Damage to Landscapes and Crops
Elk commonly impact agricultural resources by competing with domestic livestock for pasture and damaging cereal and hay crops, ornamental plants, orchards, and livestock fences. Elk also damage forest resources by feeding on seedlings and saplings of coniferous and deciduous trees. During winter, elk concentrate in areas where food is available, including pastures, winter wheat fields, and young conifer plantations. A survey conducted in 1989 indicated that elk caused damage to crops in seven states, mostly to haystacks and pastures. Elk damage appears to be a local problem that usually is dealt with locally.
Plants browsed by elk have a characteristic appearance. Vegetation is grasped between the lower incisors and the upper palate and ripped or torn, resulting in splintered and fragmented plant parts. In contrast, rabbits and large rodents clip vegetation off at a sharp 45o angle (Fig. 4). Elk damage to conifer seedlings may appear as a thorough stripping of bark from the upper half of the growing tip or “lateral”. This damage generally occurs weeks after planting, usually in early to midspring. Meadow mice gnaw or “girdle” rather than clip as larger rodents and rabbits do, or browse as elk and deer do. The appearance of damage to browsed plants is similar for elk, deer, and cattle, but their tracks and scats (droppings) are easily distinguished.
Elk tend to roam over greater expanses of habitat than deer, so the occurrence of damage by elk is more widespread and sporadic than damage by deer. Also, because elk move in groups instead of singly, the nature of their destruction to crops and pastures includes trampling, much like that of domestic livestock.
Damage by elk is often seasonal. Damage to hay and grain crops generally occurs in spring when these crops are the first succulent vegetation to emerge, and native forages are in short supply. If native forages are chronically limited, damage to crops may persist through harvest. Much of the damage to orchards occurs in winter and late spring when the growing tips of young (1- to 5-year-old) trees are high in protein and highly digestible. Damage may continue through late summer at a reduced level. Conifers are often damaged after they are planted on clear-cut sites. Elk are drawn to conifers when other food supplies are limited and/or of low nutritive quality. Elk also are attracted during spring when conifers produce new growth that is especially palatable and highly digestible. Damage to haystacks occurs during winter when there is little food available for elk on winter ranges. Elk damage to pastures usually occurs during winter and during migration periods when elk move between summer and winter ranges.
Elk usually damage areas that border standing timber because they have learned from their association with humans not to venture far out into large openings. They also prefer riparian zones and benches as opposed to steep slopes, and damage is usually distributed accordingly. Much of the damage caused by elk is in response to low availability of forage on winter range; thus crops on winter range or along migration routes are often damaged.
Damage to Livestock
Brucellosis is a bacterial disease that causes abortions in pregnant elk, bison, and cattle. The bacteria that causes the disease, Brucellosis abortus, has only been found in elk and bison populations of the Greater Yellowstone Area, according to the National Park service. The disease is transmitted among animals if they are in contact with infected birth tissues. If infection occurs, it can reduce the reproductive rate and marketability of cattle. Brucellosis was introduced to wildlife populations by infected cattle brought to Yellowstone in the early 1900s.