LONGEVITY OF SOLAR-POWERED RADIO TRANSMITTERS ON BUTEONINE HAWKS IN EASTERN COLORADO

From 1982 through 1986, solar-powered radio transmitters were attached to 23 adult and seven fledgling Red-tailed Hawks (Buteo jamaicensis), seven adult Ferruginous Hawks (B. regalis) and seven adult Swainson's Hawks (B. swainsoni) in eastern Colorado. Transmitters were attached by means of a teflon-ribbon harness as a backpack (n = 39), or epoxied and sutured to the rachis of a tail feather (n = 5). Excluding transm itters that appeared to fail immediately after release (n = 3), or tha t were lost when tail feathers were shed prematurely (n = 5), the time from release to last telemetry contact (minimum life) for adult hawks ranged from 14 to 2331 d ((x) over bar = 452, n = 26). The median min imum transmitter life for adult hawks was 352 d; 15 (58%) of 26 adult hawks Fitted with backpack-mounted transmitters that were not subseque ntly found dead on the study area (n = 2) were observed with functioni ng transmitters greater than or equal to 1 breeding season subsequent to capture. Minimum life for transmitters on juvenile hawks ranged fro m 59, to 108 days ((x) over bar = 73, n = 7) and last telemetry contac t coincided with when young dispersed from natal territories. All nine adult Red-tailed Hawks, six (86%) of seven Ferruginous Hawks, and six (100%) of six Swainson's Hawks captured and fitted with radio transmi tters during the breeding season successfully raised young to banding age in the year that they were captured. In the subsequent breeding se ason, active nests were located in eight (89%) of nine Red-tailed Hawk , three (43%) of seven Ferruginous Hawk, and four (67%) of six Swainso n's Hawk territories where adults had previously been captured. Succes s of these nests was 100% for Red-railed Hawks, 67% for Ferruginous Ha wks, and greater than or equal to 50% for Swainson's Hawks, One Red-ta iled Hawk captured as a breeding adult survived a minimum of nine bree ding seasons while equipped with a transmitter and successfully raised young to banding age in greater than or equal to 7 of those years.