Migration is a trait that the humans and animals have in common and it is driven by almost similar kind of stimuli. Safety of life and access to continuous food supply are some basic reasons which impel humans and birds alike to migrate. The only difference in the migration patterns of both these beautiful creatures is that humans choose their destinations at their own will but in case of animals, especially birds, this choice is guided by the nature which plays its role in selection of the destination and the ways and routes for the same. The migration of birds, which has been going on since thousands of years, depicts a delicate and sublime scheme of things the Nature has maintained to keep up the balance in the natural system. Under this system, when the seasons change, migratory birds move to faraway lands and contribute to the maintenance of biodiversity of host regions. Then, after spending some time there, these friends of humans fly back to their native lands and help keep the balance in their ecosystems as well. In order to guide them in carrying on this journey, the nature provides for their food requirements in form of burgeoning insect populations, budding plants and for safety of life as well as breeding offers them abundant nesting locations.
Birds, especially the migratory ones, are active stakeholders in the ecosystems of our planet and it is due to their role that the system of the nature always appears in its prime. But, man has an old habit of shooting in his own foot and this foolhardiness has resulted in a substantial decrease in the population of birds. Migratory birds are particularly falling prey to an ‘easy come, easy go’ attitude that the humans had adopted.
According to the BirdLife International — a global partn-ership of conservation organizations that strives to conserve birds, their habitats and global biodiversity — the number of species of migratory birds has decreased by almost 40 percent and that more than half of the species of migratory bird travelling the world’s main flyways have suffered serious population declines in the past 30 years. Many of them are at risk of extinction as well. Moreover, more than 90 percent of the world’s migratory birds are inadequately protected due to poorly coordinated conservation efforts around the world,
In order to attract the world attention toward issues like declining number of migratory birds, loss of their natural habitats, inadequate protection of their migration pathways, and the dangers they face in the regions of destination, since 2006, May 10 is celebrated, every year, as World Migratory Bird Day. This year, the day is being celebrated under the theme “Stop the Illegal Killing, Taking and Trade of Migratory Birds” with an aim to highlight the need for mitigating the threats faced by this important biological constituent of our planet.
The origins of long-distant migration patterns are much more complex and they haven’t yet been fully comprehended. They’ve evolved over thousands of years and are controlled, at least, partially by the genetic makeup of the birds. They also incorporate responses to weather, geography, food sources, day length, and other factors.
The bird fanciers would definitely confirm the observation that in spring and autumn seasons, the caged birds feel a certain type of anxiety and restlessness and they keep on roaming within the cage. Ethologists (zoologists who study the behaviour of animals in their natural habitats) have named this anxiety as zugunruhe which is a German compound word consisting of Zug (move, migration) and Unruhe (anxiety, restlessness).
Migrating birds can cover thousands of miles in their annual travels, often travelling the same course year after year with little deviation.
The secrets of their amazing navigational skills aren’t fully understood, partly because birds combine several different types of senses when they navigate. Birds can get compass information from the sun, the stars, and by sensing the earth’s magnetic field. They also get information from the position of the setting sun and from landmarks seen during the day.
Taking a journey that can stretch to a round-trip distance of several thousand miles is a dangerous and arduous undertaking. It is an effort that tests both the birds’ physical and mental capabilities.
For example, Rüppell’s vulture is considered the highest-flying bird, with confirmed evidence of a flight, in 1975, at an altitude of 11,300 m (37,000 ft) above sea level. On 29 November 1973, this altitude was confirmed by the pilot of the aircraft with whose engine this bird had collided. A bar-headed goose is the bird that flies at the highest altitude. Normally, it flies at an elevation of five and half miles above the sea level. This bird also flies over the peaks of the Himalayas on their migratory path.
Another bird called the Arctic tern flies a distance of as much as 49,700 miles every year. Over the 30-year lifetime of a tern, it may migrate about 1.5 million miles — the distance a spaceship would cover if it went to the moon and back three times.
The fastest flying migratory bird is the Great Snipe that is native to northwestern Russia. Scientists have confirmed that the birds fly nonstop over a distance of around 4,200 miles (6,760 km) at a phenomenal 60 mph (97 kph). No other bird can travel this rapidly over such a long distance.
