Article
Autumn Migration of Gray-Cheeked and Bicknell's Thrushes at Kiptopeke, Virginia
Journal of Field Ornithology
(1997)
Abstract
We examined the magnitude and timing of autumn migration for the Gray-cheeked/Bicknell's Thrush complex using banding data collected during 27 autumn seasons at Kiptopeke, Virginia. The average autumnal capture rate for the Gray-cheeked/Bicknell's thrush complex was 7.7 ± 8.9 (SD) birds/1000 net-h (range 0.5 to 36.4 birds/1000 net-h). For the 27 years combined, 90% of the captures occurred between 20 September and 15 October with an overall median capture date of 5 October. The timing of Gray-cheeked and Bicknell's thrush migration was compared for years where adequate morphological data were collected. All thrushes captured in these years were classified as Bicknell's, "overlap thrush," or Gray-cheeked Thrush based on wing chord. The proportion of birds within each thrush category was relatively even for the selected years with average capture rates of 3.2 ± 2.2 (SD), 4.3 ± 3.8, and 5.9 ± 6.5 birds/1000 net-h for Bicknell's, overlap, and Gray-cheeked Thrushes respectively. Median date of capture for the Bicknell's Thrush was statistically distinguishable from that of the Gray-cheeked Thrush in only one year (Mann-Whitney U-test, P < 0.001). Age ratios were highly skewed to hatching-year birds for all thrush groups. Data presented provide evidence of a relatively large movement of Bicknell's and Gray-cheeked thrushes through coastal Virginia. Historic banding information from other locations may help to clarify the migration ecology of this species complex.
Disciplines
Publication Date
Fall 1997
Citation Information
Micheal D. Wilson and Bryan Watts. "Autumn Migration of Gray-Cheeked and Bicknell's Thrushes at Kiptopeke, Virginia" Journal of Field Ornithology Vol. 68 Iss. 4 (1997) p. 519 - 525 Available at: http://works.bepress.com/bryan-watts/254/