Discovering Migration: What Birds Reveal
A snow-covered forest in winter can be a quiet place. In spring, however, this same spot is filled with the chirps, chatter, and calls of birds. Where do they go during the winter? In the past, people used to think that during the winter, birds slept in holes that they dug in the ground. Others thought they hid in the mud on the bottoms of ponds-alive, but waiting for spring. Others claimed that familiar summer birds transformed into other types of birds in the winter. The truth is, in some ways, more incredible. What birds do during this time is migrate: They fly over land and oceans without a roadmap or compass to destinations that are sometimes thousands of miles away.
Like marathon runners, birds pace themselves so they do not run out of energy before they can land. They are always adjusting speed, height, and flight path to account for changing winds, their own weight, and storms. In the spring, they retrace their paths back to their summer homes. Each fall, about five billion birds migrate south for the winter from North America. Nearly all 500 of the 650 species of North American birds migrate. Yet this is just one small part of the picture. More than half of all the bird species in the world-approximately 5,000 species-migrate, and each species is on a different journey.
Other animal species also migrate, including insects, amphibians, reptiles, fish, and mammals. Migration is happening all the time: Herds of wild beast arrive every January at green pastures in the southern Serengeti of Africa. Swarms of free tailed bats arrive each March to caves in Texas. Northern fur seals gather on Alaskan islands each June. In September, Chinook salmon swim up rivers in Washington State. If you are in the right place at the right time, you can witness these amazing journeys. Yet, no matter where you live, you can see some birds migrating. In fact, much of what we know about migration comes from studying birds.
Not all birds travel from north to south: Some travel east to west. White-winged scoters are diving ducks. They can stay underwater for up to a minute to grab shellfish from the ocean floor. In the summer, they live near ponds and lakes in Alaska and western Canada. In the fall, they fly to milder conditions on the Pacific and Atlantic coasts, where there is less snow. Other migrants do not travel very far for a big difference in climate. Instead of going north or south, they travel up and down. Mountain birds, such as brindled titmice and mountain chickadees, migrate about 1,000 feet to lower elevations. They move from high-altitude evergreen forests to wooded valleys and streams.
Even within a bird species, some birds may migrate while others do not. This is called partial migration. Robins are a sign of arrival of spring in Northern states, because they migrate south during the cold winter months. But some robins live year-round in the South. Some bird species migrate in one nonstop trip. Others stop along the way. Sea terns cannot rest for long on the water during their flights over oceans because they become waterlogged. For most birds, though, nonstop travel is unusual. It is much more common for birds to stop along the way to rest and refuel. Even a small cluster of bushes with berries can provide crucial energy for birds on the move. Birds may stay at stopover points for a few days or a few weeks, depending on how much energy they need.
They might also wait for better weather or wind conditions for the next leg of their journey. Some layover sites attract huge crowds of migratory birds. A 75-mile stretch of the Platte River in Nebraska is a gathering spot for up to nine million birds each spring. They stop to feed in the fertile wetlands along the river. Almost all of the world's sandhill cranes-numbering about 500,000-spend about six weeks on the Platte River. Mostly, they eat corn, which quickly adds fat and gets them ready for the rest of their migration. Once the cranes have fed and rested, they continue their northward migration to Canada, Alaska, and Siberia. Some birds take long perilous journeys to reach their destinations. Many duck species and water fowls travel from Siberia to Nepal to avoid cold.
The migrating birds may travel during the day, at night, or both. Ducks, geese, and swans travel during the day and at night. Some birds that travel during the day can feed while flying. Swallows and swifts, for example, feed on flying insects while they travel. In contrast, most songbirds feed and rest during the day and travel at night. It is thought that cooler and less windy conditions at night make for better flying. Hidden in the night sky, the birds are almost invisible-except for all the chattering. Only when songbirds pass in front of the moon they are visible. In fact, moon watching is a way of counting how many migrants travel at night. During migration season, a moon watcher may see as many as 200 birds an hour.
