Date of Award:

1-1-1973

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Ecology

Advisor/Chair:

J. Juan Spillett

Abstract

Objectives were (1) to evaluate the seasonal and daily use by mule deer (Odocoileus hemionus) of adjoining converted and natural pinyon pine-Utah juniper woodland (P-J) winter range, and (2) to determine the major factors influencing mule deer use of converted P-J range to provide criteria for deer management. The study was conducted on 3 sites in central, eastern, ar.d southeastern Utah between 1969-72. Data for 1969-72 on physiographic, climatic, and vegetational attributes of the three Utah study areas were related to data from approximately 10,000 deer observations, 5,000 0.01-acre pellet-group count plots, feeding observations of 1,100 deer, 220 miles of track counts on trails, and 450 radio locations of nine adult female deer. Conclusions were: (1) In the initial 12 years post-treatment, no increase in deer numbers X was correlated with P-J conversion. (2) Increasing deer use during the study was concentrated on natural P-J. (3) The bulk of the use on chainings occurred in March and April. (4) Radio telemetry indicated that, from November to May, about 55 percent of the deer within 0.5-mile of the chaining edge used the chainings at night, and 5 percent in the day. (5) Deer fed and bedded in alternate 2-hour periods. Thus, the Mayfield chainings contributed 25 to 30 percent of the deer forage, but comprised over 50 percent of the land area. (6) The greatest overwinter deer use occurred in shallow valleys and on slopes of 10-20°. Least preferred by deer were flats and hilltops. Chaining decreased the relative deer use on hilltops, increased it on hillsides, and had no effect on the use of valleys. (7) Deer use was greatest on north exposures in the natural P-J and on south exposures on chainings. (8) No edge effect existed in the initial mile of P-J away from the chaining edge, whereas, deer use of chainings declined 50 percent in the initial 0.2-mile. (9) Radio telemetry showed a mean home range radius of 0.6- mile between November and May for nine adult female deer. (10) Moon phase effected deer use on the chainings but with reversed influence between November and May. (11) Snow cover over 10 inches and wind velocity greater than 20 miles-per-hour each decreased considerably deer use of chainings. (12) An increase in shrub density increased deer use of chainings more than any other variables measured. (13) Chaining of P-J apparently decreased Cercocarpus montanus, Quercus gambelii, and Pinus edulis shrub density but increased Juni£eru~ osteosperma and Artemisia spp. Forb cover did not markedly change post-chaining, while grass cover increased by 400 percent. (14) Total forage crown cover increased 25 percent 3-12 years post-treatment. However, total palatable browse cover was less on treated than untreated range. (15) Juniperus spp., Artemisia spp. and green grasses comprised 60 to 75 percent of the over-winter diet; the remainder was composed largely of Quercus gambelii and Cercocarpus montanus. (16) Optimum tree density for deer use of P-J appears to be 50 to 100 per acre, depending upon maturity of the stand. Management recommendations are that P-J chainings should: (1) be less than 0.4-mile wide, compose no more than 20 percent of the winter range 1n a 25 year period, (2) be single chained only, (3) be confined to small valleys and gentle slopes, (4) have 20 percent slash cover, 5-10 percent grass cover, and many of the pushed-over tree tops ~eft alive, (5) be confined largely to south and west exposures, (6) be grazed in a spring- fall rotation by cattle.

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