The effects of high ungulate densities on foraging choices by beaver (Castor canadensis) in the mixed-wood boreal forest

2008 ◽  
Vol 86 (6) ◽  
pp. 484-496 ◽  
Author(s):  
G. A. Hood ◽  
S. E. Bayley
Keyword(s):  
Woody Plants ◽  
National Park ◽  
Foraging Behaviour ◽  
Competitive Exclusion ◽  
Resource Competition ◽  
Castor Canadensis ◽  
Niche Overlap ◽  
Central Place ◽  
Complete Exclusion ◽  
Management Policies

In some areas of North America previous management policies have created competition between beaver ( Castor canadensis Kuhl, 1820) and ungulates, resulting in dramatic declines in beaver populations. Some authors attribute this decline to competitive exclusion. Generally, the less niche overlap between competitors, the lower potential competition between them. Differences between foraging behaviour of beaver and ungulates suggest that they could not compete to the point of either competitive exploitation or complete exclusion except in restricted habitats. We tested this assumption under two levels of foraging intensity by ungulates by examining the effects of resource competition on beaver forage choices in the context of central place foraging theory. Ungulate densities and foraging intensity within Elk Island National Park (EINP) in Alberta, Canada, were significantly higher than those immediately adjacent to the park, where foraging pressure was lower. Within EINP, forage availability (e.g., stem densities and stem diameters) of many woody plants preferred by beaver, such as Populus L. and Salix L., were depressed by intense foraging by ungulates. Beaver adapted to the effects of high ungulate densities on forage resources by adapting their foraging behaviour. This finding suggested that competitive exploitation, rather than exclusion, exists in EINP. EINP is a productive system that offers an array of forage species, which potentially buffers the effects of competition between ungulates and beaver.

An extensive study of the foraging ecology of beavers (Castor canadensis) in relation to habitat quality

2004 ◽  
Vol 82 (6) ◽  
pp. 922-933 ◽  
Author(s):  
D Gallant ◽  
C H Bérubé ◽  
E Tremblay ◽  
L Vasseur
Keyword(s):  
Habitat Quality ◽  
Foraging Behaviour ◽  
Foraging Ecology ◽  
Castor Canadensis ◽  
Central Place ◽  
Foraging Theory ◽  
Extensive Study ◽  
Food Items ◽  
Partial View ◽  
Selection Of

The objective of this study was to examine the foraging behaviour of the beaver (Castor canadensis Kuhl, 1820) and to explain its selection of terrestrial woody plant species according to central place foraging theory. Limitations in variety of food items in most studies with regard to size and (or) distance from the central place and information on availability of forage choices give a partial view of the subject. In this study, the theory is tested in a natural environment with high variability in food items with regard to these factors. Foraging choices by beavers were inspected by measuring variables on cut and uncut trees of every species encountered within 1 m of trail systems made by 25 beaver colonies in Kouchibouguac National Park in New Brunswick, Canada, thereby quantifying the availability of the different food items. The effect of habitat quality (food availability) on the foraging behaviour of beavers was also tested. The results of this study suggest that with increasing distance from the pond, beavers in high-quality habitats selected fewer, but larger, trees and are more species selective. This selectivity was diminished in habitats of lower quality. The results of this study are consistent with the predictions of the central foraging theory.

scholarly journals Central Place Foraging Characteristics of Beavers (Castor Canadensis) and Habitat Modeling in Grand Teton National Park

2013 ◽  
Vol 36 ◽  
pp. 18-27
Author(s):  
William Gribb ◽  
Henry Harlow
Keyword(s):  
National Park ◽  
Castor Canadensis ◽  
The United States ◽  
Central Place ◽  
Habitat Modeling ◽  
Central Place Foraging ◽  
Natural Landscape ◽  
Mountain Climbing ◽  
Park Service

A significant role of the National Park Service in the United States is the preservation of pristine landscapes. The natural landscape offers the visitor the opportunity to enjoy the wonders of nature and its processes to create beautiful vistas, soaring mountains, and the interplay of vegetation communities. The visitor to the park can be a passive recreationist and observe the landscape or be an active recreationist and experience the landscape through hiking, biking, mountain climbing and a range of other activities. The key linkage between the active and passive recreationist is the landscape that they are experiencing, in one perspective or the other. Any disruption of that natural landscape diminishes the experience. Unfortunately, the perception of the disruption varies with each individual. The trail to get to a scenic vista can be overlooked by some observers, while others believe it is an example of the devastation of human impact.

scholarly journals Multiple-stage decisions in a marine central-place forager

2016 ◽  
Vol 3 (5) ◽  
pp. 160043 ◽  
Author(s):  
Ari S. Friedlaender ◽  
David W. Johnston ◽  
Reny B. Tyson ◽  
Amanda Kaltenberg ◽  
Jeremy A. Goldbogen ◽  
...  
Keyword(s):  
Foraging Behaviour ◽  
Central Place ◽  
Foraging Efficiency ◽  
Feeding Rates ◽  
Marine Animals ◽  
Air Breathing ◽  
Baleen Whales ◽  
Multi Stage ◽  
Central Place Forager ◽  
Prey Patches

