Post on 09-Jun-2020
The migration of birds
The migration of birds
• Migration is the yearly, seasonal journey undertaken by many species of birds. During this journey, birds cover distances of many kilometres.
• The most common types of migration are those carried out by birds in the spring and the autumn. In the autumn, they travel from breeding grounds in the north to wintering grounds in the south, and vice versa in the spring.
Breeding grounds
Wintering grounds
Autumnmigration
Spring migration
Natural Science 2. Secondary Education
BY-MS.S.ANITHA
• Large birds, like geese and birds of prey, usually migrate during the day.
Black geese flying in a V-formation
• But smaller birds, like robins, migrate at night.
Robin
The migration of birds
The migration of birds
Natural Science 2. Secondary Education
• Birds that migrate are called migratory birds, while birds that remain in one area are called sedentary birds or Resident birds.
Geese are migratory birds.
A sparrow is an example of a sedentary bird.
The migration of birds
The migration of birds
Natural Science 2. Secondary Education
Interesting examples
The white stork provides an example of how the amount of food available affects bird migration.
• These storks used to come to the Iberian Peninsula to spend the summer and breed. Then, in the autumn, they migrated to Africa to winter there. However, more and more storks now winter on the Peninsula.
• This is due to:
• A greater number of rubbish dumps that provide them with food throughout the year.
• It is likely that the change is also related to the higher temperatures resulting from climate change.
White stork
The migration of birds
Complete Migration
All individuals leave the breeding area
after raising their families
Most complete migrants breed in
temperate northern climates
Many complete migrants travel incredible
distances between breeding and
non-breeding habitats
Cerulean warbler Wilson’s plover Stilt sandpiper
Partial Migration
Seasonal movement by some, but not all,
individuals away from breeding area
Some overlap of breeding & non-
breeding ranges
Red-tailed hawk Herring gull Bewick’s wren
The
Sahara
• Birds like swallows, bee-eaters, storks and birds of prey including black
kites, vultures and common kestrels journey from Africa to the Iberian
Peninsula to spend the summer.
Swallows
Black kite
UNIT
5The migration of birds
Climatic Migration-summer migrants
Natural Science 2. Secondary Education
Winter Migrants
• Migratory birds follow the same migration routes every year.
• Birds that migrate from Northern Europe to regions in the south of the
continent in the winter are called wintering or pre-Saharan birds (as they
do not cross the Sahara).
• Birds like geese and cranes come to the Iberian
Peninsula from Northern Europe to spend the
winter.
The
Sahara
Crane migration
Crane
UNIT
Natural Science 2. Secondary Education
Interesting examples
• The Arctic tern travels the longest distance of any migratory bird: it journeys
from one pole to another two times a year, covering 40,000 km.
• Over the course of its life, about 26 years, an Arctic tern can travel up to 1
million kilometres.
Breeding grounds
Wintering grounds
Migratory routes
Natural Science 2. Secondary Education
Diurnal migrants Most 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 lift
Ex-Cranes, swallows,bluejay etc
DAY OR NIGHT?
Nocturnal migrants
Many birds which use powered flightare nocturnal migrants.
Night flying helps birds avoid predators
Other benefits include calmer, more stable air
They rest & feed during day
DAY OR NIGHT?
MOON WATCHINGRequires a full moon, a comfortablechair and binoculars
How do
we study migration?
BANDINGUS Fish and Wildlife Service BirdBanding 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
Why do birds migrate?
Migration is a strategy to take advantage of seasonally abundant food supplies
Weather and photo-period are triggers
SNOW BUNTING
DEC
JAN
FEB
MAR
APR
MAY
NOV
OCT
SEP
AUG
Anatomy of Flight
A fused sternum with a “keel” provides
the attachment points for the flight
muscles.
Route finding
Birds navigate by: visual landmarks, the sun, moon, stars, and routes learned from other birds
Birds also have an internal compass which issensitive to the Earth’s magnetic field
Migrating birds will maintain a true compass heading
MOON
LANDSCAPEFEATURES
SMELLS
WINDS
STARS
MAGNETICNORTH
SUNRISE
WEATHERUV LIGHT
SOUND
Fat is the currency of migration
Fat is the most important fuel for migration
Many species double their weight with fat fuel for migration
Shorebird Songbird Hawk
Typical Body Fat: PRE-MIGRATION
66% 70% 15%