BONN, Germany - Wind turbines, communication masts, tall buildings and windows, power lines and fences are responsible for the deaths of many millions of birds worldwide each year. This upcoming weekend, thousands of people around the world will take part in events to mark World Migratory Bird Day with its theme Barriers to Migration to address the many human-made obstacles birds face during their migrations.

World Migratory Bird Day is a global initiative devoted to celebrating migratory birds and for promoting their conservation. During migration, birds face natural obstacles such as expanding deserts, seas, huge mountains and other natural barriers. Now in addition, birds are increasingly being confronted with manufactured barriers on their journeys. Among the affected birds are rare and endangered species.

"Hundreds and thousands of migratory birds, including many that are protected under international wildlife treaties such as the African-Eurasian Migratory Waterbird Agreement, are killed in growing numbers by man-made barriers," said Bert Lenten, executive secretary of AEWA and initiator of the World Migratory Bird Day campaign.

"Some of these cases could quite easily be avoided by introducing technical measures for reducing this often avoidable cause of destruction," he said.

Lenten says that so far little attention has been given to possible solutions, but solutions do exist.

However, each year the number of wind turbines, power lines, skyscraping radio, TV and cell phone transmission masts, reflecting plate glass windows, tall buildings and other structures continues to grow, often without consideration of avoidance and mitigation measures known to reduce avian mortality through collisions with these structures.

In addition to a number of known mitigation measures specific to each type of structure, particularly the location and placement of structures such as wind farms and power lines along major migratory routes or near areas regularly used by large numbers of feeding, breeding or roosting birds, can affect the likelihood of collisions.

Placement of structures along important wetlands, river valleys and in coastal areas where large numbers of migratory birds congregate, are likely to increase the risk to migratory birds.

Collision risks also are increased or diminished by the intensity and use of lighting and size - the more lighting in place and the taller the structure is, the more dangerous the objects are for birds. Bad weather and darkness also influence the collision rate.

Overhead power lines stretch for millions of kilometers globally and the resulting carpet of surface cables continues to increase. Apart from the risk of electrocution faced by birds, which results from poorly designed power poles, the cables themselves constitute objects for potential collisions.

Fast-flying birds, so-called poor fliers due to their small wings, and birds lacking in agility are especially at risk; they tend to hit conductors and ground wires, frequently at night and in poor weather conditions.

Migratory birds are also threatened by climate change and the barriers that this will create through habitat change. "For example, wind turbines are an essential component of our response to climate change, and are therefore important to bird conservation," said Dr. Jonathan Barnard, Senior Programme Manager at BirdLife International. "Ironically, however, these turbines also add to the man-made obstacles that birds face on their journeys, and so it is critical that these wind turbines are correctly sited and respect conservation guidelines."

One of the most susceptible types of migrant are soaring birds, such as large birds of prey, which are funnelled in their thousands each year along predictable routes which avoid large bodies of water and high mountains.

"At migration bottlenecks for soaring birds, many birds are killed as they collide with man-made barriers," said Barnard.

BirdLife's Migratory Soaring Birds project aims to address these threats, as well as habitat alteration, pollution and illegal hunting. "We are working with key economic sectors to better understand the underlying causes of the threats to soaring birds, and develop best practice guidelines," said Barnard. "This will be achieved through regional awareness-raising and training, combined with six pilot projects in partnership with the key stakeholders across the Middle East and northeast Africa."

Over 100 separate events in 44 countries have been registered to date on the World Migratory Bird Day website www.worldmigratorybirdday.org.

Some governments are taking action. Today, an Memo of Understanding was signed between the Partnership for the East Asian - Australasian Flyway and the South Korean Ministry of Environment allowing the City of Incheon to host the Secretariat of the Partnership. The signing ceremony was held as part of an International Symposium on the Future and Vision of East Asian-Australian Flyway Partnership in Incheon City. It was also announced that the Nakdong Estuary has been included in the Flyway Site Network as from May 1, 2009. There are now 79 sites officially under the Flyway Site Network.

Most World Migratory Bird Day events focus on education and bird watching.

In Bangladesh, for instance, the Wildlife Trust of Bangladesh, Bangladesh Bird Club, Dhaka University Tourist Club, Zoology Department of Dhaka University, Bangladesh Forest Department, Bangladesh Bird Preservation Society, and Channel i -- a TV channel and participating in an event at the Teachers Students Centre, Dhaka University.

The program will be inaugurated by Secretary of the Ministry of Environment and Forests Dr. Mihir Kanti Mazumder, who will discuss human-made barriers to migration with representatives of the conservation groups.

A migratory bird photo exhibition, a rally, a children's art competition on birds, a debate on "Why birds?," a bird book exhibition, a cultural program, and a bird fair, which will include an exhibit of important birds prepared by students of the Art Institute of Dhaka University.

"My strong hope is that World Migratory Bird Day will help raise awareness of these barriers and that action will be taken to reduce the impact of some of these man-made structures on migratory birds," said Lenten.