(Adapted from Animal Behaviour by Gretel H Schueller and Sheila K. Schueller)
A. Study the following word list and find their synonyms and antonyms as shown in the example. Write NA if the word does not have a synonym or antonym in the list.
Example:
Word | Synonym | Antonym |
witness | onlooker, viewer, bystander, spectator | participant |
Word | Synonym | Antonym |
transform | change, remodel, revamp | stagnate, hold on |
incredible | unbelievable, amazing, wonderful | credible, plausible |
roadmap | guideline, plan, direction | NA |
retrace | backtrack, recall, recollect | forget, reminisce |
grab | clutch, snatch, capture | free, liberate, release |
elevation | height, altitude | flat, level, lowness |
waterlogged | soaked, sodden | dehydrated, dry, arid |
refuel | refill, replenish, restock | deplete, exhaust |
cluster | array, bunch, clump | NA |
crucial | vital, fundamental | trivial, insignificant, unimportant |
perilous | risky, dangerous | harmless, precarious, terrifying |
B. Complete sentences (a-f) with their correct endings (i-vii).
Sentence | Correct Ending |
a. In the past people had the misconception that | iv. birds hid underground or changed into some other birds. |
b. To supply themselves with energy | ii. some birds stop to feed themselves with grains. |
c. When the weather is favourable in spring | iii. birds fly back to their habitats. |
d. As a sign of partial migration | i. some birds travel to a different place while others do not. |
e. To wait for favourable weather | v. some birds choose to fly during the night. |
f. For better flying conditions | vi. birds fly rapidly like marathon players. |
C. Answer these questions
a. What is incredible about the migration of birds? |
Answer: The incredible thing about bird migration is that they fly long distances without a roadmap or compass to reach their destinations. |
b. What things do birds consider while flying to their destinations? |
Answer: Birds consider factors such as changing winds, their own weight, and storms while flying to their destinations. |
c. Which animals other than the birds migrate to new places? |
Answer: Other animals that migrate to new places include insects, amphibians, reptiles, fish, and mammals. |
d. What do scoters dive underwater for? |
Answer: Scoters dive underwater to grab shellfish from the ocean floor. |
e. Which birds travel up and down instead of going north to south? |
Answer: Mountain birds, such as brindled-titmice and mountain-chickadees, travel up and down instead of going north to south. |
f. What is the partial migration of birds? |
Answer: Partial migration of birds refers to the phenomenon where some birds of a species migrate to different places while others do not. |
g. Why can sea terns not stay long in water? |
Answer: Sea terns cannot stay long in water because they become waterlogged, making it difficult for them to continue flying. |
h. How do birds feed themselves during their journeys? |
Answer: Birds feed themselves during their journeys by stopping at locations with food sources, such as clusters of bushes with berries, to rest and refuel. |
i. What are the signs of birds flying in the night sky? |
Answer: The signs of birds flying in the night sky include their chattering and visibility when passing in front of the moon. |
Word Meaning
Word + Phonetic Transcription |
chirps /tʃɜːrps/ |
tweets, trills |
High-pitched bird sounds |
chatter /ˈtʃætər/ |
prattle, babble |
Rapid and continuous talking or noise |
transformed /trænsˈfɔːrmd/ |
changed, converted |
Underwent a significant change or conversion |
incredible /ɪnˈkrɛdəbl/ |
unbelievable, amazing |
Extremely difficult to believe or amazing |
roadmap /ˈroʊdˌmæp/ |
plan, guide |
Detailed plan or guide for a journey |
destinations /ˌdɛstəˈneɪʃənz/ |
locations, endpoints |
Places where birds travel to |
pace /peɪs/ |
stride, rhythm |
The speed or rate at which something is done |
account-for /əˈkaʊnt fɔːr/ |
explain, justify |
Provide an explanation or justification for something |
retrace /riˈtreɪs/ |
backtrack, revisit |
Go back along a path that has been previously traveled |
fall /fɔːl/ |
autumn, descend |
The season between summer and winter |
amphibians /æmˈfɪbiənz/ |
frogs, salamanders |
Cold-blooded vertebrate animals that live both on land and in water |
reptiles /ˈrɛptaɪlz/ |
snakes, turtles |
Cold-blooded vertebrate animals with scaly skin and laying hard-shelled eggs |
swarms /swɔːrmz/ |
groups, masses |
Large groups of insects or animals moving together |
free tailed /friː teɪld/ |
bats |
Bats that have a long, slender tail that extends beyond the tail membrane |
fur seals /fɜr siːlz/ |
sea lions |
Marine mammals with thick fur and external ear flaps |
Chinook salmon /tʃɪˈnʊk ˈsæmən/ |
fish |
A type of salmon found in the Pacific Ocean and rivers of North America |
