King Vultures feed on carrion and typically find their food by sight, soaring and transect-sailing at moderate heights over forests and open country. The majority of research suggests that King Vultures do not have olfactory sensors to locate carrion by smell; an experiment on captive King Vultures found that they were unable to locate hidden food by smell (Houston 1984), and the author suggested that they soar at high altitudes and locate carcasses by watching the activities of Cathartes vultures below. Lemon (1991), however, found that in primary forest (continuous closed canopy) in Costa Rica King Vultures located carrion independent of other vulture species, frequently being the first to arrive at small to medium-sized carcasses. In Venezuela King Vultures have been know to follow jaguars (Schlee 2007). King Vultures can use its heavy beak and larger size to tear a carcass open and typically eats first due to its large size (Houston 1994). However, the interaction among the members of a large guild of scavengers can be more complex. In northern Peru Turkey Vultures Cathartes aura (the only species with well-developed olfactory senses) usually arrive first at a carcass, followed by Black Vultures (Coragyps atratus), and Andean Condors (Vultur gryphus) arrived last (Wallace and Temple 1987). Whenever King Vultures were present, both Turkey and Black Vultures always were present, Crested Caracaras (Caracara cheriway) were present 47% of the time, and Andean Condors 36% of the time. King Vultures usually arrived in pairs, or in apparent family groups of three. Although as many as eight King Vultures were observed together around a carcass, there were never more than five individuals at the carcass at a time. Similar patterns were observed in Venezuela, where Turkey or Lesser Yellow-headed (Cathartes burrovianus) vultures were the first to arrive at a carcass (Houston 1988).
In a study comparing Black, Turkey, Lesser Yellow-headed and King vultures, King Vulture was the only species that was large and strong enough to move or turn over a larger carcass such as a calf (Houston 1988). A comparison of feeding morphologies among vulture assemblages classified King Vulture as a "ripper" with wide skull and strong beak, as compared with "gulpers" and "scrappers" with narrower skulls and weaker beaks (Hertel 1994). King Vulture exhibits a significantly different feeding behavior than Black, Turkey and Lesser Yellow-headed vultures; it is more likely to use both feet as an anchor when tearing food (Houston 1988). Although the number of King Vultures present was positively correlated with the size of the carcass, there was no evidence that they preferred larger carcasses; they were frequently observed feeding on carcasses < 1 kg (Houston 1988).
King Vulture perches in trees, high in the canopy, where they are often not seen (Ferguson-Lees and Christie 2001). They perch in squatting position with head lowered; frequently sunbathe with wings outstretched.
Flight – King Vulture takes off with heavy wing beats mixed with short glides; sails or soars, often very high, on level wings with upswept tips (Ferguson-Lees and Christie 2001). Can drop from the sky at great speed with noisy wings. King Vultures tended to fly higher than Cathartes vultures, most of them over 500 ft above the ground. They use thermal upcurrents to reach high altitudes and then soar or sail rapidly cross-country between thermals. When flying at lower altitudes, because of higher wing loading than Cathartes vultures, they frequently have to flap their wings for short periods (Houston 1988).
King Vulture adults and immatures play with their crops, which become distended into large bare red, and gray or reddish gray balls respectively (Ferguson-Lees and Christie 2001).