Futures Project! About Bird Migration
Some birds, like song birds, change their behavior when migrating. Normally, active in the daytime, songbirds migrate at night. They fly all night and land at sunrise to rest and look for food.
Birds need to bulk up so they have the energy it takes to get where they are going...and some birds go a long way! They can lose 1/4 to 1/2 their body's weight during this time. Just imagine a poor songbird; they weigh less than 18 grams - about as much as three pennies!
The feather is one amazing piece of bird equipment. Lightweight, strong, adaptable, waterproof, streamlined - there is a feather for every need on a bird's body! It's thick, it's wet, most times it's noisy, it's green and it's teeming with life. The rain forest world is a paradise for bird life...and the numbers of species that call a rain forest home is astounding. For example, in Southern Peru a scientist found that when he stood in one place and "without taking a step" he could count more than 160 species of birds at one time! And in Ohio the forests are temperate, and they experience a different phenomenon...they have fewer species and higher numbers of each of those species.
Migration is triggered by sunlight...diminishing or increasing day length tips off the birds and they feel that urge to travel! Bird migration is one of the most fabulous phenomena in all of nature. It is the great global strategy for survival that shifts millions of birds across hemispheres twice each year. Scientists believe that the incentive underlying migration is food availability and that this behavior evolved as an adaptive strategy whereby birds could maximize their chances for survival by optimal utilization of food resources. The numbers of birds that use this traveling trick are tremendous. Of the 650 or so bird species that nest in North America, 338 of them, or more than half, migrate back and forth from the tropics each year.
The Wing's of the Americas Program protects birds at risk by protecting critical habitat throughout the Americas. One of the goals of the program is to protect important breeding and wintering habitats of migratory birds.
The Edge of Appalachia Preserve System is a magnificent natural system encompassing more than 12,000 acres in south central Ohio. This system harbors an exceptional array of plant and animal species and is a haven for an extraordinary amount of migratory birds. The Nature Conservancy owns and manages the Edge of Appalachia Preserve System in partnership with the Museum of Natural History & Science, a division of the Cincinnati Museum Center.
There are a couple of key differences between the avian diversity in these two ecosystems. For example, all birds have territories...places they stake out as their own. They know them, mark them and defend them from intruders of their own species. On average, tropical birds have territories that are about ten times the size of temperate forest birds' territories. But the diversity can remain very high since there is incredible overlapping of territories of different species. In general, the more structurally diverse the habitat, the more likely it is to contain a higher diversity of birds. That's because there are many more places to hide and find food in a diverse habitat. And there is no more diverse region in the world than the rain forests of Central and South America. Ornithologists estimate that over one third of all bird species live in these forests. And a diverse habitat provides myriad microhabitats, not just for birds, but for all the things they depend upon for food. There are more insects, fruits, flowers and seeds all year round in the tropics than anywhere else on Earth.
When you think of a rain forest, you may think of parrots and toucans, but you should also think of ruby-throated hummingbirds and sharp-shinned hawks and scarlet tanagers. These birds call the United States or Canada home for part of their year. It is pretty amazing to have two such different addresses. But, both of their addresses, and some campsites between them, are imperative for the health of many species of birds that they think of as their own.
What does a migration year look like?
Neotropical Migrants are bird species that breed in North America in the summer and migrate in the fall to Central or South America where they spend the winter.
Ohio covers over 41,000 sq. miles, most of which is used for residential, agricultural or industrial purposes. Where do the birds fit in? The beach is not just for sunbathing. Migrating shorebirds need a healthy shoreline ecosystem to meet their feeding and resting needs as they travel to it twice a year.
Let's look at the state of New Jersey and its rich migration pathway as an example: the initial fall migrants arrive just a few days after the first day of summer! There are certain shorebirds and sandpipers who breed very far north and have to travel over the equator and beyond. July sees the migration of other species of shorebirds. August includes songbirds on their way south. In September hawks and many other species increase the migration numbers to a high tide. October and November migrations include the waterfowl and seabirds. December urges the last remaining migrants. Even in January and February winter finches might be seen heading south just as the light begins to turn and the first north-bound birds pass in the sky. Hence, migration takes a while and the beginnings and endings actually overlap!
One benefit of this lengthy process is that birds can share key feeding and resting areas, because they are there at different times. When speaking of migration it is necessary to mention the all-time champion frequent flyer among birds. Arctic terns travel farther than any animal other on Earth; in fact, they spend more time migrating than doing anything else. Feeding on small animals in the cold, rich polar waters, these birds fly over 20,000 miles every year.
Most migratory bird species that breed in the Edge of Appalachia Preserve System spend the winter south of the U.S. Border. Migratory birds have three very important places in their small lives. They need nesting habitats, stopover habitats and wintering habitats. If any one of these pieces is lost to them, they are lost. The reason these areas are so essential is that habitat is the single most important need of migrating birds. All their needs are met in each specific habitat area.