Air-breathing marine animals face a complex set of physical challenges associated with diving that affect the decisions of how to optimize feeding. Baleen whales (Mysticeti) have evolved bulk-filter feeding mechanisms to efficiently feed on dense prey patches. Baleen whales are central place foragers where oxygen at the surface represents the central place and depth acts as the distance to prey. Although hypothesized that baleen whales will target the densest prey patches anywhere in the water column, how depth and density interact to influence foraging behaviour is poorly understood. We used multi-sensor archival tags and active acoustics to quantify Antarctic humpback whale foraging behaviour relative to prey. Our analyses reveal multi-stage foraging decisions driven by both krill depth and density. During daylight hours when whales did not feed, krill were found in deep high-density patches. As krill migrated vertically into larger and less dense patches near the surface, whales began to forage. During foraging bouts, we found that feeding rates (number of feeding lunges per hour) were greatest when prey was shallowest, and feeding rates decreased with increasing dive depth. This strategy is consistent with previous models of how air-breathing diving animals optimize foraging efficiency. Thus, humpback whales forage mainly when prey is more broadly distributed and shallower, presumably to minimize diving and searching costs and to increase feeding rates overall and thus foraging efficiency. Using direct measurements of feeding behaviour from animal-borne tags and prey availability from echosounders, our study demonstrates a multi-stage foraging process in a central place forager that we suggest acts to optimize overall efficiency by maximizing net energy gain over time. These data reveal a previously unrecognized level of complexity in predator–prey interactions and underscores the need to simultaneously measure prey distribution in marine central place forager studies.

scholarly journals The impact of the provision of water for game on the woody vegetation around a dam in the Kruger National Park

Koedoe ◽  
1991 ◽  
Vol 34 (2) ◽  
Author(s):  
I. Thrash ◽  
P.J. Nel ◽  
G.K. Theron ◽  
J. Du P. Bothma
Keyword(s):  
Relative Density ◽  
Woody Plants ◽  
National Park ◽  
Dominant Species ◽  
Canopy Cover ◽  
Kruger National Park ◽  
Woody Vegetation ◽  
Colophospermum Mopane ◽  
The Impact ◽  
Combretum Apiculatum

Quantitative inventory surveys were done on the woody vegetation in permanently marked plots at distance intervals from the Wik-en-Weeg Dam, Kruger National Park, in 1973. The surveys were repeated in 1990 so that changes in the community composition, the density and the canopy cover and the survival of the woody vegetation could be determined in relation to distance from the dam. Relationships with distance from the dam were shown for the relative density ofCombretumapiculatum in all height classes, the relative canopy cover of the second height class of woody plants, the relative canopy cover of C. apiculatum plants, the survival of all height classes of woody plants and the survival of C. apiculatum and Colophospermum mopane plants. It was concluded that the provision of water for game at the Wik-en-Weeg Dam had an impact on the woody vegetation in the vicinity. The relationships of parameters of the two dominant species, Combretum apiculatum and Colophospermum mopane, with distance from the dam were compared. Combretum apiculatum parameters were more sensitive to impact associated with the dam than those of Colophospermum mopane.

scholarly journals Competition between sympatric wolf taxa: an example involving African and Ethiopian wolves

2018 ◽  
Vol 5 (5) ◽  
pp. 172207 ◽  
Author(s):  
Tariku Mekonnen Gutema ◽  
Anagaw Atickem ◽  
Afework Bekele ◽  
Claudio Sillero-Zubiri ◽  
Mohammed Kasso ◽  
...  
Keyword(s):  
Group Size ◽  
Competitive Exclusion ◽  
Niche Overlap ◽  
Rodent Species ◽  
Suitable Habitat ◽  
Range Contraction ◽  
Central Ethiopia ◽  
Disturbed Areas ◽  
Dominance Pattern ◽  
Prey Depletion

Carnivore populations are declining globally due to range contraction, persecution and prey depletion. One consequence of these patterns is increased range and niche overlap with other carnivores, and thus an elevated potential for competitive exclusion. Here, we document competition between an endangered canid, the Ethiopian wolf (EW), and the newly discovered African wolf (AW) in central Ethiopia. The diet of the ecological specialist EW was dominated by rodents, whereas the AW consumed a more diverse diet also including insects and non-rodent mammals. EWs used predominantly intact habitat, whereas AWs used mostly areas disturbed by humans and their livestock. We observed 82 encounters between the two species, of which 94% were agonistic. The outcomes of agonistic encounters followed a territory-specific dominance pattern, with EWs dominating in intact habitat and AWs in human-disturbed areas. For AWs, the likelihood of winning encounters also increased with group size. Rodent species consumed by EWs were also available in the human-disturbed areas, suggesting that these areas could be suitable habitat for EWs if AWs were not present. Increasing human encroachment not only affects the prey base of EWs, but also may impact their survival by intensifying competition with sympatric AWs.

POLYMORPHUS PARADOXUS SP. NOV. (ACANTHOCEPHALA) PARASITIZING BEAVERS AND MUSKRATS IN ALBERTA, CANADA

1957 ◽  
Vol 35 (4) ◽  
pp. 525-533 ◽  
Author(s):  
Robert Connell ◽  
A. H. Corner
Keyword(s):  
New Species ◽  
National Park ◽  
Castor Canadensis ◽  
Avian Host ◽  
Elk Island National Park ◽  
Relationship Of ◽  
A New Species

A new species of Acanthocephala, Polymorphus paradoxus, is described from beavers (Castor canadensis) and muskrats (Ondatra zibethica) from a lake in Elk Island National Park, Alberta. A species of amphipod in the lake was heavily infected with larval Acanthocephala, although the possible relationship of this infection to that in the beaver and muskrat has not yet been determined. While all other species of Polymorphus have been described from birds, a possible avian host of P. paradoxus has not yet been found.

Central Place Foraging by Beavers (Castor canadensis) in a Complex Lake Habitat

2009 ◽  
Vol 162 (1) ◽  
pp. 62-73 ◽  
Author(s):  
Thomas R. Raffel ◽  
Nicole Smith ◽  
Catherine Cortright ◽  
A John Gatz
Keyword(s):  
Castor Canadensis ◽  
Central Place ◽  
Central Place Foraging
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