Arb Notes for April 7 – An Obscure Sign of Spring

7 April 2011
A campus squirrel thoroughly cleaning a discarded muffin wrapper.
A campus squirrel thoroughly cleaning a discarded muffin wrapper. Photo by Audrey Kan ’18.

As the climate has warmed over the last week you may have noticed buds on trees, the grass growing greener, the frolicking of squirrels, or birds singing profusely in the morning sunlight. But if you are sitting indoors, feeling rather grumpy, like me, about only being able to look out at the cheerful community of plants and animals thriving in Bambi-esque harmony, you may not feel positioned to appreciate such things. What follows is a list of springtime behavior for the overburdened studentry of Carleton College, who can no longer feel joy:

1) As the snow melts, the hidden corpses of winter are revealed. Beetles of family Silphidae hone in on the scent of decaying flesh, often tracking down corpses before other “decomposers” are able to make use of them. A pair of Silphids digs beneath the corpse, covering it with the removed dirt and debris until it is out of reach of other insects, ensuring that there will be no competition in consuming the corpse. The female then lays her eggs on the putrid mass, so that her offspring may feast upon meeting the world.

2) The birdsong around us means that a number of passerine species are preparing to breed. If successful, they will feed their offspring in earnest until they fledge and leave the nest. But what to do with the excrement produced by these altricial residents of such close quarters? Fortunately, songbirds have an adaptation for that: fledglings surround their refuse with a layer of mucus membrane shed from their innards, creating what’s called a “fecal sac.” The adult then consumes the fecal sac or, if not hungry, drops the sac on a crowded sidewalk, picnic table, or vehicle near the nest.

3) The female red squirrel (Tamiasciurus hudsonicus) is in estrus for only one day each year. She makes the most of it, mating with 4-16 males over the course of the day. Territorial males are all too willing to oblige, chasing females and the powerful, pheromone-laden scent they produce. With such limited time for both partners, the day becomes a hedonistic celebration of reproduction. It’s unclear when this day will occur, but keep your eyes peeled if you’re out in the Arb.

  – Owen McMurtrey ’12, for the Cole Student Naturalists

Thumbnail photo by Joanne Bouknight

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