Mangy wolves suffer hefty calorie drain on cold, windy winter nights
Mar30

Mangy wolves suffer hefty calorie drain on cold, windy winter nights

An unwelcome dieting plan: severe mange infection could increase a wolf’s body heat loss by around 1240 to 2850 calories per night, which is roughly 60-80 percent of the average wolf’s daily caloric needs. During winter, wolves infected with mange can suffer a substantial amount of heat loss compared to those without the disease, according to a study by the U.S. Geological Survey and its partners, published as an Accepted Article (preprint release of the accepted manuscipt) yesterday in ESA’s journal Ecology. The lost calories equal about two to four extra pounds of elk meat per day, said lead author Paul Cross. “By definition, parasites drain energy from their hosts. In this study we estimated just one portion of the energetic costs of infection,” said Cross. “Even when parasites do not kill their hosts they are affecting the energy demands of their hosts, which could alter consumption rates, food web dynamics, predator-prey interactions and scavenger communities.” Sarcoptic mange, present in one of 10 known packs in Yellowstone as of 2015, is a skin disease caused by a mite that burrows into the skin, causing irritation and scratching that then leads to hair loss. In the early 1900s, the Montana state wildlife veterinarian introduced mange to the Northern Rockies  in an attempt to help eradicate local wolf and coyote populations. Using a remotely triggered thermal camera to capture vivid and colorful images, Cross and colleagues gathered body temperature data from mange-infected gray wolves in Yellowstone National Park and compared that to a sample group of healthy captive wolves with shaved patches of fur to simulate mange-induced hair loss. Using these data, they quantified the level of heat loss, or energetic costs, during the winter months. Read a summary of the research from the USGS or check out the research article: Cross, P., Almberg, E., Haase, C., Hudson, P., Maloney, S., Metz, M., Munn, A., Nugent, P., Putzeys, O., Stahler, D., Stewart, A. and Smith, D. (2016), Energetic costs of mange in wolves estimated from infrared thermography. Ecology. Accepted Author Manuscript. doi:10.1890/15-1346.1...

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Animal Jurisprudence

AFTER co-authoring a 2005 paper imagining “Re-wilding North America” with giant Bolson tortoises, camels, horses, cheetahs, elephants and lions, Harry Greene received a lot of hate mail. Corresponding ecologists hated the idea of deliberate transcontinental introductions of any kind.

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Seeing (less) red: Bark beetles and global warming

This post contributed by Jesse A. Logan, retired research entomologist living in Emigrant, Montana. The Greater Yellowstone Ecosystem (GYE) is an ecological reserve of regional, national and international significance. This collection of National Parks, National Forests, wildlife reserves and tribal lands is generally recognized as one of the last remaining large, nearly intact, ecosystems of the Earth’s northern temperate region. Climax whitebark pine (Pinus albicalus Engelman) forests comprise the majority of forested habitat above 2,750 meters and extend to the highest elevation as a crooked krumholtz growth form. By functioning as both a foundation and a keystone species, whitebark pine is an important ecological component of the GYE. Unfortunately, the foundation whitebark forests of the GYE are facing catastrophic collapse due to a combination of an introduced pathogen, unprecedented attack by a native bark beetle and climate change. Whitepine blister rust is a pathogen introduced near the turn of the past century, and its effect is to first compromise the reproductive capacity of the tree, eventually (requiring an average of twenty years in the GYE) leading to the tree’s death. On the other hand, attack by the native mountain pine beetle either immediately leads to the  tree’s deaths, or the tree successfully defends itself and repulses the attacking beetles. The seriousness of these threats to the integrity of high-elevation forests is indicated by the recent finding by the US Fish & Wildlife Service that whitebark meets the criteria for a threatened or endangered species; in addition, despite their risk of extinction, the FWS did not add whitebark to the endangered species list due to lack of sufficient funding. Under historic climate regimes, these high elevation forests were simply too cold for the mountain pine beetle (MPB) (Dendroctonus ponderosae) to thrive. Although, past MPB-caused whitebark pine mortality did occur during periods of unusually warm weather—for example, in the 1930s—these outbreaks were short-lived and limited in scale. With the publication of the first Interngovernmental Panel on Climate Change report in 1990, research on the potential for increased MPB activity in whitebark pine began to occur. Model predictions of high intensity MPB outbreaks began to be realized across the southern range of whitebark pine by the early 2000s. By 2005, USDA Forest Service Aerial Detection Survey (ADS) data showed significant MPB caused mortality across large areas of GYE whitebark pine. This mortality is first evident by large numbers of red trees (symptomatic of trees killed the previous summer), subsequently followed by vast areas of gray trees — the residual ghost forest — is shown in the photos above. In those photos of Hoyt Peak from Avalanche Peak near Sylvan Pass, Yellowstone National...

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Fear as an ecosystem engineer

This post contributed by Cristina Eisenberg, conservation biologist at Oregon State University Over the past three years I have conducted thirteen hundred focal animal observations on elk in the northern and southern Rocky Mountains. This involves patiently watching one animal at a time for up to twenty minutes and recording its wariness–that is, the amount of time it spends with its head down feeding versus head up, scanning for predators. Prey group size and a host of environmental factors can influence vigilance behavior. My research questions have to do with whether the vigilance of ungulates—such as elk, deer and other hooved animals— varies based on wolf population dynamics or other environmental factors that can influence predation risk. For example, would lone wolves passing through an area occasionally, but not denning there (as is the case with a returning wolf population in the Southern Rocky Mountains) have the same effect as several well-established packs using an area? Do terrain features such as downed wood, which may make it more difficult for an elk to escape a wolf, increase elk wariness? And could fear-based behavior vary by season, age and sex of the animals observed, herd size or human management of wolves? Termed the ecology of fear by ecologist Joel Brown, these predator-driven dynamics can have far-reaching effects on ecosystems via trophic cascades. Trophic cascades are the direct and indirect effects of an apex, or top, predator in a food web. In 1974 in the Aleutian archipelago, Jim Estes and his colleagues found that removing sea otters releases their primary prey, sea urchins, from predation. As sea urchins explode in number, they consume vegetation unsustainably, thereby reducing habitat for other species such as fish. The presence of a predator, such as the wolf, affects prey foraging behavior as prey try to balance the need to detect predators with meeting their  nutritional needs. These behavioral effects have been observed between spiders and their grasshopper prey by Oswald Schmitz and colleagues, as with sea urchins in terrestrial systems: Intensive browsing can lead to herbivores literally eating themselves out of house and home and, consequently, to a loss of biodiversity and ecosystem destabilization. Lacking apex predators to keep ungulates in check, ecosystems can support fewer species, such as birds and butterflies , because the plants that create habitats for these species have been over-browsed. Some predators and their prey naturally fluctuate in population size; this cycling can leave noticeable marks on the landscape. However, scientists are finding that these interactions are complex beyond the typical ebb and flow of predator and prey numbers. Assessing ungulates and large carnivores in the northern hemisphere, conservation biologist...

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Ecosystem snapshot: reassessing the role of wolves in Yellowstone

Yellowstone National Park is home to more than 1,350 species of vascular plants and numerous species of mammals, amphibians, reptiles and birds—not to mention the natural landmarks such as Old Faithful Geyser. Among the inhabitants of Yellowstone is the famous quaking aspen, a deciduous tree that has significantly declined in the park since the 20th Century, due in large part to elk grazing.

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