The Tres Marias Hummingbird (Basilinna gracilis) is an endangered species of hummingbird found only on three small islands off the western coast of Mexico. With an estimated population of less than 1000 individuals remaining in the wild, conservation of this unique bird is critical.
The Tres Marias hummingbird is a small bird, measuring just 3-4 inches in length. The male has metallic green upperparts and white underparts, with an iridescent reddish-pink throat patch or gorget. The female lacks the colorful gorget and is duller overall, with grayish-green upperparts and pale gray underparts. The long, slender bill of both sexes is slightly downcurved.
Range and Habitat
As its name indicates, the Tres Marias hummingbird is endemic to the Tres Marias Islands, located about 60 miles off the coast of Nayarit, Mexico. These islands have a subtropical climate and are covered in deciduous and evergreen forests. The hummingbird inhabits a range of forested habitats on the islands, including oak, pine-oak, and tropical deciduous forests. It occurs at elevations from sea level to over 5000 feet.
Like all hummingbirds, the Tres Marias hummingbird feeds on the nectar of flowers and small insects. Its long bill allows it to access nectar from long, tubular flowers not reachable by other birds. Some of the key flower species it visits include ocotillo, various cacti, and forest understory plants such as lilies and coralroot orchids. The hummingbird also hawks small insects in flight, providing an essential source of protein.
Breeding and Nesting
The breeding season for the Tres Marias hummingbird runs from November to May. Males perform courtship displays, flying in u-shaped patterns to impress females. Once paired, the female builds a tiny cup nest out of plant down, spider webs, and lichens, attached to a branch or vine. She lays just two pea-sized white eggs. The female alone cares for the eggs and nestlings. The chicks fledge in about 3 weeks. Not much else is known about the breeding habits of this rare species.
Threats and Conservation
This hummingbird’s extremely limited range and small population size put it at high risk for extinction. The primary threat is habitat loss due to logging, agriculture, and development. Predation by invasive species such as cats and rats is also a problem. Drought and other severe weather events could also have disastrous impacts on an already struggling population.
The Tres Marias Islands were designated a federal biosphere reserve in 2000. While this protects the land, more active conservation measures for the hummingbird itself may be needed. Suggested actions include habitat restoration, control of invasive species, establishing nest protections, and captive breeding programs. Further research into the ecology and demography of this species would also help inform conservation strategies.
The Tres Marias hummingbird is a little-known species, but it holds cultural significance for the islands where it resides. The bird’s delicate beauty and mysterious origins feature in local folklore. For the small human population of the islands, this unique hummingbird has become a symbol of their home and natural heritage. Its potential disappearance represents the loss of part of their identity and inextricable connection to the land.
The Tres Marias hummingbird is at grave risk of extinction in the coming decades if conservation action is not taken swiftly. Its population shows no signs of stabilizing, and habitat loss continues. While captive breeding could be a last resort, the priority should be preserving natural areas and ecological integrity of the islands. This may require limiting development and tourism. If protected and restored, the islands could continue supporting this endemic hummingbird for generations to come. The fate of the species now lies primarily in human hands. With rapid action, we can ensure the Tres Marias hummingbird remains an integral part of its island home into the future.