1. FOGSL Mystery of Migration Devaka K Weerakoon Field Ornithology Group of Sri Lanka

2. FOGSL Some of the animals in our surroundings are present throughout the yearSome of the animals in our surroundings are present throughout the year There are some birds that appear during a certain time and disappear again after a while which is repeated faithfully year after yearThere are some birds that appear during a certain time and disappear again after a while which is repeated faithfully year after year Sometimes during certain months of the year we see large number of butterflies fly in the same directionSometimes during certain months of the year we see large number of butterflies fly in the same direction

3. FOGSL These observations have captured mans imagination raising questions such asThese observations have captured mans imagination raising questions such as –Why do animals undertake such journeys? –How do they find the way? In fact study of migration dates back to Aristotle (384 - 322 BC)In fact study of migration dates back to Aristotle (384 - 322 BC) In his book Historia Animalium he wrote that some creatures move south during winter to avoid the cold and return back during the spring. He also recognized that some migrate short distance while other travel a long wayIn his book Historia Animalium he wrote that some creatures move south during winter to avoid the cold and return back during the spring. He also recognized that some migrate short distance while other travel a long way

4. FOGSL Migration gave rise to lot of myths as wellMigration gave rise to lot of myths as well Aristotle proposed that some birds hibernate during the winterAristotle proposed that some birds hibernate during the winter Aristotle was also responsible for theory of transmutation where he proposed some birds change into others (red start – Eurasian robin) with the arrival of the winterAristotle was also responsible for theory of transmutation where he proposed some birds change into others (red start – Eurasian robin) with the arrival of the winter Barnacle/ Brent geese (Anser bernicla – the goose from barnacles) arose from Barnacles (Lepas antifera - the goose bearer)Barnacle/ Brent geese (Anser bernicla – the goose from barnacles) arose from Barnacles (Lepas antifera - the goose bearer) In 1955 Olaus Magnus, wrote that swallows spend winter under waterIn 1955 Olaus Magnus, wrote that swallows spend winter under water

5. FOGSL It is not possible to give a simple definition for the term migrationIt is not possible to give a simple definition for the term migration Nature exist in infinite variety as does the phenomenon we refer to as migration making it impossible to capture it within a single common definitionNature exist in infinite variety as does the phenomenon we refer to as migration making it impossible to capture it within a single common definition What is Migration?

6. FOGSL Breeds in the north and winters in the southern hemisphereBreeds in the north and winters in the southern hemisphere Barn Swallow (Hirundo rustica)

7. FOGSL Found in North AmericaFound in North America Heads south to winter in Central AmericaHeads south to winter in Central America In spring it flies north againIn spring it flies north again Few makes it back to where they startedFew makes it back to where they started Monarch (Danaus plexippus)

8. FOGSL Spawns in rivers of North America and EuropeSpawns in rivers of North America and Europe As they develop they drift down to the seaAs they develop they drift down to the sea When they become adults they swim back to freshwater to breedWhen they become adults they swim back to freshwater to breed Atlantic Salmon (Salmo salar)

9. FOGSL Tiny microscopic animals that are at the bottom of marine food chainsTiny microscopic animals that are at the bottom of marine food chains In summer they occupy the surface layer feeding on phytoplankton and breedingIn summer they occupy the surface layer feeding on phytoplankton and breeding In winter they descend to deeper colder water and does not feed at allIn winter they descend to deeper colder water and does not feed at all Zooplankton

10. FOGSL All four are clear examples of migration and yet there are many differencesAll four are clear examples of migration and yet there are many differences Barn swallow – Seasonal movement over a long distanceBarn swallow – Seasonal movement over a long distance Monarch – Seasonal movement over long distance but does not complete the tripMonarch – Seasonal movement over long distance but does not complete the trip Salmon – Once in a life time journey over a long distanceSalmon – Once in a life time journey over a long distance Zooplankton – Seasonal movement over short distanceZooplankton – Seasonal movement over short distance There are Commonalities and Clear Differences

11. FOGSL Why Do Animals Migrate? To avoid cold weatherTo avoid cold weather To make use of an seasonal abundance of a food sourceTo make use of an seasonal abundance of a food source To Breed or spawnTo Breed or spawn To disperse or avoid crowdingTo disperse or avoid crowding Retreat to a place of safetyRetreat to a place of safety Slow down the metabolismSlow down the metabolism Avoid predators during early life stagesAvoid predators during early life stages

12. FOGSL What Kind of Animals Migrate? ZooplanktonZooplankton Flatworms, star fish, lobsters, crabsFlatworms, star fish, lobsters, crabs

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14. FOGSL What Kind of Animals Migrate? ZooplanktonZooplankton Flatworms, star fish, lobsters, crabsFlatworms, star fish, lobsters, crabs Insects Butterflies, locusts, aphids, social insectsInsects Butterflies, locusts, aphids, social insects

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16. FOGSL What Kind of Animals Migrate? ZooplanktonZooplankton Flatworms, star fish, lobsters, crabsFlatworms, star fish, lobsters, crabs Insects Butterflies, locusts, aphids, social insectsInsects Butterflies, locusts, aphids, social insects Fish – Salmon (Anadromous move from marine to freshwater), eel (catadromous – from freshwater to sea), move within marine habitatFish – Salmon (Anadromous move from marine to freshwater), eel (catadromous – from freshwater to sea), move within marine habitat

