Toucan Barbet Semnornis ramphastinus

  • Order: Piciformes
  • Family: Semnornithidae
  • Polytypic: 2 subspecies
  • Authors: Christina Rueda, Ana MarĂ­a Pardo, and Aura Viviana Buitrago
Sections

Breeding

Toucan Barbets are cooperative breeders (Restrepo and Mondragón 1998). Cooperative breeding is a reproductive strategy in which a breeding couple is helped by other adults or immature individuals in functions such as nest building, territory protection, incubation of eggs, feeding of young, and protection of the nest (Skutch 1961). In this way, nest productivity can be increased. This is adaptive not only for the parents but also for the helpers since the cost of young dispersal sometimes exceeds the benefit that can be gained from staying to help raise fledglings of the same kin. In other words, if resources are limited or the species is highly territorial leaving in order to establish a territorial breeding ground can be very difficult (Jetz and Rubenstein 2011). In the case of Toucan Barbets, the limiting resource seems to be the trees in which these birds can construct nests, since both female and male excavate nests in the trunks of dead trees of the Lauraceae family. Besides, this species is territorial so establishing a new territory in the first year is not easy (Restrepo and Mondragón 1998) and it has been observed that the process of maturation is quite slow. For example, it takes about four months for the bill to fully develop (Short and Horne 2001). So, staying the first year for the young can signify a greater gain than dispersing and not being able to breed, or even than dispersing and being able to breed but producing a small number of progeny, because they are helping nests that will raise close siblings. Cooperative breeding can result equally from environmental pressures and from evolutionary inheritance. It has been found that in passerines environment conditions such as variation in temperature or rainfall are strong predictors whereas in nonpasserines phylogeny is a better predictor for cooperative breeding systems (Jetz and Rubenstein 2011). Cooperative breeding is present in at least 14 species of African barbets, which is the sister group of the family Ramphastidae and New World Barbets (Lybiidae), and also in at least two species of basal toucans (Pteroglossus sp.). So, as Semnornis perhaps is the sister group of all other members of the family Ramphastidae (see Systematics), and its ancestors also were cooperative breeders, this behavior is probably basal in toucans (Restrepo and Mondragón 1998). However, it should be noted that cooperative breeding is not present in other Neotropical Barbets, so according to this hypothesis it would have been lost at least two times in the clade of New World barbets and Ramphastidae.

Specimens in breeding condition were collected at one site in Colombia from February-May (Miller 1963), but the breeding season may be more protracted, with juveniles reported as late as November (Short and Horne 2001).

The nests of Toucan Barbets are located in cavities that they excavate with their beaks. The trees used for this purpose are mostly dead trees of the family Lauraceae, especially species of Ocotea and Nectandra (Restrepo and Mondragón 1998). The mean height of nest cavities at one site was 12.5 ± 5.9 m above the ground, in trees with a mean height of 19.0 ±  7.0 m (n = 15), and a dbh of 38 cm (Restrepo and Mondragón 1998).

Toucan Barbet eggs apparently are undescribed; typically, eggs of toucans and barbets are white (Short and Horne 2001).

The duration of incubation is around 15 days and total attention to the nest and fledglings lasts around 80 to 140 days (Restrepo and Mondragón 1998), in which feeding rates are high in comparison to toucans (Short and Horne 2001). There is both maternal and parental care and the rate of visits to the nest in females and males is about the same, but it has been observed that males can spend more time incubating if there are no helpers. The helpers are present in most of the breeding attempts, and they participate in the incubation, brooding, and feeding activities. The reproductive success of the nests is augmented in those nests that have helpers: Restrepo and Mondragón (1998) report that the fledglings produced per breeding attempts is 1.1 ± 0.7 (n = 15) in nests that have helpers while in nests that do not have helpers this number is 0.5 ± 0.7 (n = 13). Having helpers during the breeding season is an advantage because the cost of reproduction is reduced for the breeding pair and it will be easier to produce a second clutch during the breeding season. In addition, helpers can be useful to chase predators away and protect the territory. However, the optimum group size for breeding seems to be set at three (Restrepo and Mondragón 1998).

Recommended Citation

Rueda, C., A. M. Pardo, and A. V. Buitrago (2014). Toucan Barbet (Semnornis ramphastinus), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/nb.toubar1.01