Kirtland's Warbler Study

June 5, 2014 by Nathan Cooper

Just over two weeks are in the books here in northern Michigan, and a lot has gone on in such a short period of time. The females were just rolling into town during our first day in the field, but we heard plenty of males singing right from the start. Females of migratory species usually arrive after the males, enabling them to judge potential mates on habitat-related qualities, such as the size and quality of the territory they're defending.

As the season has progressed we've seen more and more female birds and have shifted our focus toward determining if they are building a nest. Having seen a few females with nest materials in their bills through the end of May, we finally got a major monkey off our backs on the first day of June—finding our first nest of the year.

The morning was winding down and Nathan wanted to double-check a pair sitting on a territory right next to our truck before we called it a day. He had seen the female looking "anxious" earlier in the morning and was convinced he was near her nest. Before I could double-back to assist for a second look, he had already tracked our girl placing some dried up grass and needles under a small Jack pine. A few steps farther back and using another pine as cover, Nathan struck the perfect balance between standing close enough to track the bird and standing far enough away to give her the security to go about her business building a home for her future young.

Drawing back the curtain of freshly-leaved shrubs revealed a small, brown cup made up of interwoven twigs, needles, and grasses, and built into the side of a small depression that enveloped the base of a young pine. After tracking a dozen or so females carrying nesting material without finding a nest at the end of the rainbow, we were ecstatic to finally find nest #1, or NWC01 as it will be known henceforth.

With hopes of finding many more, this was an important first step in understanding the behaviors indicative of a female close to her nest. Unlike their male partners, the females tend to stay low to the ground and rarely make a noise beyond their sharp, singular call note. We'll take every edge we can get in learning how to track these elusive birds through the thick plantations of Jack pine.

Much to our delight, the Kirtland's warbler isn't the only species setting up shop amongst the rows of Jack pine. As is often the case, setting aside a large chunk of land with the intention of conserving a particular species of interest has the added benefit of placing other species under the same protective umbrella.

small olive and yellow bird
Nashville warblers share the same habitat as Kirtland's warblers. Photo by Jerry Acton.

Nashville Warblers and Palm Warblers are the main warblers sharing the expanses of Jack pine with the Kirtland's, and Ovenbirds and Yellow-rumped Warblers are often heard from the adjacent, taller stands of pine that have outgrown Kirtland's warbler suitability.

A plethora of sparrows are fairly easy to find, including Eastern Towhees, Dark-eyed Juncos, Chipping Sparrows, Grasshopper Sparrows, Clay-colored Sparrows, Field Sparrows and Lincoln's Sparrows. We've stumbled upon a Common Nighthawk and a Northern Harrier roosting in a couple of more open areas. Blue Jays and Brown Thrashers seem as abundant as ants, and Upland Sandpipers are scattered throughout the clear-cut fields being prepared for future plantings.

The coming days will hopefully bring many more nests and the first attachings of geolocators. Stay tuned.

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