Male Kirtland’s Warbler

In the northern half of Michigan’s Lower Peninsula 150000 acres, approximately 235 square miles, of mainly Jack Pine (Pinus banksiana) are managed to provide habitat for the endangered Kirtland’s Warbler (Setophaga kirtlandii). At any given time approximately 38,000 acres are suitable nesting habitat.

After an area is logged, it is furrowed and then planted with 6 inch [15 cm] tall Jack Pine seedlings. Some Oaks (Quercus spp.) and some tall Pines (Pinus spp.) are left to provide perching sites for the warbler’s territorial singing. Jack Pines are not planted in continuous stands but contain grassy openings. Kirtland’s Warblers nest on the ground, normally at the edges of these openings. When the pines are 5-8 feet (2-3m) in height nesting begins. Nesting continues as long as there are branches touching the ground and the branches of adjoining trees. Four to eight years are required for the pines to reach nesting size and they are suitable for nesting for 12-15 years. After another 30 years or so, the forest is cut for pulpwood and the cycle begins again.

Figure 1 Photo by Bob Anderson copyright 2009

Figure no. 1 shows a Kirtland planting at the end of its first year. Furrows are still visible and you can see the tops of seedling Jack Pines. Figure no. 2 shows the same area five years later. Oak #1 has grown but the “pine stand” is mostly unchanged. Kirtland’s Warblers started to nest in the Figure no. 2 stand.

Figure 2 Photo by Dave Bissonette copyright 2014

Management areas produce habitat for other species. Hill’s Thistle (Cirsium hillii) is a state threatened species. At most two feet [.6m] high it has large, pink, flowers that dot the plantings. Wood Lily (Lilium philadelphicum) and Sweet-Fern (Comptonia peregrina) also inhabit the areas.  Northern Apple Sphinx Moth larva (Sphinx poecila) feed on Sweet-fern.

Hill’s Thistle

L Northern Apple Sphinx Moth larva R Wood Lily

The Kirtland’s management areas are helping the warbler to recover. It is also altering the landscape, providing homes for a large number of other species.
Copyright 2015 by Donald Drife

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