Effects of rabbits and rodents on natural vegetation in the United States

Scope and Method of Study: A search of available literature was made to discover the effects on natural vegetation of as many species of rabbits and rodents as possible. Each genus is treated separately (with the exception of Tamiasciurus and Sciurus), and information is given concerning food habits (qualitative and where possible, quantative) and probable economic value.Findings and Conclusions: Jack rabbits tend to prefer overgrazed or otherwise open areas and can hold these areas in a preclimax state or practically denude the area of desirable vegetation. Snowshoe hares may destroy many seedlings, but this action can be useful in thinning crowded stands. Cottontails girdle trees at times, but this usually occurs during the winter when other vegetation is unavailable. Other rabbits are generally thought to be of no particular harm to natural vegetation.Harmful rodents are usually present in reduced numbers on well managed areas and cause no great amount of damage. Some smaller rodents may be present in dense stands of vegetation, but generally they are of no harm due to their size, numbers or their diet which may consist predominately of insects. However, populations of both rodents and rabbits may become great enough to cause localized trouble at times, and some control may be needed.Although many investigations have been made, it was determined that more work needs to be done in certain geographical areas where effects of some species are uncertain or unknown