Post Description

[edit] 6. "Signals and Songs"
Broadcast 25 November 1998, this installment describes ways of communicating. A colony of fieldfares in Sweden deters a raven from raiding a nest by collectively raising an audible alarm. However, in an English wood, all species co-operate to warn each other surreptitiously of approaching danger. By contrast, a sunbittern is shown expanding its plumage to discourage a group of marauding hawks. The members of the finch family exemplify how colour aids recognition. Birds have excellent colour vision, and the feathers of many species react to ultraviolet light. Flocking birds, such as sparrows, also have a 'ranking system' that determines seniority. In Patagonia, Attenborough demonstrates the effectiveness of sound: he summons a Magellanic woodpecker by knocking on a tree. The nature of tropical rainforests means that their occupants tend to make much louder calls than those in other habitats, and several such species are shown. Saddlebacks vary their calls so that even individuals from different areas can be identified. The dawn chorus provides a mystery, as there is still much to learn about why so many different birds sing together at the same time of day. (Proclaiming territory or attracting mates are two likely reasons.) Finally, Attenborough introduces the Superb Lyrebird as one of the most versatile performers: it is a skilled mimic, and this particular one imitates not only other species, but also cameras, a car alarm and a chain saw.

[edit] 7. "Finding Partners"
 
A male Great Frigatebird (Frigata minor) nesting on Genvoesa in the Galapagos.Broadcast 2 December 1998, this programme discusses mating rituals. If a male bird is on the lookout for a partner and has a suitable nest, it must advertise the fact, either by its call, a visual display or both. The frigatebird provides an example of the latter, with its inflated throat pouch. The hornbill's courtship, among that of many others, also runs to the offer of a gift. For some species, dancing can also be an important component, and grebes are shown performing a pas de deux. The cock-of-the-rock, which dances solo within a group, is contrasted with the team performance of the manakin. Once trust has been established between a pair, mutual preening can follow. After mating, the individuals usually remain together to rear their eventual family. In this regard, the rhea and the phalarope are highlighted as unusual because in both instances, it is the male that incubates the eggs. Some females judge a prospective companion on its nest-building ability, and this is a conspicuous part of the weaver's behaviour. The bowerbird puts on one of the most elaborate displays: a hut-like construction, completed by a collection of objects designed to impress. Competition among males can be fierce and in Scotland, Attenborough observes rival capercaillies engaging in battle ? after one of them chases the presenter. Avian polyandry is not widespread, but is illustrated by the superb fairy-wren, where the male's family can easily comprise young that it did not father.

[edit] 8. "The Demands of the Egg"
Broadcast 9 December 1998, this episode explores the lengths to which birds will go to ensure that their chicks are brought into the world. Attenborough begins on an island in the Seychelles, where sooty terns, which have hitherto spent their lives on the wing, have landed to lay their eggs. This is a necessity for birds, as eggs are too heavy to be borne in the air for any considerable length of time. It is imperative that nests are kept as far away from predators as possible, and unusual locations for them are shown, such as: behind the water curtain of Iguazu Falls in South America (as chosen by swifts), cliffs on Argentina's coast favoured by parrots, an ants' nest occupied by a woodpecker, and a tree hole inside which a female hornbill seals itself. Eggs require warmth, and some nests are insulated by the owners' feathers, others from ones found elsewhere. External temperatures dictate how the eggs are incubated. The snowy owl has to do so itself, because of its habitat; however, the maleo is able to take advantage of solar heating. The amount of eggs laid also varies: for example, the kiwi lays just one, whereas the blue tit will deposit many. Their mottled surface serves to camouflage them. Birds that steal eggs include toucans and currawongs. A number of strategies are employed to deter the thieves, as illustrated by the yellow-rumped thornbill, which builds a decoy nest atop its actual one, and the plover, which distracts marauders by feigning injury.