Photograph by Klaus Nigge, National Geographic Stock
Published August 30, 2013
People have pondered the question for centuries: How do migrating birds find their way between far-flung breeding and wintering grounds? Do they have some genetic GPS to steer them along time-honored routes? Or do they learn the way from parents or elders in the flocks?
New research shows that, at least in the case of whooping cranes, the birds do learn the route from their older and more experienced companions—and all of them get better at navigating with age and experience.
Flying groups that include a migration-savvy, seven-year-old crane veer off-course 38 percent less than groups in which the oldest birds are only a year old, according to an eight-year study of whooper migration between Wisconsin and Florida. On average, the one-year-olds that don't follow older birds veer off the flight path by 60 miles (97 kilometers).
But the cranes' migration ability improves steadily with age, the study shows. Groups with even one of these older birds deviate less than 40 miles (64 kilometers), on average, from the most efficient route.
Other likely variables for navigation success, including gender and the size of flying groups, appeared to make no difference in the results. University of Maryland ecologist Thomas Mueller, a co-author of the study, and his team theorized that the older birds recognize landmarks better and may also know how best to cope with bad weather—two skills they apparently pass on to the young birds that follow their lead.
"As the oldest bird in the flying group gets older, it seems that there's dramatic improvement in its migratory efficiency for about the first five years," Mueller said. "There is a very big difference if the oldest bird in a flying group is one or two years old or if it's five or six or seven years old. A bird can be pretty young and still have great success," he added, "as long as it flies with a bird that is pretty old."
Detailed whooper migration data is a silver lining to a near-tragedy. America's whooping cranes were within a whisper of extinction during the mid-20th century, when as few as 16 individuals survived. Only a large-scale, international captive breeding and conservation effort enabled the species to survive—and ultimately made this discovery possible.
Mueller and colleagues took advantage of eight years of detailed migration data compiled on birds bred in captivity and released in Wisconsin's Necedah National Wildlife Refuge for a journey to their Florida breeding grounds. (Related: National Geographic Explorers: Tracking Migration of Dragonflies, Sparrows, and Bees.)
Previous studies have suggested that learning plays some role among migrating species.
"What's new here, I think, is that this shows learning takes place over so many years and that these older birds are crucial to the younger birds," Mueller explained. "That was difficult to look at before because the data simply didn't exist. Usually tracking data on animals lasts for a year or two years if you're lucky."
As part of unprecedented efforts to save and reintroduce the endangered North American whooping crane (Grus americana), scientists collected data to gauge the success of breeding, training, and the birds' subsequent 1,300-mile (2,100-kilometer) migrations. Individual birds were identified and tracked with satellite transmitters, radiotelemetry, and human observers.
"Usually you don't even know if a bird is two or three or four years old," Mueller continued. "There are lots of [previous] comparisons between juveniles and adults, but here we had the full progression of many years as well as the information of how old the birds were, how they were related to one another, and exactly where and when they migrated."
What Does This Mean?
The whooping crane research is important new evidence showing how bird migration is, at least in part, a learned skill. But it won't put to rest the long-running debate on the respective roles played by genetics and social learning.
In fact, Mueller said, the study suggests an interesting combination of genetics and learned behavior at work. It begins when the time comes for the cranes' first fall flight to their southern wintering grounds and the captive-bred animals are actually guided by humans who fly ultralight aircraft all the way to Florida. (Related video: "Rare Cranes Taught to Migrate.")
"If you think about even that initial migration, it needs to be at least somewhat learned," he explained. "They may have a natural tendency to migrate in the fall, but we don't think many would get anywhere where they could survive without some training."
But genetics do begin to play a more easily visible role on the return trip, he added.
"Then after they've been shown the route once, in the spring they know it's time to initiate a return and there's a genetic component in play there. Because nobody has showed them this, so it's genetics combined with the learned knowledge from the trip south in the fall." (Related: "Secrets of Whale Shark Migration Revealed.")
Co-author Sarah Converse, a research scientist with the U.S. Geological Survey's Patuxent Wildlife Research Center, has worked extensively with the Whooping Crane Eastern Partnership, which runs the eastern migratory population reintroduction program.
She said the current challenge of the reintroduction is poor breeding success—but the study suggests the possibility of future improvement.
"Our results suggest that an effort to restore whooping crane populations isn't just an effort to restore a biological population, but also an effort to restore a culture, where knowledge is transmitted across generations via learning, rather than genetics," she said.
"We can imagine that the low breeding success that we are currently struggling with in this reintroduced population might actually improve over time, with increased experience and learning of appropriate breeding behaviors. For example, maybe chicks learn from their parents how to themselves be successful parents. Overall, these results suggest that patience may well be important if we hope to restore migratory whooping cranes to eastern North America."
