PIBO MIGRATION SUMMARY
SEPTEMBER 1st - 10th, 2010

Cape May Warbler

It was a generally quiet start to September as warm weather continued to dominate in the region, but a strong cold front moved through on the evening of the 4th which produced a lot of migrants on September 5th, and this activity continued off-and-on throughout the remainder of the summary period.

While Double-crested Cormorants and a variety of gull species have remained active at the tip, including 14,000 cormorants counted on September 4th, it's been a very quiet time for shorebirds this Fall, with just small numbers of Black-bellied Plovers, Sanderlings, and a few 'peeps' noted in August and early-September. Hawks have been quite scarce as well, with only ones-and-twos of a small variety of birds encountered, although the raptor migration is just starting to get underway.

Strong southwest winds and plus-20º C morning temperatures from the 1st - 4th made for a fairly quiet time for songbirds and there was little to report save for small numbers of thrushes and warblers and a few migrant flycatchers and vireos. Just forty-five birds were captured in 165 net-hours (.27 birds/net-hour) over four days, and an average of only thirty-two species was recorded on the census.

As is often the case, however, a large backlog of birds appeared once the temperature dropped on the evening of the 4th, and PIBO staff and volunteers were kept busy both on the census and in the netting area. In all, 130 birds of twenty-five species were captured (2.17 birds/net-hour) on September 5th and a season-high 63 species was recorded during the official count period. Blackpoll Warblers and American Redstarts were numerous, with 42 and 28 individuals banded, respectively, along with a nice variety of other birds in moderate numbers. A total of nineteen warbler species was tallied on the day (including fifteen species banded), and five season 'firsts' were noted - Solitary Sandpiper, Marsh Wren, Blue-winged Warbler, 'Western' Palm Warbler, and Lincoln's Sparrow.

The temperature crept back up again and not much activity was recorded on the 6th and 7th, but another wave of birds appeared on September 8th when 60 birds were captured, including 25 American Redstarts. It remained active during the next two days, with 93 birds banded on the 9th and 109 on the final day of the summary period, along with 64 species recorded in the official count area on the 10th. Swainson's Thrushes were documented in good numbers, with 35 birds banded over two days, along with a nice variety of warblers, vireos (including 4 Philadelphias), and small numbers of flycatchers.

In all, 492 birds were banded from September 1st -10th in 507 net-hours for an average catch rate of 0.97 birds/net-hour. The top five species encountered in the nets were American Redstart (90 banded), Blackpoll Warbler (83), Swainson's Thrush (61), Magnolia Warbler (42) and Ovenbird (31).

PIBO's next migration summary will be posted on September 22nd.

Photo: Sumiko Onishi