Designed by Paul Smith 2006. This website is copyrighted by law.
Material contained herewith may not be used without the prior written permission of FAUNA Paraguay.
Photographs on this web-site were taken by Paul Smith, Hemme Batjes, Regis Nossent,
Alberto Esquivel, Arne Lesterhuis, José Luis Cartes, Rebecca Zarza and Hugo del Castillo and are used with their permission.
CATHARTIDAE - NEW WORLD VULTURES
Five species of scavenging raptor-like birds. Though traditionally included as part of the Falconiformes, a link to the Ciconiiformes and a close relation to the storks has been proposed. This is supported by skeletal, cranial and muscular characteristics as well as certain behavioural similarities such as defecating on the legs for cooling purposes. The group has a long evolutionary history with the earliest fossils dating back 35 million years. New World Vultures are not closely related to Old World Vultures and certain similarities in structure and behaviour are likely the result of convergent evolution. As in the Old World Vultures, New World Vultures are scavenging carrion-feeders and rarely or never kill their own prey. They have low metabolic rates, digest food efficiently and minimise energy expenditure with almost exclusively soaring flight on huge wings. These adaptations may have arisen as a means of survival because of their unpredictable food source, enabling them to conserve energy when food supply is low. On the other side of the coin Vultures are capable of heating huge amounts at any one sitting thanks to an extensive crop, and they are able to efficiently convert excess energy into fat resources. Vultures possess powerful, hooked bills and a bare head and neck. Though it is often proposed that this is to prevent soiling of head feathers when feeding at a carcass, the character is also present in species which do not habitually "dip" their head into a carcass when feeding. An alternative theory is that it has a thermoregulatory function, with vultures experiencing wide and sudden temperature variations between soaring at altitude and feeding on the ground. One of the unique characteristics of New World Vultures is the lack of an internal septum in the nostrils so that looking through one allows you to see through to the other side. Cathartes has a highly-developed sense of smell, though the other species apparently do not have a sense of smell and will often follow Cathartes vultures to a kill. Vultures have large, but weak feet that are not adapted for grasping having a small, non-functional hallux. There is slight webbing between the toes, which has been hypothesised to act as a braking device upon landing. Moult is remarkably slow taking several years for a complete replacement of the flight feathers. Secondaries and tail feathers are moulted out of sequence resulting in a sometimes "tatty" appearance, especially in immature birds. There is no sexual dimorphism. Below is a brief summary of the major characteristics of the four genera in Paraguay.
Cathartes - Long, broad wings and long tail. Colourful head pattern and dull plumage. Soar on V-shaped wings with frequent tilting.
Coragyps - Small. Short, rounded wings and short, wedge-shaped tail. Dull head pattern and plumage. Frequent flapping in amongst soaring flight.
Sarcoramphus - Large, mostly white body plumage. Colourful head pattern with grotesque wattles.
Vultur - Huge, long, rectangular wings. Bicoloured plumage. Dull head pattern with grotesque wattles.
REFERENCES
Brown L & Amadon D 1989 - Eagles, Hawks and Falcons of the World - Wellfleet Press.
Campbell B & Lack E 1985 - A Dictionary of Birds - T & AD Poyser.
Ferguson-Lees J & Christie DA 2001 - Raptors of the World - Houghton Mifflin.
Houston DC 1994 - Cathartidae Handbook of the Birds of the World Volume 2 - Lynx Ediciones.