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18. FOGSL What Kind of Animals Migrate? ZooplanktonZooplankton Flatworms, star fish, lobsters, crabsFlatworms, star fish, lobsters, crabs Insects Butterflies, locusts, aphids, social insectsInsects Butterflies, locusts, aphids, social insects Fish – Salmon (Anadromous move from marine to freshwater), eel (catadromous – from freshwater to sea), move within marine habitatFish – Salmon (Anadromous move from marine to freshwater), eel (catadromous – from freshwater to sea), move within marine habitat Amphibians and reptilesAmphibians and reptiles BirdsBirds

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21. FOGSL What Kind of Animals Migrate? ZooplanktonZooplankton Flatworms, star fish, lobsters, crabsFlatworms, star fish, lobsters, crabs Insects Butterflies, locusts, aphids, social insectsInsects Butterflies, locusts, aphids, social insects Fish – Salmon (Anadromous move from marine to freshwater), eel (catadromous – from freshwater to sea), move within marine habitatFish – Salmon (Anadromous move from marine to freshwater), eel (catadromous – from freshwater to sea), move within marine habitat Amphibians and reptilesAmphibians and reptiles BirdsBirds MammalsMammals

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26. FOGSL Human Migration

27. FOGSL Classification of Migration Complete migration - Cyclic event where the migrant travels along distance and returns to the original locationComplete migration - Cyclic event where the migrant travels along distance and returns to the original location Partial migration – Short distance migrationPartial migration – Short distance migration Re-migration – migration cycle completed by off springRe-migration – migration cycle completed by off spring Removal migration – One way movementRemoval migration – One way movement

28. FOGSL Types of Migration North South MovementsNorth South Movements East–west journeysEast–west journeys Circuits of the land and oceanCircuits of the land and ocean Trips up and down mountainsTrips up and down mountains Vertical movements through the water column of seas and lakesVertical movements through the water column of seas and lakes

29. FOGSL Where do they migrate and from to?

30. FOGSL How do they Find the way? Navigation vs OrientationNavigation vs Orientation Navigation – Finding the way to a known location through unknown territoryNavigation – Finding the way to a known location through unknown territory Orientation – Finding the way to a known location through familiar territoryOrientation – Finding the way to a known location through familiar territory Navigation is done byNavigation is done by Sun, moon and starsSun, moon and stars Routes learned from other birdsRoutes learned from other birds Detecting the earths magnetic fieldDetecting the earths magnetic field Land marks – visual, olfactory, auditoryLand marks – visual, olfactory, auditory

31. FOGSL How do we study this Phenomenon? SIGHTING Observations using binoculars or a spotting scope BANDING US Fish and Wildlife Service Bird Banding Laboratory RADAR (NOAA) Several years ago, researchers at Cape May counted 14 million birds in one night RADIO TELEMETRY Carl Safina followed a single radio-tagged albatross throughout its range

32. FOGSL When do they Migrate? Diurnal migrants Most birds which rely on gliding or flap & glide flight are diurnal migrantsMost birds which rely on gliding or flap & glide flight are diurnal migrants The chief benefit of daytime flight is thermals – rising currents of warm air that provide liftThe chief benefit of daytime flight is thermals – rising currents of warm air that provide lift Nocturnal migrants Many birds which use powered flight are nocturnal migrantsMany birds which use powered flight are nocturnal migrants Night flying helps birds avoid predatorsNight flying helps birds avoid predators The air is calmer and more stable at nightThe air is calmer and more stable at night

33. FOGSL Where do birds spend their time while in Sri Lanka

34. FOGSL Main Migratory Routes

35. FOGSL Major “fly-ways” to the country

36. FOGSL Principal Entry Points

37. FOGSL Major routes of dispersal within the country

38. FOGSL Some Record Migrations The longest insect migration is the monarch butterfly. It travels up to 4,750km in the autumn.The longest insect migration is the monarch butterfly. It travels up to 4,750km in the autumn. The largest migrant is the blue whale. It reaches a length of 24-27m.The largest migrant is the blue whale. It reaches a length of 24-27m. The longest recorded journey in water is a leatherback turtle, which travelled 20,558km in 647 days.The longest recorded journey in water is a leatherback turtle, which travelled 20,558km in 647 days.

39. FOGSL Bar-tailed Godwits have the longest known non- stop flight of any migrant, flying 11,000 km from Alaska to their New Zealand non-breeding areas.

40. FOGSL Some Record Migrations The highest migration is the bar-headed goose that can reach up to 9,000m altitude.The highest migration is the bar-headed goose that can reach up to 9,000m altitude. The Arctic Tern has the longest-distance migration of any bird, from its Arctic breeding grounds to the Antarctic non-breeding areas, a sea journey of over 22,000 km (14,000 mi).The Arctic Tern has the longest-distance migration of any bird, from its Arctic breeding grounds to the Antarctic non-breeding areas, a sea journey of over 22,000 km (14,000 mi).

41. FOGSL What are the problems they face? Habitat destruction – loss of resting areasHabitat destruction – loss of resting areas HuntingHunting Climate changeClimate change Changes in landscapeChanges in landscape Dam constructionDam construction