A beautiful Canada Warbler among many that landed during a rain squall with strong winds (photo by Ian Davies). One of an estimated 28,900 Blackburnian Warblers observed that fateful May 28th (photo by Tom Auer).

It’s an exciting time of the year for anyone who appreciates the spring migration of warblers and other songbirds during May. When you think of the best warbler migration you have witnessed, keep the date May 28th in mind. During that now famous day, 108 species of birds were sighted at the Tadoussac Bird Observatory in southeast Quebec, including unheard of numbers of birds, including an estimated 721,620 warblers! High estimates of individual species included 144,300 Bay-breasted Warblers, 108,200 Magnolia Warblers, 108,200 Cape May Warblers, 50,500 American Redstarts, 28,900 Blackburnian Warblers, 14,400 Canada Warblers, 3,600 Northern Parulas, 3,600 Wilson’s Warblers, 2,900 Black-throated Green Warblers, 1,450 Chestnut-sided Warblers, and 950 Blackpoll Warblers!

There were also lesser numbers of Black-and-white Warblers, Prairie Warblers, Orange-crowned Warblers, Black-throated Blue Warblers, Palm Warblers, Yellow Warblers, Mourning Warblers, Nashville Warblers, Common Yellowthroats, Ovenbirds, and Northern Waterthrushes. Of course, there were some warblers that flew by so quickly that it was impossible to identify them by species; these “unidentified warblers” numbered 109,555!

Unfortunately, with the rate of migration taking place combined with the small size of the birds and the distances involved, it was not possible to get a really accurate count of the most abundant species, but the estimates are best-case estimates conducted by seasoned birders familiar with the process. The numbers listed above were submitted by Ian Davies with Francois-Xavier Grandmont, Sarah Dzielski, Thierry Grandmont, Tim Lenz, and Tom Auer during a count period of 9 hours and 41 minutes. Ian described it in a simple sentence: “Today was the greatest birding day of my life.”

Now That’s a Big Day!

This most historic warbler count was made May 28, 2018 in southeast Canada – at Tadoussac Dunes, near the Tadoussac Bird Observatory in southeast Quebec. Tadoussac is a quaint village just north of the most northwest point in Maine and 135 miles northeast of Quebec City, where the St. Lawrence Seaway expands into an Atlantic estuary, and where the Saguenay River meets the St. Lawrence.

Ian Davies continued to describe the conditions and birding action as “Southwest winds overnight led to high hopes for the morning, compounded by dawn rain in the area. Our first stop was fruitless, with a handful of warblers moving, but nothing notable. We decided to head for the Tadoussac dunes anyway.

”Upon our arrival (5:45am), it was raining. A few warblers passed here and there, and we got excited about groups of 5 to 10 birds. Shortly before 6:30am there was a break in the showers, and things were never the same. For the next 9 hours, we counted a nonstop flight of warblers, at times covering the entire visible sky from horizon to horizon. The volume of flight calls was so vast that it often faded into a constant background buzz.

“There were times when there were so many birds, so close, that naked eyes were better than binoculars to count and identify species. For hours at a time, a single binocular scan would give you hundreds or low thousands of warblers below eye level [from ground level to eye level].

“The flight lines varied depending on the wind direction and wind speed. All birds were flying southwest. When the wind calmed, birds were high, often inland or farther out over the river. High winds (especially from the W, or SW), brought birds down low, sometimes feet from the ground and water. Rain also [kept birds low], and the most intimate experiences with migrants occurred during a rain squall and strong wind period. Hundreds of birds stopped to feed and rest on the bare sand, or in small shrubs.

“Counting birds and estimating species composition was the biggest challenge of the day, balancing the need to document what was happening with the desire to just bask in the greatest avian spectacle I’ve ever witnessed. A significant effort was made to estimate movement rates throughout the day, and those rates combined with species-specific movement estimates were used to estimate the species totals. I made a couple attempts to video, but the videos only hint at the magnitude of the spectacle. (During the most intense migration period, from 12:49 to 1:13pm, Ian estimated the number of warblers passing by at 72,000 in 24 minutes!)

Total Warblers = 721,620, but …
“To our knowledge, the previous warbler high for a single day in the region was around 200,000, which was the highest tally anywhere in the world,” Ian noted. “Other observers in the area counted multiple hundreds of thousands, so there were likely more than a million warblers moving through the region on May 28, 2018. Thank you to the Observatoire d’Oiseaux de Tadoussac for monitoring these movements for decades, and sharing the wonder of this place with the global birding community. There’s no place like Tadoussac.”

To refer to Ian Davies’ original eBird report, see eBird Checklist - 28 May 2018 - Dunes de Tadoussac - 108 species (+3 other taxa) and for more information about the Tadoussac Bird Observatory, refer to Home – Tadoussac Bird Observatory (bing.com)