Fall Bird Migration In The Yard

Now that Fall is upon us, you will notice a lot of changes in the birds visiting your yard.   Fall treesSome of these changes you’ve already noticed no doubt – like the disappearance of summer birds such as swallows, orioles, and grosbeaks – to name a few.  Depending on what part of the continent you live in, hummingbirds may be gone as well.

One reason for these changes is that nesting season is over, and birds leave the territories they staked out in the spring to keep rivals out.  This is also driven by changes in food availability.   By later in September, a lot of insect populations have either fallen way off or ended altogether.  And many birds shift their diets over to natural foods such as berries and seeds, which typically ripen in the late summer or fall.  This can cause birds to not show up at feeders as much.

But, another big trend in backyard bird populations now is driven by migration.  Many birds leave areas where they nested and head either south, or sometimes just to lower elevations where weather is milder and food is more available.  This shift can sometimes cover a few hundred miles or many thousands of miles.  Here are a few examples…

1.  Goldfinches typically move hundreds of miles southward into ranges where there may be less snow and weed seeds are easier to find.  So, birds from say, Missouri may appear in Texas during the fall (a state where goldfinches are not found in the summer).  Conversely, goldfinches from Ontario may winter in Ohio or Michigan for example.

2.  Purple Martins, the largest members of the swallow family will breed in a range extending from northern Michigan all the way to the Gulf Coast.  But, they leave these areas starting in August and migrate to spend winters in central Brazil.

3.  The king of all migrating birds, the Arctic Tern, (not exactly a backyard bird I realize!) leaves it’s summer nesting area in the Arctic and flies tens of thousands of miles to the waters of Antarctica!

In general, birds with specific diets that don’t adapt or change with the season, must migrate much further (usually to the southern hemisphere where the seasons are the reverse of those up in North America) than other more adaptable birds.  Birds that have 100% insect diets (like swallows) are good examples of this migration behavior.

So, getting back to your yard, if you keep a watchful eye, you are likely to see numbers of migrating birds coming through your habitat from now thru October/November.  These are usually birds that summer further north, but could also be “local-yokels”.    Warblers and sparrows are two groups of birds that are common migrants.  Most warblers winter in Central and South American, but some are found in the deep southern states all winter.  Sparrows generally winter further south in their range.  For example, song sparrows leave the far northern states, but can often be found in Ohio and Indiana.  In the west, Fox Sparrows are commonly seen in fall and winter, but not as much in the breeding season.

Some migrants will be attracted to bird feeders and birdbaths to stock up on fuel for the long trip south.  This is a good reason to keep them filled with fresh birdseed and water.  Other non-seeding eating birds will dine on fruit and seed bearing bushes and plants, or try to find the few remaining insects.  So, it pays to keep your binoculars handy this time of year.

Finally, in all areas, there are some birds that don’t migrate at all.  They are most often seed eating birds or scavengers/predators like hawks, crows, jays, certain gulls, and owls.   In the southern and temperate coastal areas, there are usually more year-round species.

One way to learn about the marvel of bird migration is took look at the range maps in your bird field guide.  These show approximately where each species breeds, and then spends the winter months.  This will give you insights into the behaviors and habits of each bird in your yard, and when you might see them again.

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Cornell Lab of Ornithology