All life on earth has evolved to adapt in some manner to the seasonal changes in climate that are experienced everywhere except in the tropics. But what does an animal do when it becomes just too hot or too cold for it to survive? There is only one answer really and that is to move. This movement of animals from one area to another is called a migration. Some animals migrate vast distances between continents, and others might need only to move a few kilometers to find the conditions they need to survive.

Migrations are not always brought about as a result of extreme temperature variations, many animals move to find food, while others migrate to find the optimum conditions for them to breed.

Arabia has many examples of migrations. The local inhabitants have noticed the pattern of these migrations over thousands of years and have used this knowledge to enable them to survive.

The grass eating animals in the deserts of Arabia have always needed to migrate from one area to other and do so after the rains. Because the desert is so dry, some years rain may fall on only small patches of the desert. Animals such as gazelle therefore need to travel long distances when this happens so they can find the areas where the grass is plentiful. Sir Wilfred Thesiger, in his famous book Arabian Sands, describes how the bedouin would follow the Arabian oryx on their migration so that they too could find grazing for their camels and goats.

This great cycle of nature has gone unchanged for thousands and thousands of years, but as it is dependent upon so many factors it is sensitive to disturbance. The animals are also very vulnerable on their migration, as they expend much energy to reach their goal. Man should regard himself as the proud custodian of these great wonders of our natural world and should try his best not to disturb this delicate balance.

Butterfly Migration

Kevin Thompson, an entomologist at Arabia�s Wildlife Centre, gives us an insight to the magic moves of butterflies.

Many animals around the world migrate at certain times of the year and insects, such as butterflies, are no exception. The plain tiger butterfly Danaus chrysippus, one of the better-known butterflies in the region, is a good example of an Arabian migratory insect.

The plain tiger is highly visible at times when conditions are favourable, usually from early spring to summer. As summer progresses their numbers decrease drastically, but by the next spring the plain tigers are back again in full force. Can they really reproduce that quickly and efficiently?

One of the reasons for the �sudden� appearance of this butterfly is that it moves from place to place (in search of food) in groups. These butterflies stop to feed in any areas where nectar-producing plants are found, usually after rain. They also stop to lay eggs on specific plants that are suitable for their larvae to feed upon after they hatch. These food plants are from the milkweed family, Ascelpidaceae, the most common of which is the sodom�s apple, Calotropis procera. As long as food is available, the butterflies will remain.

There are enough zones with differing climates in the Arabian Peninsula to ensure that the plain tiger population can be sustained throughout the year in one area or another. So, when there is rain next in your area, look out for the plain tiger ­ you might just get a colourful surprise.

MARINE MIGRANTS
Robert Baldwin is a marine biologist based in Oman. He has written many books and articles on whales, dolphins and other marine life, and is considered an expert in his field. He writes about Oman�s marine migrants ­ what we know and what we would like to know.

Among the most fascinating of Oman�s marine life are the mighty whales and endangered sea turtles. Both of these groups of animals are known to undertake incredible journeys in search of food, sanctuary from predators and a place to breed.

Turtles
Green turtles are found throughout Oman where they come to nest on remote shores and feed in rich coastal habitats. Many return here each year and whilst they are away they are known to migrate great distances. Omani turtles have been found as far away as the United Arab Emirates, Qatar, Bahrain, Yemen, Saudi Arabia, Eritrea and even the Maldive Islands. If the turtles involved had taken direct routes to these places, then the minimum distance travelled would be 879 kilometres and the maximum a staggering 2,527 kilometres!

Whales
The largest animals ever to have lived on earth are the whales, some of which grow to a mass of over 100 tonnes. Feeding this huge bulk is a major task and whales must therefore seek out parts of the world�s oceans that can provide them with enough to eat. The cold, nutrient-rich waters of the north and south poles are like a cold store of food for whales. To reach them, many whales make long journeys every year from the warm waters of the tropics where they breed. These journeys may take them several thousand kilometres and several months of non-stop swimming.

