Riddle: What creatures can be between 2.8 and 3.5 inches long, have 5-inch wingspans and weigh no more than a quarter?

Answer: Ruby-throated hummingbirds!

Weights can range from 2 to 6 grams with males averaging 3 grams and the females averaging 4 grams. In comparison, a penny weighs 2.5 grams and a quarter weighs 5.4 grams.

The male and female of this species can be distinguished from one another, and this is known as sexual dimorphism.

The adult male has a throat patch called a gorget of iridescent red feathers with black edges and a forked black tail. The red iridescence is dependent on the light and appears dull from many angles.

The female has a notched tail with outer feathers banded in green, black and white and a white throat that may be plain or lightly marked.

Juvenile males resemble adult females, although the throat markings are more defined in the young. The vocalizations of ruby-throated hummingbirds are rapid, squeaky chirps, which are used primarily for threats. For example, males may vocalize to warn another male that has entered his territory.

South for the winter

Hummingbirds are migratory, spending most of the winter in Florida, Central America, and Mexico.

During migration some hummingbirds make the 900-mile trip nonstop that includes crossing the Gulf of Mexico.

During migration in the fall, older male and female birds are better prepared for the long-distance flights than first-year birds because they have higher body weights and the experience to guide them.

This journey seems impossible because part of their journey takes them over the Gulf of Mexico which is a 500-mile trip lasting more than 20 hours when there is no food or rest areas.

Researchers discovered the tiny birds can double their fat mass in preparation for their Gulf crossing, then expend the entire calorie reserve from fat.

Built to withstand the elements

Adults are not social, other than during courtship and when the females are caring for their young. Both males and females of any age are aggressive toward other hummingbirds. They may defend territories, such as a feeding territory, attacking and chasing other hummingbirds that enter.

Hummingbirds have one of the highest metabolic rates of any animal, with heart rates up to 1,260 beats per minute, breathing rate of about 250 breaths per minute even at rest.

During flight, hummingbird oxygen consumption per gram of muscle tissue is approximately 10 times higher than a triathlon runner.

Hummingbirds have amazing adaptations which allow for unique flight patterns. Hummingbirds fly forward, backward, upside-down, and can hover in midair.

During hovering, hummingbird wings beat up to 80 times per second.

Nectar from flowers, flowering trees, small insects, and spiders, are its main food. Although hummingbirds are well-known to feed on nectar, the insects and spiders are an important source part of protein, minerals, and vitamins in the diet of adult hummingbirds.

Hummingbirds show a slight preference for red, orange and bright pink flowers for nectar sources.

Not in it for the long road

As typical for their family, ruby-throated hummingbirds are thought to be polygynous which means do not form bonds with one mate.

Sometimes one male will mate with many females, or one female will mate with several males. In either case, males depart immediately after the reproductive act and females provide all parental care.

Usually nesting in deciduous trees about 10-20 feet off the ground, the female alone constructs the nest and cares for the eggs and young. The nest is composed of scales removed from buds and lichen on the outside all bound together with spiders’ webs. The inside is lined with plant fibers, such as dandelion, cattails or thistle, and some nests have been lined with animal fur.

Most nests are well-camouflaged. Old nests may be occupied for several nesting seasons, but they are repaired before each use.

Females produce one or two clutches of eggs each summer, laying between 1-3 eggs each time. Females feed the chicks from 1 to 3 times every hour by regurgitation, usually while the female continues hovering. When they are 18 to 22 days old, the young leave the nest and make their first flight.

The oldest known ruby-throated hummingbird to be banded was 9 years and 1 month of age.

Interesting fact

An interesting fact that I read was almost all hummingbirds of 7 years or more in age are females, with males rarely surviving past 5 years of age. The reasons for this include the high energetic demands of defending a territory and the stress of migration.

A variety of animals prey on hummingbirds. Due to their small size, only very swift predators can capture them because a free-flying adult hummingbird is too nimble for most predators. Merlins and kestrels (falcons), are nimble enough and swift enough to catch the hummingbirds. Crows, blue jays, squirrels, cats and snakes also prey on them.

Praying mantises have been known to ambush hummingbirds at feeders.

Jeannie Carl is a naturalist at the Carbon County Environmental Education Center in Summit Hill. The center rehabilitates injured animals and educates the public on a variety of wildlife found in the area. For information on the Carbon County Environmental Center, visit www.carboneec.org.