Ruby-throated hummingbirds are the only breeding hummingbird species in Eastern North America. These tiny birds can be tricky to identify, especially when it comes to telling apart males and females.
Size and Shape
In general, male ruby-throated hummingbirds are slightly larger than females. Males tend to measure 3.5 inches long, while females are usually about 3.25 inches long. However, this difference in size is subtle and can be difficult to discern in the field.
Males also tend to have a slightly longer bill than females, but again this is a very subtle difference. Bill length ranges from 0.6-0.9 inches on males and 0.5-0.7 inches on females. So there is some overlap in bill length between the sexes.
The best physical characteristic to look for is the shape of the tail feathers. Male ruby-throats have forked tail feathers that form a V-shape when spread. The outer tail feathers are pointed and elongated. Females, on the other hand, have square-tipped tail feathers that do not form a forked shape.
Plumage
In terms of plumage, ruby-throated hummingbird males have vibrant, iridescent plumage on their throats. When the light hits just right, it shows as a bright crimson-red patch. This bright red throat patch is how the ruby-throated hummingbird gets its name.
Females lack the vibrant iridescent throat patch. They have white undersides on their throats. In some lighting conditions, it may appear lightly speckled with red-brown spots, but never the bright ruby red patch that males display.
Both male and female ruby-throats have green feathering on their backs and heads. Males tend to have brighter, more colorful green plumage, while females are slightly duller. But the difference is subtle and green sheen can vary quite a bit depending on lighting conditions.
Behavioral Differences
Male and female ruby-throated hummingbirds exhibit some different behaviors, especially during the breeding season. Here are some behavioral clues for telling males and females apart:
- Males are territorial and will chase other males from their feeding areas. Females do not generally show the same territoriality.
- Males perform elaborate courtship displays, flying in loops and dives to impress females.
- Males may perform a territorial display by flying back and forth in a U-shaped pattern.
- In general, males tend to be a bit bolder and more aggressive, while females are shyer and more apt to avoid human presence.
However, these behavioral differences can be subtle and are most notable when males are seeking mates during spring and summer.
Juvenile Ruby-throats
Juvenile ruby-throated hummingbirds can be very difficult to identify by sex. Young birds lack the bright red throat patch and forked tail shape that help identify adult males. Here are some clues for sexing young ruby-throats:
- Immature males may show a few scattered iridescent red or orange feathers on their throats, rather than a full red patch.
- Very young males may show some forked tail feathers, though the fork is less pronounced than adults.
- Immature males have darker and greener overall plumage than females of the same age.
Without behavioral clues, even experts sometimes cannot reliably sex juvenile ruby-throats. It is best to record the unknown juvenile as an “immature hummingbird” rather than guessing at its sex.
Time of Year
When ruby-throated hummingbirds are observed can provide additional clues to help determine sex:
Time of Year | What’s Usually Observed |
---|---|
February – April | Adult males returning from migration, establishing breeding territories |
May | Females returning from migration, courted by males |
June – July | Females on nests incubating eggs; males still aggressive and territorial |
August – September | Juveniles and adult females at feeders; adult males rarely seen |
October – November | Migrants passing through while heading south |
In early spring, the ruby-throats at feeders are almost guaranteed to be males. By late summer, adult males have mostly vanished while more females and juveniles will appear at feeders.
Conclusion
Telling male and female ruby-throated hummingbirds apart can be tricky. The most reliable field marks are the male’s bright red throat, forked tail, and aggressive territorial behavior. Females lack the embellished throat, have rounded tails, and are less aggressive around feeders.
Subtle differences in size, shape, and plumage provide supporting clues. Juveniles are especially difficult to sex and often cannot be identified conclusively. Knowing when males or females are most likely to be observed based on migration and breeding chronology also helps in making an identification.
With practice, patience, and a sharp eye, one can reliably distinguish between male and female ruby-throated hummingbirds.