Toucan barbet

Toucan barbet
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Aves
Order:Piciformes
Family:Semnornithidae
Genus:Semnornis
Species: S. ramphastinus
Binomial name
Semnornis ramphastinus
(Jardine, 1855)

The toucan barbet (Semnornis ramphastinus) is a barbet native to the humid montane forests of western Ecuador and Colombia. Along with the prong-billed barbet it forms the family Semnornithidae, and is closely related to the toucans. It is a medium-sized barbet with striking plumage and a robust bill.

Taxonomy and systematics

The toucan barbet was described by the Scottish naturalist William Jardine, who placed it in the new genus Tetragonops. In 1899 Charles Richmond of the United States National Museum discovered that the genus name was preoccupied (meaning it had been used earlier for another genus) and placed the toucan barbet and its sister species the prong-billed barbet in a new genus Pan, after the ancient god of the forest.[2] The following year Richmond issued a correction as the name he had chosen was itself preoccupied (by the chimpanzees) and placed the two species in the new genus Semnornis.[3]

Historically the toucan barbet was placed with the other barbets in the large Capitonidae family. This family included African and Asian representatives. DNA studies and an examination of the morphology of the family found that this arrangement was paraphyletic, as the New World barbets are more closely related to the toucans (family Ramphastidae) than they are to the Old World barbets.[4][5] In particular, a close phylogenetic relationship between the genus Semnornis (which contains the toucan barbet) and toucans was found. The two lineages were more closely related to each other than even Semnornis and the other New World barbets.[6] This led to a breakup of the barbet family, and the separate lineages are now considered to be distinct families; the toucan barbet is, together with the prong-billed barbet, now placed into the family Semnornithidae. An alternative arrangement is to combine all the barbets and the toucans into a single family, which due to priority would be the toucan family.[5]

There are two described subspecies, the nominate race, found in Ecuador, and the subspecies S. r. caucae from Columbia. S. r. caucae, named for Cauca in Columbia,[7] was described in 1941 by Nils Gyldenstolpe.[8]

The specific name, ramphastinus, is modern Latin for toucan-like, based on Linnaeus' genus Ramphastos (1758).[9]

Description

The toucan barbet has a robust bill

The toucan barbet is a medium-sized robust barbet, of 19 to 21 cm (7.5–8.3 in) long and weighing 80–115 g (2.8–4.1 oz).[8][10] The beak is robust with a yellow maxilla and a light green mandible, both with dark ends. The plumage is colourful and includes a black crown, "mask" and thin cervical collar. There are long occipital feathers and a conspicuous white stripe behind the eye, which has a bright red-colored iris. The nape of the neck is golden-brown and becomes yellow towards the rump. The throat, upper breast and sides of the nape are grayish-blue. The lower breast and middle belly are bright red, while the lower belly is yellowish green. The wings and tail are grey.

There is little sexual dimorphism; both sexes are almost identical except for the female being slightly less bright,[11] and the female lacks the tuft on the black plumage of the nape. Immature birds are duller than adults, and don't develop prongs until they are four months old.[8]

Habitat and distribution

Cloud forest in Ecuador

The species is native to the humid forests of the western Andes, from the Andean slopes of northwest Ecuador to southwest Colombia, at altitudes of 1,400–2,400 m (4,600–7,900 ft).[11] It uses all forest strata, shwoing some preference for the upper canopy of the forest (11–20 m (36–66 ft)) and the subcanopy (6–10 m (20–33 ft)).[12] The species will also use secondary forest and forest edge habitats.[13] Evidence suggests that these birds are very specific when it comes to choosing trees for nesting. It usually prefers old trees in the Lauraceae family. As nesting trees of sufficient diameter are not very common in these forests, habitat loss through logging is impacting the species.[10]

Behavior and ecology

The toucan barbet is usually found in pairs or small groups perched silently on long horizontal branches, making them hard to find unless active or singing. It is a territorial bird that usually lives in small groups of 3–6 individuals. In the absence of interference these groups can occupy a certain territory for a year or longer. The flight is characterized by being hurried and noisy.[10]

The species is territorial, with territories range between 4.0 and 10.6 ha, with an average of 5.8 ha. Most of the territory will consist of mature forest, although the species can adapt to live in forests with small areas of secondary forest or pastures. Toucan barbet groups show a marked territorial behavior towards other groups or species, which is usually made clear by the loud duets of breeding pairs. The territory is actively protected by the breeding pair by chasing of intruders; the helpers assist in this, especially near the nest.[10]

Calls and displays

Toucan barbet calls are unmistakable, composed of loud shrieks that travel long distances. It is usually sung in duet by the breeding pair, simultaneously or in syncope by both sexes during the breeding season, usually for territorial display. The frequency of calls change with each season, being more common at the beginning of the year and declining in frequency after April.[10] The toucan barbet can also produce clicking sounds.[11]

When nests are threatened by predators or competitor species that might steal the nesting site members of the group will make a rattling call followed by pecking and knocking wood to drive the competitor or predator away. If this fails the group will begin to mob the intruder. Mobbing behavior is more common if a group is involved as opposed to just a pair.[10]

Feeding

Toucan barbet feeding on berries

The species is frugivorous, feeding on a variety of fruits mixed with other foods. A comparison of the diets of the New World barebts found they were more frugivorous than the other barbets, and their diets were more similar to that of toucans.[14] 62 different species of fruit from 20 families have been reported as being eaten; fruits of Cecropia trees have been shown to be especially important as food sources, as well as Clusia. Other food taken includes insects such as termites, small reptiles, nectar, tree sap, and flower petals.[11] The exact composition of the diet varies by season, with insects being more commonly taken in April. The diet of nestlings has more insect prey than that of adults, with 54% being fruit and 42% being insects.[8]

