Desperately seeking territory: the Kirtland’s Warbler

Sometime in June, somewhere around the Great Lakes, perched at the very top of a tree in a young, densely growing forest, a male Kirtland’s Warbler throws back his head and lets rip with a series of bubbly, clear notes that steadily rise in pitch, tempo, and volume: chip-chip-che-way-o. Spring is here! I’ve found the perfect spot, he calls.

He had to work hard to find it. This is a bird that has come back from the brink. In 1973, when legislation to protect endangered species was introduced in the United States (1977 in Canada), the Kirtland’s (Setophaga kirtlandii) was one of the first on the list, its global population down to an estimated 300-500 birds. Now it’s up to 5,500, breeding mostly in Michigan, where conservation efforts started in the 60s.

The habitat that meets this bird’s needs is so specific. It occurs only in the Great Lakes basin, mainly south of the Canadian Shield: Sandy soil with young pine and oak trees, 10 to 20 years old, growing densely with frequent clearings, with an understory of native shrubs and ground cover of native forbs and grasses to generate the insect populations and fruit required to feed young. It nests on the ground, sheltered by the boughs that sweep down to soil level. As the trees age, they drop these lowest branches and these warblers have to move on.

The desired conditions are created naturally as a fire sweeps through, a regular and necessary occurrence for North American forests. And the male Kirtland’s Warbler knows how to identify the perfect spot. After wintering in the Bahamas, he returns to the breeding grounds in spring and makes long exploratory flights across the landscape, looking down to spot the areas where a forest fire a decade earlier will have created trees and other vegetation of precisely the right mix. When he finds it, he advertises - and hopefully the females arrive.

On the historic breeding grounds in Ontario, although many areas were suitable, European settlement brought agriculture, commercial forestry, urbanization, fire suppression and invasive plants. Young pine-oak forest has not been part of the plan.
KIWA Tracking Map 2017
That doesn’t stop the bird from searching. This was vividly demonstrated during a recent presentation by ecologist Peter Burke to the Midland Penetanguishene Field Naturalists (MPFN), when he showed the tracking of Kirtland’s Warblers that had been tagged in the Bahamas in the winter of 2016-17. Six of them criss-crossed Ontario, as can be seen in the map reproduced here.

“When I first saw this my jaw dropped,” said Burke, then with Savanta Inc. which is now GEI Consultants. “You could see birds going as far east as Kingston! And some of them are going back west and coming back east and then going south and then going north.” It was obvious to him that the birds looking for something.

“These creatures are hardwired for looking across the Great Lakes basin for fire-based services,” he explained. “It’s a thousands-year-old ecological process for the region, Southern Ontario does have pine-oak communities. The birds just must know this.”

There had been occasional sightings of Kirtland’s in Ontario through the years, but the only places where they were known to breed was at a military base, Garrison Petawawa, and one other location, with zero to two pairs reported from year to year.

Their presence wasn’t the result of management by the Department of National Defence. The habitat was created incidentally, doing base things like artillery practice and fire control exercises, Burke said. Add sandy soil and a history of pine-oak forest and the warbler was able to hang in. Barely.

But elsewhere in the province, intentional management has been taking place, thanks to the County of Simcoe where restoration was undertaken in two tracts, starting in 2016. An amazing milestone was achieved last year when several male Kirtland’s Warblers were heard singing in the Packard Tract, halfway between Angus and Barrie.

This was a Canadian first – the creation of breeding habitat for the Kirtland’s Warbler, a bird with fewer than 5,500 individuals, with a core population 800 kilometres away in Michigan

It had been seven years since Burke had first dropped in on the Simcoe County forestry department to float the idea, five years since county council authorized the go-ahead for restoration of the Museum Tract, which was severely degraded by years of use by the Canadian Pacific Railroad. The Packard Tract was in better shape when it was purchased in 2011, with an existing Red and White Pine plantation.

