Meeting Abstract
Individual differences in behavior that frequently covary with stress responsiveness have been demonstrated in a number of taxa. We determined that individual differences in neophobic behavior are repeatable over multiple years in a free-living bird. Florida scrub-jays (Aphelocoma coerulescens) were categorized along a continuum of timid to bold based upon their response to novel objects. Individuals were tested repeatedly over 3 years and at different times of the year (i.e., life history stages). Degree of neophobia was highly repeatable in individuals tested 2 to 6 times (R = 0.50, p < 0.000001, n = 134). We considered several factors that may have influenced performance. There were no differences in scores based on test experience (F3,64 = 2.080, p = 0.11) or the size of the group present during testing (F1,299 = 0.054, p = 0.82). Even scores from young birds that were trapped one day prior to the novel object test did not differ from individuals that had never been trapped (F1,30 = 0.91, p = 0.35). We did, however, see a sex difference with males exhibiting bolder behavior than females (F1,142 = 9.36, p = 0.003). Stress-induced corticosterone levels of 1-year-old birds were correlated with neophobia, in that boldness was negatively related to stress responsiveness (F1,46 = 6.88, r2= 0.13, p = 0.012). Analysis of a fourth year of novel object tests is currently in progress. Another measure of the timid to bold continuum, approach distance to a researcher, was highly repeatable between years (R = 0.57, p < 0.00001, n = 52). Approach distance was positively related to neophobia scores, as birds that most closely approached a researcher were the boldest in the neophobia tests (F1,111 = 13.32, r2 = 0.11, p = 0.0004).
