At eBird, data quality is of paramount importance, and we put a lot of time and effort into building the data quality process. From developing better automated data filters, to growing and managing the network of much appreciated volunteer experts who help review data, we strive for a clean dataset. In some cases this process is straightforward. Rare birds are rare, and these will always be flagged for review. But what about the common species? When two similar species occur together regularly in a region we can’t easily automate the data verification process. For example, Black-capped and Carolina Chickadees both occur in New Jersey, but there is only a small area of overlap. Which Chickadee do you see? Are you reporting the correct species from your backyard? Over the years we’ve discovered a few groups of common birds that are often misidentified. This article is the first in a series to help shed light on these frequently misidentified species groups.
Chickadees are frequently encountered birds across much of North America, visible at backyard feeders and most wooded areas. They are common where they occur, and in many parts of the country only a single species is possible. Chickadees are largely resident, with only the extreme northern populations of Boreal, Black-capped chickadees moving marginally south in some years, and Mountain Chickadee moving down-slope to lower elevations in some winters. But in general, chickadee movements are rare! They do form small flocks during winter, and often associate with other woodland birds.
The name “Black-capped Chickadee” could refer to any bird in this group, as all species have black or dark brown caps. Despite this, not all chickadees are correctly identified as “Black-capped Chickadees”! Black-capped Chickadee does not occur across the southern United States, and distinguishing it from other similar species where ranges overlap can be problematic. The biggest issues arise where it overlaps with Carolina Chickadee. The two are very similar in appearance, and birders need to use caution in the zones of overlap. There is no shame in reporting a bird as Black-capped/Carolina Chickadee if you’re unsure. Excellent treatments of chickadee identification can be found in any field guide (e.g., The Sibley Guide to Birds), and we won’t duplicate those efforts here. Instead we’ll focus on distribution, and help you realize how each species occurs across the landscape.
The first step to accurately identifying chickadees is figuring out which species occurs in your area. In many places there is only one possibility. If you live in east Texas you’re seeing Carolina Chickadee–done deal! In other places several species occur together, and in these places you need to be more careful. Check the range maps and notes below to help determine which chickadee(s) occur in your area. These are ordered from the most widespread to extremely local.
Black-capped Chickadee is widespread across much of North America, absent from the Mid-Atlantic and Southeast, and from the Southwest. It barely reaches northern California on the Pacific Coast. It is a bird of mixed decidous and coniferous woodlands, occurring from sea level to more montane regions, and further south at high elevation in many places (e.g., the Appalachians).
Widespread and common throughout the Southeast stretching west through Central Texas, the Carolina Chickadee is the only chickadee species across most of its range. It occurs in a narrow band with Black-capped stretching from coastal central New Jersey through southeast Pennsylvania, and then rarely together west through Missouri. More study is needed to determine exactly where they hybridize in many areas (if at all). In the narrow band of known overlap hybrids do occur, though these are often exceedingly difficult to identify. It is completely appropriate to report chickadees from the range of overlap simply as ‘Black-capped/Carolina Chickadee’, indicating that it is one or the other, but a positive identification was not reached.
The appropriately named Mountain Chickadee occurs throughout the montane West. It is rarely encountered outside of these regions, and is strictly an irruptive winter wanderer at lower elevations, occurring more frequently in some years. It occurs with Black-capped, Boreal, and Chestnut-backed Chickadees in a few places in the Northwest, but always look for this species distinctive white eyebrow. Beware, however, of late summer birds that are worn. At this time of year the eyebrow can be much less obvious.
Though widespread throughout the forests of northern North America, the Boreal Chickadee is less frequently encountered by birders than the Carolina Chickadee. Boreal Chickadee occurs only rarely south of the northern forests during ‘irruption years’, when a few make it to New England (mostly at feeders). It is not to be expected out of range, however, and any reports outside of the boreal forest will be subject to scrutiny.
Chestnut-backed Chickadee is primarily a bird of the Pacific Coast, stretching inland across Washington into parts of British Columbia and inland to Idaho. Across much of its southern range it is the only chickadee species, but it occurs regularly with Black-capped in the Northwest. Luckily it is relatively easy to identify, having a dark chestnut back and brownish flanks.
The Mexican Chickadee is the most range-restricted of all the North American chickadees, just stretching across the border into the mountains of extreme southeast Arizona and southwest New Mexico. If you aren’t birding in the Chiricahuas in southeastern Arizona, you almost certainly aren’t seeing a Mexican Chickadee!
The next time you see a chickadee in your yard, first remember where you are, and make sure the species you’re reporting matches up with the possibilities in your area. Then take the next step and make sure to identify the bird based on its field marks and voice.