Birds migrate to move from areas of low or decreasing resources to areas of high or increasing resources. The migration of birds can be classified into two categories of distances and changing seasonal weather patterns. It means that the short-distance migrants move only a short distance, as from higher to lower elevations on a mountainside. Medium-distance migrants cover distances that span from one to several states while long-distance migrations are usually beyond international borders. Similarly, in winters, some birds move from their breeding grounds in north to reach to tropical plains of the west while some migrate from mountainous regions of the north to reach Indus plains and tropical plains in the west whereas in autumn, birds from Siberia, Russia and adjoining areas migrate toward the countries in Middle Eastern countries as well as Pakistan. The abundant supply of insects and vegetation after the monsoons attracts the birds of Palearctic regions.
But, on the other hand, illegal activities of humans are not only causing a steep decline in the population of birds but, in a broader context, do also leave their injurious and deleterious impacts on the society as a whole. Conservation, agriculture and tourism are the most affected by these activities. Legal gaming also gets affected by such illegal acts. But, it’s a painful reality that in most societies such activities are accepted as a normal thing; that’s why they still exist.
There are over 10,000 bird species globally with, on average, over 400 species occurring per country. Among them 2274 are the species of migratory birds. Research by National Geographic reveals that up to 4.5 billion birds, representing around 185 species, fly from Europe and Asia in the north to southern Africa and back every year. And, the routes birds tend to take to get from the winter feeding grounds to the summer breeding grounds and back are called flyways. The International Wader Study Group identifies eight flyways used by migratory birds. Among them 3 are in the Americas: the Pacific Americas Flyway, Central Americas Flyway and Atlantic Americas Flyway, which connect the high Arctic to the southernmost tip of the American mainland.
In addition, three flyways consist of Palaearctic–African flyway, among which are included East Atlantic Flyway, Mediterranean/Black Sea Flyway and East Asia/East Africa Flyway. These flyways constitute the world’s largest bird migration system with over two billion passerines and near-passerines migrating from their breeding grounds in Europe and central and western Asia to winter in tropical Africa each year.
The Central Asian Flyway is the shortest flyway in the world and it lies entirely within the Northern Hemisphere. It connects a large swathe of the Palaearctic, which consists of Europe, Asia north of the Himalaya foothills, northern Africa, Japan, Iceland and the northern and central parts of the Arabian Peninsula, with the Indian Subcontinent. Fewer species use this route because of the formidable barrier presented by the Tibetan plateau and Himalayas.
The eighth flyway is the East Asia/Australasia Flyway which extends from Arctic Russia and North America to New Zealand and is used by over 50 million migratory waterbirds.
The migratory birds come to Pakistan through Indus Flyway which is also called the Green Route. The famous route from Siberia to various destinations in Pakistan over Karakorum, Hindu Kush, and Suleiman Ranges along the Indus River down to the delta is known as International Migratory Bird Route Number 4. The migratory birds spend winters in different wetlands and deserts of Pakistan, which are distributed almost throughout the country, from the high Himalayas to coastal mangroves and mudflats in the Indus delta.
The birds start on this route in November and by March, they start flying back home. Previously, these birds used to arrive here from October but due to the phenomenon of climate change, their migration trends are also changing and experts opine that the tenure of these birds’ stay in Pakistan has decreased substantially.
According to Dr Thomas Jones Roberts, the most renowned authority on Pakistan’s wildlife and an internationally acclaimed ornithologist, there are a total of 668 bird species in Pakistan. However, Prof Dr Zulfiqar Ali of the Zoology department of University of the Punjab opines that there are 380 species of migratory birds in Pakistan and the most prominent of them are waterfowls, houbara bustards, cranes, teals, pintails, gadwalls, mallards, geez, spoonbills, waders, pelicans and raptors. After passing through Pakistan, many birds go as far as India and Sri Lanka that is the final destination of these birds in this region.
Among the migratory birds coming to Pakistan, the one which comes here from the farthest is Wilson’s Petrel. This bird undertakes flight from its breeding area in South Pole and is seen in Karachi during summers and monsoon seasons after covering a distance of 12900 to 14500 kilometres (8000-9000 miles).
