The Short-tailed Woodstar (Myrmia micrura) is a small hummingbird found in western South America. With an average body length of only 9 cm (3.5 in) and weighing around 5 grams (0.18 oz), it is one of the smallest hummingbird species in the world. This tiny bird gets its name from its very short, squared-off tail.
The Short-tailed Woodstar has a predominantly green plumage on its head, back, wings and tail. The upperparts are metallic golden-green while the underparts are greener. The short tail is green on top and rufous-colored below. The male has a glittering violet-blue throat patch, known as a gorget. The female lacks the colorful gorget and is duller overall, with a whitish throat. The bill of the Short-tailed Woodstar is slim, straight and black. The legs are also black.
Males and females look similar except for the gorget. Juveniles resemble adult females but have buffy edges to their plumage feathers. These tiny hummingbirds produce a high-pitched monotonous call described as “seep” or “zip.”
Range and Habitat
The Short-tailed Woodstar is found along the Pacific slope of the Andes Mountains in far western South America. Its range extends from southwestern Colombia through western Ecuador, northwestern Peru and extreme northern Chile.
This species is found at elevations between 1000-4000 meters. It inhabits semi-open areas near treelines and forest edges such as mountain meadows, scrublands, forest clearings and gardens. Short-tailed Woodstars prefer areas with plenty of flowering plants and shrubs where they can easily feed on nectar.
Food and Feeding
Like all hummingbirds, the Short-tailed Woodstar has a specialized diet consisting of nectar, tree sap and small insects. Its main food source is flower nectar. It uses its slender, tube-like tongue to drink the nectar while hovering in front of flowers. Some of its favorite nectar sources include plants from the genera Bomarea, Fuchsia, Salvia, Abutilon and Puya.
The Short-tailed Woodstar has adaptations for hovering in place, allowing it to efficiently feed while beating its wings up to 70 times per second. Along with taking nectar, the bird will supplement its diet with small insects like gnats, aphids and spiders. It catches insects in flight or gleans them off foliage.
To meet its high metabolic demands, this tiny bird must consume approximately half its body weight in nectar each day. Throughout the day, it visits hundreds of flowers to get enough nourishment. It feeds on the wing, using its slender bill to pierce the base of tubular flowers in order to access the nectar.
Reproduction and Breeding
The breeding season for Short-tailed Woodstars varies across its South American range. In Ecuador, breeding takes place between February and June. Further south in Peru, the season is November to February.
Males defend small territories with plentiful flower resources where they display for females and mate. The males perform elaborate courtship rituals, flying in loops and arcs above the female while vocalizing. Once paired, the female builds a tiny cup nest out of plant fibers, lichen and moss. She constructs the nest on a horizontal branch or in a rock crevice, often overhanging a stream.
The female lays just two tiny white eggs, about the size of a pea. She incubates the eggs alone for 15-19 days. The nestlings hatch with closed eyes and few feathers. Both parents feed the chicks regurgitated food, mainly nectar and insects. After 23-26 days, the young fledge from the nest. The female may raise 2-3 broods per season.
Most populations of the Short-tailed Woodstar appear to be resident, remaining in the same area year-round. Altitude determines habitat suitability. During winter when flowers are scarce at high elevations, the hummingbirds may migrate downslope to warmer climates with more abundant food. Those that breed at lower altitudes are typically non-migratory.
Conservation Status and Threats
With an extremely small global population estimated at only 2500-9999 mature individuals, the Short-tailed Woodstar is classified as Vulnerable by the IUCN Red List. Some national listings categorize the species as Endangered in Chile, Rare in Ecuador and Near Threatened in Peru.
The major threat facing this tiny hummingbird is habitat loss. Conversion of its native habitat for agriculture, development, mining and logging has led to declines. Climate change poses another long-term threat by shifting the elevational range where key food plants can grow. Introduced species like honeybees may compete with native birds for flower nectar.
More research is needed to fully understand population sizes and trends for this little-studied species. Protecting areas of high-elevation habitat will be crucial for the conservation of the Short-tailed Woodstar. Initiatives to maintain connectivity between protected zones along mountain chains can provide habitat corridors. Enforcing limits on habitat destruction while allowing sustainable forestry and grazing practices can also help preserve populations.
Fun Facts about Short-tailed Woodstars
– The green and rufous plumage provides excellent camouflage as the hummingbird feeds among flowers. The vibrant male gorget is hidden when the bird faces away.
– Like all hummingbirds, the Short-tailed Woodstar can fly backwards and hover in mid-air by rapidly beating its wings in a figure-8 pattern. The wings turn at the shoulder, allowing precise maneuverability.
– This tiny bird has one of the highest metabolism rates in the animal kingdom. At rest, its heart rate can be over 500 beats per minute. In flight, it may exceed 1200 bpm.
– To conserve energy on cold nights, the Short-tailed Woodstar enters a state of torpor by lowering its body temperature and slowing its metabolism up to tenfold.
– The species name “micrura” is derived from the Greek words for “small” and “tail” – an apt description of this hummingbird’s very short tail.
– Short-tailed Woodstars utilize a technique called trap-lining to efficiently feed on flower nectar. They repeatedly visit favorite flowers in a consistent order or “trapline.”
– Hummingbirds have excellent memories and can remember the locations of reliable food sources from season to season. They play a key role in pollination.
In summary, the diminutive Short-tailed Woodstar is a fascinating hummingbird exquisitely adapted to feed on nectar in the Andean highlands. Protecting remaining fragments of its specialized habitat will give this Vulnerable species a better chance of survival in the long-term. More research and monitoring of populations are needed to support conservation strategies going forward.