Hand-rearing king vultures
Monday, 15 August 2022
At Burgers' Zoo, we prefer animals to raise their young without zookeepers' intervention. Young animals learn vital skills from their mothers and—depending on the species—their fathers. In certain species, the father actually plays a more important role in this respect. Older siblings may also assist in the process; in some cases, the whole group is involved in forming the young into fully-fledged group members. Animals raised by humans lack these essential, species-specific skills as they grow up, making it difficult to reintroduce them to their conspecifics later. In some cases, there are very important reasons for hand-rearing a young animal. This time: king vultures.
Burgers' Zoo managed the European population management programme for king vultures for many years. With the arrival of the Mangrove, we decided to no longer exhibit king vultures, but back in the day, we managed to breed successfully with these unique birds with some regularity. At one point, we had a pair that successfully laid fertilised eggs but whose male unfortunately often pecked at the eggs, forcing us to use hand-rearing in this case. Genetically, both birds were important to the European population management programme, and their offspring would represent an important bloodline within the studbook.
The fertilised egg was quickly removed from the nest before the male could peck it out again. This egg was then successfully incubated in an incubator. Mirrors were installed in the incubator to help the young imprint on its own species, and a stuffed adult king vulture was placed in front of the incubator. Young king vultures grow rather slowly. At first, the young birds develop a white downy plumage, with the head remaining bare, which is typical of most vulture species. The chick was permanently housed in the incubator to ensure the perfect, pleasant temperature for the young bird.
The zookeepers fed the chick a special menu using tweezers—intestines of day-old mice soaked in pepsin so that they had already been digested to some extent. Pepsin contains physiological salts and comes from the abomasum of a fasted calf. Pepsin is also used to curdle cheese, for example. Feeding the chicks started with tiny bits of food because day-old mice are not that big, let alone their intestines. As the bird grew, the day-old mice intestines were replaced with rat intestines, also soaked in pepsin. Later, when the bird grew even larger, it was given pieces of meat and eventually whole mice and rats that it could eat itself.
Fortunately, the hand-rearing of this king vulture turned out to be a success story. The young female later successfully formed a pair with an unrelated king vulture and raised natural broods herself without needing human help to raise her young. King vultures form pairs for life, so the young female could not be introduced to her parents after hand-rearing, as they would not appreciate her presence once she was old enough to leave the nest. Fortunately, we successfully paired our hand-reared animal with a new male, resulting in a youngster!
