What is World Migratory Bird Day?
World Migratory Bird Day is a global awareness-raising campaign highlighting the need for the protection of migratory birds and their habitats. On the second weekend each May, people around the world take action and organise public events such as bird festivals, education programmes and birdwatching excursions to celebrate World Migratory Bird Day.
"Barriers to migration" - WMBD theme for 2009
Year by year in autumn and spring majestic avian flocks depart for their long journeys following the call of the wild and paths of their ancestors. For some, it is a long, exhaustive and dangerous journey, sometimes stretching thousands of kilometers from the Arctic to the southern tip of Africa and beyond. Migratory birds have to cope with a scarcity of food, stopover sites that are shrinking in area, predators, hostile weather and the expanse of seas, huge mountains and endless deserts. Yet, humans have created additional obstacles to further complicate their journeys.
Dazzling spotlights from city skyscrapers, tall glass windows and guy wires of television towers can be invisible to birds and cause collisions that result in bird fatalities. Proliferating communication towers and masts, wind turbines, tall buildings, power lines, and fences kill or harm huge numbers of birds each year and represent increasingly fatal barriers which have a detrimental impact on entire populations of migratory birds.
Although kills like these are often unintended and frequently avoidable - thousands of new structures are built each year, often along the migration paths of migratory birds. Many of the world's coastlines and mountaintops, utilized for the generation of wind power, reside along some of the world's best known and major migration routes. New wind turbine developments are still being planned around the world, sometimes without a detailed assessment having been carried out on the potential environmental impacts they may cause , let alone the effect they could have on migratory birds.
The aim of World Migratory Bird Day (WMBD) 2009 is to raise awareness on some of these man-made barriers to migration and to inform people about the impact these structures can have on migratory birds and on their migration. A "truly green" development in renewable energy, architecture and urban planning is one, which aims to minimize all possible environmental impacts, including those on migratory birds and other species.
- Taken from the World Migratory Bird Day website
Do visit the site to find out more about the various barriers to migration, and how each of these barriers can take a heavy toll on migratory birds.
In Singapore, the most obvious barrier to migration would be the threat posed by 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.
Over at the Bird Ecology Study Group, there are 2 articles that mention blue-winged pittas (Pitta moluccensis) crashing into windows; while 1 survived and was subsequently released, the other was already dead when discovered. The blue-winged pitta is an uncommon winter visitor and passage migrant in Singapore, and it is likely that other migratory bird species are also affected by collisions with glass windows.
The Bird Ecology Study Group has more articles on birds and glass windows, including incidents involving pied triller (Lalage nigra) and laced woodpecker (Picus vittatus). There are even more anecdotes of bird-glass collisions in the following posts:
Birds and glass windows - 1
Birds and glass windows - 2
Birds and window panes
The most interesting incident however, has to be this one, where a large raptor crashed into a window with so much force that the glass broke!
Another possibly significant barrier to migration in Singapore is light pollution.
The luminous glow of artificial light over cities and towns obscuring the stars at night, which astronomers describe as 'light pollution', takes a large toll on bird populations as well as distracting and confusing them during their migration. Birds are frequently deceived by bright lights on misty and stormy nights, when their usual points of reference – the stars – become invisible. In these cases, bright artificial lights caused by our ever-expanding urban landscapes attract migratory birds, leading to their disorientation, which in turn, can lead to changes in their usual flight path and migratory course. Following the wrong cues, they can be sent off course and their precious energy stores, which are needed to complete the onward journey are squandered. Light pollution also prevents birds from choosing the ideal stopover sites and some get involved in endless "lit-beam circling" until they drop from exhaustion or collide with surrounding objects.
As far as I know, such a phenomenon is not well-studied locally, although I won't be surprised if there is some impact on birds. On more than one occasion, I have looked up at night to see birds flying around the bright lights of tall skyscrapers, although I was unable to identify the bird species. I wonder if there is any chance of finding bird carcasses scattered around buildings in the city centre, especially when the migration season is at its peak.
Migratory birds all over the world already face a vast multitude of threats, from destruction and fragmentation of breeding and winter habitats and loss of vital stopover and feeding grounds, to deliberate hunting by humans. The effects of climate change will no doubt affect many more species. Many of these birds already face seemingly insurmountable challenges, undertaking incredible voyages that take them across vast expanses of sea and desert, and above the peaks of the highest mountains.
May we continue to be amazed and inspired by these natural wonders for many more generations to come, and may we find it within ourselves to grant these long-distance travellers safe passage.
Related post: Migration (25th March, 2009)