Posted | filed under Weekly Reports.

The Black Bears have finally begun to agree that there are no berries left at our station and have made themselves scarce, so we have started opening our ground-level nets. To compare capture rates between time periods with different effort put into netting, we keep careful track of when we open and close each net and calculate daily net-hours. This total suggests if we caught more birds because there were more birds to capture, or if we simply had more nets open. One net being open for one hour is one net-hour. If we simultaneously have three nets open for the same hour, then we have three net-hours even though only one hour has passed. If we can have all fourteen of our nets open for the full seven hours of daily monitoring, we have achieved full net-hours.

Between the “bearpocalypse” and scattered rain, we failed to achieve full net-hours anytime from August 1 to 27. Despite August’s reduced net-hours and ongoing wildfires in Western Canada, the overall fall migration season is turning out to be fairly average with 2,080 birds banded so far this year, close to the average of 2,326 bands per fall. While we have captured 53 species and expect a few more to arrive from their tundra breeding grounds, our top five most frequently banded species make up 60% of all captures.

In fifth place are currently White-throated Sparrows with 76 banded. This species is a short-distance migrant and we will continue seeing them through September. In fourth, and below their usual ranking of second most-frequently-banded are American Redstarts with 156. Last year our final Redstart was detected on September 15, and we are already passed their peak in migration of late July, so they may slide deeper into the rankings yet. In third place are Swainson’s Thrushes with 297 banded, who are similarly passed their peak migration, and in second are Tennessee Warblers with 336, which is above their seasonal average of fourth place although we could not find many breeding locally.

And in first place is, of course, Myrtle Warblers (a subspecies of the Yellow-rumped Warbler) with 383 banded and the second peak of their migration just beginning. This is almost always our top banded species in the fall and they hold the title of our most banded species in 30 years of captures by a wide margin with over 17,000 banded, well beyond second place’s American Redstarts with just over 10,000 banded. We started the week by counting 71 Myrtles, but ended it with 2,211, for a total of over 5,500 Myrtle Warblers observed in seven days.

Above: Myrtle Warblers finally took their place as our most frequently banded species of the fall – where they will likely stay until the end of the season. This Myrtle was banded on August 29, 2023 when we counted over 2,200 members of this species, but banded only 27.

The end of August brings the end of our time with our fantastic seasonal staff, but it also ushers in a new beginning. On September 1, we will start up our owl migration monitoring program to band Northern Saw-whet and Boreal Owls. We are currently assessing which weekend might provide the best odds at capturing an owl for our annual Family Owl Night, so stay tuned!

By Robyn Perkins

LSLBO Bander-in-Charge