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The that thinks it’s a cow "IRDS¬DONT¬NORMALLY¬GRAZE¬¬IN¬HERDS ¬DIGEST¬FOR¬HOURS¬AND¬ EMIT¬A¬SMELL¬OF¬FRESH¬¬*AMES¬0ARRY¬lNDS¬OUT¬MORE¬ ABOUT¬THE¬HOATZIN¬n¬3OUTH¬!MERICAS¬MOST¬EXTRAORDINARY¬BIRD 4HE¬HOATZIN ¬SEEN¬HERE¬IN¬0ERUS¬ 4AMBOPATA¬.ATIONAL¬2ESERVE ¬IS¬ A¬MISlT¬THAT¬HAS¬RIPPED¬UP¬THE¬

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"LUNDERING¬INELEGANTLY¬ THROUGH¬THE¬FOLIAGE ¬THE¬ HOATZIN¬HAS¬THE¬AIR¬OF¬ SOMEONE¬WHO¬HAS¬JUST¬ BEEN¬RUDELY¬AWOKEN¬ addling along a tributary of Hoatzins are often said to smell of fresh 0 Ecuador’s Napo River shortly cow manure or sweet-smelling hay as a after dawn, I felt closer to the by-product of their unconventional diet. rainforest than on any of my previous visits While wondering if the legend of their to this glorious region. A tangled mesh of scent had any basis in fact or belonged in vegetation cascaded down from the canopy the realms of folklore, I rounded a bend in above and trailed in the water next to my the river and there they were: half a dozen canoe. Iridescent blue Morpho butterflies gawky-looking draped over a shrub, the size of dinner plates sailed past, almost busily tucking in. within touching distance, and squirrel A couple of the group flapped about monkeys cavorted in the waterside trees. clumsily to find a new sprig on which to I thought I heard the yelp of a giant gorge themselves. One wasn’t eating at 'ETTING¬AIRBORNE¬IS¬A¬STRUGGLE¬FOR¬THE¬PONDEROUS¬ otter, while closer to hand the siren- all, instead perching almost motionless in HOATZIN ¬WHICH¬SELDOM¬ATTEMPTS¬TO¬mY¬FAR¬ like call of a screaming piha – surely a shaft of early morning sunshine. That’s the noisiest bird in the rainforest – another thing about hoatzins – nothing reverberated through the understorey. It they do is ever in a hurry. shaped tail used to maintain balance while was all stirring stuff, but something was scrambling around in vegetation. The missing. Hoatzins (Opisthocomus hoazin), &ASHIONåSTATEMENTå black, russet and cream plumage has a hint those zoological curiosities, were what By no stretch of the imagination could of the Georgian gentleman. had lured me here. I didn’t want to leave they be described as beautiful – a few But the elegance stops there. Hoatzins without seeing – or smelling – them. assorted handsome features, to be sure, but are awkward birds who spend most of A gang of the unusual birds had been the sum total of these parts almost borders their time scrambling round on bushes here the previous day, but they had moved on the grotesque. Yet I’ve always found surrounding South American waterways. on. The reason why was clear – the tree in a quirky charm in the species’ eclectic Their flight is laboured, with many a which they had been spotted was stripped appearance. A funky mohican crest and comical crash-landing, and their flouncing bare. Uniquely among birds, hoatzins are neon-blue facial skin surrounding a beady gait probably gave rise to one of their local folivores, or -eaters. They’d simply red eye are accessorised by dramatic, Brazilian names: cigana, meaning gypsy. scoffed the lot and gone to find more. cape-like wings and an extravagant fan- Hoatzins have intrigued and befuddled scientists ever since they were first described by German zoologist Statius Müller in 1776. Taxonomists have spent (OATZINSåHAVEåINTRIGUEDåANDåå decades deciding how to categorise these unusual birds, originally placing them with BEFUDDLEDåSCIENTISTSåFORåCENTURIES , then moving them around 

