This is one of North America's true warbler Meccas: the sandy jack pine country of the upper lower peninsula of Michigan. And for one reason, the federally endangered Kirtland's Warbler. At a glance, it doesn't look like great warbler country. Dwarf pine carpet dry sandy soils, and there's scarcely a broad-leaved deciduous tree to be found.
We visited a promising area near Grayling, and it didn't take long to score. The birds are quite finicky about their habitat preference, utilizing Jack Pines from 5 to about 15 feet in height. Kirtland's Warblers are not exactly shrinking violets, and have loud rollicking songs that almost sound as if they run the tune through a Marshall amp with a tinge of reverb.
A bit of poking around and perseverance and we were rewarded with good looks at a singing male. There were at least three others in earshot, too.
By the 1970's, numbers of this exceedingly rare warbler had crashed. Less than 200 singing males were present. A better understanding of the bird's habitat requirement led to better management, and last year there were over 2,500 singing males. A heavy hand with Brown-headed Cowbird control has also been vital to the restoration of Kirtland's Warbler.
This is the magical tree in the land of the Kirtland's Warbler: Jack Pine, Pinus banksiana. Those tough little cones require heat to unseal the gummy pitch that shutters the scales, so that seeds can be released. Fire management does this, and burning is the tool that has spiked the warbler population.
Jack Pine "barrens" are anything but barren. It had been a while since I've roamed these haunts, and I was struck by the diversity of flora growing throughout the pine stands. And staggered by the number of moths. They were everywhere, obvious even on a bright sunny day. Of course, all of those moths are producing boatloads of caterpillars, and that's what is fueling these warblers. By the time the pine stands get into their late teens, they have begun shading out the understory, reducing plant diversity, and consequently moth numbers.