70%) than by nonbreeders (25%). Dominant breeding females initiated pack activities almost 4 times more often than subordinate breeding females (30 vs. 8 times). Although one subordinate breeding female led more often than individual nonbreeders in one pack in one season, more commonly this was not the case. In 12 cases breeding wolves exhibited nonfrontal leadership. Among subordinate wolves, leadership behavior was observed in subordinate breeding females and other individuals just prior to their dispersal from natal packs. Subordinate wolves were more often found leading packs that were large and contained many subordinate adults.

Canadian Journal of Zoology↗

USGS2001

Winter severity and wolf predation on a formerly wolf-free elk herd

We studied wolf (Canis lupus) predation on elk (Cervus elaphus) in Yellowstone National Park from 17 March to 15 April 1997 (severe winter conditions) and from 2 to 31 March 1998 (mild winter conditions) 2-3 years after wolves were reintroduced to the park. Elk composed 91 % of 117 kills. Data comparisons for 1997 versus 1998 were: hunting success rate, 26% versus 15%; kill rate, 17.1 kg/wolf/day versus 6.1; percent of kill consumed in first day, 7 versus 86; percent femur marrow fat of adult kills, 27 versus 70; calf:adult ratios of kills, 2:33 versus 17:23; sex ratio of kills, 14M:19F versus 17M:6F; mean age of elk killed, males 6.1 years, females 15.2 versus males, 4.8, females 13.0. Winter severity influenced the wolf-elk relationship more than the naivete of the elk herd to predation by wolves.

Journal of Wildlife Management↗

USGS2000

Wolf-bison interactions in Yellowstone National Park

We studied interactions of reintroduced wolves ( Canis lupus ) with bison ( Bison bison ) in Yellowstone National Park. Only 2 of 41 wolves in this study had been exposed to bison before their translocation. Wolves were more successful killing elk ( Cervus elaphus ) than bison, and elk were more abundant than bison, so elk were the primary prey of wolves. Except for a lone emaciated bison calf killed by 8 1-year-old wolves 21 days after their release, the 1st documented kill occurred 25 months after wolves were released. Fourteen bison kills were documented from April 1995 through March 1999. All kills were made in late winter when bison were vulnerable because of poor condition or of bison that were injured or young. Wolves learned to kill bison and killed more bison where elk were absent or scarce. We predict that wolves that have learned to kill bison will kill them more regularly, at least in spring. The results of this study indicate how adaptable wolves are at killing prey species new to them.

Journal of Mammalogy↗