Scasta J.D.,University of Wyoming |
Duchardt C.,University of Wyoming |
Duchardt C.,Urbana University |
Engle D.M.,Oklahoma State University |
And 3 more authors.
Ecological Engineering | Year: 2016
Extirpation of the ecosystem engineer (bison) and its interaction with fire, coupled with the utilitarian concept of moderate grazing, have contributed to homogenization of grassland habitat in North America. Although cattle may serve as a proxy for bison, combining fire with cattle grazing has been uncommon and to date managers have not always successfully applied cattle and controlled burns as tools to manipulate grassland vegetation heterogeneity and increase habitat diversity. Using an information-theoretic approach, we assessed factors constraining the fire-grazing interaction ecological process to engineer habitat structure of grasslands via patch-burn grazing. We assessed how grazing, fire, and biotic and abiotic features in tallgrass prairie influenced establishment and maintenance of low vegetative structure in burned patches, the positive feedback driving the fire-grazing interaction, and subsequent structural heterogeneity across a pasture. Four pastures were divided into three patches with a different patch burned annually in March/April from 2007 to 2013. Cattle were stocked from light to heavy (1.1–4.4 AUM/ha) from May to October (∼150 days) with access to the entire pasture. We hypothesized that the exotic C3 grass tall fescue (Schedonorus arundinaceus), lag-time between burning date and the date cattle were put into experimental pastures, and burn date would be the constraining factors. However, the most informative model included stocking rate, date of burn completion, and precipitation. The lightest cattle stocking rate did not establish low vegetative structure in the burn patch, which resulted in the lowest heterogeneity among patches. The heaviest cattle stocking rate established but did not maintain low vegetative structure in the burn patch. The intermediate cattle stocking rate maintained the lowest vegetative structure in the burn patch and the greatest heterogeneity among patches, i.e., the best efficacy of patch-burn grazing to engineer habitat structural heterogeneity. The relationships of stocking rate to burn patch vegetative structure and to landscape heterogeneity were both quadratic and were both optimized at intermediate stocking rate. © 2016 Elsevier B.V.
Datta-Roy A.,Indian Institute of Science |
Mohapatra P.P.,Wildlife Biologist |
Dutta S.K.,Indian Institute of Science |
Giri V.B.,Bombay Natural History Society |
And 6 more authors.
Zootaxa | Year: 2013
Sepsophis punctatus Beddome 1870, the only species of a monotypic genus, was described based on a single specimen from the Eastern Ghats of India. We rediscovered the species based on specimens from Odisha and Andhra Pradesh state, India, after a gap of 137 years, including four specimens from close to the type locality. The holotype was studied in detail, and we present additional morphological characters of the species with details on natural history, habitat and diet. The morphological characters of the holotype along with two additional specimens collected by Beddome are compared with the specimens collected by us. We also briefly discuss the distribution of other members of the subfamily Scincinae and their evolutionary affinities.
Camp M.J.,University of Idaho |
Camp M.J.,Washington State University |
Rachlow J.L.,University of Idaho |
Shipley L.A.,Washington State University |
And 2 more authors.
Rangeland Journal | Year: 2014
Livestock grazing is one of the primary uses of sagebrush rangelands in western North America; therefore, an understanding of the ecological implications of grazing on habitat quality for sagebrush-dependent wildlife is needed to help land managers balance multiple objectives for land use. We studied effects of cattle grazing on components of habitat for an uncommon sagebrush habitat specialist, the pygmy rabbit (Brachylagus idahoensis), which has been petitioned for endangered or threatened status in the USA. We evaluated multiple components of habitat before and after grazing in replicated control and treatment plots in a mesic, high-elevation sagebrush-steppe environment in south-western Montana, USA. We predicted that grazing would decrease the biomass of herbaceous forage, alter security cover, and increase rate of collapse of rabbit burrows, and we expected that these effects would be more pronounced during summer than spring. As expected, cattle grazing reduced the biomass of perennial grasses available to pygmy rabbits after grazing that occurred during either spring or summer, and the biomass of forbs after spring grazing. In contrast, grazing did not markedly influence the functional properties of vegetation related to predation risk or the integrity of rabbit burrow systems. In the context of the stocking rate of the allotments in our study (7.3 acres/Animal Unit Month, 2.95ha/Animal Unit Month), annual cattle grazing did not seem to markedly change habitat for pygmy rabbits in our study area; however, longer-term and higher intensity grazing might result in more pronounced habitat changes. Understanding the ecological implications of cattle grazing on habitat quality for pygmy rabbits and other sagebrush-dependent wildlife can guide conservation strategies for these species on sagebrush rangelands managed under multiple-use policies. © Australian Rangeland Society 2014.
