- Order: Piciformes
- Family: Ramphastidae
Chestnut-mandibled Toucans are largely frugivorous. Being generalists, they will eat from a wide variety of fruiting trees and play a vital role in seed dispersal. Preferred food sources include Virola, Casearia, Cecropia, Protium, Hampea, and Trophis spp. (Howe 1977, 2004; Skutch 1980). Virolas are especially important food sources for Chestnut-mandibled Toucans. For example, 45% of V. sebifora fruit eaten by birds is consumed by R. swainsonii (Short and Horne 2001). Casearia corymbosa is also a vital food source for toucans since it fruits throughout months when very little else is available. Howe (1977) observed Chestnut-mandibled Toucans feeding extensively on Casearia during Costa Rica’s early dry season, but noticed virtual abandonment when other fruits (Virola and Protium) came into season.
Chestnut-mandibled Toucans also sometimes take lizards, large insects, and the eggs and young of other birds. Insect prey includes cicadas and walking sticks (Howe 1977). They have also been recorded attempting to chase and snatch flying termites out of the air (Skutch 1972, Short and Horne 2001). Mindell and Black (1984) observed a pair of toucans cooperatively hunt and consume a small lizard (see Behavior). As for vertebrate prey, Chestnut-mandibled Toucans have been known to raid the nests of Social Flycatchers (Myiozetetes similis), Tropical Kingbirds (Tyrannus melancholicus), Boat-billed Flycatchers (Megarynchus pitangua), Collared Aracaris (Pteroglossus torquatus), and some woodpeckers (Picidae) (Skutch 1972, Short and Horne 2001). One R. swainsonii even drove a Double-toothed Kite (Harpagus bidentatus) from its nest and ate one of the eggs (Laughlin 1952).
Despite what may seem like a voracious appetite for meat, animal matter only makes up a tiny portion of the diet of the Chestnut-mandibled Toucan. Adult birds eat over 90% fruit and are thought to mainly catch prey for their young (which require extra protein for growth). In one study that analyzed stomach contents, none of the six R. swainsonii stomachs examined held any animal matter whatsoever (Remsen et al. 1993).
Chestnut-mandibled Toucans mostly range in the treetops, where they forage singly, in pairs, or in small groups, although larger numbers may gather where food is plentiful. Reportedly forages higher than other “keel-billed” Ramphastos (Hilty and Brown 1986) but occasionally takes fallen fruit from the ground. While foraging, toucans hop from branch to branch, reaching, hanging, plucking, and twisting off whatever fruit they can find. Their beak often helps in this respect since it allows the toucan to reach out and grab fruits while maintaining a center of gravity (Short and Horne 2002). Once fruit is in its possession, a Chestnut-mandibled Toucan will usually toss its head back and swallow it. For particularly large fruits and prey, toucans will sometimes hold it down with one foot while they feed (Short and Horne 2002).
Smaller, slow-moving prey (such as insects and frogs) is gleaned from branches and epiphytes. Bird nests are sought out during breeding season, where the toucan’s bill helps by allowing it to reach deep inside nest cavities (Short and Horne 2002). Chestnut-mandibled Toucans are not usually known for pursuing mobile prey, although there is one record of a pair cooperatively hunting down a lizard (Dactyloa frenata). One toucan repeatedly flushed the lizard from hiding while the other pursued it lengthwise down a tree trunk (Mindell and Black 1984). Once prey is caught, it usually is killed by crushing action of the beak.
Flight is slow and undulating. Flies with rapid, shallow wingbeats followed by glides (Stiles and Skutch 1989). Often perches horizontally. Because of their size and general lack of predators, Chestnut-mandibled Toucans often spend up to several hours resting and foraging in a single tree (Howe 1977).
Chestnut-mandibled Toucans frequently call from a tall, exposed perch above the canopy (e.g., a dead, emergent tree) and pairs will often chorus together near dawn and dusk. Calls are usually given with vertical head movement: the head is thrown up on the first note and gradually lowered (Short and Horne 2001).
Chestnut-mandibled Toucans spend a considerable amount of time preening, resting, scratching, and exhibiting "comfort behavior." Preening is mostly with the bill, although the enormous bill size and shape can be somewhat limiting. For this reason, allopreening is common. Pairs will often sit next to each other and take turns preening each others’ head and neck feathers. Clayton and Cotgreave (1994) also noted a Chestnut-mandibled Toucan scratching and rubbing its face against a tree limb- presumably to get rid of skin parasites.
Chestnut-mandibled Toucans usually bathe in water-filled hollows or crevices in trees, and when sleeping will bend their tails backwards over their heads (a trait known only in toucans) (Short and Horne 2002).
Chestnut-mandibled Toucans do not hold territories per se, but often dominate favored fruit trees, using aggressive displays to drive away rivals, other birds, smaller toucans, and even mates. Pairs usually occupy and defend neighboring trees, although a male will sometimes present his tree as a "gift," allowing the female to feed from it (Short and Horne 2001).
