Toucans
Toucans are so often depicted by artists and designers that they have become symbol of the warm forests of 
tropical America. Of all the rich bird life of theNeotropics, probably only hummingbirds are more often illustrated.
The most prominent feature of toucans is their bills, often vividly colored, which are much lighter in weight than they appear. A thin horny outer sheath encloses hollow which is crisscrossed by many thin, bony, supporting rods. Despite this internal strengthening, toucans’ bills are fragile and sometimes break. Nevertheless, some manage to survive a long time with part of their bills conspicuously missing. The big-gets bill of any toucan is that of the maltose toucan which accounts for 20CM of the bird’s total length of 66cm (8 of 26in).
Naturalists have speculated for centuries about the uses of the toucan’s exaggerated beak. It enables these heavy, rather clumsy birds to perch inside the crown of a tree, where branches are thicker, and reach far outwards to pluck berries or seeds from twigs too thin to bear their weight. Seized in the tip of the bill, food is thrown back into the throat by an upward toss of the head. This behavior explains the bill’s length but not its thickness or bright coloration. The diet of toucans consists mainly of fruit but includes insects, an occasional lizard and eggs and nestlings of smaller birds. The huge. Vivid beak so intimidates distressed parents that not even the boldest of them dares to attack the plunderer perching beside its nest. After the toucan flies and unable to defend its back in the air, an enraged parent may pounce upon it, to withdraw prudently before the larger bird alights. The varied patterns of toucans’ bills may help these birds to recognize each other. In Central American forestsChestnut-mandibled and Keel-billed too-cans have such similar plumage that they are only readily distinguished by their bills—and voices. The Keel-billet’s beak indelicately tinted with all but one of the colors of the rainbow, whereas that of its relatives largely chestnut, with much yellow on the upper mandible. Possibly the bills also play a role in courtship.
Toucans are moderately gregarious and fly in straggling flocks, one after another, rather than in compact hands, like parrots. In flight, the big Rarnphastos toucans beat their wings a number of times, then close them, whereupon they lose altitude, although borne downward by their great, forwardly directed beaks. Immediately the black wings are widely spread, the fall is converted into a short glide, followed by more wing beats that recover the lost altitude. Thus the toucan traces anundulatory course from one treetop to another that is rarely far distant. Toucans prefer to remain high in trees, where they hop from branch to branch. They bathe in pooh of rain water in hollows high in trunks and limbs—never, apparently, at ground level. They offer food to their companions and, perching well apart, preen them with the tips of long bills.
Toucans are playful birds and often engage in various games. After striking their bills together, two clasp each other’s bill sand push until one is forced backward from the perch and retreats. Another individual may then cross bills with the winner, and
The victor in this bout may be challenged again. Participants in such a wrestling match reveal no sign of aggression. In another form of play, one toucan tosses fruit which another catches in the air, then throws it in similar fashion to a third, who may pitch it to a fourth member of the flock.
Toucan’s arc often reported to sleep inhales, but this is only known to occur in the medium-sized araucarias and the Guianantoucanet
The big Ramphastos toucans appear tones regularly in holes resulting from the decay of tree trunks, the availability of which may limit the number of breeding pairs. A favorable hole, in sound wood within orifice just wide enough for the adults to squeeze through, may be used year after year. The hole may be only a few cm or 2M (6.5ft) deep. A suitable cavity near the base of a trunk may tempt toucans closer to the ground than is normal. Smaller toucans often occupy woodpeckers’ holes, some-times evicting the owners. They may cleanout and enlarge existing cavities, and some-times try to carve their own holes in soft, decaying wood, but apparently rarely with success. The nest chamber is never lined, but the 2-4 white eggs rest upon a few chipset the bottom, or upon a pebbly bed of regurgitated seeds of various sizes, shapes and colors, which grows thicker as incubation proceeds.
Parents share incubation and are, forbids of their size, impatient sitters, rarely remaining at their task for more than anhour and often leaving their eggs un-covered. Far from trying to repel intruderswith their great bills, the least threat causesthem to slip out and fly away.
