Chart 1:

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CHART 1: This chart shows the change in frequency of newly banded Ruby-throated Hummingbirds, Archilochus colubris, throughout the breeding season, as indicated by 23 years of records (1984-2006) from Hilton Pond Center for Piedmont Natural History near York, South Carolina USA.

RTHU begin returning to York in very late March (early banding date 27 Mar), with an initial peak during the last two weeks of April. New arrivals level off until about 1 June, when there is another rush of unbanded birds, possibly indicating a "second wave" of migrants from the tropics. (NOTE: The huge peak near the end of May is an artifact resulting from 30 May 1997 being the single heaviest day of banding ever with 26 new RTHU captured, followed by 11 new birds on 31 May; these two days had been preceded by a two-week period when the bander was away from the site.)

New birds dribble in throughout the month of June at Hilton Pond, with a sudden increase in numbers beginning the middle of the second week in July; this results primarily from the appearance of the summer's first fledglings. (The valley in the last week in July is a a result of the "SB Factor," short for "Sunny Beaches" because the Master Bander was historically absent from Hilton Pond for a family vacation at the coast.) Young birds continue to swell the ranks, with numbers peaking at the end of August. There is a gradual decline of unbanded RTHU during the first two weeks of September, followed by a sudden, drastic drop beginning about 15 Sep. By the end of September and into October very few new captures are expected, with the last RTHU leaving Hilton Pond by mid-October (late date 18 Oct).

Also see Chart 8 for differences in banding dates for adult and juvenile RTHUs.

All text, data, and graphics © Operation RubyThroat

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