Chestnut-mandibled Toucans are believed to form long-term pair bonds, although this needs to be further studied. Pairs will often allopreen and “courtship feed”, where the male feeds the female regurgitated fruit. Sometimes, a male will present the female with a fruiting tree that he is guarding from other intruders, allowing her to feed in it or even take control while he moves to a nearby tree (Short 2002). Copulation takes place without preliminary displays (Short and Horne 2001).
Social and interspecific behavior
Chestnut-mandibled Toucans usually forage in pairs or small groups, although they may gather in larger numbers where food is plentiful (Hilty and Brown 1986, Stiles and Skutch 1989, Short and Horne 2001). At feeding sites, they compete heavily with other frugivores and can be quite aggressive, displacing other birds. In one particular study, Chestnut-mandibled Toucans were responsible for 11 of 15 instances of interspecific aggression (Chang et al. 2008). The majority of victims were oropendolas (Psarocolius), aracaris (Pteroglossus), and other Ramphastos, all species, as Chang et al. noted, that share similar diets. Intraspecific aggression also occurs, but may be less common. Because of their large size, Chestnut-mandibled Toucans exhibit dominance over other toucan species such as Keel-billed (Ramphastos sulfuratus) and Choco (Ramphastos brevis) toucans. They sometimes feed in mixed-species flocks, although Chestnut-mandibled Toucans will often displace smaller Keel-billed Toucans after following them to a food source (Short and Horne 2001).
Despite agonistic interactions at food sources, Chestnut-mandibled Toucans nesting in proximity to Keel-billed Toucans do not exhibit aggressive behavior near the nest site. One record from Barro Colorado Island (Panama) showed both species nesting within 17 m of each other (Skutch 1972).
Little is known about the visual, aesthetic, or functional purposes of the Chestnut-mandibled Toucan’s large and gaudy bill. Recent research has shown that the congener, Toco Toucan (Ramphastos toco), can modify the amount of blood flow to its bill and can thus use its bill as a thermal radiator to distribute heat away from its body (Tattersall et al. 2009). However, this does not imply that the extremely large bills of these birds evolved for this purpose. The large bill may also help the bird while raiding other species’ nests (Short and Horne 2002). As Skutch (1972) recalls: "I have never seen even the boldest flycatcher, enraged by the violation of its nest, dare to come within range of a perching toucan’s beak; even small hawks are, as we have seen, intimidated by it." Most birds, however, will attack and harass toucans that come within range of their nests. Boat-billed Flycatchers (Megarynchus pitangua), which Skutch refers to as having a "moral antipathy" towards toucans, readily meet and harass a toucan in mid-flight (Skutch 1972). Perhaps the bill plays a role in inter and/or intraspecific social interactions but there is no data to support or refute this hypothesis.
Little is known about predation on this species. Because of their size, Chestnut-mandibled Toucans probably have very few, if any, regular predators. Some larger species of raptor may prey on adults, although this is probably rare in occurence.
When feeding in a mixed flock setting, Chestnut-mandibled Toucans tend to ignore the alarm calls of smaller birds (Howe 1977).
Breeding season length:
Breeding season varies depending on latitude: March-June in Costa Rica (where fledglings are reported in May), January-July in Panama and Colombia, and December-May in Ecuador (Short and Horne 2001).
Nests and nest-building:
Chestnut-mandibled Toucans are cavity-nesters, but incapable of excavating. They nest hollow tree cavities where decay has caused the wood to rot (Stiles and Skutch 1989). Accounts have been published for only two nests, both of which indicate that Chestnut-mandibled Toucans nest very high above the ground (between 9 and 30 meters) (Skutch 1972).
Clutch size and eggs:
Clutch size is believed to be two or three eggs (Short and Horne 2001). Eggs and nest contents remain undescribed.
Incubation and nestling period:
Renesting, multi-brooding, and invervals between nests:
From the few records available, both parents are known to care for the young and defend the nest. Skutch (1972), for instance, observed an adult toucan flying out of the nest and driving off a kinkajou (Potus flavus).
Populations and Demography
Several species of chewing lice (Order: Phthiraptera) parasitize Chestnut-mandibled Toucans, including Ramphasticola hirsuta (Hellenthal et al. 2005), Austrophilopterus cancellosus (Price and Weckstein 2005), Myrsidea vitrix, and M. extranea (Price et al. 2004), all of which are found only on Ramphastos toucans. There is no information related to topics such as age at first breeding, life span and survivorship, dispersal, or population regulation.
Rice, Ari A., J. D. Weckstein, and J. Engel. 2010. Chestnut-mandibled Toucan (Ramphastos swainsonii), Neotropical Birds Online (T. S. Schulenberg, Editor). Ithaca: Cornell Lab of Ornithology; retrieved from Neotropical Birds Online: http://neotropical.birds.cornell.edu/portal/species/overview?p_p_spp=303416