Parrots
Evelyn Sanford writes:
Agave gentryi and Rhynchopsitta terrisi Ecology in the Sierra Madre Oriental, Mexico.
Agave gentryi is a monocarpic perennial occurring in the high montane pine and chaparral ecosystems of the northern Sierra Madre Oriental in Mexico. The panicle of A. gentryi is used by the endangered Psittacid, Rhynchopsitta terrisi, commonly known as the Maroon-fronted parrot, for perching and as a minor food source. I hypothesized that the activities of R. terrisi resulted in a lower rate of sexual reproduction among populations where use by the parrots was great than in little-used or unused populations. I explored this hypothesis by conducting inventories and measuring cover comprised by A. gentryi in three different populations with differing rates of use by R. terrisi. I also inventoried individuals with inflorescences in the same three populations and classified the fullness of each individual's panicle according to an ordinal ranking system. The fullness of the panicle was considered a possible indicator of detrimental effect of parrot activities on the plant's reproductive effort.
A significant difference in the proportions of individuals with inflorescences in different stages of reproduction was found between the population with greatest intensity of parrot use and the other two populations. Furthermore, significant differences were also found between the distributions of panicle fullnesses in the most-used population and the
distributions in the less-used populations. These findings suggest that the activities of R. terrisi may have effects on the sexual reproduction of A. gentryi; however, it is not clear whether the net effect of these activities is negative or positive.
