Fincel M.J.,South Dakota Game |
James D.A.,U.S. Fish and Wildlife Service |
Chipps S.R.,U.S. Geological Survey |
Davis B.A.,West Virginia University
Journal of Freshwater Ecology | Year: 2014
Diet studies have traditionally been used to determine prey use and food web dynamics, while stable isotope analysis provides for a time-integrated approach to evaluate food web dynamics and characterize energy flow in aquatic systems. Direct comparison of the two techniques is rare and difficult to conduct in large, species rich systems. We compared changes in walleye Sander vitreus trophic position (TP) derived from paired diet content and stable isotope analysis. Individual diet-derived TP estimates were dissimilar to stable isotope-derived TP estimates. However, cumulative diet-derived TP estimates integrated from May 2001 to May 2002 corresponded to May 2002 isotope-derived estimates of TP. Average walleye TP estimates from the spring season appear representative of feeding throughout the entire previous year. © 2014 Taylor & Francis.
Gigliotti L.M.,South Dakota Game
Human Dimensions of Wildlife | Year: 2011
The benefits of Internet-based surveys are often exaggerated with claims that Internet surveys are always faster, better, cheaper, and easier for researchers than conventional survey methods. This case study compares two side-by-side surveys of South Dakota resident spring turkey hunters (traditional mail survey vs. by e-mail with link to the Web-based survey: sample size of 1,200 each). With approximate equal effort to contact hunters the Internet survey received a 44% return rate compared to a 75% return rate from the mail survey. Until the issue of sample validity is solved and response rates increased an Internet survey by itself cannot be relied on to collect valid, scientific human dimensions information. However, a mixed-mode survey design that incorporates Internet surveys with traditional survey methods is discussed as a way to solve for sample validity and non-response methodological issues associated with Internet surveys while achieving some of the cost saving benefits of Internet surveys. © Taylor & Francis Group, LLC.
Cook R.C.,National Council for Air and Stream Improvement Inc. |
Cook J.G.,National Council for Air and Stream Improvement Inc. |
Vales D.J.,Muckleshoot Indian Tribe |
Johnson B.K.,401 Gekeler Lane |
And 15 more authors.
Wildlife Monographs | Year: 2013
Demographic data show many populations of Rocky Mountain (Cervus elaphus nelsoni) and Roosevelt (Cervus elaphus roosevelti) elk have been declining over the last few decades. Recent work suggests that forage quality and associated animal nutritional condition, particularly in late summer and early autumn, influence reproduction and survival in elk. Therefore, we estimated seasonal nutritional condition of 861 female elk in 2,114 capture events from 21 herds in Washington, Oregon, Wyoming, Colorado, and South Dakota from 1998 to 2007. We estimated ingesta-free body fat and body mass, and determined age, pregnancy status, and lactation status. We obtained estimates for most herds in both late winter-early spring (late Feb-early Apr) and in autumn (Nov-early Dec) to identify changes in nutritional condition of individuals across seasons. Body fat levels of lactating females in autumn were consistently lower than their non-lactating counterparts, and herd averages of lactating elk ranged from 5.5% to 12.4%. These levels were 30-75% of those documented for captive lactating elk fed high-quality diets during summer and autumn. Body fat levels were generally lowest in the coastal and inland northwest regions and highest along the west-slope of the northern Cascades. Adult females in most herds lost an average of 30.7 kg (range: 5-62 kg), or about 13% (range: 2.6-25%) of their autumn mass during winter, indicating nutritional deficiencies. However, we found no significant relationships between spring body fat or change in body fat over winter with winter weather, region, or herd, despite markedly different winter weather among herds and regions. Instead, body fat levels in spring were primarily a function of fat levels the previous autumn. Thinner females in autumn lost less body fat and body mass over winter than did fatter females, a compensatory response, but still ended the season with less body fat than the fatter elk. Body fat levels of lactating females in autumn varied among herds but were unrelated to their body fat levels the previous spring. Within herds, thinner females exhibited a compensatory response during summer and accrued more fat than their fatter counterparts over summer, resulting in similar body fat levels among lactating elk in autumn despite considerable differences in their fat levels the previous spring. Level of body fat achieved by lactating females in autumn varied 2-fold among herds, undoubtedly because of differences in summer nutrition. Thus, summer nutrition set limits to rates of body fat accrual of lactating females that in turn limited body condition across the annual cycle. Pregnancy rates of 2- to 14-year-old females ranged from 68% to 100% in coastal populations of Washington, 69% to 98% in Cascade populations of Washington and Oregon, 84% to 