The Curious Lives of Nuthatches
Updated: May 3, 2021
Even if you know few things about me, you can probably tell that I’m obsessed with owls. But what many may not know is that nuthatches also hold a special place in my life. I’m not really sure why. It could be the cute sounds they make: squeaks and beeps. Or the way they defy gravity moving up and down trees and hanging from branches. I’m also attracted to their strange name “nuthatch”…what even is that? Apparently, it’s a misinterpretation of an earlier name “nut-hack”, which describes exactly what it sounds like, the birds’ behavior of picking at bark and seeds (Gruson 1972). Whatever it is, I’ve always been enthralled with these small birds.
Across the world, 27 species are currently recognized; many more than living in North America would have you think. We live in the doldrums of nuthatch diversity! Move over White-breasted Nuthatch, show me the Blue Nuthatch…how about the Beautiful or Velvet-fronted Nuthatch?
Nuthatches are in family Sittidae. In fact, all nuthatches are in a single genus, Sitta. Based on current taxonomy, they are quite closely related, even species worlds away from one another. For example, the endangered Giant Nuthatch of southeast Asia—the largest species—is a “sister species” to White-breasted Nuthatch of North America (Pasquet et al. 2014). This means these two are more closely related to each other than any of the other nuthatches. Another odd relational match-up is our North American Red-breasted Nuthatch, which is most closely-related to the Corsican and Snowy-browed Nuthatches of the Old World. No doubt these cases have added fuel to the hypothesis that nuthatches originated in southeast Asia before extending across the planet (Pasquet 1998).
The place of nuthatches on the avian tree of life is not well-understood. Currently, they’re believed to be most closely related to wrens, treecreepers, and gnatcatchers, to name a few of their major relatives (Oliveros et al. 2019). Don’t let the taxonomists bog you down, this is bound to change. However, if you want to explore the taxonomy, there's a cool tree of life for birds. You can zoom in on nuthatches using the search feature on the upper right—or flex your taxonomy muscles and see if you can find them on your own!
For the most part, members of the family are woodland-dwellers. However, there are a couple of species that occupy a somewhat different niche than their relatives. These are the two “rock nuthatches” that occur in the arid Mediterranean and Middle East, where they make a living in rocky outcroppings, rather than forests. Despite habitat differences, nuthatches are easily recognizable: short bills, stout tails, robust feet. The latter allows them to cling to the sides of trees (and rocks), defying gravity as they move up, down, and upside-down.
Here in North America, our four recognized species are woodland inhabitants: one with irruptive populations, one that may be masquerading as a single species when it is in fact multiple, and two range-limited pine specialists. Tied for most widespread across the continent are Red-breasted (Sitta canadensis) and White-breasted Nuthatches (Sitta carolinensis). The former is a species almost exclusively associated with coniferous forest. This adds a complexity to its movement patterns and results in the Red-breasted Nuthatch being one of the world’s best examples of an irruptive migrant.
Red-breasted Nuthatches breed in coniferous forests of northern North America, as well as mountains of Appalachia and the west. During the breeding season they eat arthropods hidden in tree bark, but during the nonbreeding season, their diet switches to seeds from conifers like firs and pines. As other conifer seed-eaters could attest, this is a blessing and a curse. Seeds and nuts can be plentiful in some years, but these mast-producing trees aren’t always prosperous.
Every few years, mast crops within the nuthatches’ normal range fail, resulting in a need to temporarily move elsewhere. It’s in these years Red-breasted Nuthatches are driven south in search of food. In some years we’re lucky to see a handful of them in the south-central U.S. But in winters like we just had, nearly every sizeable pine stand was home to its very own Red-breasted Nuthatch or two…or three…or more! The abundance of shortleaf and other pines in the southeastern U.S. provide safe, seedy harbor for Red-breasted refugees when northern seed crops fail (Ghalambor and Martin 2020).
I’ve had the pleasure of seeing Red-breasted Nuthatch across its range; from the Adirondacks of New York, to the Rockies, and temperate rainforest of southern Alaska. I never get tired of them! Their presence can be determined by a “yank, yank, yank”, sometimes given slowly, sometimes quickly. Various other “beeps”, I call them, can tip the keen observer to their presence. While they may sound similar to the next species, the Red-breasted’s vocalizations are, in my opinion, nuttier and more earthy. Maybe that description only works with food—let’s go with nasally.
