Early migrants erupted over Beaver River this week. While the week began slowly, during the two nights beginning on 13 and 14 August, there was a steady of stream of migrants from about an hour after sunset to an hour before sunrise. The five most abundant birds were American Redstart (an estimated 189 birds), Black-and-white Warbler (182), Yellow Warbler (171), Magnolia Warbler (132), and Canada Warbler (116). It seems almost unbelievable that Canada Warbler, a species at risk, would be the fifth most abundant bird this week. Its spectrogram (see photo at right) is one of the most unmistakable of all night flight calls. Canada Warbler has been increasing every year that I have been monitoring in Southwest Nova Scotia. Compared to this week in 2018, the estimated number of Canada Warblers increased by 43 birds or by 59%.
Overall, the total number of flight calls increased by 17% compared to the same week last year at Beaver River and by 6% in total estimated birds. The number of estimated birds that increased compared to last year were American Redstart (+13%), Black-and-white Warbler (+107%), Yellow Warbler (+22%), Magnolia Warbler (+9%), Bay-breasted Warbler (+188%), Blackburnian Warbler (+16%), and Northern Waterthrush (+66%). Only the Chestnut-sided Warbler declined significantly (-51%). A total of 18 warbler species were recorded during the week.
There were very small numbers of sparrows (4 in total) but a Nelson’s Sparrow was unusual for this early in the migration. Small numbers of 5 species of shorebirds were recorded. The first Swainson’s Thrush of the autumn migration was noted on the morning of 15 August.