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(OATZINS¬SIT¬FOR¬HOURS¬ DIGESTING¬THE¬LEAVES¬THAT¬  the avian family tree from pigeons to hoatzins, which they use to help scramble tissue. The birds ‘chew’ the leaves before FORM¬THE¬BULK¬OF¬THEIR¬DIET and rails to . The use of out of the water and in the trees before swallowing, and ridges inside their crops DNA analysis seems to have made things their adult wings are fully developed. help to break down the leaf bulk further so more, rather than less, complicated – It is now thought that this trait evolved it can be processed more easily. In digestive while it has ruled out some relationships, separately in hoatzins, rather than being matters, hoatzins have more in common scientists still cannot identify a close inherited directly from and with and sheep than with their relative. Today, the hoatzin is other early birds. feathered relatives. part-way through being sequenced and in Hoatzins digest their food very, very the meantime it has been given its own "RANCHINGåOUT slowly. A meal can take as long as 45 hours family, (from the Greek for Whatever the truth about the hoatzins’ to pass from bill to cloaca. This is why ‘those with long hair behind’). past, their diet makes them unique. They these birds loaf around for up to 80 per The hoatzin split from other bird groups are the only birds known to possess a cent of their time – they are effectively a long time ago, though precisely how and foregut fermentation system. This highly chewing the cud. /0)34(/#/-53¬(/!:). when remains unclear since there is only specialised arrangement equips them to There is a downside to having such one undisputable related – part of a process the huge quantity of foliage they a supersized crop. Hoatzins only have skull that was found in Magdalena Valley, need to provide enough energy to survive, enough space left inside their bodies for a ,!4).å.!-%¬/PISTHOCOMUS¬HOAZIN , and described in 1953. This since the leaves that form the bulk of their simple, reduced sternum (breast bone) and #/--/.å.!-%¬(OATZIN¬AKA¬@STINK¬BIRD has not stopped scientists from speculating diet are low in nutrients. puny flight muscles. Small wonder then 3):%¬LENGTH¬ CM¬ IN ¬¬ on the bird’s primitive status, with one The hoatzins’ oesophagus and enlarged that they are such weak flyers. I have seen WEIGHT¬ G¬ OZ  describing the hoatzin as long ago as crop serve as fermentation chambers. birds so engorged that they can’t take off $)%4å(OATZINS¬EAT¬LEAVES¬AND¬BUDS¬OF¬OVER¬¬ 1898 as “living evidence of the transition Inside are anaerobic bacteria that secrete and simply sit for hours, beaks gaping and SPECIES¬OF¬PLANTS ¬INCLUDING¬SEVERAL¬TOXIC¬TO¬ between reptiles and birds.” The claim was enzymes able to break down the otherwise wings drooping, until they have at last OTHER¬BIRDS¬!¬¬STUDY¬IN¬6ENEZUELA¬FOUND¬ largely due to the wing claws of young indigestible cellulose present in plant processed their meal. THEIR¬DIET¬CONSISTED¬OF¬¬PER¬CENT¬LEAVES ¬¬ Besides their reputed odour and their PER¬CENT¬mOWERS¬AND¬¬PER¬CENT¬FRUIT cow-like eating habits, hoatzins are "2%%$).'