Without any breeding pairs of Bearded Vultures in captivity, attaining chicks in Southern Africa can be quite challenging and often entails different practices compared to our European programme.
In this article, we document the stages of the 2021 captive breeding season for Bearded Vultures in Southern Africa, from harvesting eggs to rearing chicks.
Establishing a captive breeding programme in Southern Africa for Bearded Vultures
The Bearded Vulture sub-species (Gypaetus barbatus meridionalis) living in South Africa and Lesotho is considered Critically Endangered in Southern Africa. After the species suffered more than a 30% decline in recent years, urgent action was needed to safeguard its small and isolated population, restricted to the Maloti-Drakensberg Mountains. This is where an ambitious conservation programme came to life.
When the Bilateral (Lesotho and South Africa) Bearded Vulture Recovery Programme run by the Bearded Vulture Task Force took the decision in 2015 to establish a captive population in southern Africa, the African Raptor Centre based near Durban in South Africa began #Bred4theWild. This programme involves the captive-breeding of Bearded Vultures along the same lines as the European Bearded Vulture Captive Breeding Network, coordinated by us at the Vulture Conservation Foundation (VCF) on behalf of EAZA’s EEP (Bearded Vulture EEP).
The Southern African programme aims to create a genetically viable captive population from 20-30 non-related founder birds over the upcoming years. These founder birds will be used to breed young chicks that can be released back into the wild. In 2015, the only Bearded Vulture in captivity was an adult female, Lesli, rescued from a traditional healer. So, to attain chicks, conservationists from the African Raptor Centre need to harvest second eggs from wild nests. Bearded Vultures usually produce a clutch of two eggs, but will only raise one young due to an evolutionary behaviour called ‘canism’ where the older chick kills the younger one. The team takes the second egg from the nest without affecting the wild birds and then rears the chick in captivity.
The 2021 captive breeding season for Bearded Vultures in Southern Africa
Start of the breeding season in the wild
In the southern hemisphere, Bearded Vulture pair bonding and nest building take place in April and May. By mid-June, wild pairs start laying their clutches, and subsequently, the 54-day incubation period commences. During this time, members of the Bearded Vulture Recovery Programme spread across the Maluti-Drakensberg range, monitoring known pairs to check breeding activity.
Bearded Vulture harvest season
By late July, the egg harvest period begins. Specialized teams face challenging landscapes, hiking and climbing high up in the mountains to access the remote Bearded Vulture nests and retrieve the second egg from each nest. Upon retrieving the eggs, the team transports them in the safest and quickest way possible to the African Raptor Centre for incubation. In the end, the team retrieved seven eggs, exceeding their initial objective of six.
Since there are no adult Bearded Vulture pairs available within the programme, the eggs need to be artificially incubated. Around four times a day, the team removes the eggs from the incubator and exposes them to outside temperatures, stimulating a thermal shock, which is a protocol developed by the VCF. The thermal shock promotes gas exchange (CO2 and O2) and, consequently, the embryo’s development. Essentially, it replicates the behaviour of the parental swap in the wild, where one parent leaves the nest to forage and the other takes over the incubation duties.
Every evening, the harvested Bearded Vulture eggs are ‘candled’ to monitor their development. It involves shining a light into the large end of the egg to identify embryonic movement and progress. Unfortunately, the team realised that one of the seven harvested eggs was unviable during this process.
When the chick breaks into the air sac of the egg, it begins vocalizing or chipping, signalling that hatching is around the corner. The staff’s team closely monitors the hatching process and sometimes needs to assist the chicks.
The team uses three important methods when rearing chicks to ensure they grow up to behave like their wild conspecifics, enabling them to breed – use of a puppet for feeding, socialization among chicks and exposure to an adult bird.
Feeding chicks with a Bearded Vulture puppet
After a week from hatching, chicks become aware of who is feeding them. Therefore, to prevent human imprinting, where they would recognize humans as their species, the staff uses a Bearded Vulture puppet when feeding the young.
Socializing chicks with one another
They raise the chicks socially, allowing visual contact, but separated with a container or a barrier, preventing the chicks from potentially hurting each other.
Exposing chicks to an adult
At 20 days of age, the chicks can thermoregulate. That’s when the team moves them outside to a rearing enclosure pothole to introduce them to the ‘surrogate parent’. The front of the pothole is barricaded to prevent the adult bird from potentially injuring the growing chick.
Determining the sex
The DNA blood sexing results revealed a perfect balance of three males and three females for the 2021 harvest. Skewed sex ratios can prove a challenge in any breeding programme when it’s time to pair birds. Overall, this programme has a couple more females than males in the breeding group.
Monitoring their development
The team weighs the Bearded Vulture chicks every week and records their physical development to ensure they reach their weight milestones, suggested by the Bearded Vulture EEP guidelines.
As they develop, the young vultures have more feathers and less fluff, and the new grey and white mottled feathers almost cover their thick grey down, which is still visible on their necks and the back of their heads. These feathers form the bird’s first juvenile plumage. The eye sclera also starts to become visible. The distinctive red ring around the eye of the Bearded Vulture is so characteristic of the species.
As they reach three months of age, the barriers separating Bearded Vulture chicks from each other and the older birds drop, allowing for direct interaction between them as they leave out of their nest platforms.
By early December, the Bearded Vulture chicks are ‘fully-fledged,’ meaning they acquired their first flight feathers and left the sanctuary of the nest for the first time.
The addition of these young Bearded Vultures to the programme in Southern Africa is a significant milestone. Congratulations to our partners for their brilliant work over the 2021 breeding season.