Why Do Birds Migrate?

Can’t you just picture it? A little bird in its hammock swinging in the tropical breeze while it sips a pina colada. Now why on earth would that silly bird want to leave such a beautiful, warm place; exhaust itself flying thousands of miles in some instances to get back to the cold springtime of the northern climes? What is it, crazy?

Scarlet Tanager spends its winters in South America and comes back up north to breed
Scarlet Tanager spends its winters in South America and comes back up north to breed | Source

Actually there are many valid reasons for leaving 'home' when it comes time to breed.

It's not all sun, sand and tropical fruit. Birds have to compete with year round residents that have adapted to their own environment. The native birds know the best food sources, and they guard them with great zeal. They are also keenly aware of their territory and the best nesting sites. Strangers are quickly and vehemently dispatched from those areas!

The warmer the environment, the more likely it will harbor abundant parasites and nasty diseases that might harm the un-naturalized northern visitors should they opt to stay rather than migrate northward.

Birds' immune systems can quickly become overwhelmed and compromised when exposed to foreign infectious bacteria and viruses. Because they do not live in the warmer climates all year, immunity becomes an issue.

Rose Breasted Grosbeak arrives up north in early May
Rose Breasted Grosbeak arrives up north in early May | Source

They come home just in time for the insect and plant population explosion. Birds migrating north in spring arrive at the exact right time. Everything is beginning to sprout and turn green. That means that the bugs are happily staking their claims to all of this abundance. Protein in the form of insects and creepy crawlers is necessary for strong, fast growth of baby birds. Timing, as they say, is everything!

Baby Robins in nest
Baby Robins in nest | Source

Heat is the enemy of baby birds. That's why mama bird can leave the nest to forage for food. She will turn the eggs at least once every day to make sure they are kept at a constant temperature. Northern birds have adapted to springtime temperature swings.

Mama bird has a 'brood patch'. That is a spot on her breast without thick feathers. She places the brood patch over the eggs to sense whether or not they need warming. If so, she dutifully keeps them covered and warm until the eggs have the necessary heat to maintain the young growing inside.


Eastern  Kingbird
Eastern Kingbird | Source

Daylight gradually increases so that foraging for food becomes easier. Southern climates have the same daylight hours most all season. The further north you go, the longer the days become in summertime. Also, different plants bloom at different times, Along with these varied flowers, seeds, nuts and berries come the insects that use the plants as hosts and food for their larvae. The amount and variety of food available helps our backyard birds to thrive.


So how do our feathered friends know when its time to leave?

1. The length of daylight hours triggers a release of certain hormones that tell a bird's body "it's time to store fat for a long journey".

2. Growing new more streamlined feathers helps to cut down on drag and improve aerodynamics while flying long distances.

3. Because natural predators like hawks are much less likely to hunt at night, songbirds use the nighttime hours for a safer flight.

4. Flying at high, cooler altitudes helps keep them from overheating from their constant exertion. They will also encounter tailwinds to help them 'coast' and glide, allowing for rest periods while in flight.

American Robin migrates only short distances as a rule
American Robin migrates only short distances as a rule | Source

Robins generally migrate from dozens of miles up to a thousand miles away from their summer breeding grounds.

Depending upon the season, not all birds migrate that far from where they were born and raised. Sometimes they go no further than a couple of states away, just to find a warmer climate. It doesn’t have to be tropical.

Still other birds fly all the way from the frigid arctic southward in search of food and relief from the bitter cold.

Varied Thrush migrates from east to west and back again.
Varied Thrush migrates from east to west and back again. | Source

Birds like the Varied Thrush migrate East to West. This robin-like bird is native to the Pacific Northwest, but spends its winters in the midwestern states. It aggressively defends its territory by turning its back on an intruder and lifting its tail up!

Click here to listen to it's strange buzzing call.


Black Capped chickadee dining on sunflower seeds.
Black Capped chickadee dining on sunflower seeds. | Source

My chickadees here in the northeast choose to stay all winter long. I welcome their cheery, friendly behavior. Whenever I add new foods to the bird feeder, they are the first to investigate!

Still other chickadees migrate from east to west and back again.

Chickadees readily accept manmade bird houses as long as the entrance hole is 1-1/4" to 1-1/2" in diameter.

Catbirds are fond of taking many baths!  This one found a puddle after a summer rain shower.
Catbirds are fond of taking many baths! This one found a puddle after a summer rain shower. | Source

Catbirds migrate from the southern states northward to Pennsylvania and into New England in early summer.

Once in awhile there is what is called an irruption. That is defined as a bird population arriving in a completely different habitat than it normally prefers

This happened recently with a large flock ofsnowy owls, whose 'home' is in the frozen arctic.

Snowy Owl Irruption

Pair of Canada Geese navigating by the sun
Pair of Canada Geese navigating by the sun | Source

How do they navigate?

