Sword-billed hummingbird

The sword-billed hummingbird (Ensifera ensifera) is a neotropical species of hummingbird from the Andean regions of South America. It is the sole member of the genus Ensifera and is characterized by its unusually long bill; it is the only bird to have a beak longer than the rest of its body. E. ensifera uses its bill to drink nectar from flowers with long corollas and has coevolved with the species Passiflora mixta. While most hummingbirds preen using their bills, E. ensifera must use its feet to scratch and preen due to its bill being so long. This uncommon bird is also one of the largest hummingbird species.

For the orthopteran suborder Ensifera, commonly known as crickets, see Ensifera.

Sword-billed hummingbird
Male in eastern Ecuador
Female sword-billed hummingbird (right) with a buff-tailed coronet

Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Apodiformes
Family: Trochilidae
Subfamily: Trochilinae
Genus: Ensifera
Lesson, 1843
Species:
E. ensifera
Binomial name
Ensifera ensifera
(Boissonneau, 1840)
Distribution range of the sword-billed hummingbird

Taxonomy

The sword-billed hummingbird was first described by Auguste Boissonneau in 1839.[2] Like all hummingbirds, it is a part of the family Trochilidae under the order Apodiformes. It is monotypic, meaning it is the only species within its genus. The name ensifera ("sword-wielder") is derived from Latin ensis (sword) and ferre (to carry), and refers to this hummingbird's remarkable beak length.

In 1939, there was a subspecies Ensifera ensifera caerulescens described, based on a specimen at the Royal Albert Memorial Museum. However, in 1990 ornithologist Gary R.Graves determined it was not a subspecies, but the same species with a slight discoloration due to the preservation process of the specimen.[2]

Description
Depiction of the sword-billed hummingbird by Ernst Haeckel

Sword-billed hummingbirds perch on the mid- to upper-level branches of neotropical trees.[3] Lengths are 13–14 centimetres (5.1–5.5 in) from the tail tip to the base of the bill, with males slightly larger on average than females.[3] The bill can additionally be over 10 centimetres (3.9 in) long. Individuals weigh between 10–15 grams (0.35–0.53 oz), making it one of the largest species of hummingbirds.[4] As is characteristic of hummingbirds, E. ensifera can fly backwards and hover in the air.[5] It also exhibits higher than average wing-disc loading than other members of its family.[6]

E. ensifera displays sexual dimorphism where plumage varies between males and females. Males have a coppery bronze head, bronze green back, bright green underbelly, blackish green throat, and bronze green tail. Females have a similarly colored head and back, a white belly speckled with green, a more olive colored throat, and grayish white edging around the tail.[3]

Bill

The defining trait of this species is a beak longer than the rest of its body (excluding the tail). The tongue is also unusually long to span the length of the tube-shaped bill. The beak is black in color and curves slightly upwards.[7] These adaptations help the hummingbird feed on flowers with long corollas that are inaccessible to other species.[6]

Habitat and distribution

Ensifera ensifera is a neotropical hummingbird found throughout tropical montane cloud forests of Bolivia, Colombia, Ecuador, Peru and Venezuela.[8] It is found at higher elevations of 1,700–3,300 metres (5,600–10,800 ft), but the most common occurrences are between 2,400–3,100 metres (7,900–10,200 ft).[3] This is a preferred habitat due to the concentration of nectar producing flowers.[6] It is a year-round resident of all three Andes ranges, with no known migration patterns.[7] While the species is considered to have stable numbers and a wide geographic range (over 60,000 square km), it is unevenly distributed and hard to find, making the species difficult to research.[9]

Behavior
The long corolla of Passiflora mixta is coevolved with the bird's bill as a pollination strategy.
Female sword-billed hummingbird feeding in flight

Diet and feeding

The sword-billed hummingbird is a specialist species, feeding on the nectar of specific flowers. Its abnormally long beak allows it to feed from flowers with long corollas, especially from the genera Passiflora and Datura, which include the most heavily hummingbird-pollinated plant species.[10] E. ensifera usually drinks while in flight and is a trap-line feeder, visiting the same flowers in a consistent, patterned sequence. This promotes flower pollination and outcrossing.[6]

Perching and preening
Perching male sword-billed hummingbird

The bird perches with its bill angled upwards to reduce the strain of the heavy beak and improve balance.[7] The length of the bill is so long, it also forces the sword-billed hummingbird to use its feet to groom, even though this takes longer than traditional beak methods.[11] Preening is important to remove ectoparasites and spread oil across the feathers.[11]

Reproduction

Females and males are polygamous and may mate with several individuals to increase reproductive success.[12] Eggs are laid usually in February and March, and only the female stays to feed and guard the nest.[3][12] Further research should be conducted on the number of broods and survival of offspring since little is known.