¬4HEY¬BREED¬DURING¬THE¬RAINY¬¬ (OATZINSå LOAFåAROUNDåFORåUPåTOååPERå endowed with another typically bovine birds have been recorded – and they are on locally grown vegetation and even SEASON ¬OFTEN¬WITH¬SEVERAL¬PAIRS¬NESTING¬IN¬ characteristic: they are highly social. The noisy. An entire family may engage in a successfully hatching chicks, but the birds CLOSE¬PROXIMITY¬4HE¬FEMALE¬LAYS¬TWO¬TO¬FOUR¬ birds form family flocks of up to a dozen cacophony of grunts, squawks and hisses, did not survive. ¬ON¬A¬SIMPLE¬TWIG¬PLATFORM¬IN¬A¬TREE¬ CENTåOFåTHEIRåTIMEåCHEWINGåTHEåCUD or so individuals. Colonies of 40 or more often delivered in unison. The birds In contrast to jaguars, toucans OVERHANGING¬WATER¬USUALLY¬ONLY¬ONE¬CHICK¬ are usually set off by one particularly and macaws, hoatzins are somewhat mEDGES¬ABOUT¬¬DAYS¬AFTER¬HATCHING¬!¬¬ enthusiastic individual, who leads the rest unconventional icons of the Amazon CO OPERATIVE¬BREEDER ¬UP¬TO¬SIX¬@HELPERS ¬ of the ensemble in a bizarre chorus. jungle. For the record, I couldn’t detect INCLUDING¬THE¬PREVIOUS¬YEARS¬OFFSPRING ¬MAY¬ $)'%34)6%¬-!')#¬(OW¬DOES¬THE¬HOATZIN¬DO¬IT any smell from the birds I saw during my HELP¬BREEDING¬PAIRS¬TO¬REAR¬THEIR¬YOUNG 4OURISTåTHREAT trip, but I found all the other specialised ,/.'%6)49¬5P¬TO¬ABOUT¬¬YEARS¬IN¬THE¬WILD Because their meat is generally regarded as characteristics of this remarkable bird (!")4!4å!.$å2!.'%¬7ATERSIDE¬¬ unpalatable, hoatzins are rarely hunted and exactly as promised. Rest assured, this AND¬OTHER¬TREES¬AND¬BUSHES¬BESIDE¬LAKES ¬RIVERS¬ the principal threat to them comes from avian enigma will continue to defy the AND¬SWAMPS ¬¬¬ disturbance and habitat destruction. They norms of the natural world. -!).å4(2%!43¬,OSS¬OF¬HABITAT¬AND¬ are often tame and seemingly tolerant of ;!åVERSIONåOFåTHISåARTICLEålRSTåAPPEAREDåINå""#å7ILDLIFEå-AGAZINE= DISTURBANCE¬BY¬HUMANS ¬PARTICULARLY¬TOURISTS¬ humans, but research in tourist areas has GETTING¬TOO¬CLOSE indicated a more worrying picture. In å(/ #/.3%26!4)/.å34!453¬#OMMON ¬BUT¬WITH¬A¬ %) 2004, researchers placed microphones in *AMESå0ARRYåIS¬A¬"RITISH¬WILDLIFE¬JOURNALIST¬ AND¬AUTHOR¬OF¬A¬NUMBER¬OF¬¬ PATCHY¬DISTRIBUTION¬ACROSS¬ITS¬RANGE hoatzin nests at Cuyabeno in Ecuador both BOOKS¬ON¬NATURAL¬HISTORY ¬INCLUDING¬ in tourist areas and undisturbed nesting 2AINFOREST¬3AFARI¬#ARLTON¬"OOKS ¬ sites. They discovered that in the tourist sites the heart rates and stress levels of the 'UYANA 3URINAME &RENCHå'UIANA 4)/.å"9å3(%5 +5

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4 SECOND ¬THE¬GIZZARD ¬HAS¬POWERFUL¬MUSCLES ¬AND¬ @#HEWING¬THE¬CUD¬ADDS¬MORE¬SALIVA¬AND¬BREAKS¬FOOD¬ STOMACH¬CHAMBER¬AND¬GIZZARD¬ARE¬MUCH¬SMALLER¬THAN¬ 3OUTH Zoo in 1931, but died soon after arrival. spectacular natural history programs HOLDS¬SWALLOWED¬GRIT¬AND¬SMALL¬STONES¬FOR¬GRINDING DOWN¬FURTHER¬BEFORE¬IT¬ADVANCES¬THROUGH¬THE¬SYSTEM IN¬OTHER¬BIRDS¬AND¬IT¬TAKES¬MANY¬HOURS¬TO¬DIGEST 0ACIlCå !RGENTINA More recently the housed a from BBC Earth on BBC America. /CEAN MEET YOUR PLANET: '%449 å small group in the 1990s, feeding them www.bbcearth.com

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