Most birds migrate in the spring and the fall. They use the stars, moon and/or sun to help them find their way. Migratory birds have built-in magnetic receptors that help them orient their flight plan to the magnetic impulses emanating from the earth.

Other birds follow flyways that have been established over milennia, and which have also been genetically programmed into their behavior. Some travel long-established migratory routes and can recognize geological landmarks.

Still others of our feathered friends use the sun and/or stars by which to find their way to and from their destinations. Don’t let that little tiny brain fool you. It is jam-packed with all kinds of built-in survival tactics, the extent of which I suspect we are just now learning about.

North American Migration Flyways

North American Migration Flyways
North American Migration Flyways | Source

There are hazards along the way. The excessive light from cities distorts their star navigation abilities. Sadly some become disoriented and lost. Storms and bad weather account for more fatalities, blowing birds off course. They can lose their way and perish.

Of course, predators of the 4-legged variety such as wild dogs, cats and others are always a threat, as well as hunters.

Collisions with high buildings, windows, wind turbines, aircraft and vehicles account for a very large percentage of unsuccessful migration treks.

Because our human habitat is constantly expanding, what once was a great stopover for exhausted, hungry birds in some cases has turned into a housing development. Unable to find adequate food and water accounts for another high mortality rate in birds trying to get home.

Researchers continue to tag and monitor migrating birds to study their routes and the dangers they may face along the way.

It is estimated that a staggering ONE BILLION birds never complete their journeys. A sad fact that thankfully is being addressed by some larger cities and universities. Research continues to help our little flyers have a better chance to ‘make it back home’.

There is hope. The links below will take you to some of the many sites detailing the newest programs and radar systems being tested and implemented to make bird migration safer. Their goal is to find ways to prevent these needless and tragically high bird mortality rates.


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Were You Aware That So Many Birds Never Make It Home? 10 comments

JKenny profile image

JKenny 4 years ago from Birmingham, England

Great article, grandmapearl. Really enjoyed reading that. I like the look of the Varied Thrush, wish we had them in the UK and the Black Capped Chickadee looks very similar to a bird over here, called the Marsh Tit. Great work.


grandmapearl profile image

grandmapearl 4 years ago from Southern Tier New York State Author

Thank you so much JKenny. I'm very glad you enjoyed this Hub. The Varied Thrush is a beautiful bird. Is your Marsh Tit a friendly, busy bird like our Chickadee? This year since our winter has been so mild and dry, these little guys are already gathering nesting material!


rsusan profile image

rsusan 4 years ago from South Africa

Interesting hub, Connie! We can see that our swallows are preparing to leave yet again. But they will be back come Spring. It always amazes me that these tiny birds can travel such a long way. And then manage to find their way back to the exact same spot without fail. Nature sure is wonderful.

Rika


grandmapearl profile image

grandmapearl 4 years ago from Southern Tier New York State Author

Hi Rika, So glad you stopped by and enjoyed this Hub. It's always good to hear from you! I know when I hear the first robins of spring I am delighted. They don't usually travel very far away from here, but they herald a new beginning and all things green and warm. Your comments are very much appreciated!


Nell Rose profile image

Nell Rose 4 years ago from England

Hi, great hub, really interesting! I never even thought about the heat affecting them, and of course virus's etc, so I learned so much from this! and I had a quick peek at your bird site, really lovely, cheers nell


grandmapearl profile image

grandmapearl 4 years ago from Southern Tier New York State Author

Thank you Nell. You just made my day! I really appreciate your great comments and clicking through to my website. I'm always glad to see your smiling face!


aviannovice profile image

aviannovice 4 years ago from Stillwater, OK

Connie, this is a wonderful and very clear hub. Voted useful and up. I enjoy birds as much as you do by photographing them daily and writing about them weekly. Will be following you, too.


grandmapearl profile image

grandmapearl 4 years ago from Southern Tier New York State Author

aviannovice, so glad you stopped by! Thank you for your great comments and votes. Coincidentally, I just bought a bridge camera so I can take much better pictures of my backyard birds. I may ask for some advice on taking good photos!


Sylvia 3 years ago

Grandma Pearl, your information about birds is just what hubby and I need. We've somehow got a habbitat for chickadees and cardinals and others. We keep a bath and a small water fountain full of fresh water and different places for food. It's so much fun to watch those sweet little things. They sing and play and even fight sometimes. Anyway...thanks for passing on the informative story of birds.


grandmapearl profile image

grandmapearl 3 years ago from Southern Tier New York State Author

Hi Sylvia! I'm so glad you stopped by and enjoyed this article. Good for you for making a great place for your backyard birds to eat, drink and be birds! I am pleased when I hear that people like you care enough to help our songbirds to survive. You are very welcome. Stop by anytime!

Pearl

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