As summer draws to a close, and as fall is opening, so is the opportunity for birds, butterflies, and other migrant travelers to leave their summer digs and jump on the bandwagon to set off for distant shores.
We humans operate off a schedule set way in advance. We know when we’ll be able to extend a vacation by virtue of a holiday and, thanks to excellent weather reporting, we have pretty good knowledge of what the weather conditions will be like at our destination. But how do birds, butterflies, and other migrants know it’s time to go, and how do they survive until they get to Shangri-La where they’ll winter over? How do they know how to get there? What do they do along the way?
All sorts of clues tell birds when it’s time to fly. With Monarch butterflies, it’s generally the “children of August” that make the up to 2,500-mile-long migration to the forests in central Mexico where the east coast migrants winter over. Thought is that the milkweed they feed on is very, very mature, rather different from its spring chemical composition; the different chemicals the caterpillars absorb push the adult into diapause, a non-breeding state. Since they won’t breed until after a vacation in a warm spot, they take off to find their warm home.
From shorter days in the late summer/fall to ambient temperatures, the clues pile up for birds and other migrants. Somehow or other, shorter days, cooler temperatures, chemicals, whatever – the birds and butterflies just know. It’s time. Time to take to wing and fly with all the might that can be mustered.
Even more amazing, they seem to know the routes ahead of time. There are actually four major bird migratory routes in the USA. How do they know which one they should use? Still a mystery, but they manage, year after year.
Here on the Eastern Shore, we know we will find hordes of geese arriving in incredibly noisy flocks. Ospreys, who begin their migrations – first parents, then fledglings – in August/September, are a harbinger of summer when they arrive and the death knell of summer when they disappear. Bald Eagles, many of whom moved north after the kids fledged, return for the great fishing the Bay offers, perhaps planning their family, which will break egg sometime in January, perhaps early February. Meanwhile, nests are built and plans are made.
At least 500 different bird species will migrate the up to 3,000-mile-long flyway through the Eastern Shore. Beginning, for some species, in Greenland, the Appalachian Mountains and coastal wetlands are guideposts for these vigorous flyers. Some stalwart species even fly over the open ocean, dropping back to land to feed and rest. The Blackpoll Warbler, Bobolink, Yellow and Black-billed Cuckoos, Connecticut and Cape May Warblers, Bicknell’s Thrush, and American Golden-Plover are known to fly across the open ocean unless storms force them inland. Perhaps it’s safer. No predators. No pathogens. No tall buildings with spooky windows. It’s great, just don’t take a nap.
Many, many flyers are all following similar paths south (fall) or north (spring). Red Knots are marathon flyers, achieving 25,000 miles by the time they’ve gone south and north. Go, Red Knots! Meanwhile, the Broad Winged Hawk, one of the rare raptors (birds of prey) that fulfills a complete migration, follows the mountains, utilizing updrafts and thermals created by the changes of elevation.
For
Monarch butterflies, it’s an even stranger picture. Birds may live for several years, and it’s possible they learn the routes from others of their kind, but for Monarchs, the migration is undertaken alone, without guidance from elders. Still, our Monarchs find their way, flying high, so high they’ve been spotted from airplanes. These super-flyers will leave diapause, and begin their reproductive process, after wintering over in Mexico. Come spring they leave their Oyamel fir trees near Mexico City and fly to southern locations, where they will breed. Their children will fly further north, stopping to breed in milkweeds along the way. Finally, in August, they will start the long, long migration to an Oyamel fir just for them.
Unsurprisingly, many don’t make it to their final destination. Whether from dehydration, starvation, storms, exhaustion or even – let’s hope not – getting lost, only the fittest – or maybe luckiest – will make it to the promised land.
Can we plant our yards to create ideal conditions for migrants? Absolutely!
Monarchs, despite their lower metabolism during migration, still need nectar to boost their reserves to fly. Whatever you can do to ensure there are lots of non-GMO or treated, joyously blooming flowers for their feeding will help enormously. Many “weeds” are, in fact, prolific bloomers during the migration period. If you can manage a wild area where milkweeds, goldenrods, horsetails, thistles, etc. can live in peace, you’ll help those struggling flyers. We can place juicy fruit out floating in bird baths or on raised surfaces to entice tired, thirsty, and hungry butterflies. If you do this, make sure the fruit is organic – let’s not poison them – and that the fruit is raised high enough to discourage other fruit lovers, like rats, raccoons, and groundhogs. Or place it out in daytime hours, when butterflies will find it, and take it in when the sun goes down.
Birds, being made of sterner stuff than butterflies, need more “oomph.” Insect eaters love grasshoppers, crickets, beetles, larvae, and moths, while hummingbirds, like the Monarchs, are interested in energy (migration time in spring/fall is a great time to put out a hummingbird feeder). Other insect eaters and hummingbirds are thrilled beyond measure by spider webs – they can munch on the poor spider’s bounty and…oh, well…the spiders themselves. Bark can be full of overwintering insects (some of which will survive, and feed winter birds as well as spring migrants/nesting birds).
Many grasses, shrubs and some trees have wonderfully filling and nutritious berries and seeds for migrating birds. Viburnums, blackberries, sunflowers, elderberries, serviceberries, even pines (seeds), birches, sumacs, pokeweed, and many grass varieties provide sustenance to these busy creatures. This is not, of course, an exhaustive list of worthwhile plants.
Like it or not, those horrible “weeds” are frequently the best attractant for the protein-rich insects, grasshoppers, crickets, leaf hoppers, etc. that will result in a strong, capable, ready-for-anything bird at the end of its journey.
Go long, nature gardeners. Mother Nature salutes you.
Maureen Rice is a naturalist/gardener living in Talbot County. She is the author of “Not! Your Granny’s Garden.” Email notyourgrannysgarden@explodingcoder.com to receive the blog straight to your inbox.
Bird Migration: Look for bird migratory paths here:
Real Time: Bird Migration Explorer, Audubon Society
Learn About: Flyways of the Americas, Audubon Society
Monarchs: Read about Monarch migration here:
Monarch Joint Venture
https://monarchjointventure.org/monarch-biology/monarch-migration