Elaborate behaviour

Ornithology, the science that studies birds, has revealed a multitude of extraordinary skills and behaviour among this animal group, ranging from complex social behav-iour to the use of tools for certain tasks. It would be unrealistic to try and examine all of them here.
Great seducers

If we choose to discuss seduction among birds, this is not only because of an im-pressive diversity in the displays and other methods employed by males to conquer a female, but also because this behaviour often conflicts with a particularly im-portant evolutionary pressure i.e. predation. A considerable number of species has to find a subtle balance between getting noticed by their partner or partners without attracting the attention of nearby predators.
An overwhelming majority of birds (90%) are monogamous, forming long-lasting partnerships, with low ‘divorce’ rates. Among polygamous birds, most are polygy-nous, i.e. males mate with several females simultaneously or in succession, alt-hough a certain number of species are polyandrous. We find the most spectacular displays among the polygamous species.

The greater bird-of-paradise is one species that has developed a particularly impres-sive and elaborate courtship. Males display in trees above the ground and congregate in a ‘court’ while females keep to themselves. Males will initially congregate on a sec-ondary perch and flap their wings rapidly. They will then move to the main viewing perches, erecting the large plumes on their rumps over their backs and extending their wings. They subsequently lower their bodies close to the branch they occupy, retract their wings, leave their tail plumes erected, and prance along their branch. The birds will then freeze with their beak pointed downwards, wings extended once again, and tail plumes still upright. Males will assume this last position, referred to as the ‘flower position’ when females are present, for inspection purposes.
Other courtship behaviours in addition to the physical dance can consist of bill-wiping, in which the male pauses the dance and brushes both sides of his beak on the branch, as well as leaf-tearing, hanging upside down from the branch, and vocalisa-tions. Males use eight variations of calls within courtship rituals, each linked to a sec-tion of the courtship dance.

Males spend the majority of their time during the mating season at their respective display grounds. They begin calling before sunrise and cease shortly after sunset. They feed very briefly and rarely, moving away from display grounds in the heat of the afternoon, and returning before dusk.
Males of the satin bowerbird species (Ptilonorhynchus violaceus) build specialised stick structures, called bowers, which they decorate with blue, yellow and shiny ob-jects, including berries, flowers, and any plastic items they find around them. As males mature they use more blue objects than other colours. Females visit these and choose which male they will allow to mate with them. In addition to building their bow-ers, males carry out intense behavioural displays called dances, but these can be viewed as threat displays by females. Recent research has shown that females choose their mate in three stages: visits to the bowers before nests have been built and while males are absent, visits to the bowers before nests have been built and while males are present and finally visits to certain males after nests have been built, leading to copulation with the happy chosen one.
Male satin bowerbirds are known to destroy or steal from the bowers of other birds, particularly those of their competitors.

Sometimes migratory

Many groups of animals migrate but of all of them, birds are undoubtedly the ones that do so most spectacularly. In the proper sense, migration is characterised by its predictability and its periodicity; birds move from their breeding grounds to their win-ter quarters.
In most cases, migrations are latitudinal i.e. along a north-south axis, taking species from northern to temperate regions or temperate to tropical regions and back again. Nevertheless, they can also be longitudinal, along east-west lines, or altitudinal.
An estimated 40% of Palearctic species spend the winter away from this region.
Migration is genetically programmed and subject to an endogenous rhythm condi-tioned by various factors, the most important of which is the photoperiod or the varia-tion in day length compared to night. However, when departure is imminent, more delicate and subtle factors also play a part, such as temperature, wind and cloud cover.
From time immemorial, the phenomenon has greatly fascinated human beings. We have recently discovered that birds which migrate during the day use the position of the sun to navigate, while nocturnal migrants use the position of the stars. Birds also use the earth’s magnetic field, particularly useful on cloudy days. Finally, over shorter distances, birds are capable of recognising territorial features, such as coast-lines, mountains, rivers, etc.

The willow warbler (Phylloscopus trochilus) is a small passerine weighing less than 10 grams. We know that this species is capable of flying from Siberia or even Alaska to spend the winter in sub-Saharan Africa, a trip of 10,000 to 13,000 km, returning to the same breeding grounds the following spring with incredible accuracy.

The Arctic tern (Sterna paradisaea) makes the longest annual migration of around 30,000 km from Greenland to the Weddell Sea in Antarctica and back again, not nec-essarily by the most direct route either.