Spring will be here soon (hopefully) and with it will come our beautiful and amazing migratory birds. Have you ever wondered where they spend our winter months? And why do they migrate, while other birds stay put?
Birds migrate to move from areas of low or decreasing resources to areas of high or increasing resources. Food and nesting locations are their biggest calling cards for spring migration. Exploding insect populations, budding plants and lots of room bring the birds north.
Our permanent, non-migratory birds are much less dependent on insects in their diets, so they can stay in place. Northern Cardinals, Black-capped Chickadees, White-breasted Nuthatches, most of our woodpeckers and others are adapted to the food supplies available year-round. They must endure harsh conditions, but don’t face the perils of long journeys.
Many of the birds that arrive here in early spring didn’t travel far. American Robins and Eastern Bluebirds may not have gone any further south than Southern Iowa.
Other birds, like Killdeer, House Wrens, Brown Thrashers and many of our native sparrows spend winter in the Southern United States.
Neotropical birds are the champions of long distance flight. They’re called “Neotropical” because they live in the tropics except when they migrate north for their breeding season.
When they come to our area, some will come to our feeders or water features, some will stay here, but many will pass through to the boreal forest or even the tundra north of us to breed.
Neotropical birds fly thousands of miles every year. It’s estimated that 350 species of birds follow migration paths north from the West Indies, Mexico and Central and South America. (And of course, return south in the fall.)
Almost all songbirds migrate at night. There are a number of reasons they do this. There are fewer predators (hawks don’t fly at night.) The air is calmer and cooler. Less turbulence makes for easier flying, and birds in sustained flight generate a lot of heat.
How do birds know when to migrate? Much mystery still remains, but generally it’s thought that the change in the length of daylight hours triggers hormonal changes. For about three weeks before they leave, they eat voraciously.
Some species will gain fat equal to as much as forty percent of their original weight. And, they’ll need it! They’ll fly from five-hundred to over a thousand miles across open water, with no place to stop.
Storms or strong headwinds may spell disaster for them over the ocean. Over land, the weather may force them down, delaying their arrival. Thousands of birds may descend in relatively small areas, appropriately called “fall outs”.
How do they navigate? Another real mystery. Stars? Earth’s magnetic field? Land marks? (Not too many of them in the Gulf of Mexico.) Inborn navigation systems? Maybe it’s a combination of many things.
I can’t talk about where all our wonderful neotropical birds come from, but I’ll highlight a few.
Baltimore Orioles come to us from the West Indies, Southern Mexico and all the way from northern South America. When they arrive, they will be looking for orange halves and grape jelly.
Rose-breasted Grosbeaks come to us from Southern Mexico down to NW South America. Rose-breasted Grosbeaks love Nurta-Saff or regular safflower seed when they get here from their long journey. They will use both flat feeders and tube feeders with a tray.
Indigo Buntings winter in the West Indies, Central America and Northern Bolivia. These beautiful birds will be looking for nyjer seed and/or white millet. Present it in a tray feeder as they are not very good at getting it out of finch feeders yet.
Most of our tiny warblers migrate from the West Indies, Central and South America. Warblers LOVE moving water so be sure to have yours up and running when they arrive.
A very common, but not much noted, neotropical bird in Iowa is the Barn Swallow. This aerial acrobat makes its way from Central and South America. Barn Swallows eat insects so they are not attracted to our feeders.
Its cousin, the Purple Martin, goes even farther south, to South American all the way to Brazil. Purple Martins feed on insects. If you want them to set up housekeeping in your neighborhood, have their house open and ready to go when the scouts arrive. Typically, they arrive in our area between April 15th and May 1st.
Of course, I can’t leave out our most amazing migrant, the Ruby-throated Hummingbird. It may not fly the farthest, but it does fly 500-800 miles across the Gulf of Mexico from its homes in Mexico and Central America. (And remember that’s twice a year.) Considering that it weighs less than a nickel, I find that an almost unbelievable feat! When the hummingbirds arrive from their incredible journey, they are ready for some hummingbird nectar in a pretty red hummingbird feeder. Be sure to keep it fresh, old nectar is harmful to hummingbirds.
I hope this adds a bit of awe and wonder to the joy you feel when our beautiful neotropical birds return. Have you feeders and water features ready for them, they’ve just made an incredible journey!
Most neotropical birds begin arriving end of April, first part of May. Be ready for them, because after they’ve been here awhile, they are harder to attract.
View the Ruby-throated Hummingbird Migration here:
Watch the Purple Martin migration map here: www.purplemartin.org/research/
The website: www.learner.org/jnorth has migration maps for various bird species including Baltimore Orioles, Robins, Barn Swallows, Red-winged Blackbirds. It has other interesting migration maps of when the frogs start singing and when the Monarchs begin migrating as well.
More information about the routes of the neotropical bird migration can be found here:
Enjoy Your Birds!
Ellen S. Montgomery