Dan L Campbell

Indirect Methods for Avoiding Damage: The best way to avoid damage is to have knowledge of wildlife behavior in your area. This is not necessarily an easy task, but some activity patterns remain similar from year to year. If nearby plantations have been damaged during the first growing season when bud-burst is later, there may be only one bud-burst. You can usually expect higher percentages of trees damaged in subsequent years.

To help avoid winter damage by deer, winter forage such as trailing blackberry should be encouraged. When planting, it is usually best to plant the sites most susceptible to damage as late in spring as possible. This will depend upon elevation as areas become snow free and will also depend on the typical ‘snowline’ elevation for the area. Deer and elk will often spend longer periods just below elevations with deeper snow, causing more browsing damage in that area.

Encouraging or even seeding early flowering preferred forbs for deer will reduce spring damage to conifers. Caution should be used in the selection of forage plants. Some plants such as vine maple are very palatable but usually scattered, and will attract deer and elk into an area and cause increased damage to conifers. Red huckleberry is highly preferred wildlife forage and if well distributed will reduce damage to conifers. Plants that compete with tree growth, particularly some perennial grasses and shrubs, should be avoided.

Direct Methods for Preventing and Avoiding Damage: Measures to stop wildlife damage include fencing or individual plastic mesh Vexar type seedling protectors. Fencing should be considered for deer and elk if it is economically feasible and does not cause access problems. Vexar protectors should be considered for an area when there are a variety of wildlife species causing problems over a period of several years. The mesh should extend both above and below the ground, over the upper root system, to protect from voles, mountain beavers, or pocket gophers. Deer and elk require plastic mesh tubes 30 inches to 36 inches long. Although they will browse taller trees, the amount of damage is usually less significant. Repellents and aversive conditioning methods may be most effective and economical when the period of damage has been identified and there is good access to the conifers. Applications now available are applied either just after bud-burst, in early winter, or at time of planting. The powdered egg formulations and “Seadust” powder are most effective. Repellents must be registered under pesticide regulations. Non-chemical aversive conditioning methods have been developed, but have not yet been applied under field conditions.

If populations of big game become too abundant there should be increased hunting to reduce the numbers of animals within an area. This is becoming difficult in some areas as more homes are built.

Trapping can provide short term benefits against mountain beavers and pocket gophers.Mountain beaver trapping should be considered before timber harvest or thinning, when animals are less numerous, and burrow systems can be recorded during timber cruises so that sites to trap can be easily located. Although an occasional weasel, mink, spotted skunk, or opossum will be trapped, off-setting the trap trigger will avoid most weasels, and the other species use the mountain beaver burrows less frequently than weasels.

Baiting with poison baits can provide short term reduction of some rodent populations, but even registered baits are not necessarily effective. Burrow systems will nearly always be re-occupied within a short time. Baits generally cannot be used in areas within the ranges of threatened or endangered species. Safe fumigants for burrowing rodents are being developed, but caution is advised when using fumigants because of safety problems. Some fumigants although registered, have been ineffective against burrowing rodents. Mountain beavers and pocket gophers spend most daytime hours in their nest, where they are most susceptible to fumigants. Daytime use of fumigants is usually safer for non-target species because much of their burrow activity is at night.

Editor’s Note: This is the second part of a three-part series by Dan Campbell. He is a retired USDA Wildlife Research Biologist and heads the private consulting firm of Wildlife Services, Inc.