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  • 1
    Electronic Resource
    Electronic Resource
    Ecological and genetic spatial structuring in the Canadian lynx (2003)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 425 (2003), S. 69-72 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The Canadian lynx, distributed all across the northern part of North America, is well known for its regular population cycles—cycles that have different underlying structures in different parts of Canada. Using both nuclear and mitochondrial DNA markers, we report here a close resemblance ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature01942
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The influence of snow on lynx and coyote movements: does morphology affect behavior? (1991)
    Springer
    Oecologia 88 (1991), S. 463-469 
    Details
    ISSN: 1432-1939
    Keywords: Lynx ; Coyote ; Snow ; Morphology ; Behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We studied sympatric lynx (Lynx canadensis) and coyotes (Canis latrans) to assess how morphological disadvantages to locomotion over snow affected movement patterns. Both species are of similar size and mass, but the feet of lynx are much larger, and coyotes were found to have 4.1–8.8 times the foot-load (ratio of body mass to foot area) of lynx. This resulted in greater mean sinking depths of coyote limbs, although the magnitude of the difference was less than that in foot-load. Coyotes exhibited stronger use of behavioral patterns that reduced negative effects of snow on movements. Coyotes were most abundant at low elevations where snow was shallow, whereas lynx were mostly at higher elevations. Coyotes also used areas at both elevations where snow was shallower than average, while lynx used areas where snow was deeper. further, both species used travel routes where snow was shallower than it was near the track. Coyotes traveled on harder snow and used trails more frequently, thereby tending to reduce sinking depths to those similar to lynx. The behavioral repertoire of coyotes reduced the morphological advantage of large feet possessed by lynx; however, overall sinking depths were still greater in coyotes. Snowshoe hares (Lepus americanus) were the main prey of both species, and their foot-load was less than that of either predator. Hare kills by coyotes occurred after fewer bounds than did those by lynx, and the large difference between foot-loads of both species of predators may have forced coyotes to ambush rather than chase hares, as did lynx.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317707
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of late winter food addition on numbers and movements of snowshoe hares (1984)
    Springer
    Oecologia 62 (1984), S. 393-400 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Peak (1980) and early decline (1981) populations of snowshoe hares were supplied with extra food in late winter to test the hypothesis that snowshoe hare populations are limited by food supply. Food supplemented populations increased through immigration in both years but the response was more pronounced in the early decline population. Animals supplied with extra food lost less weight, had higher survival in some cases, and males began to breed earlier. Immigrants to the food addition area were of two types: those that established home ranges on or near the area and those that spent only a brief time there before returning to their initial range. The possibility that these latter individuals were prevented from remaining on the food grid by residents is discussed. Results indicate that food supply is one factor that can limit peak and declining populations of snowshoe hares but the relation of spacing behaviour to food supply and numbers must also be considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384273
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  • 4
    Electronic Resource
    Electronic Resource
    A natural feeding experiment on a declining snowshoe hare population (1986)
    Springer
    Oecologia 70 (1986), S. 194-197 
    Details
    ISSN: 1432-1939
    Keywords: Snowshoe hare ; Food ; Population declines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A snowshoe hare (Lepus americanus) population on a 9-ha area was supplied with extra natural food by chopping down large white spruce (Picea glauca) and aspen (Populus tremuloides) trees throughout 3 winters from 1981 to 1984. Hares fed vigorously on the downed trees, but the phase of decline of the ten-year cycle occurred equally on control and experimental grids from 1981–1983, and we could detect no improvement in survival or reproduction on the food area. Growth rates were improved on the food grid during the first winter of the decline (1981–82). We concluded that food shortage is not necessary for the cyclic decline of snowshoe hares in the southern Yukon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379239
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  • 5
    Electronic Resource
    Electronic Resource
    Intensity of territorial defense in red squirrels: an experimental test of the asymmetric war of attrition (1990)
    Springer
    Behavioral ecology and sociobiology 27 (1990), S. 217-222 
    Details
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Red squirrels defend exclusive, individual territories year round, 20% to 50% of females do not breed in any given year, and breeding females raise juveniles on their territories. Breeding is asynchronous, and the offspring of early-breeding females are more likely to hold an independently won territory than are late-born offspring. Based on the asymmetric war of attrition, we made the following predictions: (1) squirrels would respond more intensely to the calls of unfamiliar individuals than to the calls of neighbors; (2) breeding females would respond more intensely to unknown calls than would non-breeding females or males; (3) early-breeding females would respond more intensely than would late-breeding females to unknown calls; and (4) all classes of squirrels would respond similarly to the calls of neighbors. Playback experiments supported the predictions. Alternative hypotheses of kin selection, risk of infanticide, and seasonal difference in intruder pressure could not explain the results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00180306
