Influence of Roost Site Selection on the Energetic Efficiency and Distribution of Starlings and Blackbirds: A Way of Controlling Blackbird Populations Near Airports

摘要

In an effort to ascertain the energetic savings realized by blackbirds utilizing various roost sites and to compare the thermoregulatory benefits afforded by different types of roosts, this study utilized data on the metabolic rates of blackbirds and starlings with forced convection. Measurements of the percent cover and the wind velocity in several roost types were used to compare and contrast the energetic requirements of blackbirds and starlings utilizing these types of roost sites at night during the winter. Energy budgets were calculated for all groups of birds in various roost types from values for net radiation exchange and metabolic rates with forced convection. The calculated metabolic rates of all species tested except the starling exceed their peak metabolic capabilities at -10 C in the open and in a deciduous roost with 18% cover. In the pine roost (75 to 96% cover) calculated metabolic rates were below peak metabolic capabilities for all birds except the female redwing blackbird. Habitat manipulation by thinning was suggested as a possible control method for blackbirds and starlings. This would increase net radiative and convective heat loss such that it would no longer be thermally advantageous to use that roost to alleviate energetic stress. (Author)