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

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.

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Foraging behaviour in tammar (Macropus eugenii) and parma (Macropus parma) wallabies

Australian Journal of Zoology ◽

10.1071/zo02041 ◽

2003 ◽

Vol 51 (3) ◽

pp. 297

Author(s):

R. G. Lentle ◽

S. Haslett ◽

I. D. Hume ◽

K. J. Stafford ◽

M. Kennedy ◽

...

Keyword(s):

Predator Avoidance ◽

Foraging Behaviour ◽

Search Time ◽

Macropus Eugenii ◽

Food Items ◽

Significant Difference ◽

Different Dimensions ◽

Selection Of

Captive parma and tammar wallabies, when offered ryegrass sward in plots, visited ungrazed plots more frequently and spent longer grazing on them than on plots that were previously grazed but not visibly depleted. There was no significant difference between the two species with respect to the pattern of time spent grazing between plots, but parma wallabies tended to visit ungrazed plots more frequently than tammar wallabies. When offered carrot pieces of different dimensions both species preferred carrot pieces of greater mass, regardless of shape. Both species favoured eating in the upright (bipedal) position despite the fact that the use of this position prolonged search time between bites. Although the two species are able to forage optimally when grazing, the greater efficiency of the bipedal posture in predator avoidance may result in the selection of larger food items whenever possible.

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

Canadian Journal of Zoology ◽

10.1139/z08-029 ◽

2008 ◽

Vol 86 (6) ◽

pp. 484-496 ◽

Cited By ~ 16

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.

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Neither large nor small: intermediate-sized food items for the cubs of the Patagonian gray fox (Pseudoalopex griseus)

Canadian Journal of Zoology ◽

10.1139/z98-161 ◽

1998 ◽

Vol 76 (12) ◽

pp. 2281-2284 ◽

Cited By ~ 8

Author(s):

Sonia C Zapata ◽

Alejandro Travaini ◽

Miguel Delibes

Keyword(s):

Central Place ◽

Foraging Theory ◽

Central Place Foraging ◽

Fecal Samples ◽

Gray Fox ◽

Food Items

According to central place foraging theory, adult Patagonian gray foxes (Pseudoalopex griseus) behaving efficiently should consume on the spot those food items too large to be carried and those too small to warrant being carried to the den. Consequently, fox cubs should be provisioned with intermediate-sized items. We tested this prediction by analyzing 96 fecal samples from adult foxes and 82 fecal samples from cubs belonging to three different dens collected near Junín de los Andes in the province of Neuquén, Argentina, from November 1994 to January 1995. As predicted, adult foxes consumed carrion of large ungulates (large items) and arthropods and berries (small items) significantly more often than cubs did. Cubs ate more intermediate-sized vertebrates, from lizards and birds to rodents and hares. Medium-sized armadillos, which are difficult to handle and transport, were consumed only by adults. Cubs ate some insects, which were probably captured by the cubs themselves near the den.

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Linking time budgets to habitat quality suggests that beavers (Castor canadensis) are energy maximizers

Canadian Journal of Zoology ◽

10.1139/cjz-2016-0016 ◽

2016 ◽

Vol 94 (10) ◽

pp. 671-676 ◽

Cited By ~ 3

Author(s):

Daniel Gallant ◽

Lisa Léger ◽

Éric Tremblay ◽

Dominique Berteaux ◽

Nicolas Lecomte ◽

...

Keyword(s):

Habitat Quality ◽

Time Budget ◽

Castor Canadensis ◽

Optimal Foraging Theory ◽

Foraging Theory ◽

Limiting Factors ◽

Future Research ◽

Net Energy ◽

Net Energy Intake ◽

Infrastructure Maintenance

According to optimal foraging theory, consumers make choices that maximize their net energy intake per unit of time. We used foraging theory as a framework to understand the foraging behaviour of North American beavers (Castor canadensis Kuhl, 1820), an important herbivore that engineers new habitats. We tested the hypothesis that beavers are energy maximizers by verifying the prediction that they allocate time to foraging activities independently of habitat quality in Kouchibouguac National Park of Canada in New Brunswick, where nearly five decades of unabated colonization by beavers led to family units established in habitats of varying quality. We observed the behaviour of 27 beavers at seven ponds from May to August 2001, at dusk and dawn. Habitat quality did not influence time that beavers allocated to foraging. This finding supported our hypothesis. The only factor in the best model explaining time spent foraging was the progression of spring and summer seasons (weekly periods). Limiting factors such as infrastructure maintenance and intermittent reactions to danger remain poorly understood for this important herbivore. Future research should focus on establishing the importance that habitat quality (food availability) and environmental stress (weather, predators) have on shaping its time budget and, consequently, its survival and reproductive success.