Perhaps equally as cosmopolitan across our vast continent is the White-breasted Nuthatch. Unlike its smaller cousin, this species is primarily found in deciduous forest. They are mostly non-migratory, choosing to remain on a home range year-round. Despite being very common, surprisingly little is known about their habits during the breeding season, when they are silent, tending young in tough-to-access natural cavities.
During the nonbreeding season, White-breasted Nuthatches are commonly associated with mixed foraging flocks that ramble through their territories. You might also catch them at a backyard feeding station, taking seeds to cache for later (Petit et al. 1989). Like the Red-breasted Nuthatch, they often make themselves known with a “yank, yank, yank”. Don’t be confused by this identical descriptor, the White-breasteds “yanking” is noticeably lower in pitch and less nasally.
The life of the White-breasted Nuthatch seems peachy at this point, but I have yet to mention the species may be an imposter! A few studies during the last decade show some significant genetic differences among several major groups of White-breasted Nuthatches (Spellman and Klicka 2007, Walstrom et al. 2012). While the American Ornithological Society failed to split the species in 2013, their interest was piqued for future conversations. If compelling results end in a species split, North Americans would have at least 3 more nuthatches on our hands: Carolina Nuthatch, Rocky Mountain Nuthatch, and Slender-billed Nuthatch. These groups of our current White-breasted Nuthatch are not only distinct genetically—which is what really matters when splitting—but also distinct in plumage, bill characteristics, and vocalizations.
One of the main reasons the AOS decided not to split the species in 2013 was because there was little study of the dirty word in species-splitting: hybridization. It isn’t well known how much these major groups hybridize where they overlap or if they produce viable offspring. If hybridization is common and successful, the prospect of three species would likely fall apart. Nevertheless, what fun! If you’re a North American road warrior like I am, enjoy the task of noting characteristics among the White-breasted Nuthatches of the region you find yourself in.
Here we’re left with the other two North American nuthatches, both pine specialists of different sorts, and both cooperative breeders. I’ll get into more of that in a minute, but cooperative breeding is rare in North America and these are the only two nuthatches in the world that do it! It’s hard to choose the cooler of these two look-alikes, so I’ll just start with the one that I’m most familiar with.
The Brown-headed Nuthatch (Sitta pusilla) is synonymous with mature, open pine forest of the southeastern U.S., a sad preference in a country that’s been hungry for pine over the last 150 years. Southern pine forests have been among the hardest hit by logging during this time period, reducing mature pine stands to young, overcrowded forests, or neat plantations that end up harvested at a relatively early age. For those familiar with southern pine ecosystems, you’ll recognize the names of some of their neighbors: Bachman’s Sparrow and Red-cockaded Woodpecker. The latter has done quite poorly during the last century and was only recently removed from the endangered species list, thanks to ongoing and intensive restoration efforts (Jackson 2020). Some of these efforts include controlled burning and timber thinning to maintain a historical level of openness on the forest floor.
With America’s desire for pine, the Brown-headed Nuthatch has been extirpated from much of its historic range, including Missouri and northern Arkansas. Sadly, there doesn’t seem to be a happy ending yet. Based on Breeding Bird Survey data from the last half-century, Brown-headed Nuthatch populations have declined an estimated 23% range wide (Sauer et al. 2011). It has been particularly difficult for this nuthatch and its neighbors because pine forest in the south is naturally patchy, hanging in the balance of a sea of oak-hickory forest (cue conversation about ecological islands and metapopulation dynamics). For this reason, colony-nesters like the nuthatch and Red-cockaded Woodpecker have adapted. At the end of the breeding season, some young of the year will disperse in search of other optimal pine stands that were once not so difficult to find. Today, leaving their natal pine patch can be uncertain, if not deadly (Cox and Slater 2007). Historically, this colonization allowed genetic diversity to be preserved, but now species like this need a lot of help. Physically moving individuals to other sites has been one of the keys to successful management of Red-cockaded Woodpecker (Jackson 2020). Is this something the Brown-headed Nuthatch needs too?
Despite their plight, this nuthatch is still common in the right habitat, some of which is protected and managed with the forest’s historic makeup in mind. From sandy pine hammocks of southern Florida to the Piney Woods of eastern Texas, you’re likely to observe these tiny birds with their white undersides, steely backs, and shiny cocoa-brown caps. A population of them even inhabits pine forest of Grand Bahama Island! They’re almost always heard first and are rarely alone. High-pitched pipping, like an endless squeaky toy, alerts the observer to their presence.
