My data is anecdotal, but I am optimistic that the cold snaps and snows of this winter will not affect the wrens as badly as the cold snaps of the 1970's did. When I moved here in 1972,  I never saw Carolina Wrens in the suburbs, as I often do now, nor did they come to my feeders. They were regular birds in wooded areas containing thick undergrowth but much less numerous than they are today. Also, the cold snaps of the 1970's lasted much longer. I remember one in the mid seventies after which it was normal  for a year or two to miss Carolina Wren on a typical day of birding the Kansas City area.
Here's what's different now:
There are a lot more wrens to start with.
Apparently having evolved to handle suburban habitats, more can take advantage of feeders.
This winter's cold snaps have only lasted a few days.
Carolina Wrens have a high rate of reproductive productivity, laying 4 to 6 eggs and raising 2 or 3 broods per year.. 
Bob Fisher
Independence, MO
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