Habitat use, productivity, and nest predation of Rio Grande turkeys

Abstract

The productivity and habitat use of Rio Grande turkeys (Meleagris gallopavo intermedia) was evaluated from May 1976 through November 1977 on the Welder Wildlife Refuge near Sinton, Texas. During the summers of 1976 and 1977 predation rates were also determined for 350 dummy wild turkey nests. Ana lysis of nest predation rates showed that rotational grazing systems and longer pasture deferment from livestock grazing significantly increased nest survival over continuous grazing and shorter pasture deferment. Predation rates were higher in riparian-woodland and bunch grass-annual forb communities than in mesquite (Prosopisglandulosa) - mixed grass. Predation rates were also higher inside a 387-ha coyote (Canislatrans) exclosure than in a similar open pasture. No differences were found for soil type, cover type, egg type, or the effects of hair-catchers at nests. Based on hair samples and other data, striped skunks (Mehpitismephitis) and raccoons (Procyonlotor) were the major nest predators on the Welder Refuge, whereas coyotes, armadillos (Dasypus novemcinctus), and snakes were probably of minor importance. No patterns of nest predation could be characterized based on method of nest destruction or related sign. Average hatching dates for the West Refuge turkey population were 6 June 1976 and 30 May 1977. Productivity was over twice as high in 1977 (117 poults:100 hens) as in 1976 (52 poults:100 hens) . This higher productivity may have been related to heavy late summer-early fall rainfall which preceded the 1977 nesting season or to an early spring green-up which may have resulted in the early onset of nesting behavior. Seasonal use of plant communities was determined for the following seasons: mating, March; nesting, April-May; brooding, June-August; fall shuffle, September-October; winter flock stability, November-February. Analysis indicated that from the mating season to the period of winter flock stability, turkeys decreased their use of the open riparian-savannah habitat and increased their use of the denser riparian-woodland habitat.