Millions of birds killed worldwide by man-made barriers each year

World Migratory Bird Day (WMBD) Poster 2009Bonn,
Nairobi 8 May 2009
- This upcoming weekend (9-10
May 2009), thousands of people around the world will be
taking part in World Migratory Bird Day (WMBD) events to draw attention to
the many man-made obstacles birds face during their migration.The
central theme for this year’s World Migratory Bird
to highlight the effects man-made structures such as wind
turbines, communication masts, tall buildings and windows,
power lines and fences have on migratory birds.

During migration birds face a number of natural obstacles
such as expanding deserts, seas, huge mountains and other
natural barriers. Yet, next to these natural barriers,
birds are increasingly being confronted with man-made
barriers on their journeys.

These man-made structures can not only disturb the migratory
movements of birds, but it is estimated that bird-strike
due to collisions with man-made structures is responsible
for the deaths of many millions of birds worldwide each

Among the affected bird species are abundant as well
as rare and endangered species. Man-made barriers are
believed to be a growing threat and are likely to be a
significant contributor to the decline in many populations,
especially those of scarcer, more vulnerable bird species.

“Hundreds and thousands of migratory birds, including
many that are protected under international wildlife treaties
such as the African-Eurasian Migratory Waterbird Agreement
(AEWA), are killed in growing numbers by man-made barriers.
Some of these cases could quite easily be avoided by introducing
technical measures for reducing this often avoidable cause
of destruction” said Bert Lenten, Executive Secretary
of AEWA and initiator of the World Migratory Bird Day

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

Logo: World Migratory Bird Day (WMBD)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 dramatically 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 also likely to increase the risk
to migratory birds.

Although man-made barriers represent an increasing
problem for migratory birds worldwide, so far little attention
has been given to possible solutions. 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
” said Bert Lenten.

Dedicated people and organisations around the world will
be using World Migratory Bird Day (WMBD) this upcoming
weekend to conduct events, which will help draw attention
to the impact of man-made barriers on migratory birds.
Over one hundred separate events in 44 countries have
already been registered on the WMBD website so far.

Notes to Editors

World Migratory Bird Day (WMBD)

World Migratory Bird Day (WMBD) is a global initiative
devoted to celebrating migratory birds and for promoting
their conservation worldwide. This year WMBD will take
place on the weekend of 9-10 May and its central theme
will be ‘Barriers to migration.’

World Migratory Bird Day is being organised by the African-Eurasian
Migratory Waterbird Agreement (AEWA) and the Convention
on Migratory Species (CMS) – two international wildlife
treaties administered by the United Nations Environment
Programme (UNEP) and other partners.

People and dedicated organisations around the world will
be using the event to draw attention to man-made barriers
and their impact on migratory birds. Over one hundred
separate events in 44 countries have already been registered
on the WMBD website so far (see:
Activities to mark WMBD include bird festivals and bird
watching trips, public discussions, exhibitions, presentations,
bird rallies and other educational and public events.

For more information please see:

Barriers to migration (background
on this year’s WMBD theme)

Windows and tall buildings

Windows of all sizes and types, even small and narrow
windows, from those found on tall buildings to those used
in residential houses are very dangerous for birds. Ornithologists
usually call them “invisible killers” due
to the large number of deaths and injuries they cause
regardless of species, age, sex and the conditions in
which collisions occur. Attracted by the reflection of
trees or plants located near the windows, birds try to
pass through them, sometimes, at top speed. This can lead
to fatal or other injuries or simply exhaustion as they
attempt to overcome the invisible barrier and end up falling
to the ground and thus becoming easy prey. Predators such
as cats often lie in wait for their victims to quickly
remove them. Moreover, some studies show that about half
of those birds, which manage to fly away, die later due
to injuries received. These facts are often unknown to
those observing bird strikes, as they tend to think collisions
do not actually harm birds and that they are able to fly
away without any lasting damage.

Wind turbines

Although wind turbines are a form of clean technology
for renewable energy production and therefore an important
tool in combating climate change, they also represent
a danger to migratory birds. Wind turbines, especially
when standing isolated in large-scale wind farm developments,
also represent a severe potential hazard for migratory
birds. Their blades rotate at speeds of up to 200 kilometres
per hour and, when placed along the major migratory routes
of birds, wind turbines can become extremely dangerous
obstacles causing both injuries and fatalities to many
species of migratory birds. In addition to causing collisions,
wind turbines are also known to cause displacement of
migratory birds and are considered especially detrimental
in areas where there is a known high concentration of
migratory birds, for example at major stop-over and feeding
sites. Like other obstacles that are surrounded with lights
for air traffic safety, wind turbines equipped with bright
lights can also attract disorientated birds and lead to
fatal injuries during the night.

