| A unit of Lasting Forests
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A Total Forest Management Plan
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Cover and food are key elements in the lives of most species of wildlife. 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 can be considered to be timely energy-budgeting structures and space.
No matter what its characteristic, it must be at the right place and available at the time of need. This means it must be managed actively for an area as if in a timber rotation so that the amounts are stabilized, some decomposing or growing out of service, others being added and moving into suitable space for the intended animal populations. "Putting in a brushpile" is not managing cover. Managing steady replacement of a large set of well-designed, well placed brushpiles for a stated, desired group of wild animal species in an area might be.
Cover seems especially effective when located near foods. Managing its juxtaposition may be as effective as providing cover.
In the past, "resting and roosting, breeding and feeding", were sufficient categories for thinking about cover. It is now important to blend within the entire list of the cover-related behavior of the animals the threats for which cover is needed:
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."
Depth as cover or refuge was noted in 1988 by McIvor and Odum in their paper on behaviors of tidal fishes. It relates as well to terrestrial animals, with different species frequenting distinctive forest layers (insects, bats, birds) and soil layers (e.g., insects, arthropods, terrestrial pulmonates). Depth and reduced risk is related to food available and predation pressure.
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) or other creatures can be considered excellent cover for many species.
The practical value of knowing all of these relations is that some can be created or changed but the most frequently used value is in explaining why one area has different animals or animal abundance than the other.
Teepee-shaped brush piles are 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. (I would try for 3-chain distances (triangle-corners) in quail areas). In most cases, 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 and move within an area. They reduce the risks of moving between points. Where to place migration routes within the appropriate or acceptable structures for teaching and learning about wild faunal management is a question unanswered.
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| Moose foraging on on winter range, near Jackson Hole; snow covered mountains in background. |
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| Lakes may block classic big game herd migration routes and intensify foraging losses. |
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. There is often surplus or uneaten food. Rarely are there well distributed surplus places for the functions listed at the top of this page.
Snags and tree holes are cover for many animals. Consider studying the section on that topic.
Space or opportunities for separation from people or predators is a form of cover.
Legal protection, preventing shooting migrating birds or limiting the period in which it is possible, may be considered an unusual form of cover.
Open-grown conifers, e.g., cedars, yews, or junipers trimmed to "hedge-out", or clusters of red-pine (10-20) trees can be useful components of the designed space for animals.
References
McIvor, C.C. and W.E. Odum. 1988. Food, predation risk, and microhabitat selection in marsh fish assemblage. Ecology 69(5): 1341-1351.
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Last revision January 17, 2000.