Following the Aug. 10 rain that stilled bird activity, things were looking up for us as we were able to open our ground level nets for most of the next two days.
The good luck was not to last, as last week’s black bear made a reappearance to again force us to close our ground level nets as a precaution. Since our nets were mostly closed once again, just 139 birds were banded this past week, bringing our fall total up to 1,115 birds banded from 46 species.
Banding is an important component of our monitoring protocols to detect species that migrate discreetly and to measure a sample of birds. However, it is not our only technique. Even with our nets closed we can struggle to keep up with identifying and documenting foraging flocks and overhead migration.
Our migration monitoring station is strategically located on the shoreline near the foot of Marten Mountain. Most songbird species will not fly over open water where they risk being attacked by raptors, nor will they move over high elevations where the weather is sometimes poor. They often favour vegetated lowlands. So, the lake pushes songbirds east to the shoreline and Marten Mountain pushes them west in a funnelling effect that sends them racing over our heads.
To record all this overhead migration, we have three counting methods: census, visual migration counts, and incidental counts. During census we record every bird detected over half an hour and a 700 m route. Census takes place in the first two hours of the day when bird activity is typically at its peak.
Yet birds can migrate throughout the full seven-hour monitoring period, so we do five-minute-long visual migration watches hourly in the parking lot. These short counts ensure that we have data to directly compare movements between days despite busy nets, wind, rain, or bears.
Lastly, everything else not captured in the nets, census, or visual migration counts, is recorded through incidental counts which may receive less effort from one day to the next if we get too busy in the building banding birds.
Just in the last seven days, we recorded over 7,000 birds from 75 species observationally, bringing us to over 21,500 bird encounters from 109 species since we began fall monitoring on July 12.
To identify these encounters in the seconds we get as birds fly overhead, we quickly take in a few hints: calls, flight behaviour, size, colouring, and, perhaps most importantly, tail shape and pattern.
For example, although we often rely on their distinct “tick” flight call, purple finches, like most other finch species, have strongly forked tails with no markings. In contrast Tennessee warblers have short, mostly square tails with no markings and American redstarts have long, square tails with orange or red tail spots very close to the body.
If you’d like to see our many overhead specks, we host tours most Wednesdays and Saturdays in August – contact the Boreal Centre for Bird Conservation to learn more, at 780-849-8240.