|Title||Rabbit herbivory and its effect on cladode, flower, and fruit production of Opuntia violacea var macrocentra (Cactaceae) in the northern Chihuahuan Desert, New Mexico|
|Publication Type||Journal Article|
|Year of Publication||1993|
|Authors||Hoffman M.T, James CD, Kerley G.IH, Whitford WG|
|Journal||The Southwestern Naturalist|
|Keywords||article, articles, Cactaceae, Opuntia, herbivory, lagomorph, journal, journals, lagomorph, herbivory, lagomorph,Lepus, herbivory, lagomorph,Sylvilagus,herbivory, Opuntia, herbivory, Opuntia,phenology, phenology, herbivory, rabbit, SEE <LAGOMORPH>|
We studied the timing and effect of black-tailed jackrabbit and desert cottontail herbivory on a platyopuntia species, Opuntia violacea var macrocentra at a site on the Jornada del Muerto, 35 km north of Las Cruces, New Mexico in the northern Chihuahuan Desert. Total monthly fecal pellet dry mass collected around the base of individual opuntias over 15 months indicates that both rabbit species exhibit a seasonal preference for this opuntia with the greatest grazing pressure evident during dry seasons or when little annual or new growth of other perennial plants is present. Neither rabbit species appears to graze small opuntias possessing less than three cladodes. They also appear to avoid grazing new cladodes, since more than 80% of the cladodes produced in May 1990 survived for six months. The proportion of individual opuntias grazed increases with increasing cladode number size class as does the mean fecal-pellet dry mass collected around the base of individual opuntias. Spinescence did not affect grazing intensity over the 15-month study period. Instead, plant size and grazing history appear to be the most important determinants of grazing intensity. Although statistically not significant, there is a trend on our data which suggests that above-average rabbit hebivory may negatively affect cladode, flower and fruit production in intermediate opuntia size-classes only. For individuals with either very few or very many cladodes these parameters appear unaffected by rabbit herbivory. However, the strongly-skewed size-class frequency distribution indicates that recruitment of juvenile opuntias into the population is little affected by rabbit herbivory.