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Tree Swallow selection for wetlands in agricultural landscapes predicted by central-place foraging theory

The Condor ◽

10.1093/condor/duaa039 ◽

2020 ◽

Author(s):

Andrew S Elgin ◽

Robert G Clark ◽

Christy A Morrissey

Keyword(s):

Habitat Selection ◽

Central Place ◽

Foraging Theory ◽

Agricultural Landscapes ◽

Tree Swallow ◽

Field Margins ◽

Central Place Foraging ◽

Prairie Pothole ◽

Prairie Wetlands ◽

Selection For

Abstract Millions of wetland basins, embedded in croplands and grasslands, are biodiversity hotspots in North America’s Prairie Pothole Region, but prairie wetlands continue to be degraded and drained, primarily for agricultural activities. Aerial insectivorous swallows are known to forage over water, but it is unclear whether swallows exhibit greater selection for wetlands relative to other habitats in croplands and grasslands. Central-place foraging theory suggests that habitat selectivity should increase with traveling distance from a central place, such that foragers compensate for traveling costs by selecting more profitable foraging habitat. Using global positioning system (GPS) tags, we evaluated habitat selection by female Tree Swallows (Tachycineta bicolor) at 4 sites containing wetlands and where terrestrial land cover was dominated by grasslands (grass, herbaceous cover) and/or cultivated cropland. We also used sweep-net transects to assess the abundance and biomass of flying insects in different habitats available to swallows (wetland pond margins, grassy field margins, and representative uplands). As expected for a central-place forager, GPS-tagged swallows selected more for wetland ponds (disproportionate to availability), and appeared to increasingly select for wetlands with increasing distance from their nests. On cropland-dominated sites, insect abundance and biomass tended to be higher in pond margins or grassy field margins compared to cropped uplands, while abundance and biomass were more uniform among sampled habitats at sites dominated by grass and herbaceous cover. Swallow habitat selection was not clearly explained by the distribution of sampled insects among habitats; however, traditional terrestrial sampling methods may not adequately reflect prey distribution and availability to aerially foraging swallows. Overall, our results underscore the importance of protecting and enhancing prairie wetlands and other non-crop habitats in agricultural landscapes, given their disproportionate use and capacity to support breeding swallow and insect populations.

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Optimising the selection of food items for FFQs using Mixed Integer Linear Programming

Public Health Nutrition ◽

10.1017/s1368980013003479 ◽

2014 ◽

Vol 18 (1) ◽

pp. 68-74 ◽

Cited By ~ 9

Author(s):

Johanna C Gerdessen ◽

Olga W Souverein ◽

Pieter van ‘t Veer ◽

Jeanne HM de Vries

Keyword(s):

Linear Programming ◽

Integer Linear Programming ◽

Mixed Integer Linear Programming ◽

Selection Process ◽

Saturated Fat ◽

Mixed Integer ◽

Monounsaturated Fat ◽

Food Items ◽

Milp Model ◽

Selection Of

AbstractObjectiveTo support the selection of food items for FFQs in such a way that the amount of information on all relevant nutrients is maximised while the food list is as short as possible.DesignSelection of the most informative food items to be included in FFQs was modelled as a Mixed Integer Linear Programming (MILP) model. The methodology was demonstrated for an FFQ with interest in energy, total protein, total fat, saturated fat, monounsaturated fat, polyunsaturated fat, total carbohydrates, mono- and disaccharides, dietary fibre and potassium.ResultsThe food lists generated by the MILP model have good performance in terms of length, coverage and R2 (explained variance) of all nutrients. MILP-generated food lists were 32–40 % shorter than a benchmark food list, whereas their quality in terms of R2 was similar to that of the benchmark.ConclusionsThe results suggest that the MILP model makes the selection process faster, more standardised and transparent, and is especially helpful in coping with multiple nutrients. The complexity of the method does not increase with increasing number of nutrients. The generated food lists appear either shorter or provide more information than a food list generated without the MILP model.

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Untangling the environmental from the dietary: dust does not matter

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2016.1032 ◽

2016 ◽

Vol 283 (1838) ◽

pp. 20161032 ◽

Cited By ~ 59

Author(s):

Gildas Merceron ◽

Anusha Ramdarshan ◽

Cécile Blondel ◽

Jean-Renaud Boisserie ◽

Noël Brunetiere ◽

...

Keyword(s):

Critical Role ◽

Tooth Wear ◽

Textural Analysis ◽

Significant Determinant ◽

Intrinsic Properties ◽

Dental Microwear ◽

Natural Conditions ◽

Evolutionary Mechanisms ◽

Food Items ◽

Selection Of

Both dust and silica phytoliths have been shown to contribute to reducing tooth volume during chewing. However, the way and the extent to which they individually contribute to tooth wear in natural conditions is unknown. There is still debate as to whether dental microwear represents a dietary or an environmental signal, with far-reaching implications on evolutionary mechanisms that promote dental phenotypes, such as molar hypsodonty in ruminants, molar lengthening in suids or enamel thickening in human ancestors. By combining controlled-food trials simulating natural conditions and dental microwear textural analysis on sheep, we show that the presence of dust on food items does not overwhelm the dietary signal. Our dataset explores variations in dental microwear textures between ewes fed on dust-free and dust-laden grass or browse fodders. Browsing diets with a dust supplement simulating Harmattan windswept environments contain more silica than dust-free grazing diets. Yet browsers given a dust supplement differ from dust-free grazers. Regardless of the presence or the absence of dust, sheep with different diets yield significantly different dental microwear textures. Dust appears a less significant determinant of dental microwear signatures than the intrinsic properties of ingested foods, implying that diet plays a critical role in driving the natural selection of dental innovations.

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Multiple-stage decisions in a marine central-place forager

Royal Society Open Science ◽

10.1098/rsos.160043 ◽

2016 ◽

Vol 3 (5) ◽

pp. 160043 ◽

Cited By ~ 21

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.

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