Lodge, beaver

Ankley, G.T., G.J. Niemi, K.B. Lodge, HJ. Harris, D.L. Beaver, D.E. Tillitt, R.R. Schwartz, J.P. Giesy, P.D. Jones, and C. Hagley. 1993. Uptake of planar polychlorinated biphenyls and 2,3,7,8-substituted polychlorinated dibenzofurans and dihenxo-p-dioxins by birds nesting in the lower Fox River and Green Bay, Wisconsin, USA. Arch. Environ. Contam. Toxicol. 24 332-344. 

Beaver picking up experimental sticks in a food choice experiment. The animal will transport the sticks through the water to the lodge. There one or more beavers will consume the bark. The peeled sticks will be released into the water and can be found floating or stranded in the dam... 

Herbivores such as deer, bovids, rodents, or marsupials encounter a great diversity of plant secondary metabolites (PSMs). These PSMs greatly affect the food choices these animals make. In turn, herbivores affect plants by stimulating induced defenses as a consequence of browsing. For food choice experiments in the wild we need animals that can be found predictably in certain places at certain times. The beaver (Castor canadensis or C. fiber) is such a species. Beavers stay year-round near their lodges and readily accept food provisions. 

When beavers first colonize a site they begin by harvesting the most palatable species, such as aspen (Populus spp.) or willow (Salix spp.). Over time, they change the vegetation by their selection of trees for food and construction of dams and lodges. Eventually, often only the least preferred conifers are left, and the beavers move to a new area until some of the depleted vegetation has regenerated. Beavers move back in, and the cycle repeats. 

Place samples in the evening, shortly before beavers emerge from their lodge. This way you minimize the risk that other herbivores, such as deer, will eat or sample the food first. (If that is a real possibility, the twigs have to be fenced off with high chicken wire, leaving 20 cm so open at the bottom for the beavers). 

At an active site lives a beaver family, consisting of parents, yearlings, and kits of the year. During the daytime they stay in their lodge which can be a bank... 

Carefully walk around a pond, especially near lodge and dam. Look for scent mounds. These are little piles of mud at the water s edge that smell more or less strongly like beaver castoreum, depending on the time since marking. 

To study beaver responses to defined scent stimuli we place an artificial scent mark near an active beaver lodge and record the animals responses. 

In the afternoon or early evening before the beavers emerge from their lodge, build a scent mound from mud, scooped up from the pond, just as the beavers do. Use a little garden trowel, or in a pinch, a plastic tub. Wear rubber or plastic gloves to avoid contamination with human scent. About 1 1 of mud suffices. Place the scent sample on top of the scent mound. If you use commercial, dried, and ground beaver castoreum, sprinkle a teaspoon full over the mud. For dissolved scent samples, place a large cork or bottle cap on scent mound. 

Ankley GT, Niemi GJ, Lodge KB, Harris HJ, Beaver DL, Tillitt DE, Schwartz TR, Giesy JP, Jones PD, Hagley C (1993) Arch Environ Contam Toxicol 24 332... 

Ratio (vol %) of hydrocarbons to n-hexane Minas Beaver Lodge... 

Beaver are known to respond readily to artificial castoreum scent marks that are placed near the lodge (Hodgdon, 1978 Muller-Schwarze and Heckman, 1980 Svendsen, 1980 Bollinger, 1980). They sniff, paw, and mark such scent marks (Muller-Schwarze et al., 1983). This stereotyped and elaborate behavior provided the bioassay in the present study. 

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