Jack Pine Planting for Kirtland's Warbler Habitat
Truly a Great Lakes National Forest, the Hiawatha National Forest of Michigan’s Upper Peninsula provides visitors a chance to explore more than 75 lakes, including 3 of the 5 Great Lakes, and 600 miles of streams. Within this lake-filled forest, visitors can hike and swim, visit six lighthouses, and spot diverse wildlife, including gray wolves, deer, monarch butterflies, bald eagles, and one of North America’s rarest songbirds, Kirtland’s warbler.
Our tree planting efforts on Hiawatha National Forest contribute to the recovery of this rare bird, a habitat specialist that requires young jack pine stands for breeding and nesting. Between 2011 and 2018, we’ve planted 382,000 jack pine seeds and seedlings across hundreds of acres of the forest.
After arriving from its winter grounds in the Bahamas in the spring, the warblers breed and nest in young jack pine forests of Hiawatha National Forest. They nest on sandy soil underneath young jack pines that are between 6 and 22 years old, 5 to 20 feet tall, and have enough space between them for adequate sunlight, yet dense with abundant foliage. Why such specificity? When the trees are about six years old, the lower branches are just long enough to reach near the ground and hide a nest underneath, while the sunlight keeps the foliage alive and fluffy. As the trees age, taller branches block sunlight to the lower branches, which then begin to die and can no longer conceal a nest.
The loss of suitable habitat prompted the Kirtland’s warbler to be one of the first species to be protected under the Endangered Species Act of 1973. Historically, fire played an important role in jack pine ecosystems. Fires cleared out thick brush and old trees, and allowed the jack pine’s serotinous cones to release seeds and regenerate new stands of young jack pine essential for Kirtland’s warblers. Decades of fire suppression has yielded dense older stands, inhibiting the establishment of young stands and restricting the warbler’s habitat. Habitat management and tree planting helps to imitate the effects of fire and create suitable habitat for the warbler.
While Kirtland’s warblers remain rare, these habitat specialists are on the rise and they were recently removed from the federal list of endangered species. Their numbers have increased from about 200 pairs in the early 1970s to about 2,300 pairs in 2019 at their nesting grounds in northern Michigan, Wisconsin, and Canada.
Our efforts to improve Kirtland’s warbler habitat through tree planting have been supported by a diverse mix of individual, small business and corporate supporters. Since 2012, NFF tree-planting partner Lands’ End has been a leader of our reforestation efforts on the Hiawatha National Forest and beyond.