Modern Wild Faunal Resource System Management
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Cover and food are key elements in the lives of most species of wildlife. First, think of area, for cover must like everything else, "be somewhere." There are many different types of cover and they each have different value or importance to each species. Since there are typically 250 species of animals associated with your area, the analysis and decisions become very difficult. Food can be substituted for some types of cover. Taking in energy can be balanced with not losing energy by some species. Cover is energy budgeting structures and space.
Cover is typically measured as horizontal or that covering an area. It might be well conceived as a volume within which the animal volume exists. Overhead cover as protection from avain predators is important for ground-feeding animals. It can be estimated by a densitomenter.
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| Developed wildlife clearing M-8 in Big Levels wildlife area, 1941. Winter condition with lack of concealing cover along edges. |
As for poachers, there is also cover for observers such as ecotourists and photographers, cover that prevents animals from being disturbed.
Distance or separation from disturbance may be considered a special type of "cover" An example is the separation of the edge of an island (e.g., resting waterfowl) from predators, human disturbance, etc. Short distance between den and food may be an alternative way of looking at distance and related directly to juxtaposition. A distance-apart matrix may be useful analysis. Night is the most profound cover and many animals utilize it very effectively. Species have not been selected against, they survive based on their ability to live and forage under the cover of darkness. See the section on Lunar Forces.
Soil and litter, like night, is the cover needed by a large number of animals. The moles and shrews are conspicuous examples but snakes, salamanders and other build or use burrow systems. These burrow systems, like trails (see below), reduce energy costs and provide one or more of the above listed types of cover.
Vegetation can provide many types of cover. Rocks, caves, and other structures can provide additional types of cover. Windbreaks and other types of fences should be considered for improving conditions for some species. Holes created by groundhogs (woodchucks, Marmota monax) or other creatures can be considered excellent cover for many species.
Teepee-shaped brush piles provide excellent cover. Because only the ends of brush and logs are touching the ground, the pile lasts longer and serves animals longer than flat piles. Teepee shapes shed snow and water and have little wind turbulence causing energy loss in animals. No one knows the proper distance apart for these structures. In most cases, the probable behavior of the species being managed and the amount of available materials will determine the distances. In general, many small piles, about 8 feet in diameter, are better than one large one. Planting or encouraging vines, some food-bearing, can improve the conditions. Where there are options, put the brush piles at the corners of triangles of hedgerows, fence rows or planted lanes. Brush piles decompose and change in their ability to meet the needs of different animals. Different bird species use different brushpiles of different age. A plan of management much like forest rotation is needed. Branches can be replaced and replenished or new piles created, typically on a rotation of 5 to 8 years. Prey production (salamanders and rodents) may be the primary yield from the mature pile with its deep decomposing wood and litter. Placing tiles or rocks or old culverts under the brushpiles can enhance their use and value. Slow-to-decompose posts or logs can add to nesting site quality at the center of the pile.
Strangely, trails can be considered to be cover. They are structures that allow animals to reduce the energy required to survive in an area. They reduce the costs and risks of moving between points. Where they exist and are used by animals, cover alternatives may be considered.
Where "less is more," thin trails on steep mountain slopes provide resting and escape space. Similarly, for antelope or the Indian onager, vast areas devoid of vegetation provide resting and escape space - allowing full use of keen sight and avoidance behaviors.
Many modern wildlife managers now think that having ample well-distributed cover may be more important to more animals than having available food for them. Reducing loss of energy seems more difficult than finding energy for consumption.
Ivlev's (1961) index of cover electivity is:
E = r - p/2
where
r = proportion of cover used
p = proportion of cover type available
When E is -1 there is a suggestion of avoidance; where the other extreme, +1, suggests selection of the cover type.
Snags, tree holes, and down logs are cover for many animals. Consider studying the section on that topic.
Open-grown conifers, e.g., cedars or junipers trimmed to "hedge-out", or clusters of red-pine (10-20) trees can be useful components of the designed space for animals.
See Cover Map Uses.
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Last revision September 7, 2002.