Dr. Lloyd Glenn Ingles (c) California Academy of Sciences

What are deer doing in my yard?

Idaho's mule deer and white-tailed deer are "edge" species, preferring to browse in open areas near forests or dense shrubs. Our urban landscapes, with their innumerable edges, are consequently very attractive to deer. On average, deer eat about 7 pounds of food-3 percent of their body weight-each day. They're most active in the early morning and evening. Deer like to nibble, tasting first one plant, then another, and will return to your yard repeatedly if they've learned they'll find good things to eat there. While they like some plants-and some stages of plant life-better than others, they're far from fussy. Deer also drink 2 to 4 quarts of water a day-sometimes from birdbaths or water features. Typically, they have one or two fawns each spring, although triplets aren't unusual for white-tails.

Benefits and conflicts

Who doesn't enjoy watching these graceful animals, especially with their adorable fawns at their sides? But deer can cause extensive damage to urban landscapes, orchards, and vegetable gardens by feeding and trampling on plants and by rubbing antlers against young trees and shrubs. Young garden and landscape plants can be severely damaged or killed by these visitors' spring and summer browsing; indeed, deer have a special yen for tender new shoots and buds. They'll include fruit in their diet during the summer, acorns during the fall, and lichen, dead leaves, twigs, bark, and evergreen boughs in the winter.

Strategies for coexistence and control

Habitat modification: Although deer become decreasingly selective as they become increasingly hungry, there are some plants they are less likely to eat than others. Among the plants that deer resist are those that have a strong scent, thick or leathery leaves, or fuzzy, bristly, or spiny textures. Many deer-resistant plants are poisonous throughout the year or at some stages of growth. See www.colostate.edu/Depts/CoopExt/wildlife/deer.htm for suggestions for deer-resistant plants.

Fencing: Typically, it takes an 8-foot-tall fence-plastic mesh, wood, chain link, or wire-to keep deer from jumping into your yard, although a 5-foot height may work for a solid fence. (Deer are reluctant to jump into an area they can't see.) Keep them from crawling under the fence by securing it close to the ground. Electric fencing-one to five wires temptingly baited with a 1:1 mixture of foil-wrapped peanut butter and peanut or vegetable oil-can effectively exclude deer from small areas; successfully lured into being shocked, they learn to stay out. Protect individual trees or shrubs by encircling them with staked wire or plastic mesh. Some commercially available trunk wraps are designed to protect bark from antler-rubbing.

Frightening devices and repellents: An active dog running loose in a fenced yard can effectively deter deer. Odor- or taste-based repellents-both commercially produced and homemade-can help if they're applied repeatedly, especially after rain or irrigation, and if the same repellents aren't used for too long: once deer accommodate to a particular repellent, it loses its ability to deter them. Flashing lights, for example, work briefly but deer soon learn to ignore them. If you're spraying a repellent on a food product, be sure to check the product label to verify that that's an approved use.

Trapping: Constraints of labor and expense usually make live-trapping and removing deer unfeasible.

For more information

Reduce Deer Damage in Your Yard, Oregon State University Extension Service, http://extension.oregonstate.edu/catalog/pdf/ec/ec1557.pdf

Wildlife Damage Management Fact Sheet Series: White-Tailed Deer, Cornell Cooperative Extension, http://wildlifecontrol.info/ccewdmp/Publications/Deer_factsheet.pdf

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