The Carolina wren has expanded its range to Maine, and while you may not see them, chances are good that you will hear them. Carolina wrens have a loud rolling song – a repeated “tea-kettle, tea-kettle, tea-kettle” – that you can hear all throughout the year. Julio Cortez/Associated Press

Readers will hopefully be familiar with the red-bellied woodpecker as a species that has rapidly expanded its range northward in response to climate change. I’ve written about them here a few times as a very visible indicator of the changing bird life around us, and many inquiries come because people see in their (outdated) field guides that the bird “shouldn’t be here.” We’ve been getting quite a few inquiries lately about another species expanding its range: the Carolina wren.

Many people will know wrens for their characteristic cocked tail, but the Carolina stands out from its cousins thanks to its large size, and bold white supercilium (eyebrow) against a rufous head and body. Don’t get confused by the poorly named winter wren, our smallest wren which migrates away from Maine in the winter. French ornithologist Louis Jean Pierre Vieillot clearly was not thinking of Mainers when he gave the species its name “hiemalis” (meaning “of winter”) in 1819. Our house and marsh wrens also migrate away from Maine during the winter, so the Carolina is generally going to be the only one you see here while snow is on the ground.

If they are around and you don’t see them, chances are good that you will hear them. Carolina wrens have a loud rolling song – a repeated “tea-kettle, tea-kettle, tea-kettle” – that you can hear all throughout the year, especially on these late winter days when the amount of daylight extends and ambitious birds begin testing their songs.

A question about these wrens came in from Jean Noon of Springvale, as well as an interesting observation that they watched the wren foraging around their horse barn for spider eggs and fly larva. This is a fascinating piece of the Carolina wren’s range expansion story, because unlike the aforementioned red-bellied woodpecker that people often see visiting their bird feeders, the wren’s diet is primarily insects. Carolina wrens are occasionally seen taking seeds like sunflower hearts, or happily taking advantage of a suet cake you’ve put out, but much of their diet will be made up of the insects and spiders they find in the landscape – even in the winter. While the vast majority of our spiders are dormant in the winter (and even those may be a nice find for a wren) there are some that remain active.

So we are seeing the Carolina wrens expanding their range northward, now breeding in Penobscot County and regularly wintering along the coast through Waldo County. They do struggle and get pushed back during some harsh winters. Interestingly, it doesn’t appear to be the cold that bothers them as much as the food availability, or lack thereof. This was well documented during January and February of 2015 when we had back-to-back-to-back nor’easters come through. Looking at data from citizen science projects like Cornell’s eBird (ebird.org) we can see the wrens were being seen with greater frequency each year, until those 2015 storms dropped significant amounts of snow with each pass. By the last of those blizzards, which dropped over a foot of snow, the frequency (percent of checklists reported that include that species) of Carolina wrens had dropped from 3.5% to nearly zero. Since then, though, numbers have only gone up and up, with a record-setting high frequency of over 6% in February 2021.

MORE WINTER ACTIVITY

Speaking of spiders active in winter, I thought it’d be worth commenting on a slew of questions that have come recently regarding some insects – and even amphibians – that people are finding out on the snow. Many of these sightings coincided with some of the warm spells we were having: remember that 50-plus-degree day between the snowstorms? No, the earlier one. Or was it the one between those? Anyway, you get the point – as confusing as this unexpected warm weather can be for us, it can be even worse for wildlife.

There are quite a few insects, especially flies, that you can see out on a warm winter day. One that may really surprise you is a certain caterpillar. The large yellow underwing (noctua pronuba), which is unfortunately a non-native “cutworm,” is a showy moth that overwinters in its larval stage. On warm winter days it can often be seen inching across the snow as it searches for a quick meal.

Those short warm spells rarely have any effect on our true hibernators, like groundhogs, but you’ll often see (or smell) increased activity from species like skunks or opossums. These mammals do remain active throughout the winter, but will have periods of deep sleep when you won’t see them around.

We also got a few reports of salamanders wandering the snowy surface, which is an unfortunately risky venture for them. While they should be brumating in the winter (the cold-blooded animal equivalent to hibernating), ambitious amphibians may come out of their burrows in search of a pool to breed in during these warm periods if enough thawing has occurred. From the salamander’s perspective, these thaws are no different from those in the spring that would signal it is time to breed.

Some of these critters may be able to find a safe place to return to until a true spring thaw arrives; others will not be so lucky. There are some rehabbers in the state, like the Center for Wildlife in Cape Neddick, that are equipped to help animals like salamanders, but it is helpful to remember that we are also watching nature’s selection at play. I won’t get into the effects humans are having on our planet in this short column, but keep in mind that these are just outlier cases. Sometimes the “early bird will get the worm” and sometimes those worms are still frozen underground.

Do you have a nature question for Doug? Email questions to ask@maineaudubon.org and visit maineaudubon.org to learn more about backyard birding, native plants, and programs and events focusing on Maine wildlife and habitat. Maine Audubon leads free bird walks on Thursdays, 8 to 10 a.m., at the Gilsland Farm Audubon Sanctuary in Falmouth.