With the arrival of Sharp-tailed Sparrows and Nelson’s Sparrows, our spring migration is finished. These two species are the last or our migratory breeding birds to arrive in Maine.
I trust that you had the chance to enjoy the spring migration. A few days were very exciting with significant fall-outs of warblers, tanagers and thrushes.
Today, I will provide a second-hand report on what has to be one of the most mind-boggling birding experiences ever. Ian Davies and five colleagues collected the data reported here. My report is based on Ian’s field notes.
The setting is May 28, 2018 at the Tadoussac Bird Observatory (Observatoire d’Oiseaux de Tadoussac) in Quebec. The location is on the north shore of the St. Lawrence River, just northeast of the confluence of the Saguenay River with the St. Lawrence. The habitat here is a series of sand dunes, offering hence great visibility of arriving migrants.
The team of birders was excited about the possibilities of a good day for migration because southwest winds had blown through the night and dawn rain was expected. Throw in a habitat like the Tadoussac dunes that provide a refuge for exhausted migrants flying over the St. Lawrence River and you have all the ingredients for a fall-out.
Starting at daybreak and birding for almost 10 hours, the team recorded 108 species of birds. That is a nice total but breaking the century mark for species is not unusual during spring migration. Rather, it was the total number of migrants that was simply flabbergasting.
Buoyed by the weather conditions, the team was hoping for a great day of birding. Their first stop yielded no birds so the team decided to head for the Tadoussac dunes. Great choice!
Arriving at 5:45 AM, the team was excited by groups of 5-10 warblers. The showers let up around 6:30 AM and the warbler floodgates were opened. For the next nine hours, the birding team did their best to count a non-stop flight of warblers. Sometimes the birds darkened the sky from horizon to horizon. I can’t help but think of the sky-darkening clouds of Passenger Pigeons that John James Audubon described that took four days to pass.
To cut to the chase, the birding team counted over 721,000 warblers at Tadoussac! I’ve never experienced a fall-out to rival this one but even with less impressive fallouts, the birding is bewildering. There are so many birds – where do you look?
To the credit of the Tadoussoc birders, censuses of the birds were taken throughout the day. The protocol was to look through binoculars at a flight line of birds and count the number passing a vertical line each second. Then the binoculars were raised or lowered to a new flight line, attempting to account for all the birds flying past in a short interval.
From 7:15 AM until 8:03 AM, 84,600 warblers were counted. Another 73,500 were estimated between 9:49 and 10:38. Finally numbers started to diminish around 3 PM and only(!) 5,000 warblers were counted over the next 20 minutes when the birders called it a day.
The previous record for warblers in a day in this part of the world was around 200,000. The May 28 fallout blew the old record out of the water.
On top of the challenge of assessing the number of birds, determining the species composition posed an additional challenge. About 100,000 the birds had to go as “unidentified warbler” but most were identified.
Here are the counts of the most abundant warblers of the 22 species sighted: 72,162 Tennessee Warblers, 50,513 American Redstarts, 108,243 Cape May Warblers, 108,000 Magnolia Warblers, 144,324 Bay-breasted Warblers (20% of the total warblers), 28,865 Blackburnian Warbler, 72,162 Yellow-rumped Warblers and 14,432 Canada Warblers.
Take a look at the list, photos and videos from this remarkable day at: https://ebird.org/view/checklist/S46116491