After about 16 days of incubation the nestlings hatch blind and naked, with no trace of down on their pink skins. Like new-born woodpeckers, which they closely resemble, they have short bills with the lower mandible slightly longer than the upper. Around each ankle joint is a pad of spike-like projections, which protects it from abrasion as the nestlings stand on their rough floor, supporting themselves on heels and swollen abdomen. Nestlings are fed by both parents, with increasing quantities of fruit as they grow older, but they develop surprisingly slowly. The feathers of the smalltoucanets do not begin to expand until they are nearly four weeks old, and month-oldRarnphastos nestlings are still largely naked. Both parents brood the nestlings, sometimes the male by night, as in woodpeckers. They carry large billfolds of waste from the nest. Some, including Emerald toucanets, keeping the nest perfectly clean, whereas Keel-billed toucans permit decaying seeds to remain.
When finally fully feathered, young too-cans resemble their parents, but their bills are smaller and less highly colored. Smalltoucanets may fly from the nest when 43days old, but the larger Ramphastos toucans remain for about 5o days. Araucarias are led back to the nest to sleep with their parent shut, as far as is known, other fledglings roost amid foliage.
The biggest toucans, to species of the genus Ramphastos, are chiefly inhabitants of lowland rain forests, from which they make excursions into neighboring clearings with scattered trees. They are rarely seen at altitudes of 1, 50om (5, 000ft) above sea level. Their plumage is chiefly black or blackish and their calls are largely croaks and yelps, but the vesper song of theChestnut-mandibled toucan (dies to de,), is almost melodious when heard in the distance.
The r t species of araucarias are smaller and more slender than the other toucans. They too are inhabitants of warm forests, but rarely venture as high as 1,5oom (4,9ooft).They have black or dusky green backs, cram-son rumps and are usually black on headland neck. Their largely yellow underpartsare crossed by one or two bands of black oared. Their long bills are black and ivory white, wholly ivory white or mainly fiery red. Exceptional for this group, the Curl-crested araucaria has its crown covered with broad, shiny feathers that resemble curledhorny shavings. The calls of the better-known species are sharp and high-pitched for such large birds. They are the only too-cans which, as far as is known, regularly lodge in holes throughout the year.
Tourane’s of the genus Aulacorhynchus are small to large with mainly green plumage. Their calls are unmelodious croaks, barks and dry rattles. They chiefly inhabit cool mountain forests, between1, 000 and 3,000m (3,3oo—i 0,0ooft), and rarely descend into warm lowlands.
The five species of toucanets belonging tithe genus Selenidera dwell in rain forests aglow altitudes from Honduras to northeast Argentina. Their plumage is more variable than that of the foregoing species, and they are the only toucans of which the sexes differ conspicuously in color. The reddish brown
Bill of the Tawny-tufted toucan is prominently striped with black. Little is known of the habits of these small toucans.
Least known of all are the four species of mountain toucans which, as their generic name Indigene implies, inhabit the Andes from northwest Venezuela to Bolivia. Fromthe subtropical zone they extend far upwardinto the altitudinal temperate zone. Oneof the more colorful is the Black-billedmountain-toucan, whose light blue under-parts are exceptional in the toucan family.Its crown and nape are black. its back andwings olive brown, rump yellow, throatwhite, undertail coverts crimson and thighs chestnut. Although these and many othertoucans arc becoming rarer as their habitatsare destroyed. many remain to be studied bynaturalists hardy enough to pass longmonths in remote forests. APS
The dull plumage, remote habitat and retir-ing disposition of honeyguides disguise afamily whose behavior is among the mostextraordinary—and least known —of anybirds. They are named for the habit, of onespecies in particular (the Greater honey-guide), of guiding people and other largemammals to bees’ nests. Experiments havein fact shown that the birds prefer the bees’larvae and even their waxy comb to honey.Honeyguides combine two specializations :the unique one of eating wax and the lessunusual one of laying their eggs in otherbirds’ nests.
