Migration of birds devloped ppt

2. Outlines
● Definition of Bird Migration
● Migration Facts
● Migration Flyways
● Why do Birds Migrate?
● Types Of Bird Migration
● Disadvantage Of Bird Migration

3. Definition Bird Migration
● The word “migration” has come from the Latin word migrara which means going from one
place to another. Many birds have the inherent quality to move from one place to another to
obtain the advantages of the favourable condition.
● In birds, migration means two-way journeys—onward journey from the ‘home’ to the ‘new’
places and back journey from the ‘new’ places to the ‘home’. This movement occurs during the
particular period of the year and the birds usually follow the same route. There is a sort of
‘internal biological clock’ which regulates the phenomenon.
● According to L. Thomson (1926), bird migration may be described as “changes of habitat
periodically recurring and alternating in direction, which tend to secure
optimum environmental conditions at all times”

4. Migration Facts
● At least 4,000 species of bird are regular migrants, which is about 40 percent of the total number of birds in the world.
(Although this number will likely increase as we learn more about the habits of birds in tropical regions.)
● Birds can reach great heights as they migrate. Bar-headed geese are the highest-flying migratory birds, regularly
reaching altitudes of up to five and a half miles above sea level while flying over the Himalayas in India. But the bird with
the record for the highest altitude ever is the Ruppell's griffon vulture, which collided with a plane at 37,000 feet (that’s
seven miles!) in 1975 and was unfortunately sucked into its jet engine.
● The Arctic tern has the longest migration of any bird in the world. These black-capped, red-billed birds can fly
more than 49,700 miles in a year, making a round trip between their breeding grounds in the Arctic and the Antarctic,
where they spend their winters. The lucky bird gets to see two summers a year! And over its lifespan of more than 30
years, the flights can add up to the equivalent of three trips to the moon and back.

5. ● Speaking of long distances, the northern wheatear travels up to 9,000 miles each way between the
Arctic and Africa, giving it one of the largest ranges of any songbird. What makes this an
amazing feat is that the tiny bird weighs less than an ounce, on average.
● The award for fastest bird goes to the great snipe: It flies around 4,200 miles at speeds of up
to 60 mph! No other animal travels at such speeds for such long distances. Birds usually utilize
tailwinds (winds blowing in the same direction they fly) to help them go faster, but the snipe’s speeds
don’t seem to be a result of that.
● The bar-tailed godwit can fly for nearly 7,000 miles without stopping, making it the bird
with the longest recorded non-stop flight. During the eight-day journey, the bird doesn’t stop for food
or rest, demonstrating jaw-dropping endurance

6. ● Migration can be extremely dangerous for birds, and many don’t often make it back to their starting point.
Sometimes natural occurrences like harsh weather play a role, but many times, human activities are the cause
of birds’ untimely demise. In the United States alone, up to one billion birds die each year from
window collisions. And approximately seven million die from striking TV and radio towers in North
America annually, ABC News reports.
● To prepare for the extremely taxing effort of migration, birds enter a state called hyperphagia, where they bulk
up on food in the preceding weeks to store fat, which they’ll later use for energy on their long journeys. Some
birds, like the blackpoll warbler, almost double their body weight before flying 2,300 miles non-stop
for 86 hours.
● Even birds that don’t fly migrate. Emus, the large Australian birds, often travel for miles on foot to find food,
and many populations of penguins migrate by swimming

7. Migration Flyways
When birds head north or south during migration, they use a route
that’s called a flyway. In North America, there are four key flyways –
the Pacific, the Central, the Mississippi and the Atlantic.
Each of these flyways traces the general route that birds take as they head for warmer
weather before winter arrives. The same routes can be flown in reverse in the spring, allowing
birds to reach these safe zones prior to breeding season.
Points in next slide

8. ● Pacific Flyway – This thin flyway tends to follow the Pacific coast throughout its entire
range. Birds on the Pacific Flyway can travel as far north as Alaska and to the tip of
South America
● Central Flyway – While not on some of the world flyway maps, the Central Flyway is
a unique flyway according to North American experts. This flyway tends to follow the
eastern edge of the Rocky Mountains as it zips up through central Canada.
● Mississippi Flyway – Following the path of the Mississippi River, this flyway is notable
for its distinct lack of mountains to block or funnel migrating birds. That makes the
Mississippi Flyway the most used flyway of the American routes, particularly by water
fowl

9. ● Atlantic Flyway – Like the Pacific Flyway, the Atlantic Flyway is bordered by an ocean, and
it compels birds to hug the coastline during their migration journeys. This flyway includes
over-the-water jaunts as birds cross the Gulf of Mexico. It also includes routes that jump to
Cuba and other Caribbean islands.
● Central America chokepoint and points south – All four of the American flyways meet up
in the thin land bridge of Central America. Flyways naturally follow landmasses because birds
need food and resting points during their journey. This makes Central America a chokepoint
of sorts – most migrating birds are funneled through this tight corridor. The chokepoint also
creates a perfect hotspot for birdwatchers. In fact, some of the world’s best birding tours are
through Central America! As the flyways enter South America, they pretty much intermingle
with one another.