The toucan barbet forages for 12 hours of the day around its territory, foraging from ground level to 30 m (98 ft) up into the canopy. It forages in small groups of up to 6 birds and sometimes forms mixed flocks with tyrant flycatchers, warblers, tanagers and other frugivores.[8]

Breeding

The toucan barbet is unusual among frugivorous birds in that it breeds cooperatively, with several helpers aiding the dominant breeding pair with incubation and raising the young.[10] Groups are larger outside the reproductive season but generally shrink to three individuals in season, usually composed of previous immature offspring that stay with their parents and help with the new hatchlings. After the breeding season, the group increases due to greater acceptance of non-family members. These helpers significantly increase the reproductive success of the breeding pair.[10] The breeding season of the toucan barbet is from February through to October. Pairs may have two or even three broods per year.[8]

The toucan barbet carves out holes in tree trunks with its powerful beak which it roosts and nests inside. The nesting holes are usually dug into dead trees, usually snags with broken trunks, or more rarely in a dead branch in a living tree. Both sexes incubated the eggs; in nesting sites without helpers males took more of the incubation and brooding duties than females. The incubation period lasts 15 days, and the hatchlings fledge after 45 days. Juveniles look very much like adults, but have paler colors and a black iris. Juveniles' plumage is kept for at least two months after fledging.[10]

Predators

The toucan barbet competes with plate-billed mountain toucans for nesting sites, and that species also preys on young toucan barbets in the nest. White-faced capuchins and Neotropical dwarf squirrels are also treated as threats to nesting sites by the species.[10]

Conservation

The species is classified as Near Threatened by the IUCN. Even though still fairly common locally, its populations have decreased due to habitat loss, accelerated by massive logging operations, deforestation, cattle grazing, and mining; and illegal animal trapping, as it is caught for the local and international cage-bird trade.[1] Heavy trapping pressure, and habitat fragmentation due to forest clearing, is thought to be responsible for some localised extinctions of this species.[15]

References

  1. 1 2 BirdLife International (2012). "Semnornis ramphastinus". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
  2. ↑ Richmond, Chas (1899). "New Name for the Genus Tetragonops" (PDF). Auk. 16 (1): 77.
  3. ↑ Richmond, Charles W. (1900). "Some Necessary Changes in Nomenclature". Auk. 17 (2): 178–179. doi:10.2307/4069180.
  4. ↑ Lanyon, Scott M.; Hall, John G (April 1994). "Reexamination of Barbet Monophyly Using Mitochondrial-DNA Sequence Data" (PDF). The Auk. 111 (2): 389–397. doi:10.2307/4088602.
  5. 1 2 Prum, R. O. (1988). "Phylogenetic interrelationships of the barbets (Aves: Capitonidae) and toucans (Aves: Ramphastidae) based on morphology with comparisons to DNA-DNA hybridization". Zoological Journal of the Linnean Society. 92 (4): 313–343. doi:10.1111/j.1096-3642.1988.tb01728.x.
  6. ↑ Barker, F. Keith; Lanyon, Scott M. (1999). "The Impact of Parsimony Weighting Schemes on Inferred Relationships among Toucans and Neotropical Barbets (Aves: Piciformes)". Molecular Phylogenetics and Evolution. 15: 215–234. doi:10.1006/mpev.2000.0752.
  7. ↑ Jobling, J. A. (2018). "Key to Scientific Names in Ornithology". Handbook of the Birds of the World Alive. Barcelona: Lynx Edicions. Retrieved 3 June 2017.
  8. 1 2 3 4 5 6 Short, L. L.; Home, J. F. M. (2017). del Hoyo, Josep; Elliott, Andrew; Sargatal, Jordi; Christie, David A.; de Juana, Eduardo, eds. "Toucan Barbet (Semnornis ramphastinus)". Handbook of the Birds of the World Alive. Barcelona, Spain: Lynx Edicions. Retrieved 21 July 2017. (Subscription required (help)).
  9. ↑ Jobling, J. A. (2017). "Key to Scientific Names in Ornithology". Handbook of the Birds of the World Alive. Barcelona: Lynx Edicions. Retrieved 20 July 2017.
  10. 1 2 3 4 5 6 7 8 9 10 Restrepo, Carla; Mondragón, Marta Lucy (1998). "Cooperative Breeding in the Frugivorous Toucan Barbet (Semnornis ramphastinus)" (PDF). The Auk. 115 (1): 4–15. doi:10.2307/4089106.
  11. 1 2 3 4 Ridgely, R.; Greenfield, P. (2001). "The Birds of Ecuador". Ithaca, New York: Cornell University Press. p. 369.
  12. ↑ Laverde, O.; Munera, C.; Rengifo, M. (2005). "PREFERENCIA DE HÁBITAT POR CAPITO HYPOLEUCUS, AVE COLOMBIANA ENDÉMICA Y AMENAZADA" (PDF). Ornitologia Colombiana. 3: 62–73.
  13. ↑ Welford, Mark (2000). "The importance of early successional habitats to rare, restricted-range, and endangered birds in the Ecuadorian Andes". Bird Conservation International. 10 (4): 351–359. doi:10.1017/s0959270900000307.
  14. ↑ Remsen, J. V.; Hyde, Mary Ann; Chapman, Angela (February 1993). "The Diets of Neotropical Trogons, Motmots, Barbets and Toucans" (PDF). The Condor. 95 (1): 178–192. doi:10.2307/1369399.
  15. ↑ Kattan, Gustavo H.; Alvarez-Lopez, Humberto; Giraldo, Manuel (March 1994). "Forest Fragmentation and Bird Extinctions: San Antonio Eighty Years Later". Conservation Biology. 8 (1): 138–146. doi:10.1046/j.1523-1739.1994.08010138.x.
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