ABSTRACT
The house sparrow breeds in spring and early summer in the vicinity of human habitations. House sparrows generally remain within a relatively small flock area except for the annual dispersal of young birds in late fall and winter. Weekly counts provide an index to relative densities and show population fluctuations. A reasonably accurate population census can be made by locating all communal roosts in a relatively large study area. House sparrows are difficult to capture and quickly become trap-shy. To determine the mortality caused by the presence of collars, place collars on only half of the banded birds. Recaptures will show the difference between numbers of surviving banded and banded and collared birds. Obtain, through many visual counts in the study area, the percentage of birds having collars.
