Physical appearance is the main way most birders identify different bird species, and understanding the differences between bird plumages is critical for proper identification. As birders learn more about plumages, they are often surprised at how different birds can look from season to season as their feathers change.
What Is Plumage?
The term plumage refers to a bird's feathers, including the color and pattern those feathers produce. Some birds have a variety of plumages during an annual cycle, while other birds sport the same plumage throughout the year. While plumage is, in many cases, the easiest way to identify birds, it can be confusing as birds change plumages or adopt color variations that are less familiar to birders.
There are several basic plumages that many bird species exhibit throughout the year.
- Natal plumage: Very young birds just a few days or weeks old have natal or birth plumage. In precocial species such as ducks, the birds hatch with this plumage, while in altricial species like passerines the birds grow these fluffy feathers in their first few days of life. The coloration for these feathers is often plain and the feathers serve as both camouflage and insulation for the young birds.
- Juvenile plumage: This is the coloration young birds have during their first few weeks or months of life, usually during the summer and early fall after they have hatched. This plumage is still relatively bland to provide good camouflage, but it may begin to show mature colors and markings. In many dimorphic species, juvenile plumage resembles that of adult females, which are often more camouflaged. Juvenile plumage also often shows spotting, streaks, or other markings that help keep birds concealed.
- Subadult plumage: Birds that take several years to mature may have several subadult plumages they display during adolescence. This is especially common in raptors and gulls, both of which can take 2 to 3 years or longer to reach maturity. Until then, immature birds have less distinct plumage that gradually grows to resemble the adult plumage more closely each year.
- Basic plumage: This is a mature bird's non-breeding plumage. For many species, this is the plumage the birds display for the majority of the year, and it may be more camouflaged with duller colors and less distinct markings than during the breeding season. In dimorphic species, both genders may resemble females in basic plumage. This is also called non-breeding plumage or winter plumage. In some species, particularly ducks, it is called eclipse plumage because of the short time males' breeding plumage is "eclipsed" by this bland coloration.
- Breeding plumage: This is the most brilliant, colorful plumage for many bird species, and it is displayed during the courtship season when birds are trying to attract mates. It is most often the males that develop bold breeding plumage, and these feathers may involve extraordinary colors or unusual shapes such as long streamers. This is also called alternate plumage, nuptial plumage, or spring plumage. In some species, breeding plumage may be worn for the entire spring and summer, while for other species it may last only a few weeks.
Not all bird species display all plumage types, and when and for how long each type of plumage is displayed can also vary. Different genders may display different plumages, and even factors such as climate and geography can make a difference in a bird's plumages.
In addition to the basic bird plumages, there is a range of unusual or abnormal variations that birds can display.
- Leucism: A genetic condition that affects feather pigmentation and results in pale or white feathers, either in patches or over the bird's entire plumage.
- Melanism: A genetic condition that affects feather pigmentation and results in overly dark feathers due to an excess of dark melanin pigments.
- Albinism: A genetic condition that produces pale or white allover plumage as well as red or pink eyes, legs, and feet due to a complete lack of pigmentation.
- Baldness: A temporary condition whereby a bird sheds its head feathers or other patches during a molt or as a result of damage or disease.
- Hybrid: A genetically crossbred bird with indistinct plumage that may show colorations and markings with traits of two or more species.
- Morph: A bird displaying an uncommon but not unheard of plumage variation such as very light or very dark plumage, often a regular occurrence of leucism or melanism. Some species, such as the red-tailed hawk, have several recognized color morphs.
Regardless of a bird's age or coloration, its feathers will eventually become damaged and worn, and it is necessary to grow new ones. The process of regrowing feathers is called molting, and birds in molt may have mottled plumage that shows characteristics of both their old and new plumages. These birds may look scruffy or ragged, and they may have irregular feather tufts or bald patches as their new feathers emerge. Missing feathers on the wings and tail may also indicate a bird in its molt cycle.
Some birds, typically those without separate breeding and basic plumages, molt gradually throughout the year. Others will molt once or twice a year as they switch plumages seasonally. When seen during a molt, birds can look very different than during their familiar plumage phases.
Using Plumage for Identification
Because it is the most colorful and distinct, breeding plumage is typically the easiest phase during which to identify birds. When birds are in between phases or molting, however, identification becomes much more challenging. During these periods, birders have to take advantage of other clues to determine a bird's identity.
- Account for the season in relation to a bird's life cycle. In winter, look for basic plumages rather than breeding plumages.
- Watch for non-plumage identification clues, such as bird sounds, what the birds eat, and their general behavior.
- Watch the birds over a period of several days or weeks to see the plumage change and become more distinct. This is also a great opportunity to observe molting and learn to identify in-between birds.
Plumage may seem to be easy for identifying birds, but when a single species has several different types of plumage, it is more difficult. Understanding different plumages and when to look for them is the best way to consistently identify birds from season to season.
What Can Cause Birds To Show Weird Color Variations?, Cornell University, CornellLabs, All About Birds