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Unravelling the Avian Art of Co-operative Breeding – Londolozi Blog
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Birds have always fascinated us, from their vibrant plumage to their melodic calls although, one of the most intriguing aspects of avian life is their breeding behaviour. Among the myriad of tactics and strategies that birds employ, co-operative breeding stands out as a remarkable display of of social structure, survival, and unity.
The charismatic Red-billed Oxpecker, commonly found on or around most of the mammals seen at Londolozi, usually have up to seven helpers. Some of the helpers, both male and female, are from previous broods and will assist with nest building and feeding of the chicks.
What is Co-operative Breeding?
Co-operative breeding is a system employed by many different species of birds (and some mammals) whereby one pair (the dominant or alpha pair) of nesting birds is sometimes assisted with nest building, incubation and/or chick-rearing by one or a few other (helper) birds of the same species. This behaviour has developed over evolutionary periods because these species breed more successfully if they cooperate in their breeding efforts than if pairs attempt to breed on their own.
Different Structures of Co-operative Breeding Flocks
Depending on the species, founder flocks may be formed by a monogamous pair of birds that then integrate their offspring into the flock or it may form when a group of dispersing male birds join with a group of dispersing female birds. In the latter scenario, the birds will select a representative from either sex as the dominant or alpha member whose role will be to breed on behalf of the gene line. In both scenarios, the principle of kinship selection holds true. The members of the flock are then exerting less energy into their own breeding efforts than if they were to breed individually and yet their genes are being perpetuated through a family representative.
The endangered Southern Ground-hornbill has up to nine helpers from previous broods that are mainly made up of males. They do not assist with nest construction or incubation but rather only assist with feeding the chicks. They can often be seen patrolling the open clearings as they fan out in search of food.
Although it is not always considered to be cooperative breeding, there is reason to argue that delayed dispersal takes the same shape as this phenomenon. This becomes evident when juveniles do not disperse immediately after fledging and rather choose to remain within the natal territory for various reasons. Subsequently, these individuals will often assist in raising the next brood. The only difference is that the flock’s composition is not constant but the parents are still benefiting through additional ‘helpers’.
Although not seen as a conventional type of cooperative breeding, Red-billed Buffalo Weavers take a unique form of this behaviour. These birds will mate individually however, they will nest in colonies, which has added benefits from feeding, nest building and protection. Here two adult Red-billed Buffalo Weavers can be seen trying to chase off a much larger African Harrier Hawk looking to prey on chicks within the nest.
What are the Benefits of Cooperative Breeding?
The birds which actively employ this behaviour experience many advantages through cooperative breeding. This behaviour should assist in lowering the mortality rates of the specific species as there are more food providers and members to assist with territorial and nest defence. In some cases, helpers will also assist in the gathering of nesting materials to help build the nest and can even assist with the incubation of eggs. There is also a case to be made for the experience gained in ‘parenting’ for the helpers who may eventually disperse to create their own flock. It goes without saying that birds benefit from the principle of safety in numbers, living in flocks improves group vigilance and decreases the chances of individuals falling victim to predation.
White-Crested Helmetshrikes have between 2-8 helpers of both sexes and will take turns in a highly coordinated incubation schedule. These cooperative breeders share responsibilities of nest construction, feeding and defence.
Why Would Birds Actively Choose This Behaviour?
Considering the obvious advantages of this cooperative behaviour (which seemingly only benefits the breeding pair), the question begs;
Why would younger helpers choose to stay and not get the opportunity to breed for themselves by dispersing and finding an unrelated partner?
The Pied Kingfisher has up to 4, mostly male helpers and will only assist the dominant pair with feeding.
It must be remembered that birds, as with most animals, have an evolved ability and obligation to behave in the best interests of their genes and would therefore take any opportunity to breed in favour of helping. By choosing to stay within the flock, there are increased chances of survival for the entire group.
The charismatic little water birds that are Black Crake’s have between 1 and 4 helpers that are most likely males from previous broods. Interestingly, they do not assist with nest building but rather incubation and feeding.
They are helping to propagate more of their own genetic material than they would have should they breed with an unrelated partner. By staying within a prime territory, the younger birds can monitor vacancies in adjacent territories which could enable a move into these areas should the opportunity present itself. Lastly, younger birds which remain part of the flock could even inherit the natal area or territory should the breeding adult of the same sex die.
Black Collard Barbet’s will usually have between 1 and 4 helpers of both sexes that are likely from previous broods. They will assist the dominant pair with most responsibilities including; nest building, incubation and feeding.
Commonly referred to as the “Trainee” bird amongst Londolozi guides as when there is one there are usually a few lurking not too far away. These White-crested Helmetshrikes have between 2 and 8 helpers of which some are usually adult siblings of both sexes. They will assist the dominant pair with feeding, incubation and nest building.
To my complete surprise, the Verreaux’s Eagle Owl is also considered to be a cooperative breeder. They will usually have 1 male or female helper that is from a previous brood. They will assist the mating pair with feeding and it is unlikely to have a role in either nest building or incubation. Perhaps this is a form of ‘delayed dispersal’ cooperative breeding.
Co-operative breeding is an extremely intricate phenomenon exhibited by several different bird species (way more than I originally expected once I began further research into this topic). These intricate and diverse strategies highlight the adaptability and social complexity of the array of bird species that can be seen at Londolozi. Whether you are an avid birder or a curious nature enthusiast, by observing these species in action, we begin to make sense of and gain a greater understanding of the broader dynamics of Africa’s avian artists.
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Reece Biehler
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