What are Migratory Birds? Print

 Photo: Sergey Dereliev (UNEP/AEWA)

What are migratory birds?

{mosimage}Avian migration is a natural process, whereby different birds fly over distances of hundreds to thousands of kilometres in order to find the best ecological conditions and habitats for feeding, breeding and raising their young. For instance, when the conditions in the breeding grounds become very difficult due to low temperatures, migratory birds fly to regions where conditions are better.

There are many different migration patterns. Most birds migrate from northern breeding areas in the summer, to southern wintering grounds. However, some birds breed in the far south of Africa, and migrate to northern wintering grounds, or horizontally, to enjoy the milder coastal climates in winter. Other birds migrate in terms of altitude, moving higher up a mountain in summer, and wintering on lowlands.

Migratory birds have the perfect morphology and physiology to fly fast and over long distances. However, they often experience an exhausting journey during which they go to their limits. The Red Knot for example, a 24 cm long wader with a weight of around 220 g, breeds in Siberia and overwinters on the west coast of Africa, some of its number even going down to South Africa. During its migration it loses nearly half of its body weight. Migratory birds therefore rarely fly to their destination non-stop but interrupt their journey frequently to rest and feed, or to sit out a spell of bad weather. Exactly how migrating birds find their flyways is not fully understood. Recent experiments indicate that they orientate along the Earth's magnetic field with special light receptors in their eyes.

The symbolic meaning of birds and their journeys

{mosimage}Humans have always been fascinated and inspired by the phenomenon of bird migration. In ancient Greece the bird of Athena represented the renewal of life. A dove, with an olive branch in its beak, returned to Noah's ark to announce the end of the deadly flood. The dove remained a symbol of peace and hope. During the era of the Pharaohs in Egypt, the falcon had protective powers and was linked to royalty. For the Native Americans birds had different meanings, always positive and linked to the concepts of unity, freedom, community, safe return, love and celebration of life.

In dreams birds embody fantasy, ideas and thoughts. The image of a flying bird is immediately connected with lightness and freedom and hence the expression “to be free as a bird”. Many people associate flocks of migrating birds in the typical V-like alignment with the change of season, but also with perfection, beauty and harmony. Until the 18th century people believed that swallows sank in mires at the beginning of autumn and appeared again as amphibians in the following spring. And still today some parents mark their houses with painted storks to indicate that a new baby has been born.

In almost all cultures, for centuries flocks of birds have announced the arrival of spring, and the yearly rebirth of nature associated with it. The social acceptance of birds as messengers of life was accompanied by the knowledge that migration had indeed an important role to play in ecosystem function.

Why migratory birds need to be protected

{mosimage}Many bird species migrate in order to survive. However, migration is a perilous journey, involving a wide range of threats. Only a small number of birds are actually threatened by natural events. Sad but true, human activities are the source for most dangers migrating birds are exposed to. And as diverse as people and their habits in different countries are, so are threats the birds face.

The loss of habitats due to pollution or exploitation caused by encroachment for settlement, agriculture, grazing etc. is the main threat to migrating birds, which are dependent on finding suitable breeding and wintering grounds as well as stopover sites along their flyways where they can rest and feed. The loss of any of these sites used by the birds during their annual cycle could have a dramatic impact on the birds’ chances of survival. Also high-voltage power lines and wind turbines have a dramatic impact on birds, which are in danger of being killed by electrocution or collision. Poaching remains widely practised in countries where people are highly dependent on biodiversity for their livelihoods.

These are only a few examples and often a clear decrease of population within a species is the result of a combination of such factors and it is therefore hard to identify which one has the worst effect.

At the same time, flying over long distances means crossing many international borders and entering different political areas with their own environmental politics, legislation and conservation measures. It is clear that international cooperation between governments, NGOs and other stakeholders is needed along the whole flyway of a species in order to share knowledge and to coordinate conservation efforts.

Without cooperation all measures taken to tackle the threats to migratory birds in one country could be in vain if for example unsustainable taking is accepted in another country. The necessary legal framework and coordinating instruments for such international cooperation is provided by international agreements such as CMS and AEWA.

World Migratory Bird Day with its global outreach is an effective tool for the international community to help raise awareness on the threats faced by migrating birds, their ecological importance and the need for international cooperation to conservation them.