Wind farms are often built along coastlines and mountaintops,
usually in areas that have high wind potential, and which
often lie along the flight paths of many migratory birds.
Unfortunately, wind farms are still being built along
coastlines, mountain ridges and wetlands, sometimes without
any prior assessment of their potential environmental
impact on migratory birds and in places where there is
a known high concentration of many migratory bird species.
It is especially a cause for concern when wind farms are
constructed in areas that are frequently used by endangered
and rare bird species.

Power lines

Power lines and fences are believed to pose a particular
risk to migratory birds. Overhead power lines stretch
for millions of kilometres 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.

Communication towers and masts

Communication towers and masts are commonly high structures
located on elevated points of land and their supporting
guy wires are extremely dangerous for migratory birds.
Fast flying birds simply do not notice loose wires and
birds that are not very agile have difficulties avoiding
them. Stormy nights and bad visibility make supporting
wires even more dangerous for birds and dramatically increase
the risk of collision. Brightly lit towers in the similar
adverse conditions make bird-strikes even more likely.
Birds, especially nocturnal birds travelling in weather
conditions like fog or mist, loose their navigation cues
and get disoriented or dazzled by the lights of towers.
Mistaking them for constellations, birds tend to circle
around the lights and rarely escape fatal hits against
the wires and other supporting elements. Even if they
manage to avoid heavy strikes, birds are often badly injured
or they waste energy they need to accomplish their migration

Burdening factors

When wind turbines, power lines and other man-made structures
are placed in areas where the density of birds is high
or along major migratory paths, the probability of collisions
significantly increases. In particular, the placement
of windfarms and other structures along landscape features
such as river valleys and coastal areas, used by migratory
birds as navigation cues, is believed to significantly
increase collisions. Collision risks are also 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, as well as the physical
characteristics of birds (acuteness of vision) or flight
behaviour (flocks), also influence the collision rate.

WMBD Partners:

United Nations Environment Programme (UNEP) is the voice
for the environment in the United Nations system. It is
an advocate, educator, catalyst and facilitator, promoting
the wise use of the planet's natural assets for sustainable

Convention on the Conservation of Migratory Species of
Wild Animals (CMS; also known as the Bonn Convention)
aims to conserve terrestrial, aquatic and avian migratory
species throughout their range. It is an intergovernmental
treaty concluded under the aegis of the United Nations
Environment Programme (UNEP). Since the Convention's entry
into force, its membership has grown steadily to include
110 (as of 1 November 2008) parties from Africa, Central
and South America, Asia, Europe and Oceania.

African-Eurasian Migratory Waterbird Agreement (AEWA)
is an intergovernmental treaty developed under the CMS
dedicated to the conservation of migratory waterbirds.
The Agreement covers 255 species of birds ecologically
dependent on wetlands for at least part of their annual
cycle. The treaty covers a large geographic area, including
Europe, parts of Asia, Canada, the Middle East and Africa.
So far 62 out of the 118 countries

in this area have become Contracting Parties to the International

BirdLife International is a global partnership of conservation
organisations that strives to conserve birds, their habitats
and global biodiversity. BirdLife International has long
been committed to the conservation of migratory birds
and the habitats upon which they depend. The BirdLife
Partnership is engaged in migratory bird conservation
at numerous scales, from projects focused on individual
species or key sites, to broader policy and advocacy work
to promote migratory species conservation, and involvement
in flyway-scale projects.

Wetlands International is an independent, non-profit,
global organisation, dedicated to the conservation and
wise use of wetlands. Wetlands International works globally,
regionally and nationally to achieve the conservation
and wise use of wetlands, to benefit biodiversity and
human well-being.


Florian Keil, Information Officer, UNEP/AEWA Secretariat
on Tel: +49 (0) 228 8152451, Mobile: +49 (0)151 14701633,

Francisco Rilla, Information Officer, UNEP/CMS Secretariat
on Tel: +49 (0) 228 8152460, E-mail:

or Veronika Lenarz, Senior Information Assistant, UNEP/CMS
Secretariat on Tel: +49 (0) 228 8152409, E-mail:

at UNEP:

Nick Nuttall, Spokesperson/Head of Media, UNEP on Tel:
+254 20 7623084, Mobile: +254 733 632755, E-mail:

at BirdLife International:

Nick Askew, Communications Officer, BirdLife International
on Tel: +44 (0)1223 279809, E-mail:

at Wetlands International:

Alex Kaat, Communications Manager, Wetlands International
on Tel: +31 (0)317 486776, Mobile: +31 (0)6 50601917,

For more information please visit: (PRESS MATERIALS)

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Dernière mise à jour le 16 Juin 2014