Cooperative Breeding and Communities
In the avian world, the care of young nestlings can be an intense job, with brooding and feeding needed around the clock. In many species, pairs support each other at the nest with these tasks, while in others, a single mother or father bird might bring their young up alone.
However, for some birds, it’s not just the parents that raise the chicks; other group members known as ‘helpers’ offer valuable assistance in incubating and caring for offspring.
Unity in Rearing
A relatively rare concept, cooperative breeding is where a pair of birds receive support from other single, unmated individuals during the nesting season. Only around 3.2 percent of all bird species are observed to use variations of this practice, receiving assistance with nest building, incubating eggs, and feeding and brooding young birds from ‘helper’ birds.
Cooperative breeding benefits the survival rate of hatchlings and relieves stress on parent birds when their nesting responsibilities are shared. Non-breeding helper birds gain experience in the breeding process, as well as protection from males, ultimately improving their own chances of survival.
Pictured: An Azure-winged Magpie. Cooperative breeding benefits the survival rate of hatchlings and relieves stress on parent birds
Understanding Cooperative Breeding
Why would a young, healthy bird forgo its own chances of breeding to help another bird raise their young instead? Well, there are many reasons that cooperative breeding systems have evolved and continue today.
Theories include that cooperative breeding gives helper birds vital experience in the nesting process and improves their own chances of survival.
Read on as we’ll take a closer look below.
What is Cooperative Breeding?
The most typical breeding set-up in the avian world is for pairs to form, construct their own nest (a duty shared in various proportions between the sexes or undertaken solely by the male or female), incubate their own eggs and brood and feed their own young in the nest until they are ready to fledge.
Cooperative breeding sees these responsibilities shared between a wider group, with breeding-age birds choosing not to raise their own young, but instead taking an active role at all stages of the nesting season in helping raise another pair’s young. Helper birds can be either male or female and may be juvenile or have reached breeding age themselves.
One factor that has played a role in the evolution of cooperative breeding is a lack of suitable nest sites or food resources. By not breeding themselves every year, ‘helper’ birds relieve some of the pressure on natural resources and help to boost the chances of survival of their own species, rather than competing for limited food or territories.
Younger birds that spend time assisting pairs with nesting duties benefit from gaining experience from watching all the vital parenthood skills needed in successfully hatching a clutch and raising young and are able to replicate these when their own turn to breed arrives. This is also believed to give them an increased chance of breeding successfully and for the continuation of their species.
The Groove-billed Anis (pictured) work together in a group to construct the nest
The Dynamics of Cooperative Breeding
In cooperative breeding societies, a hierarchy exists that determines which birds breed and which birds are the ‘helpers’. In some cooperative breeding species, helpers are related, younger birds, while in others, the birds that support breeding pairs are unrelated and are just birds of the same species living in the same locality.
Read on to learn more about the dynamics of cooperative breeding.
Roles and Responsibilities
In a cooperative breeding community, the key element is the breeding pair, consisting of the dominant male and female within the population. These are generally responsible for the final say on choice of nest location and construction, and much of the incubation, but are assisted at that stage, and in feeding and brooding young by helpers, which may or may not be relatives.
Helper birds are non-breeding individuals within a population and are often offspring from a previous breeding season. They can be males or females and contribute in a number of ways, including incubating the eggs, defending the nest, and bringing food to parents and chicks.
Subordinate older females may also assist a breeding pair, helping with finding food and delivering it to the nest, and with caring for nestlings. This gives them valuable experience of how to raise young, knowledge which gives them a headstart when raising their own chicks.
Subordinate older males, less dominant than the breeding male, are also frequently observed in the role of non-breeding helper birds, although may attempt to sneak a chance to fertilize eggs in the nest. They generally help out with nest defense and gathering food for both the parents and their offspring.
Pictured: An Arrow-marked Babbler. The young of the previous season will stay to help feed and raise their siblings
Benefits of Cooperative Breeding
Shared responsibility for finding food and allocating resources increases the chances of survival within a group, as less energy is needed in the search for food when a collective effort is put into foraging.
By sharing the incubation and physically demanding brooding and feeding duties during nesting and post-hatching, birds are able to remain in better health, with higher energy levels. They do not become as easily fatigued from keeping up with the constant need to be vigilant and deliver food to hungry nestlings.