Vocalization

Other than a throated "trrr" sound, sword-billed hummingbirds make little noise.[3] The sound is short, rapid, and usually repeated multiple times. Collections of recordings from the public show the bird may vocalize during foraging and flying, but much more research into the use and variations of their vocalizations needs to be done.[13]

Co-evolution with Passiflora mixta

A distinct factor of the sword-billed hummingbird is its extreme coevolution with the species Passiflora mixta. The two species evolved together during the early radiation of the Tacsonia clade, because the hummingbird exclusively pollinated P. mixta.[14] The position of the flower's anthers and sigmas and the length of the corolla tube make it an inaccessible food source to nearly every species except E. ensifera.[10] This mutualistic relationship lets the passionflower depend on the bird for pollination, while the bird obtains a high-quality food source.[10][14] To obtain nectar, the hummingbird will stick its long bill down the corolla tube (both are almost exactly the same length), drink, then retreat and hover for a few seconds before repeating the process.[6] Other species, such as insects, may be able to access the flower's nectar but do so by puncturing the base and feeding through a hole instead of the corolla tube.[6] Additional evidence of coevolution shows species also inhabit the same territory range along the Andean mountains. Ornithologist David Snow was the first to extensively describe the relationship between E. ensifera and P. mixta.[6] If sword-billed hummingbird populations were to decline, there would most likely be a negative impact on the abundance of Passiflora mixta flowers due to their extreme coevolution.[14]

Status and conservation

The sword-billed hummingbird is considered of "Least Concern" by the IUCN.[8] There is no sign of population decline or visible threats to the species. There is also no census on global number of individuals, because of the large range of occurrence and uncommon sightings.[8] Climate change and deforestation are the two most probable threats to E. ensifera in the future since this can lead to habitat loss and decreased food sources, especially of Passiflora mixta.[10]

In art and media

BBC's documentary series Planet Earth II depicted the sword-billed hummingbird flying through the forest in the Jungles episode.[15]

References
  1. BirdLife International (2012). "Ensifera ensifera". IUCN Red List of Threatened Species. 2012. Retrieved 26 November 2013.CS1 maint: ref=harv (link)
  2. Graves, Gary (November 1990). "TAXONOMIC STATUS OF THE SWORD-BILLED HUMMINGBIRD ENSIFERA-ENSIFERA-CAERULESCENS". Bulletin of the British Ornithologists' Club. 111: 139–140 – via Biostor.
  3. L., Hilty, Steven (1986). A guide to the birds of Colombia. Brown, William L., 1929-2007. Princeton, N.J.: Princeton University Press. ISBN 9780691083728. OCLC 11234472.
  4. Burnie, D.; Wilson, D. E., eds. (2005). Animal: The Definitive Visual Guide to the World's Wildlife. DK Adult. ISBN 0789477645.
  5. Sapir, Nir; Dudley, Robert (2012-10-15). "Backward flight in hummingbirds employs unique kinematic adjustments and entails low metabolic cost". Journal of Experimental Biology. 215 (20): 3603–3611. doi:10.1242/jeb.073114. ISSN 0022-0949. PMID 23014570.
  6. Snow, David (1980). Relationships between hummingbirds and flowers in the Andes of Colombia. British Museum: Bulletin of the British Museum.
  7. "Sword-billed Hummingbird - Introduction | Neotropical Birds Online". neotropical.birds.cornell.edu. Retrieved 2017-10-15.
  8. IUCN (2016). "Ensifera ensifera: BirdLife International". IUCN Red List of Threatened Species. 2016. doi:10.2305/iucn.uk.2016-3.rlts.t22687854a93171973.en.
  9. Latta, Steven C.; Tinoco, Boris A.; Astudillo, Pedro X.; Graham, Catherine H. (2011-02-01). "Patterns and Magnitude of Temporal Change in Avian Communities in the Ecuadorian Andes". The Condor. 113 (1): 24–40. doi:10.1525/cond.2011.090252. ISSN 0010-5422.
  10. Abrahamczyk, S.; Souto-Vilarós, D.; Renner, S. S. (2014-11-22). "Escape from extreme specialization: passionflowers, bats and the sword-billed hummingbird". Proc. R. Soc. B. 281 (1795): 20140888. doi:10.1098/rspb.2014.0888. ISSN 0962-8452. PMC 4213610. PMID 25274372.
  11. Clayton, Dale H.; Cotgreave, Peter (1994). "Relationship of bill morphology to grooming behaviour in birds". Animal Behaviour. 47 (1): 195–201. doi:10.1006/anbe.1994.1022.
  12. Handbook of the birds of the world. Hoyo, Josep del., Elliott, Andrew., Sargatal, Jordi., Cabot, José. Barcelona: Lynx Edicions. 2013 [1992]. ISBN 978-8487334252. OCLC 861071869.CS1 maint: others (link)
  13. "Sword-billed Hummingbird (Ensifera ensifera) :: xeno-canto". www.xeno-canto.org. Retrieved 2017-10-15.
  14. Lindberg, Annika Büchert; Olesen, Jens Mogens (March 2001). "The fragility of extreme specialization: Passiflora mixta and its pollinating hummingbird Ensifera ensifera". Journal of Tropical Ecology. 17 (2): 323–329. doi:10.1017/s0266467401001213. ISSN 1469-7831.
  15. "Sword-billed hummingbirds are the only birds in the world to have beaks longer than their bodies. - In pictures... - Jungles, Planet Earth II - BBC One". BBC. Retrieved 2017-10-15.
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