Honeyguides are probably most closelyrelated to woodpeckers and barbets. Theyoccur only in the Old World tropics, mostin Africa but two species in Asia. Their mainhabitat is broadleaved forest, though in twogenera (f’rodotiscus and Indicator) someinhabit more open woodland. Most of theAfrican species form several groups ofclosely related species which are so similarto each other that even specialists find themvery hard to identify, especially in the field. Within each group darker-colored speciestend to live in broadleaved forest, paler onesin drier woodland. So cryptic and incon-spicuous can they he that a totally new spe-cies was described from West Africa asrecently as t 98 .1 (Eisentraufs honeyguide).In most species the somber camouflage isrelieved only by light sides to the tail whichare conspicuous in flight and possibly helpto lure potential hosts away from their nests.Only three species depart from this drabuniformity: the Lyre-tailed honeyguide ofWest Africa, in which the tail of both sexesis curved outwards and the two pin-likeoutermost feathers make (like those ofsnipes) a loud tooting noise in diving flight;the Indian honeyguide of the Himalayas,which has orange on the head and rump ;and the Greater or Black-throated honey-guide in which the male has a black throat,white cheeks, yellow shoulder-flashes and apink bill, and which is the only species inwhich the sexes have a different appear-ance. All species have zygodactyl feet (ie feetin which the second and third toes of eachfoot point forward and the first and fourthbackward), like woodpeckers, and manyalso have curiously prominent nostrils,edged with a raised ridge; several speciesseem to he attracted to wood-smoke,perhaps especially to burning wax, and mayhave a keen sense of smell connected withlocating bees’ nests, though this intriguingpossibility has not been investigated.
All species, so far as is known, includewax of some kind in their diet, though mosteat mainly insects. Birds cannot digest waxwithout the aid of bacteria in their gut ; the
existence of these has been reported in Les-ser honeyguides but not confirmed in thisor any other species. Experiments haveshown that both Lesser and Greater honey-guides can certainly digest wax somehow,since they can survive on a diet of pure waxfor about 3o days. The small species in thegenus Prodotiscus eat mainly scale insects,which are thickly coated in wax.
Male Indian honeyguides defend bees’nests, at which they feed, and to whichfemales are admitted if they will mate. Thisspecies lacks white in the tail and may nothe parasitic, since females bring young tobees’ nests and their eggs have never beenfound despite searches of nests of likelyhosts. In several other species males givesimple monotonous calls from perches towhich females come to mate ; some speciesseem to defend possible hosts against otherhoneyguides. Honeyguide eggs are laid inholes in trees or banks, in the nests of otherspecies, almost always singly. Young of atleast two species hatch with sharp hooks onthe tip of the bill, with which they puncturehosts’ eggs or kill their chicks. They havean insistent begging call which sounds likeseveral of the host young calling together.
Honeyguides are birds of forest and wood-land, and their future is as threatened asthat of their habitat. The Greater honey-guide, with its unique mutually beneficial.relationship with man , must adaptto changing human behavior as well as toshrinking habitats if it is to survive.
Any visitor to Africa is certain of hearing themonotonous repetitive calls of barbets as they occur in all the major vegetation zones ;5 African genera (39 species) are recognizedand within these there is a greaterdivergence in size, bill shape and color pat-tern than is found in Asian and Americangenera. Adaptation to more arid habitatswithin Africa is thought to have given riseto the tinkerbirds and ground barbets. Spe-cies equivalent to these ecologically do notoccur in Asia or tropical America. In thesecontinents the barbets are larger and in themain arboreal, 3 genera ( r 3 species) beingrecognized in South America and 3 genera(26 species) in Asia (where 2 genera containonly one species each). There are somenotable instances of convergence in thefamily. The Black-hacked barbet of CentralAfrica is similar to the White-mantled bar-bet of South America, and each continenthas a medium-sized brown plumaged spe-cies which is highly social.
Barbets are compact, thickset birds withrather large heads. The bill is stout, conicaland sharply tipped, being more formidablein the larger species. The Lybius species havenotched hills that assist in gripping food andin the Prong-billed barbet the tip of theupper mandible fits into a deep cleft in thelower mandible. Many have bristles aroundthe gape and chin and tufts over the nostrils.The legs are short and strong, the feetzygodactylic (ie on each foot the second andthird toes point forward, the first and fourthbackward). They climb like woodpeckersand their short tail is often used as a support.The large barbets appear heavy and cum-bersome in their movements but others (egthe Red-headed barbet and the tinkerbirds)are agile and probe and search much liketits. The wings are short and rounded, andunsuitable for sustained flight. Ground bar-bets move by inelegant hops.