In cooperative breeding communities, birds develop an effective defense network against predators, sharing information and knowledge of threats and risks in their neighborhood. Labor is also shared, taking the pressure off individual birds and making survival less of a challenge.
In harsh environments, where food resources are scarce or weather conditions are not ideal for nesting, cooperative breeding offers the benefits of an effective support network. Increased levels of care ensure that young birds receive enough food and protection and have an improved chance of survival.
Pictured: A Dunnock. Cooperative breeding offers the benefits of an effective support network
Examples of Cooperative Breeding Species
Only around 3 percent of all bird species display cooperative breeding traits when nesting. We’ll be taking a look at some of the most common examples below, so read on if you’re interested in finding out more.
Species Showcasing Cooperation
Acorn Woodpecker
Acorn Woodpeckers live in family groups, consisting of a dominant pair and their grown-up offspring from previous years’ broods as helpers.
These non-breeding helpers assist with nest excavation, incubation, and feeding young. Groups are territorial and are made up of between 2 and 15 birds, with up to 10 helpers and between 1 and 4 dominant breeding males.
Western Bluebird
While Western Bluebirds typically breed in monogamous pairs, occasional reports of cooperative breeding are reported, thought to represent between 2 and 14 percent of their population.
Helpers are usually younger offspring from a previous brood, although adults may also contribute to raising young and defending a nest site.
The Acorn Woodpecker (pictured) lives in family groups
The Western Bluebird (pictured) typically breeds in monogamous pairs
Florida Scrub-jay
A great example of a cooperative breeding species, the Florida Scrub-jay lives in an extended family group, with a dominant breeding pair and offspring from previous years.
These offspring may delay breeding for several seasons in order to support the nesting pair and help with providing food, defending territories, building and maintaining nests, and incubating eggs.
When one of the dominant pair dies, the new mate selected is usually an unrelated helper from outside the group, and helpers eventually leave the group to set up their own territories.
Pied Kingfisher
Not all Pied Kingfishers practice cooperative breeding, but many nests are maintained by non-related individuals, who aid a nesting pair with territory defense, nest excavation, and finding food resources.
In this species, most helpers are unrelated males, who stay with their group until they are ready to breed themselves.
The Florida Scrub-jay (pictured) lives in an extended family group
Not all Pied Kingfishers (pictured) practice cooperative breeding
Cooperative Breeding and Conservation
By understanding how cooperative breeding species interact with their environments and may have specific needs that differ from birds with regular breeding behavior, it’s possible to gain insight into how best to support species that rely on ‘helper’ birds to raise young successfully. Keep reading to learn more.
Conservation Implications
Recognizing species which rely on an active system of cooperative breeding is important as it allows conservation efforts to focus on prioritizing their protection. Population declines in cooperative breeding species are a concern because even a slight drop in numbers can affect breeding success.
By studying cooperative breeding species and monitoring population trends, vital research into long-term species survival can be gained, and habitats that are suitable for larger population groups can be conserved.
Human Interaction and Impact
Habitat loss and development of natural landscapes is a major factor in the survival of any birds, but particularly cooperative breeding species that require sizable habitats for successful nesting.
When habitat is lost, groups are unable to thrive in areas that have decreased in useful terrain and may move on in search of better feeding or breeding grounds, which may not even exist.
Florida scrub-jays, a well-known cooperative breeder, are a threatened species, and numbers and habitats are in decline, requiring management to offer sufficient nesting sites.
Their cooperative breeding status is believed to have evolved in response to the lack of nesting habitats. Non-breeding males may remain as helper birds for up to five years while they wait for a suitable nesting territory to become available.
Southern Ground Hornbills (pictured) are obligate cooperative breeders. The dominant pair are usually assisted by adult and immature helpers
Summary
Unusual as it may sound, cooperative breeding is a behavior that brings many survival benefits to bird species and supports the theory that more vigilant eyes on nestlings will bring an improved chance of survival, both in the immediate future and further along the line, when helper birds themselves have the opportunity to breed.
Cooperative breeding brings experience in successfully raising young to inexperienced non-breeding individuals and offers a wider benefit of survival and longevity from being part of a larger group that shares knowledge about food resources and threats from predators or environmental conditions.
By working alongside other birds, individuals develop a great degree of resilience, being able to adapt to the different and varied supporting roles they need to play to ensure the survival of the breeding adults, the young birds they are helping to raise, and ultimately themselves.