Carolinas, Black-Caps, and Hybrids, OH MY: Telling the Difference Between Carolina Chickadees, Black-Capped Chickadees, and Hybrids from Both Species
Carolina Chickadee
Order: Passeriformes
Family: Paridae
Genus: Poecile
Species: Poecile carolinensis
Black-Capped Chickadee
Order: Passeriformes
Family: Paridae
Genus: Poecile
Species: Poecile atricapillus
Carolina Chickadees and their relatives, Black-Capped Chickadees are known throughoutout the United States for their dimnuitive appearance, cute behavior, and signature chick-a-dee-dee-dee. While seen as common backyard birds for many, there is much more to these tiny and sociable birds than meets the eye. In this article, I will introduce these two species, their behavior, what they eat, and how to tell them apart from each other despite the striking similarities in physical appearance and the fact that the two have been known to hybridize with each other in hybrid zones.
Characteristics, Habitat, and Diet of Carolina and Black-Capped Chickadees
Over the years, Carolina Chickadees have proven themselves to be very adaptable because they are commonly seen in suburbs and parks with large trees. Carolina Chickadees are between 3.9–4.7 inches tall with a black cap, white cheeks, and gray wings, back, and tail. This is a social species that likes to travel and feed in flocks. Chickadee flocks will eat in deciduous or mixed deciduous/coniferous environments such as woodlands and forests. Carolina Chickadees like to breed in the cavities of trees near forest edges or in nest boxes. Pair bonds between chickadees remain stable across many years. Most chickadees stay loyal to their flock during migration with some occasionally switching depending on the situation. During the winter, Carolina Chickadees will gather in large flocks accompanied by other bird species such as Tufted Titmice, Black-Capped Chickadees, Ruby-Crowned Kinglets, Golden-Crowned Kinglets, Red-Breasted Nuthatches, White-Breasted Nuthatches, Brown-Headed Nuthatches, Brown Creepers, Downy Woodpeckers, and Hairy Woodpeckers just to name a few.
Black-Capped Chickadees share much of the same behavior, habitats, and nesting preferences as their Carolina relatives. However, Black-Capped Chickadees differ in some respects in terms of migration and abilities. Black-Capped Chickadees will, on occasion, migrate south while Carolina Chickadees tend to remain sedentary. One ability that Black-Capped Chickadees have that Carolina Chickadees do not is their ability to lower their body temperature during the winter. This sounds counterintuitive but plays a crucial function in determining the survival of many chickadees. By lowering their body temperature, Black-Capped Chickadees can enter a state of controlled hypothermia which allows them to weather the cold. While Carolina Chickadees suffer and die in the frost, their Black-Capped cousins have a higher survival rate due to this ability. It is unclear however if this ability is passed on to their hybrid offspring.
Carolina and Black-Capped Chickadees are small insectivores that like to eat small insects off of tree leaves. They also love bird feeders and are frequent visitors to backyards (especially if there are large trees nearby). To attract chickadees to your backyard, try adding black oil sunflower seeds, hulled sunflower seeds, safflower, nyjer, suet, peanuts, peanut hearts, and dried mealworms to your feeder. Chickadees are flexible when it comes to feeder type and are known to visit several types of feeders such as platform feeders, suet cages, large tube feeders, and hoppers.
Chickadees are perhaps best known for the chick-a-dee-dee-dee sound that they make when they’re communicating to each other. Even though the two species share this in common, both have a song that is unique to each of them. The Carolina Chickadee has a 4-note song (fee-bee-fee-bay) that differs from the song of her relative, the Black-Capped Chickadee (fee-bee), which is two notes long. Their songs are one of the few things that can tell these two species apart since both look so strikingly similar in terms of physical characteristics.
