PIBO MIGRATION SUMMARY
August 21st - 31st, 2010

American Redstart

It was a quiet start to the summary period but a busy and productive time mid-week, with lots of migrants moving through the area from August 23rd - 27th. Hot, humid weather and southerly winds returned to Southern Ontario on the 28th, however, and activity gradually tapered off during the final days of August.

Although the netting area was inactive from August 21st - 24th, migrants continued to arrive in small but steady numbers including Fall 'firsts' for Baird's Sandpiper, Philadelphia Vireo, Veery, Northern Parula and Black-throated Green Warbler. A female Golden-winged Warbler was banded on the 23rd. This activity was somewhat surprising given the weather - the average dawn temperature at the Point from August 1st - 26th was 23° C, with no sub-20 readings recorded.

By the same token, it wasn't a surprise when the thermometer finally dipped below twenty on August 26th that the station experienced its first significant 'fallout' of the season. In all, sixty-one species were recorded during the official count period on the 26th and 109 birds of twenty-three species were captured during sixty net-hours of operation (1.8 birds/net-hour). Magnolia Warblers were numerous, with 41 individuals tallied (23 banded), followed by good numbers of American Redstarts, Red-eyed Vireos, Veerys and Swainson's Thrushes. Fourteen warbler species were observed on the day along with increased numbers of Least, Traill's and Yellow-bellied Flycatchers, and a nice variety of other neotropical migrants.

Although the 27th wasn't quite as busy - 51 species were recorded with 74 birds banded of eighteen species - an unprecedented count of 180 Cliff Swallows were recorded departing from the tip during the census in steady waves of ten to twenty birds. This hour-long tally probably represents only a fraction of the birds on the move that day. It remained active on August 28th - sixty-one species were noted - but the winds shifted back to the south the next day and migration activity slowly-but-surely ground to a near halt.

Despite the balmy conditions it was fairly active this August compared to previous years. In all, 108 species were recorded in the 'count' area from the 1st - 31st (including 22 warbler species) and 487 birds of thirty-nine species were banded in 1047 net-hours, for an average catch-rate of 0.47 birds/net-hour.

PIBO's next migration summary will be posted on September 12th.

Photo: Sumiko Onishi