Cold spell hit bluebirds, but how bad was it?

Any time is a good time to put up a house to help these birds, but also add a word to your vocabulary about the once-endangered bluebird: Resilient

Eight years, every spring, the eastern bluebirds found the nest box in my backyard and they (usually) produced several clutches each year. Then came that disastrous ninth season and the western rat snake.

That big snake found its way past the predator guard one night and ate the whole crew, chicks and hen and all. The stinker was so stuffed he couldn’t get back out of the hole.

Not one bluebird has been back through that predator-guard reinforced and perfectly positioned opening since, although last year a pair nested in a natural tree cavity not far from the house, which was good to see.

But this spring, after February’s ice, snow and extended sub-freezing cold, I haven’t even heard bluebirds singing in the neighborhood.

Talk of bluebirds has been on the wind since the winter storms across the southern U.S. hit them hard from Texas and Oklahoma to Tennessee and Ohio. Social media accounts of bluebird nest boxes opened to find several dead adult birds inside became relatively common. But just how bad was it?

It’s only natural to worry . We feel a kind of kinship with these birds. When I was a kid, 50-some years ago, it appeared bluebirds were on the short road to extinction and the nationwide push to erect nest boxes was relatively new. Since then the birds recovered to a current designation with the international Encyclopedia of Life of “increasing” and a “species of least concern.”

But still, the birds rely on our help to provide nest habitat and, well, that winter storm was brutal.

“Nobody knows what the loss is but it’s widespread, and it’s all across the south,” said North American Bluebird Society President Bernie Daniel. But he added, “It’s disconcerting, but we’ve had this before and we’ll have it again. It’s unfortunate and that’s about all you can say about it.”

Extended cold and the ground covered with snow is what knocked southern birds for a loop. Berries are a major food source for bluebirds in winter, so if the berries are frozen, the water is iced over and the ground is covered with snow, they simply freeze to death, he said.

“We lost 90 percent of our bluebirds due to winter storms in 1976. We came back from that and we’ll come back from this,” Daniel said.


The worst note I saw on Facebook was a person who said they found half a dozen adults dead in a nest box. Our friend David John, who writes Nature Notes for the Skiatook Journal and Tulsa World, found three in one of his boxes and another outside on the ground.

Bluebirds may indeed roost together during periods of inclement weather to conserve heat, said Robyn Bailey, project leader for Cornell Lab of Ornithology’s NestWatch program.

She cited an entry in the book Birds of the World that notes: “During exceedingly cold weather or severe storms, up to 20 individuals may roost together, tightly compressed within a cavity or other confined space (Pitts 1977b). Inverted-cone configuration (heads together and bodies pointed downward) of communally roosting bluebirds in winter may increase warmth and decrease likelihood of suffocation.”

If any official group could have noted a widespread early-spring/late-winter disaster for bluebirds it would be NestWatch, which has a strong base of bluebird landlords who annually report on the progress of nesting bluebirds (as well as many other kinds of birds). I was one of them until last year and, hopefully, will be again.

Bailey noted no need for panic.

“In 2020, 3.5% of early spring nests failed due to “all young found dead in nest” and another 3.5% of nests failed due to “no eggs hatched,” she reported via email. “In 2021 (so far), those numbers are 1.5% and 10.8% respectively, so it does seem like a higher than usual number of nests failed in the egg stage but relatively few nests already had chicks in them. As the year goes on, that (percentage) will go down as nests from the typical breeding season get added...

“We have had 17 reports of dead adults in nest boxes so far this year, compared to nine last year (comparing the same time period of Feb 1-Mar 30), so nearly twice as many. Keep in mind that dead adults can be found in nest boxes for other reasons (e.g., killed by invasive species).”

Bailey said bluebirds can withstand cold temperatures and that she’s seen bluebirds in upstate New York while snowshoeing with a foot of snow on the ground. Some of our southern birds likely just hit their limits with that unusual storm.

It’s important to note that our friend in Skiatook has a new active bluebird nest at his property. My friend John Beckwith of Falcon Rods put up 10 bluebird boxes on a new property this year and he reported that seven have Carolina chickadees in them and two have bluebirds. Only one is empty and, for a first year, that’s great!

And with almost every Facebook string I’ve seen with a report of dead birds, someone else noted that they still have some bluebirds around.

Like most relatively short-term hits to wildlife the reports that come in are spotty. People like me panic because we don’t hear bluebirds where they’ve always been, but others find them, and perhaps see even more than usual.

Bailey put it well: “Bluebird populations are robust and resilient ... and quite possibly one of the most human-assisted species in North America,” she wrote. “I am confident that while this weather event was a setback, that other factors are more likely affecting their survival, such as invasive species, outdoor cats, pesticide use, and loss of habitat to development. While it is interesting to think about one-time disaster events, it is important to keep the focus on persistent, long-term threats, in my opinion. It is upsetting when we witness an unavoidable natural disaster, but I am more concerned about the threats that continue unabated each year.”

In my own backyard, 10 years ago, my neighborhood was still new. In the relatively new flood control area that makes a green space behind our home the trees were just saplings and there was much more open space for bluebirds to hunt. Across the road to the south was 80 acres of soybeans and to the east, another 80 in sweet corn. Now those fields are bare dirt and construction equipment. Soon they will hold hundreds of new homes.

The world for all of us, and for bluebirds, continues to change and populations of people and birds will move and shrink and grow again from one zone to another. In the case of bluebirds, let us hope, there will continue to be humans who put up houses to help keep the species increasing and “of least concern.”


Putting up a bluebird house? Check with these programs first


Participating in the Cornell Lab of Ornithology’s NestWatch program is pretty easy and just about anyone with a smart phone or laptop who can navigate to can do it—and it’s free.

It is a nationwide monitoring program designed to track status and trends in the reproductive biology of birds, including when nesting occurs, number of eggs laid, how many eggs hatch, and how many hatchlings survive.

The NestWatch site provides detailed of information for people new to putting up birdhouses and great guidelines and coaching for responsible nest watching practices with its Code of Conduct.

The resulting database is used to study the current condition of breeding bird populations and how they may be changing over time as a result of climate change, habitat degradation and loss, expansion of urban areas, and the introduction of non-native plants and animals.

North American Bluebird Society (NABS)

Founded in 1978. the North American Bluebird Society, at, is your source for all things bluebirds, from a hotline to contact about emergencies and links that direct you to local sources for bluebird help, to tip sheets, and tried-and-true bluebird house plans.

Wondering where you should put your bluebird houses—or maybe why your houses aren’t attracting bluebirds—this is a great place to start looking for tips.

Membership to support the conservation effort is only $20 a year, which includes a full packet of all the Bluebird fact sheets you’ll ever need and subscription to the quarterly magazine. NABS works closely with the NestWatch program as well.

Share All Things Outdoors by KJBOutdoors

Leave a comment