A burst of warblers!

Even if Summer temperatures have once again installed themselves over the Bruce Peninsula, birds are saying otherwise, continuing their slow exodus to warmer climes. In the last week, we were able to open nets every day, with only one day, on September 5th, cut short by some rain. On that day and the following one, there was a major movement of Swainson’s Thrush, with 7 and 9 birds banded, respectively.

The following day, September 6th, was quite productive for banding overall, with a total of 35 birds banded of 17 species. Together with the aforementioned Swainson’s Thrush, there was also a total of 10 species of warblers in our nets!

This fall season, we are helping out with a special project: deploying nanotags on Swainson’s Thrush! Nanotags are miniature radio transmitters, attached by loops around the legs and sitting on the bird’s back. Their signals are captured, either by hand-held radio receivers or through the Motus tower network (http://www.bsc-eoc.org/research/motus/index.jsp?lang=EN&targetpg=maps) along the migration route. There is a Motus tower right here at Cabot Head, as well as three others along the Bruce Peninsula. But they are also found throughout North America, and all the way down to Panama and Colombia. The goal of our exciting project is to learn more about the migration ecology of Swainson’s Thrush: we hope to be able to accurately map their migration route, both in terms of timing and distance travelled, as well as revealing where they tend to spend time during stopovers.

We have a total of 28 nanotags to deploy this season, each programmed to last 300 days, which would cover both this Fall, as well as next Spring, migrations. We’ve already deployed 6 of them so far, with the first one deployed on September 7th!

However, a strong and cold North wind on September 8th dashed our hopes to deploy more nanotags on that day. Indeed, in accordance with the weather, there was a meagre total of three birds caught in our nets on September 8th, with very few others seen or heard. More favourable weather returned rapidly, though: on September 9th, there were new arrivals (or FOF): Blue-headed Vireo, White-throated Sparrow, and Dark-eyed Junco (of the Slate-colored variety).

The following day, September 10th, started clear and calm, though quite cold at dawn. The air warmed up slowly throughout the morning and, when finally the sunrays were strong and warm, we witnessed a lot of fluttering through the green trees. It was like a final (?) Summer show, with an impressive total of 15 species of warblers detected that day. The nets caught a good number of birds too: 34 birds of 12 species, including 11 Black-throated Green Warblers. But many warblers were only seen and avoided our nets. It is hard to resist giving the full list of them, so here it is: Nashville; Northern Parula (FOF, with only one individual); Chestnut-sided; Magnolia; Cape May; Yellow-rumped; Black-throated Green; Palm; Bay-breasted; Blackpoll, Black-and-White and Canada warblers; American Redstart, Ovenbird; and Common Yellowthroat.

The following days were much quieter and did not boast such a remarkable list, perhaps due to the return of the Summer weather, which is also promised for much of the coming week. It will be interesting, as always, to see how the warmer temperatures affect the visual migration and the capture rate at the Cabot Head Research Station.


A nanotag, with its antenna and the loops that go above the thighs.

A tagged Swainson’s Thrush:

3 Comments on “A burst of warblers!

  1. This is really fascinating and important work, and I look forward to hearing some results one day.

  2. Extreme care is always used when banding a bird, regardless of the markers. The nanotag project has been approved by Animal Care Committee and the Bird Banding Office issued the permit for it. The tag is 0.9g, less than 3% of the bird weight. The loops go over the thighs and the nanotag sits on top of the back.