Telling the Difference between the Chickadees
It is very easy to confuse Carolina Chickadees with their relatives, Black-Capped Chickadees. For one thing, they look very similar to each other. These similarities can become even more confusing as the plumage of these two species fade before they molt during the late Spring and early Summer. However, with fresh plumage, Black-Capped Chickadees show more contrast than Carolina Chickadees in their wings with their white edges. The Carolina Chickadees’ wings, in turn, are more gray. For Black-Capped Chickadees the white area of the face is clear to the back whereas on the Carolina Chickadee the white fades into gray near the nape. For Carolina Chickadees, the division between the black throat and the white chest is straight. For Black-Capped Chickadees, this division is uneven. For Black-Capped Chickadees, the white on the nape contrasts with a greenish back which complements a slight downward bulge on each side of the “bib” (or contrast between the black and white parts of the face). These differences can be perceived with the right amount of sunlight. Black-Capped Chickadees are also usually bigger, have a larger, fluffier head, and have longer tails. Believe it not, even though these two species look almost identical, they are not closely related. In fact, the Black-Capped Chickadee’s closest relative is not the Carolina Chickadee but the Mountain Chickadee. Generally, Carolina Chickadees tend to be grayer overall while Black-Capped Chickadees have more color and contrast as well as more curious and bold. For a side-by-side comparison of the two species, see the photos below:
Another way to tell the difference between the two species is the speed by which both make the chick-a-dee-dee-dee call. The chick-a-dee-dee-dee tends to be faster and higher-pitched with Carolina Chickadees than Black-Capped Chickadees. The notes are also longer with Black-Capped Chickadees with this species producing on average 4 dees per second compared to their counterparts who do an average 6–7 dees per second. However, it is advised not to rely on this alone for identification since both species have been known to learn each other’s calls and songs (especially if they are close to hybrid zones). Hybrids have been known to do the same as well as add their own unique variations.
Hybrid Zones
Carolina Chickadees and Black-Capped Chickadees are known to hybridize in what are known as hybrid zones or regions where the breeding ranges of two or more species overlap to generate the possibility for hybrids. Unlike other animals, hybridization between birds is very common (especially among ducks and geese) due to the fact that all birds share the same basic genetic structure. Hybrids between these two species can not only combine the songs and calls of both parent species but also take on the physical characteristics of each. This can make identification almost impossible even for the most experienced birdwatchers. Carolina Chickadees are predominant in low-elevation environments in the South and Southeast United States whereas Black-Capped Chickadees dominate high-elevation environments in the North, Northeast, and Northwest United States. Hybridization between the two species occurs when their breeding ranges overlap in areas such as Kansas, Virgina, West Virginia, Ohio, southeastern Pennsylvania, North Carolina, and South Carolina. According to a study by Reudink et al. (2007), hybrids between Black-Capped and Carolina Chickadees seem to be moving northward. Their study focused on the hybrid zone in southeastern Pennsylvania. According to them, not only are hybrids moving further north but the degree of hybridization between the two species is intense within this hybrid zone. In this zone, Carolina males show dominance and attract Black-Capped females during the breeding season. Over time, they predict that in this zone Carolina traits will edge out Black-Capped traits and that Carolina Chickadees and hybrids will continue to gain ground at the expense of Black-Capped Chickadees.
Other experts have noted that Black-Capped Chickadees in general are spreading south while their Carolina counterparts are doing the same in the north. Both species have been seen as far north as New Jersey and Connecticut and as far south as North Carolina. Unfortunately, there is no surefire way to tell the difference if they are hybrids except if they mix the songs of both species together. Other than that, it can be impossible to tell definitively if a chickadee is a hybrid or not outside of DNA analysis.
Carolina Chickadees and Black-Capped Chickadees are fascinating to study and watch. Even though they look almost identical, there is no denying the fact that each species is unique in their own way. This also goes for the hybrid offspring of these species within hybrid zones. If you live in a hybrid zone in places like Pennsylvania, Virginia, North Carolina, or elsewhere, don’t beat yourself up if you find the task almost impossible to tell the difference between a Carolina, Black-Capped, and hybrid chickadee. This challenge stumps even the most experienced birdwatchers among us. Unless you’re exclusively within the range of one of these birds (far south for Carolina Chickadees and far north for Black-Capped Chickadees), identification can be difficult.
Hopefully, this article helps makes the task of identification easier. If you take away anything from this article, I hope it’s this: pay attention to the subtle details between birds. For birds, details are very important for survival and breeding. Having the same mindset can help you spot the difference between two species even if they look almost identical like the Carolina and Black-Capped Chickadees.
