Hummingbirds at Weltvogel Park Walsrode

Abstract

Who does not know the small, shimmering hummingbirds which flap their wings faster than the human eye can see? The more than 320 species of hummingbirds

exclusively inhabit the New World. They occupy forests, deserts, mountain regions and open landscapes from southern North to South America.

The smallest representative, with a size of only 5-6 cm and a weight of 2 g, is the Bee Hummingbird (Mellisuga helenae)-the male is the lightest bird in the world and not larger than a human thumb! The 11 x 8 mm eggs are only the size of a pea and weigh 0.4 g. With a size of22 cm and a weight of23 g, the Giant Hummingbird (Patagona gigas) is the largest of these tiny bird species.

 Its eggs are 20 x 12 mm and weigh 1.4 g.

Most of the hummingbirds show a sexual dimorphism. In general, the male is considerably more colorful and shiny than the female. He uses the plumage coloration as a signal during courtship or dominance displays. Especially in very territorial species the iridescent plumage coloration is highly pronounced. The duller colored females rely on 'crypsis' during the rearing of their offspring as a defence against predation. Females care for the eggs and young by themselves without the help of the males. They build a tiny, mostly cup-shaped nest made of cobwebs, plant fibres, mosses or lichens, which is placed on branches, forked twigs or attached to large leaves. The one to two white eggs are usually incubated for 16 to 19 days before the chicks hatch. After hatching, the chicks are fed many times a day for three to four weeks.

 Hummingbirds mainly consume nectar-very energy-rich food-from flowers. They search for the nectar by visiting large, brightly colored flowers. Red seems to be the preferred color due to the spectral sensitivity of the hummingbirds' eyes. The nectar is gathered with an extremely extendable bifurcated tongue which is flicked three to 13 times per second. Hummingbirds feed on insects as well but to a much lesser extent. The shape of the hummingbirds' bills are as various as the flowers of their food plants-you can find bills that are short and pointed or long and curved-all being perfectly adapted to the shape of the flower they specialize in. Hummingbirds have to feed on nectar many times a day, as a meal of nectar will pass from the crop into the intestine in only about four minutes, and it takes less than 15 minutes for the body to extract up to 99 percent of the sugar glucose.

Hummingbirds are essential for reproduction of many New World plants, as pollen is attached to the plumage of a hummingbird while it feeds at a flower. Moving on while searching for food, the hummingbird transports the pollen to the next flower. Some flowers are visited by only one or a few species of hummingbirds whereas others attract many different species. Plants which carry flowers that hummingbirds feed on provide nectar throughout the whole year-in contrast to plants which produce seasonal nectar and which are pollinated by insects.

Another special feature of hummingbirds is their flight -with the help of their flexible wings and 10 to 80 wingbeats per second, they can not only fly forward, but also back- and sideward, maneuvering like a helicopter and remaining 'motionless' in midair-thus they are able to reach even the most hidden flowers. Up to 200 wingbeats per second have been already measured in the wild. In contrast to other bird species hummingbirds beat their wings up and down to support their flight. The energy needed for the strength-sapping flight is gained from carbohydrates in the nectar.

At rest, hummingbirds breath 300 times per minute. The breathing rate can rise to over 500 times per minute during flight or when the temperature increases. In comparison to that, doves only breath 30 times and humans only 14 to 18 times per minute. It is important for such small birds with a high metabolism to save energy whenever they can e.g. while resting during the night or when the temperature is low. Therefore, the metabolism and the body temperature are decreased during the night, conserving up to 60 percent of the energy normally used. Every night the birds enter a hibernation-like state, which is triggered by the onset of the dusk.

At the end of 2011, thanks to a cooperation with a hummingbird breeding center in Trieste, Italy, two species of hummingbirds moved into a newly designed breeding center at Weltvogelpark Walsrode. In general, hummingbirds are known to be difficult to keep and breed-thus they are not found in most zoo collections. At the moment we now house the Amazilia Hummingbird (Amazilia amazilia), which prefers habitats with scrub, xerophytic steppe, thorn forest and desert areas and is also common in habitations, even in parks and gardens within cities. The females strongly resemble the males in their appearance. Like the Amazilia Hummingbird, the Green-tailed Trainbearer {Lesbia nuna) can be found in the west of South America, where it inhabits Andean regions in heights of up to 3800 m. The females are similar to the males, but the male has a remarkably 10 to 12 cm long, forked tail. This species is rarely seen in zoos and Germanywide can only be seen at Weltvogelpark.