HUMMINGBIRD SIZE & MASS

Ruby-throated Hummingbird (Archilochus colubris) are sexually dimorphic; adult males and females are different in appearance AND size. Females can be 15-25% larger than adult males.

All text & photos © Bill Hilton Jr.

On average, female (left) Ruby-throated Hummingbirds are about 15-25% larger than males with regard to mass, wing chord, and length of culmen (upper bill). It is speculated that the larger size makes the female better able to incubate eggs and brood the young; the male's smaller size may facilitate his escaping predators or performing more aerobatic courtship displays.

Typical adult female Ruby-throated Hummingbirds (RTHUs) at Hilton Pond Center for Piedmont Natural History show a wing chord between 40mm and 46mm, while adult males range from 37mm to 39mm. All RTHUs molt while they are on the wintering grounds in the tropics, losing and replacing plumage--including their wing feathers. On average, young males banded at Hilton Pond have wing chords 2-3mm shorter after they molt during their first winter, while young females have wings about a millimeter shorter after that first molt. Overall body length (tip of bill to tip of tail) in RTHUs ranges from about 70mm in males to about 90mm in females.

During the breeding season, typical male RTHUs have masses from 2.8g to 3.5g, while females average about half a gram heavier. Prior to migration, the birds goes into hyperphagia--feeding frequently and heavily and building up fat reserves; they may increase their masses by 35-70%. The heaviest female at Hilton Pond Center had a mass of 6.1g (8 Oct 1996); the heaviest male weighed 5.2g (9 Oct 1993); both birds were preparing for autumn migration.

The exposed upper bill (culmen) in a typical male RTHU averages 15mm-18mm, while females measure 17mm-21mm. Bill length is much shorter in nestlings, but the bill--and the rest of the body--usually have all reached full length by about the time a young bird fledges.

Go back to Habitat; forward to External Appearance

Up to Top of Page

If you found this information useful or interesting, please
Support

Hilton Pond Center for Piedmont Natural History
&
Operation RubyThroat: The Hummingbird Project
It's painless, and YOU can make a difference!

Just CLICK on a logo below.

Make direct donations on-line through
Network for Good:
LIKE TO SHOP ON-LINE?
Donate a portion of your purchase price from 500+ top on-line stores via iGive:
Use your PayPal account
to make direct donations:

Share Your Hummingbird Experiences Through "Hummingbird Hobnob"

Operation
RubyThroat's
On-Site
Search Engine

Operation RubyThroat is a registered trademark of Bill Hilton Jr. and Hilton Pond Center for Piedmont Natural History in York, South Carolina USA, phone (803) 684-5852. Contents of the overall project and this website--including photos--may NOT be duplicated, modified, or used in any way except with the express written permission of the author. To obtain permission or for further assistance on accessing this website, contact Webmaster.