Fostering a hooded vulture chick

Zoo Atlanta is home to four critically endangered hooded vultures: Baobob, Marula, Tai, and Acacia. Hooded vultures are found in the open savannas and woodlands of sub-Saharan Africa. At Zoo Atlanta, you can find Baobob and Marula showing off their natural behaviors in the Wonders of Wildlife Theater, and you can find Tai and Acacia on habitat in the Orkin Children’s Zoo. All four hooded vultures are part of AZA’s Species Survival Program® or SSP.

Every three years, with the help of studbook keepers and population biologists, the SSP’s program leader assesses the hooded vulture population in AZA accredited facilities and makes recommendations for them to breed, to not breed, or to move to another zoo or aquarium. These recommendations are based on several factors including habitat space, genetics, and each zoo’s and aquarium’s interest in the species. The ultimate goal of the SSP, however, is to ensure that a genetically diverse and self-sustaining population of hooded vultures is maintained at zoos and aquariums for future generations to learn about, connect with, and hopefully take conservation actions to protect them in their natural habitats. Did you know that hooded vulture populations in the wild have declined an average of 62% since the 1960s?

Zoo Atlanta’s Bird Team has the expertise and the interest in breeding hooded vultures. However, none of the hooded vultures at Zoo Atlanta are recommended to breed by the SSP because of their genetics. They’re all related to each other! So, how does Zoo Atlanta contribute to the sustainability of the hooded vulture population? By fostering, of course! Just like Tai and Acacia are not considered genetically valuable and not recommended to breed, there are pairs of hooded vultures in AZA accredited zoos and aquariums that are so genetically valuable that they are recommended to breed multiple times within the same breeding season. This is the case for a pair of hooded vultures at the Dallas Zoo named Pierre and Trudy.

Wait …let’s back up. To understand fostering in aviculture, you also have to understand the term clutch and the process of re-clutching. A clutch is the total eggs a bird lays per each nesting attempt. A re-clutch is when a bird lays more than one clutch during the same breeding season. Some birds re-clutch naturally. For instance, right in our own backyards, mourning doves will produce a clutch of eggs and raise chicks in early spring and do the process all over again in late summer. In many species of birds, including hooded vultures, it is not normal for them to lay more than one clutch of eggs per breeding season. However, if the first clutch fails, perhaps because the eggs are infertile or are snatched by a predator, the birds will often re-clutch.

When Pierre and Trudy laid their first clutch of the breeding season, Tai and Acacia had also laid their first clutch of the breeding season. The timing was perfect. Aviculturists at the Dallas Zoo simply removed the single egg from Pierre and Trudy, which simulated it being snatched by a predator, and sent it to Zoo Atlanta to incubate and hatch. Pierre and Trudy, thinking that their first clutch had failed, re-clutched several weeks later. So, while Tai and Acacia are raising Pierre’s and Trudy’s first chick of the season, Pierre and Trudy are raising their second chick of the season – all unbeknownst to them, of course.

While this sounds very simple in theory, moving eggs from one zoo to another can be logistically challenging. Eggs are artificially incubated in incubators built to maintain set temperatures, set humidities, and with the ability to turn eggs. These machines are much too complex to transport eggs, so we use brooders instead. A brooder is a machine built to maintain set temperatures and humidities but not to turn eggs. Zoo Atlanta utilizes a travel brooder with a power supply that comes from a car’s auxiliary power outlet (aka. car cigarette lighter). Two bird keepers drove to the Dallas Zoo to pick up the egg and monitor the heat and humidity of the brooder during its 12-hour return trip to Zoo Atlanta. Once at Zoo Atlanta, the egg was artificially incubated, hatched, and hand-reared until being given to its foster parents at eight days old. Hand-rearing ensures the chick is healthy and giving a good feeding response before returning it to the nest. Tai and Acacia have been taking turns feeding and brooding the chick successfully since it was given to them. The Bird Team is still weighing the chick daily to ensure proper weight gains and development. In the future, this chick will most likely be recommended to transfer to another AZA accredited facility to breed and help sustain its species.

Lauren Wilson
Curator of Birds