Young grapevines are particularly susceptible to damage by rabbits. Jackrabbits (Lepus Californicus) are the main rabbit pest, although cottontail (Sylvilagus audubonii) and the brush rabbit (S. bachmani) cause problems in some areas.|
Jackrabbits are actually hares, not rabbits. Hares are born fully furred with eyes open and are capable of hopping about immediately. Rabbits, including the cottontail, are born blind, naked, and helpless. One other distinction between the two: Cottontails form underground nests, and jackrabbits make depressions in the soil or form nests beneath brush or other vegetation. Cottontails prefer to nest in and reside near protected areas, such as brush piles, hedges, box piles, or old buildings. Jackrabbits move more freely and in a wider range. Jackrabbits are about the size of house cats with large, long ears, short front legs, and long hind legs. They normally hop about, but when frightened they can outrun most dogs.
Jackrabbits breed from early spring to late summer, although breeding may continue where winters are mild. Females may produce more than one litter a year, especially on irrigated land. After a gestation period of about 6 weeks, a litter (usually of three or four) is born. Larger litters are produced in spring. An adult female may produce 14 or more young per year.
Rabbits feed on plant stems, bark, and leaves. They damage or kill grapevines by eating through bark to the cambium layer. Rabbits chew or cut young vines from near the ground to as high as they can reach and gnaw and girdle trunks. They also chew on plastic surface irrigation lines.
Jackrabbits are active from early evening to early morning throughout the year, although some are seen during the day. Their populations fluctuate and usually reach high levels every 5 to 10 years.