Warblers in October.

In the past week, we likely experienced the last very warm days of the season with highs over 20°C on October 4 and 5, accompanied by lots of rain on the latter. No banding was possible during that day, of course. The following day, October 6, brought clearing skies and an increasing wind. The banding tally was an impressive 79 birds banded, the highest of the season (by one bird!) and eight recaptures. It is possible that birds knew what was coming. Indeed, the change of weather was quite sudden and brutal for the long Thanksgiving weekend: Saturday was marked by an increasing and shifting wind and an overcast sky bringing lots of rain. A break in late morning allowed us to open the nets for three hours, which produced 45 newly banded birds. It was good to have the chance to have the nets in operation since they stayed safely furled on Sunday and Monday while wind and rain unleashed their fury in a suddenly cold air. It is the first massive cold front of the Fall moving through Lake Huron, though certainly not the last. 

Golden-crowned Kinglets were again the most abundant birds in our nets when banding was possible, alongside a few Ruby-crowned Kinglets, Brown Creepers, and the occasional Winter Wren. And of course, various sparrows, Hermit and the last Swainson’s Thrushes, and the straggler warblers.

Among the Last of Fall, there are a few forest gems (aka warblers) lingering in October, much to our delight. So far, we have recorded a total of ten species of warbler this month. Totals across the years (2002 – 2022) have ranged from five to 15 for a total of 21 different species over all years. This October, we detected the expected ones, Orange-crowned, Nashville, Yellow-rumped, and Palm Warblers. These four species are to some extent late migrants and the only ones always seen in October (except Palm Warbler in October 2004: gasp! How could we have missed it?!). A group of six warblers have been recorded in October between ten and 13 previous seasons. Among them, this Fall, four were noted: American Redstart, Magnolia Warbler, Common Yellowthroat, and Black-throated Blue Warbler. In 2023, Northern Parula were banded on October 6 and 7 (one each), a species seen in October in six previous Fall seasons and as late as October 30 in 2016. Cape May Warbler, the tenth species seen so far this Fall in October was detected on October 6, with one banded and one observed. This species is much more rare at this time of year, with one bird on October 2nd in 2018 and one on the 7th in 2021. In 2023, a total of seven warblers were detected on October 6, the day in between rainy days, likely not a coincidence. When it comes to bird migration, the unexpected is always to be excepted, so it is possible that another species of warbler will show up before the end of the banding season on October 31. Stay tuned!

Addendum: Tennessee Warbler, the 11th species of warbler for October was seen on the 11th, with two observed and one banded. The blog post was written on Monday the 9th.