Migratory birds differ from resident species in that they follow regular seasonal migrations. Migration can be quite complex and dynamic; often it is not just a simple movement from point A to point B. Many migration routes of birds are passed from generation to generation and are a result of learning and imitation. Often migration is a means of finding food; as winter approaches in the temperate zones of the northern and southern hemispheres, supplies of food such as insects, fruit, and nectar begin to dwindle. The bird’s energy requirements for maintaining body heat and the lack of insect food force many species of insectivorous birds to leave and seek a warmer climate. These birds are known as short-distance migrants and may only travel a few hundred kilometers to areas within the tropics of Cancer and Capricorn where the climate and food supply is suitable. Lowering food supplies and temperature are the cues that trigger the decision of when to migrate for many birds. This often creates large movements of many species of birds at roughly the same time, creating an impressive phenomenon known as migration waves. Birdwatching during migration periods can be an exciting and rewarding experience as many species of birds are concentrated in areas which they do not normally occupy. This makes sighting some rare or elusive species much easier than during the breeding season. At some points, migration creates spectacular events such as the mass gathering of Broad-winged Hawks in Central America and North America or wader flocks on the islands of the Yellow Sea.
Seasonal arrival and departure patterns
Some differential migrants have a complete change of habitat between the breeding and non-breeding seasons, as for example the Wood Warbler which migrates from Europe to spend the summer in central Asia. Many of the best known migrants however maintain the same habitat throughout the year and only move to avoid the climatic extremes which make their survival marginal. An example of this is the Cuckoo which winters in central Africa having left its breeding grounds in Europe or Asiatic Russia. There is also differential migration within populations of a species, with females often migrating further than males and juveniles spending their first few winters in less suitable habitat than that of adults. The study of bird migration has been transformed by the use of electronic tracking devices. This has resulted in a recognition of the complexity of migratory routes, with birds which breed in the same location often wintering in different areas. Modern tracking has also shown that some supposedly sedentary species make regular movements over a small scale of only a few kilometres. For example, the populations of many resident songbirds are inflated in the spring as birds from warmer parts of the range move up to take advantage of peak season resources in more temperate climates. Ongoing and future research will continue to provide more information about the movements of the world’s birds, and the problems that many species are facing means that understanding their migratory patterns is more crucial now than ever before.
Popular birdwatching spots during migration
Because of the varied landscapes and forests, with the exception of desert and alpine, and the variety of rainfall and distinct dry and wet seasons, Tanzania offers the birdwatcher a rich and stimulating diversity of birdlife at all times of the year. But it is true to say that as the pick of a good time and the best place will be rewarded by the best birding. The resident birds in the southern and western areas tend to be rather local and somewhat difficult to see. For most people who are primarily interested in birdwatching, a visit to these areas will be amply rewarding if much time is spent at the beginning or end of a trip to enjoy the prolific birdlife in the well-watered gardens of places like Arusha, Usa River and Moshi. But those with a special interest will do better to plan a trip in northern Tanzania mainly or even exclusively for birdwatching, and birders these days include not only easygoing firstcomers but also quite a number of devotees who want to travel hard in search of rare birds. Game viewing and birdwatching are best in the dry seasons in any area, and for northern Tanzania the prime period is the end of the year when the migrant birds from Europe, Russia, and northern Africa are present and many resident birds are breeding. Bird photography in the northern parks is well worth while then and in view of the variation in altitude and bird life it will be rewarding to spend a little time in each of several of the parks. At such times, and especially in the drier areas of northern Tanzania, the problem of getting off the regular roads and beating about the bush to find and see birds is one for which sympathetic understanding guides can surely be found.
Zanzibar serves as an important stopover and wintering destination for numerous migratory bird species that travel thousands of kilometers each year. These migratory birds arrive in Zanzibar during the northern hemisphere’s winter months, seeking refuge from colder climates and abundant food sources. Some of the migratory bird species commonly found in Zanzibar include:
- European Bee-eater (Merops apiaster): These colorful birds migrate from Europe to Africa during the winter months, including Zanzibar. They are known for their vibrant plumage and distinctive aerial acrobatics as they catch insects in flight.
- Barn Swallow (Hirundo rustica): Barn swallows migrate from Europe and Asia to Africa during the northern hemisphere’s winter. They are easily recognizable by their forked tail and graceful flight patterns and are often seen foraging for insects over open fields and water bodies in Zanzibar.
- Osprey (Pandion haliaetus): Ospreys migrate from Europe and Asia to Africa during the winter, including Zanzibar. These large raptors are skilled fishermen and can be observed hunting for fish in coastal waters and mangrove estuaries.
- Common Sandpiper (Actitis hypoleucos): These small wading birds migrate from Europe and Asia to Africa during the winter, including Zanzibar. They are often seen probing the muddy shores of tidal flats and estuaries in search of food.
- Eurasian Hobby (Falco subbuteo): Eurasian hobbies migrate from Europe to Africa during the winter, including Zanzibar. These agile falcons are skilled hunters and feed on small birds and insects caught in flight.
- Common Tern (Sterna hirundo): Common terns migrate from Europe and Asia to Africa during the winter, including Zanzibar. They are often seen diving into the water to catch fish and can be found along the coastlines and inshore waters of the island.
These are just a few examples of the migratory bird species that visit Zanzibar during the winter months. Their presence adds to the rich avian diversity of the island and provides birdwatchers with opportunities to observe a wide variety of species in their natural habitats.