Wild Ideas: Hanging out with your peeps in winter

8:45 a.m. Jan. 31, 2013
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Winter is not my favorite time of year for several reasons, including the fact that a lot of wildlife have gone south for the winter or are hibernating. Most plants are dormant, making the landscape bleaker. When wildlife are out and about, it’s often in groups.

These five-lined skinks were discovered recently brumating (similar to hibernating) in a pile of leaves and other debris in Rappahannock County. Photo by Pam Owen.

These five-lined skinks were discovered recently brumating (similar to hibernating) in a pile of leaves and other debris in Rappahannock County. Photo by Pam Owen.

I started mulling over this winter communal tendency after three events recently: a flock of vultures had briefly chosen to roost in the town of Washington, five male cardinals were sitting quietly together in one bare sapling in the forest that borders my backyard and my landlord found a half-dozen five-lined skinks hibernating under some debris near his garage.

While spring brings individuals in some species together briefly to mate (such as frogs), individuals in other species, especially birds, disperse at that time to stake out and defend territory in which to mate and raise their young. Once the breeding season is over, some species come together for a variety of reasons: protection, foraging, keeping warm or other reasons that may not be as apparent and could include social components. Winter groups may consist of just a few individuals, or, as in the case of some bird species, huge flocks – or both.

Birds are especially likely to come together in winter. Some form loose flocks, coming together to feed and roost; others may stay in flocks throughout the day. During this winter communal period, these groups have to sort out dominance, with males at the top of the hierarchy in most species.

Advantages to grouping in terms of security are pretty obvious – such as an enhanced ability to drive off or distract intruders – but wouldn’t individuals fare better when it comes to foraging? In winter, food tends to be scarcer and more concentrated in fewer areas. Insects are not active, and a multitude of plants are not producing fruit. What fruit is available is usually on late-fruiting plants, from grapes to tough-skinned winterberry.

In winter, some wildlife switch their diets to take advantage of these cold-season offerings or supplement them with fruits. Wildlife searching for these geographically concentrated foods may find sharing a better, or at least safer, strategy than doing it on their own. Winter groups are certainly more mobile than breeding pairs and can go where the food is.

Vultures are among the species that can form large groups to roost in the winter. This massing can be daunting to humans, considering the dark symbolism, unpleasant eating habits and copious amount of white poop these large birds bring with them.

Crows can also be especially annoying to humans. Like other corvids, a bird family that also includes ravens and jays, crows can be extremely vocal and loud, especially when massed in large flocks. I had a crow roost in pine trees in back of another house I rented in the county, and their convergence in the evening was indeed quite loud, but I loved having these fascinating birds around.

Dark-eyed juncos, American goldfinches, bald eagles, starlings (a nonnative species) and cardinals are among other bird species that flock up in winter. The five male cardinals in the sapling in my backyard looked like a classic Virginia Christmas card in which a male’s cheery red plumage stands out in contrast to the white and gray of the winter landscape. It was easy to figure out why these particular male cardinals were buddying up in the backyard on this occasion. I had swept a patch of the yard clear of snow and spread bird feed there. Although males dominate such winter groups, the fact that the cardinals in the sapling were all males was likely coincidental. At least as many females were nearby, and I often see them together.

The skinks found sheltering together under debris near the garage likely also were together coincidentally. Reptiles are inactive in winter to conserve energy, since they can’t generate it themselves as mammals can. Instead they seek shelter and brumate, a state similar to hibernation on or under logs, rocks, leaves or other natural debris or in underground dens. The half-dozen skinks just ended up in the pile of leaves and dirt because it was one of few options around the garage. Since my landlord was cleaning up around the garage, he transported the lizards to a safer location, piling up leaves over them to protect them.

Some snakes, including Virginia’s timber rattler, actually prefer communal denning in winter. They usually pile on top of each other, which may serve as some added protection against the cold.

   
 
 

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