The alternative name of “stinkbird” is derived from the bird’s foul odour, which is caused by the fermentation of food in its digestive system. These calls are often associated with body movements, such as wing spreading. Calls are used to maintain contact the unfeathered bird pdf individuals in groups, warn of threats and intruders and by chicks begging for food.
There has been much debate about the hoatzin’s relationships with other birds. 64 million years ago, shortly after the extinction event that killed the non-avian dinosaurs. The evolution of avian dactyly, on the other hand, is not entirely resolved to satisfaction. Sibley and Ahlquist’s previous treatment. It was not possible, though, to reliably determine the hoatzin’s closest living relatives.
While the doves did also group with the “Metaves”, no close relationship between these and the hoatzin within Metaves was recovered. Metaves instead may be a “wastebasket taxon”. This would seem to suggest that the hoatzin is at least more closely related to doves than to many of the other purported ‘coronavian’ families that previously have been suggested. Subsequent multigene studies of Ericson et al. 2006 and of Hackett et al. 2008 corroborated the Metaves clades, dependent on the inclusion of one and two genes respectively, but the latter did not recover the hoatzin with Metaves.
More recently, Houde embarked on sequencing the entire genome of the hoatzin. As of 2011, it was reported that more than 1. 4 billion base pairs of hoatzin DNA had been sequenced, roughly equal to its entire haploid genome, but that only about 2. Completion of this project would be welcomed for more reasons than resolution of hoatzin relationships.
Moreover, much might be learned by coordinating these efforts with that of the metagenomic analysis of the hoatzin foregut ruminant bacterial microflora. The newly hatched bird has claws on its thumb and first finger enabling it to dexterously climb tree branches until its wings are strong enough for sustained flight. These claws are gone by the time the bird reaches adulthood. It markedly differs insofar as that the cranium of the living hoatzin is characteristic, being much domed, rounded, and shortened, and that these autapomorphies were less pronounced in the Miocene bird. Miller discussed these findings in the light of the supposed affiliation of the hoatzins and the Galliformes, which was the favored hypothesis at that time, but had been controversial almost since its inception. Opisthocomiforms seem to have been much more widespread in the past, with the present South American distribution being only a relic.