Migration is the way most birds adapt to seasonal changes as they move between their summer breeding grounds and their winter homes. Some fly thousands of miles and cross the Gulf of Mexico and other bodies of water.
In fall they usually leave areas where the weather is severe and food sources are not plentiful and head to balmy, resource-rich environments. In spring they return to breeding areas. Migration is a diverse behavior found in all animal taxa. Migration of the birds is a natural seasonal opportunity for breeding, habitats, and feeding. It is a widespread phenomenon in nature.
Animals exhibits different types of migration that includes seasonal migration over latitudes, altitudinal, migrations that overlap with key life-history stages such as molt, and migrations that can span multiple generations over space and time. This alteration occurs between species or within species, but all types of migration includes movement from their original origin and the return back to it.
The geographical association of organisms between certain stages of annual cycle, which includes winter stages, migration, and breeding is called as Migration Connectivity. Migratory Connectivity however it may be weak or strong. Migratory connectivity has an important consequence for the conservation of migratory organisms, evolution and ecology.
These birds fly over the mountain ranges, river valleys, and other topographical features. Migration of birds is driven primarily in search of food, habitat, breeding, nourishment etc. Migration costs high mortality when hunted by humans.
- Migratory Birds
Wetlands play an important role in the health and existence of other natural resources of the state, like ground water, inland lakes, fisheries and wild life. Most of the wetlands are seems to be the resident of Migratory Birds, aquatic vegetation and fish fauna.
Due to diverse weather and varied land of Pakistan play a role as a home for the exclusive and rare birds of the world and its wetlands and lakes attracts million of the birds from the globe especially from the Siberia each year. Migratory birds are those birds that travel across national and international borders, from Arctic to tropical or subtropical zones.
Pakistan has a great variety of wetlands distributed around throughout the country which start from the coastal mangroves to glacial lakes of high Himalayas. Total wetland of Pakistan is about 7,800,000 ha. On the avifauna of Pakistan there are few reports presented.
In these reported many of the wetlands of Pakistan are discussed which are Patisar lake of Bahawalpur, Rawal Lake Islamabad, Chashma Barrage and Marala headwork’s, Rasool Barrage Birds have started arriving in Pakistan as the winter season started in Siberia (Russia) during September to November and these birds are mainly found on the costs of river Indus and Kabul.
The migratory bird fly from Siberia to Afghanistan, Karakorum range, across river Indus in Pakistan and finally towards India. This route is known in the international migration routes as `Indus Fly-way No. 4‘ or `Green Route‘. Migratory species of birds can be divided into four categories which are: short-distance migrant, local migrant, long-distance and nomadic migrants.
Species of birds like Falcons, Quails, Pheasants, Rails, Crakes, Moorhens, Coots, Pigeons, Doves, Owls, Woodpeckers, Wrynecks, Warblers, Flycatchers, Wagtails, Pipits, Shrikes, are kept under the category of migratory birds. Asian Houbara (Chlamydotis macqueenii) found in cholistan desert of Pakistan and fly through the mountains of Hindu kash, Pamir, Tien Shan & Himalaya.
Transmission of pathogens occur through the migratory birds can take place directly (biological transmission) or indirectly (arthropod-borne transmission) to the indigenous livestock and humans.
They act as a vector and can carry certain pathogens including parasites and act as a reservoir of host for transmitting certain microorganisms including Escherichia coli, Salmonella, Mycobacterium, West Nile virus and Avian Influenza virus to humans and animals.
- Pathogens Transmitted through migratory Birds
Parasites that transmit through migratory birds including Protozoa (Haemoproteus, Leucocytozoon, Plasmodium, Trichomonas, coccidia, Eimeria, Sarcosystis, Babesia), Helminths including Cestodes (Fermandezia spinnosissima, Monopylidium caenodex, Sobolevitaenia verulami, Hirundinicola chelidonariae, Aploparaksis demshini, Aploparaksis scolopacis),
Nematodes (Strongyloides, Capillaria contorta, Acuaria attenuate, Pseudoprocta decorate, Diploriaena ozouxi, Diplotriaena tridens, Dicheilonema ciconiae), Trematodes (Trichobilharzia sp., Dendritobilharzia pulverulenta, Typhlocoelum cucumerinum, Psilochasmus oxyurus, Levinseniella sp.
Epomidiostomum unicinatum, Capillaria sp., Tetrameras spp., Amidostomum acutum, Streptocara crassicauda, Sciadiocara rugosa, Porrocaecum crissum, strongyloides sp., Capillaria contorta, Sciadiocara rugosa.).
Beside Parasites wild birds also transmit certain pathogens including Bacteria, Virus and Fungus, Species of pathogens are Bacteria (Escherichia coli, Salmonella sp.,
Mycobacterium, Borrelia sp. Enterococcus, Staphylococcus, Clostridium perfringens, Listeria monocytogens, Yersinia sp., Enterobacteriaceae), Virus (West Nile Virus, Louis encephalitis virus, Western Equine Encephalitis, Influenza A virus), Fungi (Cryptococcus, Yeast, Candida sp., Aspergillus spp., Microsporum spp, Trichophyton spp).
These birds are capable of transmitting many diseases to indigenous livestock and humans which are Parasitic (Cercarial dermatitis (swimmer’s itch)), Bacterial (Ornithosis, Salmonellosis, enteritis, bloody diarrhea, Lyme disease), Viral (West Nile fever, Influenza, Encephalitis, Foot-and-mouth disease, rotavirus, CCHF, Egg-drop syndrome).
Diseases Transmit through Migratory Birds
Schistosomes causing Cercarial dermatitis (swimmer’s itch), Coccidia & Sarcocystis are transmit through Cranes, Owls, Ducks, Waterfowls, Cowbirds, and Mallards.
Ornithosis, Salmonellosis, enteritis, bloody diarrhea, Lyme disease.
West Nile virus, Influenza, Encephalitis, Foot-and-mouth disease, rotavirus, CCHF, Egg-drop syndrome virus.