Summer World_ A Season of Bounty - Bernd Heinrich [92]
Grackles must have some good reason to travel (and sleep) in huge crowds. Aside from the trivial proximal reason that they like company, what is in it for them? What is the selective advantage that makes the grackles want to be associated with others? There are many possible mutually nonexclusive reasons, such as safety in numbers; sharing information so as to find food, identify an enemy, or issue a warning; and better access to food (such as by flushing prey). But I doubt that these late-summer foraging crowds flush much prey for each other; the insects they forage from don’t fly or drop from the leaves. Better access to food, such as raven crowds gain by overpowering strong defenders, is also not a real option. Mutual education—showing each other where to find food—seems possible, but more likely they also compete for food. Only one thing is certain—they already live in a different world from the one they inhabited all summer, even though they have not yet even left the state.
21
Silent Summer
I BREW MYSELF SOME COFFEE AND THEN LEAVE TO revisit Huckleberry Bog, a haven for many plants and animals that are not found in the forest. It is surrounded by forest and edged by a cordon of dense brushy thickets growing in algae-covered water. I don tough pants and a shirt when I need to force my way through, but I don’t wear boots—they get filled with ice-cold muddy water when I get to hip-deep holes or beaver channels. Wet cold feet are obligatory, and I put on worn-out running shoes. With some relief I finally break through to enter the bog proper, where I am in the open and walk on an ancient mat of roots and sphagnum (peat) moss that has grown over a glacial pond. Some of the same tree species that grow at the periphery are also present—red maples, black spruce, and larch. But here they are scattered and look stunted, like bonsai. As if I were walking on a waterbed, each footstep depresses the root and moss mat, and it sinks a few inches, to rebound when I lift my foot—hence the name “floating bog.” Somewhere still preserved in the solid bottom below me is the pollen of plants that grew on surrounding hills after the last ice age. Did a woolly mammoth or two break through and leave its bones here also? Except for the refrain of the yellowthroat and six other birdsongs, the bog remains silent. It does not tell. But a white-throated sparrow flushes near my feet, and I gaze into its nest cup, which is sunk into the wet moss. I admire four blue-green eggs spotted and blotched in reddish brown. What don’t I see? Where is the olive-sided flycatcher? It always used to be here, perched on the tip of a tamarack and repeating its loud clarion call that seemed like the signature sound of the bog. Where are the bumblebees? They are the only bees able to forage, and pollinate, many of the bog plants (as well as commercial berry crops) when the weather is cool or otherwise not suitable for other bees.
In the early haze on this cool morning, the bog’s open expanse is a study in rich greens and pastels. The overwintered needles of the stunted black spruce are bleached to a yellowish tinge from the previous summer’s fresh blue-green. None of their leaf buds have yet opened, although the tamarack, also a conifer, had shed golden yellow needles in the fall and is now opening all of its buds on its black-and-white lichen-encrusted twigs, revealing tufts of light bluish green needles. An intricate intertwined tangle of evergreen perennials—leatherleaf, swamp laurel, rosemary, Labrador tea, lambkill,