brindled-titmice /ˈbrɪndl̩d ˈtaɪtmɑɪs/ |
birds |
Small birds with mottled or streaked plumage |
mountain-chickadees /ˈmaʊntən ˈtʃɪkəˌdiːz/ |
birds |
Small birds found in mountainous regions |
stopover /ˈstɑːpoʊvər/ |
layover, rest stop |
A temporary stay or break during a journey |
layover /ˈleɪoʊvər/ |
stopover, rest period |
A period of rest or waiting during a journey |
perilous /ˈpɛrələs/ |
dangerous, risky |
Full of danger or risk |
Extra Questions to Practice
Expandable FAQ Section
How do birds adjust their flight during migration?
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Birds adjust their speed, height, and flight path based on changing winds, their weight, and storms.
How many bird species migrate from North America in the fall?
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Nearly all 500 out of 650 bird species in North America migrate.
What are some other animal species that migrate?
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Insects, amphibians, reptiles, fish, and mammals also migrate.
Where do northern fur seals gather each June?
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Northern fur seals gather on Alaskan islands.
Why do birds make stopovers during migration?
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Birds make stopovers to rest and refuel with energy.
What is an example of a large gathering spot for migratory birds?
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The Platte River in Nebraska attracts millions of birds during spring migration.
How do swallows and swifts feed during migration?
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Swallows and swifts feed on flying insects while they travel.
What is partial migration?
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Partial migration means that only some individuals of a bird species migrate while others do not.
What is the significance of moon watching during migration?
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Moon watching helps count the number of birds migrating at night.
Where do White-winged scoters live in the summer and fall?
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White-winged scoters live near ponds and lakes in Alaska and western Canada in the summer and fly to milder conditions on the Pacific and Atlantic coasts in the fall.
How do mountain birds migrate?
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Mountain birds migrate from high-altitude evergreen forests to wooded valleys and streams.
What is the main source of food for sandhill cranes during migration?
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Sandhill cranes eat corn along the Platte River, which helps them prepare for the rest of their migration.
Do all migrating birds travel from north to south?
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No, some birds travel from east to west or travel up and down instead of north or south.
How long can diving ducks stay underwater?
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Diving ducks like White-winged scoters can stay underwater for up to a minute.
How many birds can a moon watcher see during migration season?
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A moon watcher can see as many as 200 birds per hour during migration season.
How far do some birds migrate during their journeys?
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Some birds travel thousands of miles during migration.
Why do birds make adjustments in their flight during migration?
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Birds adjust their flight to cope with changing weather conditions and conserve energy.
Why do birds migrate from high-altitude forests to lower elevations?
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Birds migrate to lower elevations to find milder climates and easier access to food.
How do birds know when and where to migrate?
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Birds use environmental cues such as day length and changes in food availability to determine when and where to migrate.
What are some challenges that migrating birds face during their journeys?
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Migrating birds face risks such as exhaustion, adverse weather, and the need to find suitable stopover sites for rest and refueling.
How far can some birds travel during migration?
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Some birds can travel incredibly long distances, spanning thousands of miles during their migration journeys.
Why is the Platte River important for migratory birds?
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The Platte River holds great importance for migratory birds as it provides fertile wetlands where they can rest and feed.