A River of Warblers: ‘the Greatest Birding Day of My Life’

At an observatory in Quebec, they were hoping for a 50,000-bird day. They saw more than half a million.

A Canada warbler.CreditIan Davies

Ian Davies got hooked on birds when he was 12. He went to a site near Plymouth, Mass., where volunteers were putting bands on migrating birds.

“They let me release a Canada warbler,” he said, “and that was just game over.”

On Monday, he saw an estimated 700,000 warblers and set the birding world all atwitter with a posting on the site eBird describing the astonishing event.

The posting begins simply:

“Today was the greatest birding day of my life.”

He may one day top it, because he is 26. But he has a good deal of experience to look back on already. In 14 years of dedicated birding, he has been to 35 countries, and is the project director of eBird, a citizen science project for gathering data from the worldwide community of birders, who contribute data on about 100 million sightings a year.

He and his fellow birders were at the Tadoussac bird observatory in Quebec, on the north bank of the St. Lawrence River. Pascal Côté, the director of the observatory who has been monitoring birds there for 10 years, said “I have never seen anything like this.” His group, at a different location in the same area, saw 200,000 birds in what was only one part of a miles-wide corridor. He said he thought the total was probably closer to 500,000, but could be higher.

It was, in any case, ten times as many as he had ever seen in a day, and, he thought, the most passerines, or perching birds, ever seen in one day in North America.

Mr. Davies’ method for counting was to calculate the rate of passage of birds across an imaginary line at different points through the day for a few seconds and extrapolate. Mr. Cô’s team counted birds at their spot with a different approach, trying to tally the actual numbers, not one by one, but in blocks. An observer might count out 10 or 50 or 100.

It was a personal trip for Mr. Davies. “We were chasing something like this,” he said yesterday in a phone conversation, still at Tadoussac, still observing and counting birds. “Our wildest hope was to have one day with 50,000 warblers.”

“As far as we’re aware,” he said, “it’s three times the number of warblers that anyone has ever seen at a location anywhere. It was basically a river of warblers. All heading southwest.” The previous record was 200,000.

These are northward migrating birds, but frequently at Tadoussac, there is a huge morning flight of warblers who have overshot the mark or have been blown off course and are heading back to known food sources before continuing on.

Earlier reporting on birding

The morning started off quiet, he said, and then the birds just kept coming. They did not quite darken the sky as passenger pigeons once did. But the group was stunned because they kept coming for nine hours.

They had to calculate the rate at which the birds were passing rather than count individuals and Mr. Davies said, “It felt sort of like a dream. How do you communicate what that dream was like to others.”

There were more than 100,000 each of Cape May Warblers, Bay Breasted warblers and Tennessee warblers.

Like the rest of the world, birders use Twitter, and they tweeted in delight:

The reason for the large number, Mr. Davies speculated, was that these are birds that eat the larvae of the spruce budworm, and their populations explode when the budworm numbers go up.

He is not sure how he is going to top this day and joked, “I need to find a new hobby.”


A picture caption in an earlier version of this article misstated the name of a bird. It is a Canada warbler, not a Cape May warbler.

James Gorman is a science writer at large and the host and writer of the video feature “ScienceTake”. He joined The Times in 1993 and is the author of several books, including “How to Build a Dinosaur,” written with the paleontologist Jack Horner.

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