Nocturnal migration during this last week in July poses a number of interesting questions about the migration that takes place in mid-summer. By late July, peak migration for some shorebirds species is well underway. Beaver River is not a significant stop-over area for many shorebirds, with a few exceptions like Sanderling or Greater Yellowlegs. Nonetheless, there was a good representation of small numbers of shorebird species passing over the monitoring station. These included, in order of the number of estimated individuals, Semipalmated Sandpiper (45), Short-billed Dowitcher (15), Spotted Sandpiper (15), Black-bellied Plover (4), Killdeer (4), Whimbrel (2), Ruddy Turnstone (1), Semipalmated Plover (1), Greater Yellowlegs (1), and Pectoral Sandpiper (1). At cruising altitudes, shorebirds are too high for their flight calls to be detected by microphones on the ground. Thus, most of these birds are likely descending to or ascending from stopover areas in the region.
Another interesting question during this week is sorting out which songbirds making nocturnal flights are moving between post-breeding feeding areas in the province and which have actually started migration. Among the birds detected this week, Savannah Sparrows (9 estimated birds), Yellow-rumped Warblers (3), White-throated Sparrows (1), Magnolia Warblers (1), and Nashville Warblers (1) are likely birds making post-breeding movements. However, some warblers are known to be early migrants, and some were recorded this week. These included Northern Waterthrush (4 estimated birds, first on 22 July), Yellow Warbler (2, first on 25 July), Canada Warbler (2, first on 26 July), Tennessee Warbler (1, first on 27 July), and American Redstart (1, first on 27 July). On the evening of 31 July and extending into the morning of 1 August, an estimated 21 Black-and-white Warblers were recorded. Although this warbler’s migration is typically from mid-August to well into September, it is known to migrate in July at times. Whether these birds were engaged in landscape or migratory movements, it is a high number for the end of July.