An immature female Anna’s hummingbird refers to a young female Anna’s hummingbird that has not yet reached full adult plumage. The Anna’s hummingbird (Calypte anna) is a small hummingbird found along the Pacific Coast of North America from British Columbia to Baja California. Let’s take a closer look at the key characteristics of immature female Anna’s hummingbirds and how they differ from adult females.
Identification
Identifying an immature female Anna’s hummingbird requires looking at several key features:
- Size – About 3.5 inches long from bill to tail tip. Small and compact like an adult Anna’s hummingbird.
- Bill – Long, straight, and very slender. All black in color.
- Throat – Grayish white rather than vibrant rose-pink like an adult female.
- Crown and face – Olive green rather than gray on an adult female.
- Nape – Olive green rather than gray on an adult female.
- Back – Olive green rather than metallic green on an adult female.
- Rump – Olive green rather than gray on an adult female.
- Belly – White mixed with pale green streaks rather than solid white in adults.
- Tail shape – Slightly forked like adult Anna’s.
- Tail color – Olive green with white tips rather than gray with white tips in adults.
The combination of the small size, all black slender bill, forked tail, and olive green plumage points to an immature female Anna’s hummingbird. Adult males have a striking magenta throat and crown, making immature females the hardest to identify.
Age
Anna’s hummingbirds have a relatively short nestling period of 18-25 days from hatching to fledging. Once fledged, the immature hummingbirds must learn to feed themselves. Their early plumage resembles adult females but generally includes more streaking on the throat and flanks.
It takes approximately one year for immature females to molt into their adult plumage. So an immature female is generally defined as a female Anna’s younger than 12 months of age.
Behavior
Despite their young age, immature female Anna’s hummingbirds display most typical hummingbird behaviors as soon as they fledge. These include:
- Feeding on nectar using their specialized tongues.
- Batting wings up to 70 times per second in hovering flight.
- Highly territorial behavior, chasing away other hummingbirds from their feeding areas.
- Perching frequently to conserve energy.
One key difference is that immatures may still pester adult females to feed them occasionally through the first few months after fledging.
Habitat and Range
Immature female Anna’s hummingbirds occupy the full range of the species up and down the Pacific Coast. Their breeding habitat stretches from southwest Canada down through California and into Baja California. These include areas such as:
- Coastal woodlands
- Chaparral
- Mountain meadows
- Backyards and gardens
- Desert oases
During migration and winter, they may occupy coastal scrub, plains, foothills, and semi-desert regions. Like adult Anna’s hummingbirds, immatures are highly adaptable and can thrive around human development.
Diet
The diet of an immature female Anna’s hummingbird matches that of adults. It primarily consists of:
- Nectar from flowers of plants like sage, lilies, fuchsias, and many others
- Small insects and spiders
- Tree sap or insects trapped in tree sap
- Sugar water from bird feeders
Their long, specialized tongues allow them to retrieve nectar while hovering in flight. The ability to exploit food sources like nectar allows hummingbirds to occupy regions other small birds cannot.
Differences from Adult Females
While immature female Anna’s hummingbirds resemble adult females in size and shape, some key differences in plumage exist:
Feature | Immature Female | Adult Female |
---|---|---|
Back | Olive green | Metallic green |
Crown | Olive green | Gray |
Throat | Grayish white with streaks | Solid white |
Belly | White with green streaks | Clean white |
Tail | Olive green with white tips | Gray with white tips |
The overall greener plumage with more streaking provides useful clues in identifying young females. Adult male Anna’s are distinguished by their bright pink throat and crown.
Interesting Facts
Here are a few more interesting facts about immature female Anna’s hummingbirds:
- They molt gradually over the course of about one year to obtain their adult plumage.
- Their tongues have grooves to help collect nectar and lap up droplets.
- They feed every 10-15 minutes when awake to power their fast metabolism.
- Nestlings grow incredibly fast, from 0.6g hatchlings to full adult size in 25 days.
- Young that hatch 1-2 days apart establish a distinct size hierarchy that dictates feeding priority.
- Their individual survival rates are estimated between 25-50% in the first year after hatching.
Conclusion
In summary, immature female Anna’s hummingbirds can be identified by their petite size, all black slender bill, forked tail, and streaky green plumage. They display remarkably advanced feeding and flying capabilities right after fledging. Over the course of approximately one year, they will gradually molt and acquire the definitive adult female plumage of gray, green, and white. Immature females are fascinating to observe as they hone their flying and feeding skills to carry them through their fast-paced hummingbird lives.