The Eubucco species of South Americahave green wings, back and tail, and under-parts of yellow streaked with green. Theydiffer from each other in the color patternof their head, throat and breast; the sexeshave different appearances. The male Red-headed barbet has the whole head andthroat scarlet shading to orange on thebreast, and a blue collar on the nape. Thefemale has blue on the side of the head, agray throat and yellow orange on the upperbreast. The sexes of the Capito species arealso different. Both sexes of the Black-spotted barbet have scarlet on head andthroat, black upperparts streaked withgreenish yellow and creamy yellow under-parts. The female differs from the male inhaving black spots on the throat and beingmore heavily spotted black on the under-
parts. Most Asian barbets are pre-dominantly green and differences betweenspecies lie in the head colors (brown, red,yellow, orange) and their pattern ; the sexesare identical in the field. The Great barbethas a yellow bill, maroon-brown upper-parts, a violet blue-black head, multicoloredunderparts (olive brown, blue, yellow) andred under-tail coverts. In contrast, there isvery little green in African barbets, and themajority are patterned black, yellow and redand their plumage is heavily spotted andbarred, much more so than in Asian andSouth American species. Some are a verydrab brown (Gymnobucco species) and havea tuft of’ rictal bristles and a head more orless bare of feathers. The sexes are alike inthe majority of species.
Most species feed on fruit, much of whichis lost when plucked from the tree, but someare more efficient and hold the fruit with afoot when eating. Petals, flower heads andnectar are eaten by some species (for exam-ple, the Great barbet, Prong-billed barbet).Most, if not all, species feed insects to newlyhatched young and some take insectsregularly, particularly termites which maybe caught either on the wing or on theground. Ants and grasshoppers are takenand the larger species (for example, theLineated barbet) occasionally take lizards,tree frogs and small birds. The Red-headedbarbet is mainly insectivorous and feeds inthe ground litter. Insect remains areregurgitated as pellets. Fruit-eating barbetsoften feed in mixed flocks of other species.There are no seasonal migrations ; local movements are governed by the availabilityof food sources.
The breeding behavior of barbets is variedbut little studied. The Prong-billed barbet inCosta Rica lays only one clutch of eggs andhas a restricted breeding season beginningin March. Other species are paired through-out the year and have a prolonged breedingseason covering both dry and wet seasonsin which three or four broods may be raised(for example, the Yellow-fronted tinkerbird)or else breed only in the wet season (forexample, ground barbets). The same hole isoften used for successive broods and isdeepened after each brood. D’Arnaud’s bar-bet, one of the ground barbets, bores a tun-nel vertically downwards into level groundand then bores horizontally before formingthe nest chamber. The Pied barbet has beenknown to use deserted nests of swallows andmartins when nest-sites are scarce. Bothsexes excavate the nest-hole, share inincubation and feeding nestlings, and innest sanitation. Feces are sometimes swal-lowed or else pounded with sawdust in thenest-hole into small halls which are thenremoved. In several of the African speciesextra helpers, often young of a previousbrood, have been recorded feeding nestlingsbut little detail is known of the cooperativebreeding. The African Gyrimobucco speciesbreed colonially and with other African spe-cies are often parasitized by honeyguides.\
Because of the difficulty of observing bar-bets, particularly the forest species, little isknown of their courtship behavior, only thatthe male frequently pursues the female. Inground barbets the male postures withraised crown feathers and struts around thefemale. Duetting is a common feature of bar-bets from all three continents. Its exact func-tion is not certain. It occurs throughout theyear and there is an immediate response bybirds to the play-back of a duet sequence.It probably helps to maintain both territoriesand family bonds. Barbets are highly ter-ritorial and aggressive to other birds (egwoodpeckers, honeyguides) and may thenhe defending a food source (fruit) or a roost-ing or nest site. Communal roosting offamily parties is frequent, even in aggressivespecies.
The metallic quality of the voices ofseveral African and Oriental species hasearned them names such as stinkerbird.blacksmith and coppersmith.
The young hatch blind and naked andhave heel pads. These may be used toenlarge the cramped nest-hole : the honey-guides that are parasitic on barbets alsohave the pads.