The breeding season is a time of frenetic activity where impassioned displays, fervent singing and hot-blooded threats all form part of the zealous competition for mates and territories. Once a male is successful in wooing his female, whether into a lifetime partnership or just for the season, the delicate nest-building process starts.
It is all about the clothes you wear and how deep your pockets are…
Male birds need to catch the eye of females using their impressive animated displays, flaunting their bright, attractive colours and showcasing their melodious songs. Some of these displays may seem life-threatening, especially if you follow a red-crested korhaan during the mating season. Also known as the ‘suicide bird’ the male has the habit of flying high into the air, then plummeting to the ground like a meteorite falling from the sky and then suddenly veering away to the side at the last moment before hitting the ground.
Other birds, like bishops, use their brightly coloured plumage and frantic “bumble-bee” flying to attract females. The lilac-breasted roller tumbles through the sky in a dramatic looping display using their beautiful colours to attract females. Birds like the rufous-naped larks present females with a “nuptial gift.” It is believed that a female will choose a male that will best provide for her and her chicks. Other species with these behaviour traits include dabchicks, kingfishers, bee-eaters, raptors and finches.
Why are females so dull?
Sexual dimorphism – which means that the male differs greatly in appearance from the female, usually because they are brighter in colour and more striking than the female. In many species this difference only lasts during the mating season when males need to attract their mate. This may be an advantage for mating but the bright colours can also attract predators. Many males will moult out, a process known as “eclipse plumage”. Bishops, whydahs, widowbirds and weavers all moult. Subtle changes can also be seen in wing patterning or males being smaller than the female.
Birds form many kinds of partnerships during the breeding season. The goal in the end though stays the same – to produce the greatest number of offspring. Monogamy means being faithful to one partner. Roughly 90 per cent of bird species are monogamous. This may last for a lifetime or only for a breeding season. Polygyny occurs when one male pairs with a number of different females. These males tend to invest little of their time and energy into parenting; roughly 10 percent of bird species are polygamous. Polyandry is a very rare and highly unusual mating system in which a female pairs with several different males. Well-known examples include the African jacana and the greater painted-snipe.
To help or not to help?
In most species, a couple will raise chicks alone, but is helped by other birds in their flock. Duties may involve nest-building, bringing food, sharing incubation or defending the brood against predators. In many cases the helpers are related to the breeding pair, often offspring from a previous brood. Brooding together also makes birds less vulnerable to predators.
One can split co-operative breeding into two main groups:
• Obligate co-operative breeders that always breed together. These include pied kingfishers, white-crested and Retz’s helmet shrikes, oxpeckers, arrow-marked babblers, southern ground-hornbills and some bee-eaters.
• Facultative co-operative breeders that always breed as a group and only under certain circumstances. Moorhens, hamerkops, Cape wagtails and African hoopoes are all examples of such breeders.
Nests come in all shapes and sizes and are made of many different kinds of materials. Birds are probably some of the best architects and builders in the world. Material can range from twigs, leaves, grass, mud, spider webs, lichen and man-made materials such as wire, glass, cotton, cement and string. One can classify bird nests into the following main categories:
Classical cup-shapes built mostly by smaller birds that are open and cup-shaped. These nests are usually concealed in branches of trees with coarser material being used for the framework and softer material for the cup.
Woven balls are an enclosed, ball-shaped structure with an entrance either on the side or at the bottom. About 130 different bird species use this design in southern Africa. Most birds nest alone but some weavers set up home in colonies.
Nests are made from sticks and twigs and can range from small to large platforms. These nests are mostly built in the forks or horizontal branches of trees.
Swallows are known to build mud shelters. Mud pellets are collected from the edges of pools and these nests can be divided into three types: open, cup-shaped nests, closed bowls with or without a short entrance and closed ball with a long entrance tunnel.
Birds like the hamerkop will build a dome-shaped “mansion” from sticks. A small entrance tunnel leads to the central chamber where they lay their eggs. Sociable weavers hold the record for building the largest nests in the world. The design of the nest helps to regulate the temperature during the hot summers and cold winters.
Many birds, especially raptors will build their nests on skyscraper-like cliffs. Due to inaccessibility these cliffs provide good security. Many birds will return to the same nesting site year after year.
Some birds prefer “camping” in the open with nests being built on the open ground. These birds rely on exceptional camouflage and birds like lapwings are very protective.
Water birds such as jacanas will build their nests on the water and are constructed from water plants.
Many birds will build their nest in hollowed-out holes in trees or in sand banks. These holes can either be made by the bird or be an existing crevice.
The art of weaving
Weavers follow a number of steps in the process of weaving their nests. This starts with selecting a suitable branch where the weaver builds a ring which will be the foundation of the nest. They will then build the roof over the ring followed by the egg chamber. Next they build the antechamber and entrance followed by the tunnel. The female will come and inspect the nest and if happy she will lay her eggs; if not the male will need to start all over again until she is satisfied!
Why build a nest?
Nests are mainly built to provide a safe and secure environment to lay and raise the chicks. Most nests are designed to prevent predators from stealing eggs or chicks.
Who builds a nest?
Some species will share the workload with both sexes assisting in building nests. In many cases the male will collect the material and the female will build the nest. Robin-chats, sunbirds and sugarbird nests will be built by the females with the males assisting with the feeding. Other species will just seize the opportunity taking over existing nests – no effort required.
Birds of feather flock together
Some birds will gather in huge and bustling colonies numbering up to thousands. Water birds are mostly colonial nesters. These colonies are located in safe sites such as thorny trees, caves, waterside locations or vegetation.
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