The research was published August 30 in the journal Science.
this is a shot in the dark but i wish to know if anyone is interested to collaborate with me and my son on a poetry book on animals, birds and marine life. We need strong visuals to go with each poem. the effort is to promote conservation and the welfare of their lives as ours depends upon it. please get back if anyone is interested and we can share some poems so you know how good and how serious we are.
one example is here so you have an idea of what i am talking about.
Claws and talons,
Feathers and fluff;
Birds are made of
Sharpness of razors
And softness of down;
They may never smile
But they cannot
Destined to soar
Beyond our ken,
They live in a world
Who always excel
In bringing you down;
They can’t let you fly,
So you leave
But birds are unfettered,
Unbridled little things,
As God gave them purpose
So did He give
I wish I was like them
And look up with awe,
As birds of a feather
Raja Changez Sultan
The Whooping Cranes are national treasures. Unfortunately ignorance and plain stupidity have severely impacted their chances for survival outside of their current established strongholds. The USFWS and other agencies have been trying to establish additional populations in the birds former Louisiana haunts, only to find several animals indiscriminately shot by ignorant locals. Perhaps education efforts in local schools and other areas may help in preventing avoidable mortality in the future, so that Whoopers can reach and old age and teach their compatriots the ways of the world.
One of the world's longest crane species
lives in eastern China, where most crane species live, and is currently
threatened by increasing development and habitat loss. The town of
Xianghai is located along the flying paths of this species.
To raise people's awareness of protecting the environment of their homeland, Xianghai School’s art teacher and her students planned to draw a mural on a wall in town. But first, they surveyed members of the community, shopkeepers, restaurant managers, and collected their various responses. The children walked into the town government hopeful and with proactive ideas, but...
Their teacher encouraged them to depict their experiences and feelings on the mural.
I live not four miles from the Migration flight training enclosure in the White River Marsh in central Wisconsin. I took pictures of two Whopping cranes on August 1st from the class of 2012 that returned from Florida in April of 2013. They where 4-12 and 5-12. When I first saw them I thought they where albino Sand Hill Cranes because they where with about 10 Sand Hills. When putting the picture on my PC I seen the bands that where on the legs. I then reported the sighting and was contacted and told they where from the class of 2012 and give their numbers.
The young animals are tend to explore their environment, which is crucial for the surviving and expending of the species. As they are aging, they learned and are used to the optimal ways they found. However, sometimes this process is devastating to individuals.
In most animals (mammals and likely larger birds) the mother keeps the young around through the first maternity, birth and rearing of young. An older sibling (usually a male) thereafter takes care of the younger ones as the mother and the older female siblings move on to further procreation. That way the knowledge gets passed on. When that pattern gets disrupted, then the first childbirth of the second litter tends to not work - the young mother doesn't know how to feed them right away, or gets so nervous that she can't feed them long enough and it takes one or even two childbirths before she learns. (So observed in a cat clan).
The breeding program of whopping cranes might be more successful if the young were left with the mother a bit longer. Also they likely follow the warming towards the south on their migrations and the veering off may be caused by local warmer air streams. But whether they mate and breed in Florida or in the next state over wouldn't really make such a difference. It means the spread will be larger, which is positive. They will all come back to their place of birth. Animals, if left to their nature, return to their place of birth to rear young and at the end of life, to die.
It might have been better to breed these birds in captivity where they are supposed to breed and let them migrate north once it gets too hot where they were born.
@Brigitte Meier You need to read more up on this. It sounds like you're interested, however, you are not informed. The Whooping Crane population got down to 15 individuals. They were completely extirpated (locally extinct) in eastern North America. So the Wisconsin/Florida population is completely reintroduced. That's why this study was done on them.
The chicks are not kept with their mothers for several reasons. One being that the mothers have precious DNA so they have more than a regular clutch size every year. Their typical clutch size is only one or two eggs with them raising only one of those chicks usually. There are not enough mothers to take care of the chicks. People dressed in crane costumes actually take care of them. The second reason is that cranes do not reproduce in captivity well. The chicks can't be left with the mothers for fear that they will not be taken care of, or even killed by their mothers.
Whooping Cranes do not breed in Florida. Florida, and the southern regions of North America, are the Whooping Cranes' wintering grounds. They breed in Alaska, northwestern Canada, and Wisconsin. That's why they are raised in captivity in the north and not the south. Check out www.savingcranes.org to learn more about the Whooping Crane captive breeding programs and the reintroduction efforts.
@Brigitte Meier so professional
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