Much like the Red-breasted Nuthatch, this species forages for bark-dwelling insects during the warmer months and switches to pine seed during winter. On occasion, you might catch them using one bark flake to pry away another in pursuit prey; a fascinating example of tool use that is rare in the bird world (Slater et al. 2020). Unlike their Red-breasted cousin, the present nuthatch is mostly sedentary. While Red-breasteds move elsewhere during winter seed shortages, Brown-headeds do not. Their tool use is hypothesized to be an adaptation to this lifestyle, allowing them to obtain food even during seed shortages; meaning they don’t have to pick up and move hundreds of miles (Slater et al. 2020).
The phrase “it takes a village” becomes reality with the Brown-headed Nuthatch. As a cooperative breeder, a group—up to six individuals—helps with young-raising activities. These “helper” birds aide in excavating a nest cavity, defending a breeding territory, and feeding both the young and female at a nest. As is the case in most birds that cooperatively breed, helpers are typically relatives, often young from a previous year (Cox and Slater 2007).
It’s always fun to find an unsolved mystery in the avian world and this species’ cooperative breeding behavior is one of them. In the present nuthatch, there’s little evidence this phenomenon influences the number of young raised successfully, unlike other species. To further the mystery, their sex ratio is believed to be skewed towards male, which most helper birds are (Cox and Slater 2007). Does the Brown-headed Nuthatch cooperatively breed to increase productivity, or is this just an easy out for surplus males? Pretty amazing!
Whatever their deal is, they are a thrill to observe. One second they’re heading up the trunk, the next second down it, then suddenly they’re upside down somewhere! I spent an hour with a pair recently, photographing them as they went about their business. A little squeaking from the writer caused an individual to stop above my head, prompting me to photograph it from a nuthatch’s point of view. I came away with a cool perspective, a very sore neck, and poop on my shoulder. If you live in the south, I encourage you to go find your local patch of mature pine and follow these curious little beauties around for a while. You’ll be glad you did.
Leaving the southern pine forest and drifting west across the prairies, you’ll inevitably hit the Front Ranges of the Rockies. As mountains rise from the lowlands, ponderosa pine parkland becomes a significant component of the region, extending south along the Cordillera through Mexico, north to Canada, and west to the Pacific Ocean. It’s in this landscape the Pygmy Nuthatch (Sitta pygmaea) takes residence. In fact, its range parallels that of the ponderosa pine almost perfectly.
The Pygmy Nuthatch is similar in many aspects to the Brown-headed Nuthatch, with colors that are slightly more muted, as if it took a dust bath. Like most of their North American relatives, Pygmies make a summer living on insects and switch to pine seeds in winter (Kingery and Ghalambor 2020). In winter, they also join mixed feeding flocks of other species, which increases food finding rate and decreases risk of predation. (This is also the case with the other North American nuthatches). In western flocks, Pygmy Nuthatches are a dominant force, typically at the lead of flock movement decisions, even in the presence of opinionated chickadees and larger woodpeckers (Hay 1977). What an impressive little creature!
In their mountain residences, Pygmy Nuthatches can experience extreme cold. For this reason, they have adaptations that check all the boxes of avian roosting behavior: 1) they enter into controlled hypothermia on the most frigid of winter nights; 2) they select cavities based on their ability to insulate; and 3) they roost in groups to increase heat inside a cavity. Literal stacks of Pygmy Nuthatches have been reported at major roosting sites, with some trees containing over 150 individuals (Sydeman and Güntert 1983). Can you imagine an entire stack of these adorable birds?
This group dynamic ties into cooperative breeding behavior similar to that of the Brown-headed Nuthatch. Unlike its cousin, however, there is evidence cooperative breeding in Pygmy Nuthatch results in healthier adults—less energy used by any single adult—and more fledglings raised successfully (Sydeman et al. 1988). For two nuthatches that likely share a recent common ancestor and are considered a superspecies, this difference in success of a single behavior is intriguing. Perhaps it just hasn’t been as well-studied in the Brown-headed Nuthatch.
The amazing lives of nuthatches are inspiring. Knowledge gaps in their life histories beg questions that will drive our desire to understand them better. Both at the scale of the species itself, and more broadly in terms of understanding how some of their behaviors—like cooperative breeding—fit into our diverse world. If you don’t want to think that deeply about nuthatches, that’s okay. More simply, they’re an easy and charismatic connection to our natural world; one that most can appreciate. I don’t think I’ve ever met anyone who disliked nuthatches. If I do, I might seriously question their integrity as a human. Writing this has me dying to jet-set around the world for nuthatches. Maybe I’ll do the first ever nuthatch Big Year. Meanwhile, go stare at a nuthatch for yourself!