Most migratory birds coming to Pakistan are waterbirds and they stay in smaller or bigger wetlands and regions located on the river banks. According to the WWF (World Wildlife Fund) database, the number of important wetlands in Pakistan is 240 and 19 of those have been declared Ramsar Sites out of which 2 are in Khyber Pakhtunkhwa, 3 in Punjab, and 9 are in Sindh while 5 are located in Balochistan.
Majority of migratory birds inhabit areas in the Sindh province where Keenjhar Lake, Haleji Lake, Indus Delta and Rann of Kutch are some important destinations. Besides these there are many other places in the country where these, migratory birds stay and among those Tanda Dam, Chashma, Taunsa, Guddu Barrage, Zangi Nawar, Hub Dam, Ochali Lake, Mangla Lake, Bund Khushdil Khan, and Rawal Lake are some notable destinations. Ochali Lake in the Salt Range is significant for White-headed Duck, a species under the threat of extinction. Balochistan’s Zangi Nawar Lake is important stay point of Marble Teal Marmaronetta angustirostris whereas mountainous wetlands are important destinations for Ferrguinous Duck Aythya nyroca, waterfowls, and Zhob River for the Siberian Cranes. Sindh’s Haleji Lake is an important habitat of waterfowls.
In the technical meeting on Wetland Conservation, held in Ankara, Turkey, in October 1967, the Indus Basin was declared to be the world’s fourth largest migratory flyway. Five years later, in International Conference on the Conservation of Wetlands and Waterfowl, held in Ramsar, Iran, it was reiterated that the wetlands of Indus are highly significant for many bird species that breed extralimitally and winter in Pakistan or in other regions of the Indian subcontinent. In spite of this profound importance, it is still a painful reality that the number of the migratory birds coming to Pakistan has reduced substantially. Prof Dr Zulfiqar Ali (Zoology department of the PU) and Manager Research and Conservation WWF, M. Jamshed Iqbal Chaudhry, both agree that this number is fast declining when compared with previous years. These experts say that a typical migratory bird relies on many different geographic locations throughout its annual cycle for food, rest and breeding. So even if we protect most of their breeding grounds, it’s still not enough – threats somewhere else can affect the entire population. So, we will have to make everything safe. In this backdrop, Prof Dr Zulfiqar Ali stresses the need for initiatives like saving wetlands from drying up, protecting them from contamination and prohibiting the illegal hunting as well as strong implementation of the policies in this regard. Mr Jamshed Iqbal, however, emphasises that there should be a strong mechanism for monitoring of migratory birds in place so that we may get authentic facts and figures in order to strengthen the research processes and evaluate the performance of the concerned institutions.
10 reasons why birds are good indicators for biodiversity
- REASON 1. Bird taxonomy is well known and relatively stable: e.g., the number of recognised bird species has grown by just 5–8% per decade in recent years compared to 15–24% for mammals and amphibians.
- REASON 2. Bird distribution, ecology and life history are well understood: e.g., over 16,000 scientific papers on bird biology are published per year.
- REASON 3. Birds are generally easy to identify, survey and monitor, and there are valuable historical data sets for a wide range of species: e.g., birds comprise over 50% of the populations included in global wildlife trend indicators.
- REASON 4. Birds are diverse, found in nearly all habitats and occur across the world: e.g., there are over 10,000 bird species globally with, on average, over 400 species occurring per country.
- REASON 5. Bird habitat requirements are typically fairly specialised: e.g., more than half of all bird species predominantly occur in one or two habitat types.
- REASON 6. Birds usually occupy high trophic levels in food webs and are relatively sensitive to environmental change: e.g., trends in farmland birds in the UK correlate with trends in land-use intensity and climate.
- REASON 7. Bird population trends often mirror those of other species: e.g., mammals, reptiles, amphibians, plants and invertebrates have shown trends similar to farmland birds in the UK since the 1940s.
- REASON 8. Bird distribution generally reflects that of many other wildlife groups: e.g., the network of key sites for bird conservation (IBAs) covers 80% of the area of those identified for other wildlife groups.
- REASON 9. Birds are economically important: e.g., pest control by birds in Canada’s boreal forests is estimated to be worth Can$5.4 billion per year.
- REASON 10. Birds are flagships for nature—they are popular, engage the public and resonate with decision-makers: e.g., 20% of people in the USA and 30% in the UK watch or feed birds regularly. Source: State of the World Birds 2013 (BirdLife)