News Article | March 8, 2016
Before the arrival of European settlers with their hunting, forest clearing and timber extraction, flocks of hundreds of wild turkeys could be found throughout North America. By the start of the twentieth century, they were on the brink of extinction. Through conservation and reintroduction efforts, however, they recovered and today, although not quite as many as the ten million estimated during the 1600s, they number about six million and are resident in every state except Alaska. While this proliferation has been deemed a great conservation story by many—maybe even the greatest wildlife conservation success of the last century—there is considerable debate surrounding the introduction of wild turkeys into California and their place in its landscape. Despite the quarter million or more now making themselves at home in the golden state, this specific species—Meleagris gallopavo (comprising four distinct subspecies and their hybrids with the Rio Grande subspecies being the most widespread)—is not considered native to California. Some 10,000–12,000 years ago, another smaller species with different morphological characteristics, the extinct Meleagris californica, did exist in southern California as evidenced by the more than 11,100 bones from at least 791 different birds found in the Rancho La Brea Tar Pits in Los Angeles. In fact, the second most abundant fossils in the Tar Pits belong to . Exactly why —originally described as a peacock—became extinct thousands of years ago in California is not known but it has been suggested that decreasing rainfall led to a loss of essential vegetation. As part of a major state-sponsored recreational hunting program, the California Fish and Game Commission introduced thousands of farm-raised turkeys into the wild from the early 1900s through the 1950s. In spite of these introductions, the population remained flat, probably because these turkeys lacked the skills to survive in the wild. From 1959 through 1999, however, the Commission, now the California Department of Fish and Wildlife, imported and released thousands of live-trapped wild turkeys (mostly of the Rio Grande subspecies from Texas) at over 200 locations, and these had no problem adapting to the California environment. Their population rapidly increased and their territory expanded throughout the state.Today, descendants of these turkeys occupy over 29,000 square miles of California—about one quarter of the state. They can make a living almost anywhere: agricultural fields and orchards, golf courses, university campuses, residential areas, urban sidewalks, freeway entrances and exits, and state and national parks to name just a few. While most of the media coverage focuses on complaints from urban and suburban residents being harassed by rafts of invading turkeys, there may be a more critical issue at stake and important questions that need to be answered: Are they causing damage to the environment and decreasing biodiversity? According to Christina Donehower, an environmental scientist at the Natural Resources Division, California Department of Parks and Recreation, much of the long-term data needed to reliably answer these questions and guide management actions is lacking. Donehower explains, “It is very likely that wild turkeys are affecting the ecological communities that they have come to inhabit in California. However, at this time, State Parks has limited capacity to devote to the monitoring and management of turkeys.” And so far, she says turkeys in California have received relatively little attention from the scientific community. Daniel Ryan, the Invasive Wildlife Biologist at Pinnacles National Park, agrees with Donehower. Ryan maintains “we need far more good scientific research on this species and the effects it has had since being dropped into the state. We need concrete answers and we don’t have the time or money to find out." Scott Gardner, a senior environmental scientist for the California Department of Fish and Wildlife echoes these views. He says “it is obvious that the turkeys are here to stay and that long-term scientific studies are needed.” These pleas are nothing new. Concerns about the turkey’s potential impact on the native flora and fauna were being raised by both government agencies and the public in the early 1990’s. In 2007, the California State Department of Parks and Recreation identified three potential negative environmental impacts of turkeys as being of immediate importance: their consumption of endangered reptiles and amphibians, their competition with ground-dwelling birds for resources and their contribution to the spread of a tree disease called sudden oak death. Also in 2007, the Laguna Santa Rosa Watershed suggested that the effects of the wild turkeys on oak recruitment, soil disturbance, and damage to sensitive native species should be investigated. To date, none of these concerns have been addressed in any long-term, comprehensive study. A short-term study conducted at one of Audubon Canyon Ranch’s Sonoma County preserves by Daniel Gluesenkamp in 2001, showed that “turkeys ate a broad variety of plants and animals and caused a tenfold increase in soil disturbance as well as a decrease in terrestrial invertebrates, herbivores, and decomposers fundamental to an ecosystem.” In 2005, Reginald Barrett, a UC Berkeley retired professor emeritus of wildlife ecology and management, conducted another short-term study on the feeding habits and behavior of wild turkeys inhabiting Annadel State Park. He found no evidence of them spreading sudden oak death, eating endangered and/or vulnerable plants, insects or eggs, or causing harm to their surroundings, e.g. through rooting up soils or damaging vegetation. In 2007, during another short-term study, Angela Gillingham found that turkeys were coexisting with quails within the same macrohabitat types without significant detrimental effects on either species. Gillingham felt that, while there was a great deal of dietary overlap, since both species have such diverse feeding preferences, barring any extraordinary environmental disasters or dramatic changes in population numbers or resource and/or habitat availability, it is unlikely that turkeys will come to monopolize available food sources. The results from these short-term studies have created controversy. The California Native Plant Society, an organization dedicated to protecting and preserving California's native plant heritage for future generations, feels that “while little is known about the impact turkeys are having, the data available indicate that the populations are too large, are in areas where they shouldn’t be and that they are affecting the environment by disturbing habitat, and eating a broad variety of native plants and animals”. On the other hand, The National Wild Turkey Federation, whose mission is “the conservation of the wild turkey and the preservation of the nation’s hunting heritage,” insists that there is much evidence that the birds are important both socially and economically, and no evidence that they are having a detrimental effect on the habitat or on any endangered species. As pointed out by the California Department of Fish and Game, however, such effects may be too subtle and too difficult to detect in the short term. When the California Department of Fish and Game began releasing turkeys into the wild, they thought the program would result in economical and recreational benefits. Unfortunately they could not foresee the ensuing problems. Gardner says that while “the original turkey introductions weren’t an environmental concern at the time, because of their overabundance in some areas and geographic spread and our current environmental concerns—especially drought— with hindsight the department might have made a different choice about introducing them.” According to Barrett and Gardner the turkey population is not now out of control or of major immediate concern for the environment. Overpopulation and increasing limited resources, however, could increase those concerns and turkeys could start to out-compete native birds for food resources. This is especially true since wild turkeys are “generalist feeders, and will eat animal matter, vegetable matter, you name it," said Barrett. So, is there a wild turkey crisis in California? Are they creating ecological problems now? Will they in the future? Possibly. Possibly not. According to Ryan, “Perhaps it will be necessary to pull out all the stops to halt their range expansion or maybe they will settle into a very normal niche in their regional environments. Turkeys, like many other introduced or reintroduced species, will probably continue to be a contentious subject in California as their population and range expand and they become more noticeable in the lives of Californians”. Perhaps then, more detailed studies will provide much-needed answers. If so, the only question left might well be whether or not the answers have come too late.