The Northern Indian Ocean region is unique in being the only ocean that has no short route to polar seas. The whales that live in this region are therefore unable to reach the cold stores of food. Despite this many different kinds of whales live here, especially, it seems, in the Arabian Sea off the coast of the Sultanate of Oman. Humpback whales, Megaptera novaeangliae, are among the most common. This species is well-known for its long migrations throughout the world, but they are apparently content to live permanently off the coast of Oman. How then do Oman�s humpback whales survive here? Why do they not attempt to migrate? What makes them different? Or, looking at it another way, has their isolation here made them different?

The answers to all these questions are only just beginning to be revealed. Each summer in Southern Arabia strong winds create rough seas and cause deep, cold water to well up to the surface. Just like the cold seas at the poles, this water brings nutrients and food for the whales, which take full advantage of the abundant prey. This may help to explain why they choose to remain here rather than migrating great distances. As a result, however, they are unlikely to meet other whales from other parts of the world�s oceans and so have evolved small changes in appearance and behaviour that make them different from all others.

MIGRATORY FALCONS AND TRADITIONAL FALCONRY
David Steed is a professional falconer, trained in the United Kingdom. For the last five years he has worked abroad as a falconer in Africa and the Middle East. David shares with us some migratory raptor knowledge.

The art of training wild birds of prey for hunting is still popular today. In most countries however captive bred or `farmed` falcons have replaced the use of wild birds. The style of falconry in the Middle East is quite different to elsewhere in the world. This is because the harsh summers are simply too hot for falcons to survive. Therefore the falcons are migratory and leave Arabia during the summer.

From September to November hundreds of thousands of birds migrate in huge flocks across the Arabian Peninsula and are followed by falcons that feed on them. The falcons spend the summer in Eastern Europe and Central Asia, then move south in the winter to the warmer climates of Eastern and Northern Africa. The peregrine falcon (Shaheen) and the saker falcon (Hurr) are the most common migrants in our area and have been used for hundreds of years in traditional falconry. The tribesmen would capture the falcon, train them in just two weeks and hunt with them for the winter season. In March or April it becomes too hot to fly. It is at this time that the wild falcons migrate back to Europe and Asia in anticipation of the cooler summer climate. Therefore the falconers release their trained birds so that they can rejoin these wild migrating flocks.

MIGRATORY BIRDS
Colin Richardson is an architect, turned professional birder residing in the UAE. He is Bird Recorder for the UAE, author of the country's standard work of reference on birds (The Birds of the United Arab Emirates) and runs a bird-watching tour agency. Colin discusses migratory routes and local bird populations.

Of the 420-plus bird species that have been recorded in the UAE, the total number of migratory species is approximately 360. The exact number of birds that pass through (and over!) the UAE on migration varies from season to season, but easily runs into millions.

We do not have enough information on exactly where these migratory birds are coming from, but we believe some spend the winter in east and southern Africa, and possibly also in southern Arabia. It can be difficult to determine the exact migratory path of individual species as they do not always fly a north-south route, but instead can follow geographical features such as mountain ranges and the Arabian Gulf. Spring and autumn routes are often different as well and we don't understand why. For example, in spring we get large numbers of warblers, shrikes and wheatears but in autumn they are largely absent. Perhaps they take a circular route? But again we are unsure as to why this may be.

Changes in climate can effect a bird's decision on moving to another area, whether this be locally or internationally. The last three years have been a drought period for the UAE. This has meant that some of the more sedentary resident species, which may only move up to a mile away from their usual feeding grounds, have declined in numbers. Instead of moving they have been conserving all their energy and food supplies, possibly even by laying fewer eggs, thus adapting to these harsher conditions. The hoopoe lark is just one example of a bird whose numbers appear to have temporarily declined.

We are short of information about migratory birds in this region and by starting some projects can only learn more. Well co-ordinated trapping and ringing projects could be undertaken in order to find out about the various routes used by different species. Satellite tagging of birds such as larger birds of prey could be done. This is an expensive, but worthwhile exercise. The information gathered could provide answers as to why huge numbers of soaring birds (birds which need rising air thermals to fly long distances) cross Arabia into Africa, but in doing so, completely avoid the UAE. These are some of the many things we have yet to discover about migratory bird behaviour.