94% in inland northwestern populations of Washington and Oregon, and 78% to 93% in Rocky Mountain populations. We found evidence of late breeding, even in herds with comparatively high pregnancy rates. Mean body mass of calves (n = 242) in 3 populations was 75 kg, 81 kg, and 97 kg, representing 55-70% of potential mass for 6- to 8-month-old calves on high-quality diets. Mean mass of 11 yearling females caught in autumn was 162 kg, approximately 70% of potential for autumn, and pregnancy rate was 27%. Mean mass of 28 yearlings caught in spring was 163 kg and pregnancy rate was 34%. Our data suggest widespread occurrence of inadequate summer nutrition. Summer ranges of just 3 herds supported relatively high levels of autumn body fat (11-13% body fat) and pregnancy rates (>90%) even among females that successfully raised a calf year after year. Most other summer ranges supported relatively low autumn levels of body fat (5-9% body fat), and reproductive pauses were common (<80% pregnancy rates). Overall, our data failed to support 2 common assumptions: 1) summer and early autumn foraging conditions are typically satisfactory to prevent nutritional limitations to adult fat accretion, pregnancy rates, and calf and yearling growth; and 2) winter nutrition and winter weather are the principal limiting effects on elk productivity. Instead, a strong interaction existed among level of summer nutrition, lactation status, and probability of breeding that was little affected by winter conditions - adequacy of summer nutrition dictated reproductive performance of female elk and growth as well as growth and development of their offspring in the Northwest and Rocky Mountains. Our work signals the need for greater emphasis on summer habitats in land management planning on behalf of elk. © 2013 The Wildlife Society.
Lehman C.P.,South Dakota Game |
Rumble M.A.,Us Forest Servicerocky Mountain Research Station8221 South Highway 16Rapid City |
Bird B.J.,U S WEST |
Fogarty D.T.,South Dakota Game
Journal of Wildlife Management | Year: 2015
We studied elk (Cervus canadensis nelsoni) parturition sites at coarse (314-km2 and 7-km2) and fine (0.2-ha) scales in the Black Hills, South Dakota, 2011-2013, following a period of population decline and poor calf recruitment. Our objective was to test whether female elk selected parturition sites across spatial scales in association with forage, terrain ruggedness, road density, or hiding and security cover. At coarse scales in forests and grasslands, female elk selected sites in areas with greater proportions of vegetation communities that provided forage (56-74% of area) and more rugged topography (194-248m) than found at random. At coarse scales in grasslands, elk selected sites in areas with lower road densities (≤1.24km/plot). At the fine scale in forests and grasslands, female elk selected sites in areas with intermediate slope (19%), closer to water (355-610m), and far from roads (541-791m). Further, elk in forests and grasslands selected sites with intermediate security cover (50-88m). We hypothesize elk selected for intermediate rugged terrain at larger scales for security from high road densities and human disturbance, but these areas may have placed elk in riskier environments for puma (Puma concolor) predation. Forest management that maintains open-canopied vegetation communities in less rugged areas and prevents ponderosa pine (Pinus ponderosa) encroachment of meadows to provide forage may be beneficial for elk. Further, elk parturition sites occurred close to roads, particularly on public lands, and agencies should consider road-use restrictions and vegetation buffers beside roads in areas with less rugged terrain, which may provide favorable calving habitat. © The Wildlife Society, 2015.
Wipf M.M.,South Dakota Game |
Barnes M.E.,South Dakota Game
North American Journal of Aquaculture | Year: 2012
The Lake Oahe, South Dakota, population of landlocked fall-run Chinook salmon Oncorhynchus tshawytscha is maintained entirely by hatchery propagation and exhibits relatively poor egg survival during hatchery incubation. This study was undertaken to determine the influence of male gametes on embryo survival. Eggs from an individual female were subdivided and subsequently fertilized with milt from four discrete males. This was repeated with three additional females using the milt from the same four males. This entire procedure was then replicated three times, using four new females and four new males each time, for a total of 16 males and 16 females. The eggs from each unique cross were then incubated discretely. There was no significant effect of spawning males on subsequent embryo survival to the eyed stage of egg development. Swim-up fry length and weight were also not significantly affected by male parentage. In contrast, there was a significant maternal effect on eyed egg survival, and swim-up fry length and weight, which varied significantly among progeny from individual females. These results suggest that the relatively poor survival exhibited by Lake Oahe landlocked fall Chinook salmon eggs during hatchery incubation is largely a function of initial egg quality from spawning females. © 2012 American Fisheries Society.