| Description |
The study pertained to the different aspects of bird life in the Oquirrh Mountains in north-central Utah, a semi-isolated range that rises from the Great Basin Desert and extends to an elevation of 10,620 feet above mean sea level. This range had never been studied ornithologically before. Objectives were determine the types of birds occurring there, their relative abundance, seasonal status, systematic position, ecologic distribution and to gather information on natural history and behavior. This study was conducted from 1971 to 1973 during which time extensive collecting was done throughout the area, particularly the first year, to obtain representatives of each species. An attempt was made to obtain series of those showing geographic variation so as to determine subspecies represented and clinal variation across northern Utah. Four census areas were established in the basic plant communities. Collecting was not performed in these areas. Information on natural history, numbers, and types of species was obtained mostly during the intensive Mation on natural history, numbers, and types of species was obtained mostly during the intensive studies in these four areas. They were visited twice a week for six weeks during the breeding season of 1972. One hundred and twenty-two species of birds are now know from the Oquirrh Mountains. They represent ten orders, theiry-three families and nincty-two genera. Fifty-three kinds are permanent residents and fifty-eight are summer residents, making a total of one hundred and eleven species of breeding birds. Nine are winter visitants and two are transients. The ecologic distribution was worked out on the basis of the four plant zones represented, with a further refinement of determining the occurrence of each species in the several plant communities present. The four census areas were set up in diverse biotic communities: I. pinyon-juniper; II. maple; III. coniferous forest and IV. mid-altitudinal riparian woodland. Twenty-nine species were found in the pinyon-juniper association with a density of twenty-four birds per day in the area, which is essentially the same as for the maple which contained thirty species and had a density of twenty-one birds per area. The coniferous forest contained the least number of species, namely twenty-seven, and a density of sixteen birds per area which was markedly less. In the riparian woodland there were thirty-five species and the density was correspondingly higher, namely twenty-seven birds per five acres. It would appear that the greatest number of kinds and the highest density in the riparian woodland is correlated with more niches afforded because of the ecotonal qualities of the area. There are also indication that with an increase in altitude, the number of species decreases. This is suggested by the results for the riparian woodland and coniferous forests. However, unfortunately, the Oquirrh Mountains for not have sufficient subalpine grassland and no tundra to test his hypothesis. The Oquirrh Mountains are centrally located in a sequence of five reanges occurring across the state at the same latitude. All of these ranges had been previously investigated. It was desired to ascertain the avifaunal position of the Oquirrh Mountains with reference to the other ranges. Twelve species show clinal variation in characters and there are different combinations of races in the several mountains. |
