More info for the terms: competition, cover, density, shrubs
Black-tailed jackrabbit populations undergo periodic peaks and lows
every 3 to 10 years [18,19,24]. Northern Utah populations, for example,
reached a peak density of 71.4 black-tailed jackrabbits/sq km in 1970,
declined to a low of 47.1 black-tailed jackrabbits/sq km in 1972
(Stoddart in [85]), and peaked to approximate 1970 levels in 1979 [88].
Large populations can overgraze ranges and depradate croplands and
conifer plantations [8,13,24,39,81]. Black-tailed jackrabbit control
methods are reviewed in several publications [26,39,50].
Range: When populations are between peaks, black-tailed jackrabbit
presence may complement livestock grazing. Daniel and others [18,19]
reported that at moderate stocking rates and average black-tailed
jackrabbit numbers, there was little competition for forage between
cattle and black-tailed jackrabbit on a Chihuahua Desert
creosotebush-honey mesquite rangeland. The black-tailed jackrabbit
browsed shrubs such as creosotebush that the cattle found unpalatable.
In addition, the black-tailed jackrabbit consumed native poisonous
plants such as locoweed (Astragulus spp.), desert marigold, and wooly
paperflower, thereby reducing poisonous plant cover. Thirty-six percent
of their total diet was composed of plants poisonous to cattle. Daniel
and others [18] also found that black-tailed jackrabbit densities were
significantly (p less than 0.10) higher on rangeland in fair condition than on
good condition rangelands. They suggested that maintaining rangelands
in good to excellent condition may be the best way to control
black-tailed jackrabbit populations.
Black-tailed jackrabbit populations in some areas of the Great Basin
have been declining for 20 to 25 years. There has been an attendant
population decline of some raptor species including ferruginous hawk
[85] and golden eagle [60]. See HABITAT RELATED FIRE EFFECTS for
further details.
Black-tailed jackrabbit browse saltcedar (Tamarix ramosissima). It is
apparently the only vertebrate herbivore in the United States to do so
[83].
Seeds of several plant species are dispersed in black-tailed jackrabbit
feces including dropseeds (Sporobolus spp.) [19] and prickly pear
(Opuntia spp.) [69].
Timber: In coniferous forests, management practices that reduce edge
also reduce black-tailed jackrabbit populations. Roads, skid trails,
and patchy canopy cover have been found to increase populations [39].
Lagomorphs can reduce conifer seedling survival. Lagomorph damage to
young conifers can be confirmed by examining injured trees. Because
they clip trees at an angle with sharp incisors, lagomorphs leave
smooth, oblique cuts on branchs and twigs. Lacking sharp incisors, deer
(Odocoileus spp.) and elk (Cervus elaphus) leave jagged tears. Clean
branch cuts and fecal pellets, which jackrabbits and rabbits often drop
at feeding sites, signal lagomorph damage [39].
Human Health: The black-tailed jackrabbit is a reservoir for several
diseases transmittable to humans including tularemia, bubonic plague,
and Lyme disease [24,53,81].
