Yellowstone wolves take a blow to their rep
Mar11

Yellowstone wolves take a blow to their rep

A well-publicized depiction of wolves revitalizing Yellowstone’s ecosystem is a myth, said writers for the NY Times’ op-ed page and a Nature news feature last week.

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Declining fortunes of Yellowstone’s migratory elk
Jun26

Declining fortunes of Yellowstone’s migratory elk

Are human choices redefining the fitness of an ancient survival strategy?

Eighteen ecologists weigh in on new data in a Forum in Ecology.

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Elk bones tell stories of life, death, and habitat use at Yellowstone National Park
Dec10

Elk bones tell stories of life, death, and habitat use at Yellowstone National Park

Josh Miller is one among a small cadre of ecologists looking at living ecosystems through the relics of their dead. by Liza Lester, ESA communications officer Flags mark bone locations as field assistant Jared Singer maps a carcass near a lake in Yellowstone National Park. Credit, Joshua Miller. ________________ JOSH Miller likes to call himself a conservation paleobiologist. It’s a label that makes sense when he explains how he uses bones as up-to-last-season information on living animal populations. “At parties I used to say, well—I’m a paleontologist; I study modern ecosystems,” Miller said. That sounded counterintuitive, so he needed a new designation, hence the conservation angle. “There are quite a few of us taking up that mantle, people passionately looking at bones—mostly in marine environments. People have done a lot with shells.” Bones, he says, are evidence of which animals lived where, and in what relative numbers. They provide baseline ecological data on range animals complementary to aerial counts, adding an historical component to live observation. In his November research report in Ecology, he assesses the habitat use of elk in Yellowstone National Park by their bones and antlers, testing his method against several decades of the Park Service’s meticulous observations. Miller came to ecology via paleontology. Now an assistant research professor in the new Quaternary and Anthropocene Research Group in the Department of Geology at the University of Cincinnati, he located and recorded the elk bone data while a doctoral student in evolutionary biology at the University of Chicago and finished analyzing the data during a brief stint at the Florida Museum of Natural History at the University of Florida, in Gainesville. His work with modern animals started as an inquiry into the fidelity of bone remains to the living ecosystems of the past. He wanted to know how faithfully the fossil record archived historical populations, variability, and change—if digging up 72 Triceratops and 44 Tyrannosaurus conjured up something real about the relative numbers of the dinosaurs when they were alive, and the ecosystem  they lived in so many millions of years ago. “Do those data mean anything, or is it just some random, biased grab bag?” he wondered. He started looking at modern, living species that could help answer the question by experiment, going out with a team of helpers among the bison, elk, and deer on the vast rolling grasslands and forests of Yellowstone’s northern range for three summers, to catalog the remains of elk of years past, They zig-zagged down huge, kilometer long sample plots looking for bones, antlers, scat—anything with a bone in it. “It turns out that bones are really informative,” he said....

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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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