A hundred years ago Carolina wrens (Thryothorus ludovicianus) were a southern bird rarely found in southwestern Pennsylvania but they expanded northward during the 20th century, even into Canada.
Carolina wrens don’t migrate so they have to cope with winter wherever they settle down. When winters are severe they die off and are rarely seen until new individuals disperse northward to fill the gaps. This was particularly noticeable after the harsh winter of 1977-78 when it took them ten years to recover their northern haunts.
Since then they’ve done quite well, a success due in part to human changes to the landscape. Warmer winters, regrown woodlots, and backyard bird feeders all make it easier for Carolina wrens to survive though it wouldn’t have been possible without a change on their part, too. In 1912 Dr. Frank Chapman considered them to be woodland birds unadaptable to human settings but by 1948 Arthur Bent observed that there was plenty of evidence they’d made the change. Indeed we see them near our homes every day.
This winter may be a tough challenge for Carolina wrens. During the polar vortex January 6-7 many birders were concerned that their favorite wrens would perish. We were happily surprised that they came through, sometimes by hiding in our buildings, during the two-day cold snap.
This week will bring another, longer round of arctic cold with temperatures down to 0oF. Will our wrens make it through this time?
Fill your feeders and cross your fingers. May our Carolina wrens be winter-hardy, greeting us with their loud calls and songs when the weather warms again.
(photo by Marcy Cunkelman)