U.S. Department of Agriculture: Animal and Plant Health Inspection Service


Document Type


Date of this Version

October 2003


Published in The Condor 105:805–810.


We determined the effects of a leg-harness transmitter on fecal glucocorticoid levels of wild male Dickcissels (Spiza americana) in captivity. During the post-breeding season of 2001, we captured 10 male Dickcissels in central Missouri and housed them in individual pens of an outdoor aviary. We radio-tagged five birds; the other five were captured and handled, but were not radio-tagged. We collected fecal samples every other day prior to attachment (31 July– 21 August) and after attachment (24 August–20 September). Body condition and morphology were similar between control and transmitter-equipped birds. We observed a significant interaction between transmitter attachment and time since attachment. Compared to baseline levels, fecal glucocorticoid metabolites were significantly lower in control (6.1 ± 13.7 ng g-1) than transmitter-equipped (102.3 ± 13.7 ng g-1) birds during the first 24 hr after attachment. Although transmitter- equipped birds showed elevated fecal glucocorticoid levels, the response was acute and returned to baseline levels within 48 hr.