But now the rules have changed. People have entered the scene in force, and each spring and fall migrating birds play a deadly game of "habitat musical chairs." Just as in the popular children's game, where in each round there is one less place to sit, each season there are less and less places for many birds to feed, rest and nest. For instance, when 20 acres of woodland are converted into 20 one-acre suburban lots, perhaps five species of birds will be able to live there, in the very same area where 65 species of woodland birds lived just one year before. And that's just on this end of the migratory path. In the tropical rain forests of Central and South America an even a greater diversity of birds are adversely effected every time a 20-acre section of forest is cleared. As a result, populations of many species that just 20 years ago were common have been shattered--reduced in many places to remnants, or memories.
However, even when all the natural elements are in place, migration is the most dangerous time for birds. For example, 60% of the songbirds hatched in spring fail to survive their first migration to make it to their first birthday; birds of prey experience even tougher odds. For example, only 25% of sharp-shinned hawks survive their first year.
Even with all the travails of migration, if there is food available, the bird is healthy, it escapes predation, there is a constant breeding ground, known stopover places, and a wintering ground intact, then this high-energy system of migration works as a highly elaborate and complex survival strategy.
Ruby-throated hummingbirds are tiny birds with huge jobs. They have to fly to find flowers, from which they feed on the nectar, and that means crossing large expanses of land and water during migration. Hummingbirds are the smallest birds in the world but possess the highest metabolism; they beat their wings 75 times per second in forward flight, and their tiny hearts reach upwards of 1000 beats per minute. The ruby-throated hummingbird nests throughout much of North America, from southern Canada to Florida and the Gulf Coast and all the states in between. But they overwinter in Central American forests, from Mexico to Costa Rica. Hence their name in Spanish, "Colobri de Paso," which means "hummingbird of the passage."
For these little birds to traverse thousands of miles twice a year is a Herculean accomplishment. But they don't migrate just for the flowers. Hummingbirds also eat small insects, spiders and even tree sap from holes drilled by sapsuckers. But they are most famous for their ability to hover in front of flowers while drinking as they fly. Their long, needle-like beaks cover even longer tongues which can be inserted deep into the throats of flowers to lap up the nectar. They even get their name, "humming-bird" due to this hovering capability. The hummers' wings move so quickly that they are impossible to see in flight and actually produce a soft humming, or buzzing, sound. In order to hover still in the air, hummingbirds have specially adapted muscles and tendons that allow their wings to rotate in a figure-eight motion rather than just going up and down as many birds' wings do. As a result, hummingbirds can get a double down stroke - one on each end of the figure-eight motion.
Hummingbirds are thought to have the fewest feathers of any bird, but they obviously use them very effectively since the annual transcontinental flights of ruby-throated hummingbirds are truly a miracle of migration.
Birds are the most ubiquitous symbols of nature and wildlife around us. No matter where you live, it is a safe bet that you can see birds right out your window every day of your life. But many bird species are in decline, and it is going to take a lot of us, with knowledge and commitment, to keep birds in their lives in the future. This concern began with birdwatching, and now it will take more than binoculars.
It took years for scientists to notice the decline in migratory birds. It took more years to piece together the causes. Now comes the next step. Now they have to take measures to stop the slide.
When habitats are at risk, the birds and wildlife that call them home are also in danger. In Ohio 90% of the wetlands have been destroyed, and the black tern, the prothonotary warbler and the little blue heron have been negatively effected by the shrinking. 95% of Ohio's of native prairies and the numbers of grasshopper sparrow, dickcissel and bobolink have declined as well. Though their woodlands have been increasing in the past decade, the diversity of these emerging forests is not as great as it originally was and such species as the golden-winged warbler, the cerulean warbler and the great crested flycatcher have felt the pressure of these habitat changes.
So, what's it going to take to save birds?
It takes a commitment in the private and the public sector to investigate the causes for the decline of bird species and to act upon ways to limit that decline. Research, increased awareness, and monitoring species are all proactive ways of showing commitment to avian diversity. However, the best way of showing this commitment is protecting habitat. In every state, they have to keep some wild places intact so that the birds can find them, whatever time of the year they are flying over.
Pete Dunne is one of the most renowned natural history writers in America. As Director of the Cape May Bird Observatory, he is a tireless organizer, advocate and communicator for the magic of wild areas.
It took a cloud of hawks on a September day in Pennsylvania to direct Pete Dunne's life to the beauty and the needs of birds the world around. Since that day when the fall migration captured his attention and his resolve, he has been spending his days observing, noting, and pointing out the wonders of birds and their specific requirements in a healthy, natural system. He spends much of his time on the eastern coast of the United States, in Cape May, New Jersey, writing and talking about birds and their needs. He also travels extensively to search, observe and understand the mysterious world of these animals that can lose gravity's grasp and fly away. The birds, the people who love them, and the world in which all of us live combine to influence this dedicated ornithologist and conservationist. His goal is a future that includes room for birds and the systems that support them.
"They are all part of a community on the planet. I would like a planet that has a lot more richness than what they are heading for right now. The idea of a stark planet doesn't appeal to me at all. I don't want to be the only show in town. I don't want to go outdoors and see nothing but other people. I want to see a lot of diversity. That's why I'm out there, to keep a lot of the elements of the mosaic." - Pete Dunne Ornithologist