10. ● Other Flyways – There are several other flyways used by birds
across the world. Like the American flyways, these routes are
generally a north-south passageway, which helps birds move to
warmer climates in the spring and fall. In total, there are five other
primary flyways – utilized by birds in Europe, Africa, Asia and
Australia

11. Why do Birds Migrate
● Migratory birds fly hundreds and thousands of kilometres to find the best ecological conditions and habitats for feeding, breeding and raising
their young. When conditions at breeding sites become unfavourable, it is time to fly to regions where conditions are better.
● The majority of birds migrate from northern breeding areas to southern wintering grounds. However, some birds breed in southern parts of
Africa and migrate to northern wintering grounds, or horizontally, to enjoy the milder coastal climates in winter. Other birds reside on lowlands
during the winter months and move up a mountain for the summer.
● Migratory birds have the perfect morphology and physiology to fly fast and across long distances. Often, their journey is an exhausting one,
during which they go to their limits. The Red Knot has one of the longest total migration routes of any bird, travelling up to 16,000 kilometres
twice a year. It breeds in Siberia and overwinters on the west coast of Africa, some even going down to the tip of South Africa.
● It is truly amazing how migratory birds can navigate with pin-point accuracy. Exactly how migrating birds find their flyways is not fully
understood. It has been shown that they are able to orientate by the sun during the day, by the stars at night, and by the geomagnetic field at any
time. Some species can even detect polarized light, which many migrating birds may use for navigation at night.

12. Types Of Bird Migration
● Seasonal: This well-known and widespread migration is predictable based on seasonal changes,
as birds move between breeding and non-breeding ranges. The height of these migration periods
is during spring and fall, though in some areas the change between wet and dry seasons are
migration
● Latitudinal: This migration is between areas of different latitudes from north to south and vice
versa. This is the most common migration type with many birds that migrate from the Arctic to
the tropics. The exact direction of migration is often determined by geographic features,
however, such as mountain ranges, coastlines, and available habitats
● Longitudinal: Similar to latitudinal migration, this type of movement is a change between
different longitudes from east to west or west to east. This is a common type of migration for
many birds in Europe, where geographic features encourage birds to move longitudinally rather
than latitudinally.

13. ● Altitudinal: Birds that breed in tall mountains often exhibit altitudinal migration. This type of migration is the move to
lower elevations in winter, when harsh weather and deep snowfall may make staying at upper elevations impossible.
Birds that use altitudinal migration may not venture far in terms of overall mileage or distance, but just a few hundred
feet of elevation can make a great difference in habitats and available resources.
● Loop: Birds that follow an annual circle are loop migrants. This migration includes two distinctly different routes to
and from breeding grounds, often taking advantage of varied resources at different times of the year. For example,
rufous hummingbirds follow a coastal route in spring on their way from Mexico to Alaska but take advantage of
mountain wildflowers on an interior southbound route in autumn. Loop migration is also common with many seabirds
and shorebirds as they use seasonal variations in wind patterns to aid their flight
● Nomadic: This movement is less predictable and can be erratic depending on available food and water resources.
Nomadic birds tend to stay within the same general range but may be completely absent from parts of that range
when resources are scarce. They will return, however, when the habitat becomes more suitable, such as after rainfall,
when prey is more abundant, or when crops ripen. Types of birds that migrate nomadically include waxwings,
phainopeplas, zebra finches, and black swans

14. ● Irruptive: Bird irruptions are highly unpredictable but spectacular migrations that bring large numbers of birds into
unusual areas, most often in winter. Unlike nomads, irruptive birds may be found far outside their expected ranges
during this type of migration, but the reason is the same: the search for suitable food and water resources. Types of
migrating birds that exhibit irruptive patterns include redpolls, varied thrushes, evening grosbeaks, crossbills, and
snowy owls.
● Dispersal: While not always considered a true migration, bird dispersal is nonetheless relatively predictable and
seasonal, though only once in a bird's lifetime. In this migration, juvenile birds are forced away from their hatching
grounds and must seek out their territories as their parents continue to use the same range. This is more common
among birds that are year-round residents of the same range and will defend their territories throughout the year,
such as woodpeckers.
● Leap Frog: A leap frog or skip migration is a unique pattern where a northern population will migrate a greater
distance to skip over a sedentary population of the same species. A year-round range is thus occupied in between the
breeding and wintering grounds of the leapfrogging population, but the individual populations do not extensively mix

15. ● Reverse: Reverse migration is an aberration among migratory birds. It is most often seen in autumn when young
birds can become confused or disoriented and instead of migrating along the expected route go in the opposite
direction. These lost birds end up as vagrants far from their traditional locations. This is not usually seen with large
numbers of birds but is more likely with individuals and isolated sightings, some of which can be quite spectacular
● Molt: Some birds migrate only to accommodate their annual molting periods. During a molt migration, birds will leave
an established range to stay at a safe, secure range while they are vulnerable and less capable of flight, even during
brief flightless periods. After the molt is complete, they will return to their regular range regardless of season or
breeding readiness. This phenomenon is seen among a wide range of duck species but is not common with other
types of birds
● Drift: Drift migration is a rare but highly anticipated event many birders hope to see. When it happens, large numbers
of migrating birds have "drifted" away from their typical migration routes, often pushed by storms. This can result in
spectacular fallout events and many rare bird sightings

16. Disadvantages Of Bird Migration
● Many youngs are not, able to reach the destination because they die during the
course of the continuous and tiresome journey.
● Sudden changes in the climate such as storms and hurricanes, strong current of
wind, fog are the causes for the death of a sizeable number of migrants
● Sometimes man-made high tours and lighthouses cause the death of migratory
birds.
● Man themselves are responsible for the death of the migrants. They shoot at these
poor birds just for their own leisure and amusement