Both sites underwent a prescribed burn, removal of the non-native Scots Pine and other invasive species, then planting and seeding of 90 species of plants know to be associated with young pine – oak woodlands of Simcoe County – all labour-intensive undertakings that required much expertise from professionals and dedicated input from volunteers.

As a measure of the fact that this was no small undertaking, here's the list of a total of 151,900 trees planted on 50 hectares of the Museum site: 106,000 Jack Pine (Pinus banksiana), 28,900 Red Pine (Pinus resinosa), 8,000 White Pine (Pinus strobus), 3,500 Black Cherry (Prunus serotina), 3,800 Red Oak (Quercus rubra), 1,100 White Oak (Quercus alba) and 600 Eastern Red Cedar (Juniperus virginiana).

And here are some of the people and organizations involved in the two projects: County Forester Graeme Davis and forest technician Will Cox (described by Burke as masterminds of the project), ecologist Ken Tuininga (then a species-at-risk specialist with Environment and Climate Change Canada), American Forests, Forests Ontario, Mary Gartshore Consulting (a renowned restoration ecologist) and Ganawenim Meshkiki - Henvy Inlet First Nations.

Although project managers had started to use audible attractions at Packard as early as 2021, the prediction generally was that the earliest date for the birds to arrive was 2023.

Burke picked up the story for the MPFN: “You can imagine our surprise when on June 9, 2022, last year, we were called to the site. It turned out that Jim Forrest of Barrie and Willem Span, who worked at the Tiffin Nature Centre just outside of Packard, had been seeing males at Packard, on their territories.”

The birds had found what they were looking for.

“It was with a little bit of disbelief that we made our way out there the next day and this is what we saw,” said Burke, displaying a picture of a bird calling from the top of a Red Pine. “We got there right at first light… to our surprise we could hear not just one but more than one Kirtland’s Warbler singing… It was quite something.”

A plan kicked into gear to share the news with the public while ensuring the birds would not be disturbed. The Ontario Field Ornithologists’ rare bird ambassador program came into play and local naturalists volunteered to be KIWA Ambassadors, on hand to greet people and explain proper conduct and etiquette for visiting birds. Over 400 people came.

The future looks promising. A Kirtland’s Warbler Ontario Working Group has been established to bring together people with expertise in topics such as planning, land acquisition and education – members are Sir Sandford Fleming College, Nature Conservancy of Canada, Oak Ridges Moraine Land Trust, Simcoe County Forestry, the American Bird Conservancy and several ecological consulting companies.

The county is considering other sites within its 33,000-hectare forest that may be suitable for restoration – Cedar Point, Orr Lake and the Crawford Tract are candidates that could have some future involvement. The Oak Ridges Moraine Land Trust is hoping to purchase a 196-acre property that has been identified as suitable for the Kirtland’s Warbler. A fundraising drive is ongoing. And it's hoped private landowners may come forward.

Now the wait is on for when the females arrive at Packard, and for when the first males decide the Museum Tract might be ready for them. What a success story! A story with real momentum, thanks to a courageous bird that never stops looking.

Midland Penetanguishene Field Naturalists – the presentation starts at 10:38 mns.

This Wisconsin site is where I got my transcription of the warbler's song. 
- 4 March 2023 at 08:03am

Fabulous article - looking forward to seeing it this spring.
- 4 March 2023 at 08:28am

Great story, thanks for letting us know about this, Kate!
Ian Cook
- 17 March 2023 at 02:24pm

Excellent article that concisely covered what I needed to know in a well written style
Channa Jayasinghe
- 4 July 2023 at 03:13pm

Hope this project will succeed in the sites in Simcoe becoming established as a suitable habitat for the Kirtland Warbler. I was fortunate to hear its call on my first visit last year and then on the second time, a male landed on a pine right next to me and sang its song. Such a wonderful experience of seeing probably the most rare warbler of North America (if Bachman's Warbler is now extinct).
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