SEQUENTIAL CAVITY USE IN A COTTONWOOD BOTTOMLAND

I studied the patterns and frequency of cavity reuse in a community of cavity-nesting birds in a cottonwood bottomland along the South Platt e River in northeastern Colorado from 1985-1987. Of 100 cavities occup ied in 1985, 56% were reused in 1986; 38.5% of 122, cavities occupied in 1986 were reused in 1987. Of 81 old cavities monitored in both 1986 and 1987, 65.4% were reused at least once. Similar proportions of sec ondary cavity-nesting bird (SCNB) and primary cavity-nesting bird (PCN B) cavities were reused in both years. Reoccupancy by the same species was 27% and 20.5% in 1986 and 1987, respectively, and was greater for SCNB than for PCNB cavities in both years. Conversely, reoccupancy by different species was greater for PCNB than for SCNB cavities in both years. Thus, old cavities of PCNB were more available to other specie s of cavity-nesting birds, whereas old SCNB cavities tended to be reus ed by the same species that previously occupied the cavity. SCNB used a greater proportion of old cavities than did PCNB in both 1986 and 19 87. House Wrens (Troglodytes aedon) and Northern Flickers (Colaptes au ratus) reoccupied most of the old cavities.