Quick Answer
The main way to visually distinguish male and female Anna’s hummingbirds is by the color of their plumage. Adult males have iridescent magenta throats and crowns, while females have gray-green plumage on their throats and pale gray crowns. Males also have slightly longer tails than females.
Differences in Appearance
Several key physical differences can help identify the sex of Anna’s hummingbirds:
Throat Patch
The most noticeable difference is in the color of the throat. Adult males have an iridescent magenta throat patch, while females have gray-green plumage on their throats. The magenta coloring on the male’s throat is very vibrant and eye-catching when the light hits it. Females lack this colorful gorget.
Crown
In addition to the throat, the crown color also differs. Males have magenta crowns that match their throats, while females have pale gray crowns. The crown is the top portion of the head.
Tail Length
Males have slightly longer tail feathers than females. The male’s outer tail feathers extend just beyond the tips of the inner ones, giving the tail a forked look. Female Anna’s hummingbird tails are more rounded at the end.
Other Plumage
Both sexes have green backs and whitish undersides. However, the green back feathers of the male may appear slightly darker or more iridescent due to the influence of the hormones that produce their colorful throats. The female’s back and underside plumage is more uniform without these subtle variations.
Behavioral Differences
In addition to physical features, behavior can provide clues to help distinguish male Anna’s hummingbirds from females:
Vocalizations
Males make a distinctive loud chirping sound during their courtship displays. This is sometimes described as a “song.” Females may also vocalize, but their calls are typically shorter and softer.
Dive Displays
Males perform dramatic dive displays, diving from heights of 130 feet or more before pulling up quickly as they near the ground. These steep dives demonstrate physical fitness to impress females. Females do not exhibit this elaborate diving behavior.
Aggression
Males are much more aggressive in defending their feeding territories. They will actively chase other males or even larger birds that enter their territory. Females rarely act as aggressive, though they may also protect a feeding area.
Nesting Roles
Female Anna’s hummingbirds alone build the nest, incubate the eggs, and care for the young. Males are not involved in these parenting duties. A female busy nesting or feeding hatchlings is almost certainly female.
When Does Adult Plumage Appear?
The distinctive iridescent magenta throat of the male Anna’s hummingbird first becomes visible when the bird reaches sexual maturity after its first year. However, the full adult male plumage may take an additional year to fully develop.
Young females may show some reddish spots as juveniles, but these disappear as gray-green feathers grow in. By age two, males can be differentiated from females based on the contrasting throat and crown plumage.
Here is a table summarizing the age at which adult plumages emerge:
| Sex | Age Adult Plumage First Appears |
|---|---|
| Male | After first year molt, full color by two years old |
| Female | Gray-green throat appears at one year old |
Similar Species
The combination of iridescent magenta throat and green back make the male Anna’s hummingbird very distinctive. However, females may sometimes be confused with other species. These include:
Costa’s Hummingbird
Female Costa’s hummingbirds have purple throats that may appear gray-green in certain lights. They can best be distinguished by their smaller size, shorter bill, and more defined head stripes compared to Anna’s.
Allen’s Hummingbird
The female Allen’s hummingbird has a narrower tail with more orange spotting. Their gorget is more defined than in female Anna’s. Allen’s also tend to be less common than Anna’s hummingbirds.
Rufous Hummingbird
The female Rufous hummingbird is the hardest to differentiate. Like the Anna’s it has a grayish throat and green back. However, the Rufous has bold rusty colored sides rather than the more uniform green plumage of female Anna’s hummingbirds.
Here is a quick visual guide to female Anna’s vs. similar species:
| Species | Throat | Back | Other Notes |
|---|---|---|---|
| Anna’s (female) | Gray-green | Solid green | Larger size, longer bill, less head striping than Costa’s |
| Costa’s (female) | Gray-purple | Green | Smaller, shorter bill, more head striping |
| Allen’s (female) | More defined gorget | Green | Orange spots on tail, narrower tail |
| Rufous (female) | Grayish | Green with rusty sides | Bold rust color on sides |
Juvenile and Immature Plumages
Hummingbird plumages can be variable from their juvenile stage to adulthood. It’s important to look at more than just throat color when identifying young birds. Here are some tips:
Juveniles
– Both male and female juveniles have some greenish or grayish spotting on the throat
– Tail shape is a better indicator than throat at this stage
– Males have longer, more forked tails as juveniles
Immatures
– Young males may show scattered iridescent feathers coming in on throat and crown
– Young female throats are mottled gray-green
– Males have longer tails and may show aggression even before full adult plumage
Hybridization
In areas where Anna’s hummingbird populations overlap with other species, some hybridization may occur. This can result in males with somewhat intermediate throat or crown feathering. Common hybrid pairings include:
– Anna’s x Costa’s: intermediate throats with some iridescence
– Anna’s x Allen’s: mixed throat feathers and orange-tipped tail
– Anna’s x Rufous: larger size and bright gorget of Anna’s with rusty sides of Rufous
Experts may be able to identify subtle features of hybrids. For amateur birders, be aware these mixed species exist but focus on the pure species’ features for identification.
Conclusion
Telling male and female Anna’s hummingbirds apart comes down to differences in plumage, primarily throat and crown coloration. Adult males have distinctive iridescent magenta throats while females have gray-green throats. Behavioral differences such as vocalizations, diving displays, and aggression can also help confirm an identification. Juveniles and immatures are harder to differentiate, but males have longer, more forked tails from a young age. With practice recognizing key field marks, both males and females can be reliably identified. Proper identification allows birders to appreciate the diversity within this colorful and widespread hummingbird species.
