Annual Variation in Populations of Birds and Small Mammals on an Army Installation

摘要

Field studies were conducted at Fort Carson, CO, and compared to results obtained from similar studies conducted during the previous year. The results were used to determine annual variation in bird and small mammal populations and to assess this data's usefulness in indicating habitat disturbance caused by Army training activities. Data were collected on shortgrass prairie and pinyon-juniper woodland study sites. The prairie sites showed little change in bird populations or guilds between years. However, variation between years on the woodland site was significant for two bird species and one guild. The cause of this difference is not obvious, but is probably not related to habitat disturbance from training activities. There was no significant change between years in the numbers of most small nocturnal mammals collected on the prairie and pinyon-juniper sites. However, on both sites, there was a significant decrease in the number of harvest mice and a significant decrease in the number of brush mice collected. There was also a significant increase in the number of pinyon mice in the pinyon-juniper woodland site. It appears that annual population fluctuations of mammal species generally occur across habitats, at least locally. The cause of these differences is unknown, but is probably not related to training activities. (Author)