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  • 6
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    Saving endangered species using adaptive management (2019)
    National Academy of Sciences
    Details
    Publication Date: 2019-03-11
    Description: Adaptive management is a powerful means of learning about complex ecosystems, but is rarely used for recovering endangered species. Here, we demonstrate how it can benefit woodland caribou, which became the first large mammal extirpated from the contiguous United States in recent history. The continental scale of forest alteration and extended time needed for forest recovery means that relying only on habitat protection and restoration will likely fail. Therefore, population management is also needed as an emergency measure to avoid further extirpation. Reductions of predators and overabundant prey, translocations, and creating safe havens have been applied in a design covering 〉90,000 km2. Combinations of treatments that increased multiple vital rates produced the highest population growth. Moreover, the degree of ecosystem alteration did not influence this pattern. By coordinating recovery involving scientists, governments, and First Nations, treatments were applied across vast scales to benefit this iconic species.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 7
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    Empirical models of forest fire initial attack success probabilities: the effects of fuels, anthropogenic linear features, fire weather, and management (2006)
    Canadian Science Publishing
    Details
    Publication Date: 2006-12-01
    Description: Canadian fire managers seek to contain fires below some target size (here 3 ha) by initial attack (IA). Suppression failures occur when fire size at IA exceeds this target (a response failure) or if an initially small fire cannot be contained below it (a containment failure). We examined the effects of cause, season, forest fuels, anthropogenic linear features, weather, and fire management (response time, size at IA) on the probability of these two types of suppression failures, using multiple logistic regression on 1196 fires that occurred within the boreal mixedwood forest of northeastern Alberta during 1995–2002. The frequencies of containment (7%) and response failures (10%) were similar, but the latter accounted for 85% of the area burned. Response failure probability was greater for fires caused by lightning than those caused by humans and increased with longer response times, local abundance of black spruce in summer, and pine fuel under severe fire weather. We found no effect of linear features or other fuel types. Containment failure probability was related to size at IA and fire weather conditions. Our models suggest that a reduction in area burned might be possible if additional fire-specific factors affecting response failure probability could be incorporated into operational decisions.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 8
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    Potential effects of climate change on ecosystem distribution in Alberta (2009)
    Canadian Science Publishing
    Details
    Publication Date: 2009-05-01
    Description: We propose a new and relatively simple modification to extend the utility of bioclimatic envelope models for land-use planning and adaptation under climate change. In our approach, the trajectory of vegetation change is set by a bioclimatic envelope model, but the rate of transition is determined by a disturbance model. We used this new approach to explore potential changes in the distribution of ecosystems in Alberta, Canada, under alternative climate and disturbance scenarios. The disturbance model slowed the rate of ecosystem transition, relative to the raw projections of the bioclimatic envelope model. But even with these transition lags in place, a northward shift of grasslands into much of the existing parkland occurred over the 50 years of our simulation. There was also a conversion of 12%–21% of Alberta’s boreal region to parkland. In addition to aspatial projections, our simulations provide testable predictions about where ecosystem changes as a result of climate change are most likely to be initially observed. We also conducted an investigation of model uncertainty that provides an indication of the robustness of our findings and identifies fruitful avenues for future research.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 9
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    A visual index for estimating cone production for individual white spruce trees (2005)
    Canadian Science Publishing
    Details
    Publication Date: 2005-12-01
    Description: The number of cones produced by coniferous trees is commonly estimated by visual counts from the ground of a portion of the tree multiplied by a simple conversion factor. Linear conversion factors have been used to estimate total cone production by white spruce (Picea glauca (Moench) Voss). However, these conversion factors originate from other coniferous species and were often based on assumptions of cone visibility within the crown and not on empirical data. We propose a simple method for estimating the total number of cones produced by individual white spruce. We counted visible cones (an index of cone production, or cone index) on a total of 60 trees located in Alberta and Yukon, Canada, that were then felled and all cones were counted. We found that log(actual total cones) = 0.073 + 1.189 × log(cone index) is more accurate for estimating total cone numbers for white spruce than are other conversion factors (ranging from total cones = 1.5 × cone index to total cones = 3.35 × cone index), as determined using Akaike's information criterion with small sample bias adjustment and a validation data set. The relationship between the index of cone production and actual total cones produced is nonlinear, which is contrary to that proposed for various Pinus species.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 10
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    Interlinking hare and lynx dynamics using a century’s worth of annual data (2008)
    Springer
    Details
    Publication Date: 2008-04-29
    Print ISSN: 1438-3896
    Electronic ISSN: 1438-390X
    Topics: Biology
    Published by Springer
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