Sandhill Cranes and Migration Theories

 

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We know from fossilized records that the Sandhill Cranes are one of oldest birds in the world, and have been in their present form for 10, 30, or 60 million years (depending on the source). They have apparently maintained a family and community structure that allows them to live together peacefully and migrate by the thousands along a central flyway twice a year. Sandhill Cranes mate for life, and in the spring the adults engage in a complex “dance” with one another. During mating, pairs vocalize in a behavior known as “unison calling.” They throw their heads back and unleash a passionate duet—an extended litany of coordinated song. Cranes also dance, run, leap high in the air and otherwise cavort around—not only during mating, but all year long (Even young birds begin dancing and throwing sticks and grasses into the air while jumping around enthusiastically).

In their northern habitat, the female lays two eggs a year in thick protected areas at the edge of reed filled marshes. Before nesting these birds “paint” their gray feathers with dull brown reeds and mud to reduce the possibility of being seen by a predator. Born a couple of days a part, the second chick rarely survives. The fuzzy youngster that does (if it survives the first year – delayed reproduction and survival rates factor into the difficulties inherent in crane conservation and to that we must now add Climate Change) stays with its parents for about three years before reaching sexual maturity and striking out on its own, but even then the adult stays within the parameters of its extended family, and it is these families that comprise the small groups of cranes that we see flying together. During migration, a multitude of these groups travel together by the hundreds or thousands. There are no leaders and often it is possible to observe what looks like an unorganized random group (but isn’t) or diagonal thread made up of cranes flying (up to thousands of feet) above the ground.

 

In every roosting place there are a few cranes that remain awake all night alerting their relatives to would be predators, and in fact I have been awakened during the night by crane warning cries that sound higher pitched than normal. I think it’s significant that these very ancient birds have survived so long in their present form. Could it be because they understand the value of living in community, perhaps acting as models for humans who, for the most part, seem to have forgotten what genuine community might consist of?

 

Most recently these birds have been a presence in my life since last November when they first arrived, I believed for a brief stopover, before moving south to places like the Bosque del Apache to spend the winter. When I first came to New Mexico almost three years ago I was astonished and bewildered by their haunting collective cries even when I couldn’t see them which was most of the time during the month of November…

 

But this year the cranes not only stopped by but many decided to spend the winter here much to my great joy, perhaps a result of Climate Change which is shifting their migration patterns and created conditions like the extreme drought that dramatically lowered the level of the river over this last year.

My hypothesis is that the resulting shallow riffles in Red Willow River (one of which just happens to be below my house) provided many cranes with the safety they needed to roost there all winter long. For three precious months I listened with awe and wonder to pre-dawn crane murmuring and on sunny mornings watched groups of cranes take to the air with their haunting br-rilling cries. Every night I would stand outside to listen to that same contented collective murmuring just before dark as the cranes settled in for the night.

 

When they are all talking to one another (cranes need to be in constant contact with each other) it is hard to distinguish one voice from another because listening to the whole is a symphonic masterpiece. But this winter I slowly learned to identity various cries by listening to smaller groups as they took to the sky. The highest pitched belong to the youngsters, the lowest and most full bodied calls come from the males and the females speak in tongues from the middle.

 

Sandhill Cranes are omnivores and feed on land or in shallow marshes where plants grow out of the water during the warmer seasons. They prefer a diet of seeds and cultivated grains but also include berries, tubers, crayfish worms and insects and frogs depending on the season. In the field next to me they fed on wild sunflower seeds and grasses.

 

As previously mentioned Climate Change is shifting migration patterns. Some groups are now spending their entire lives in one place like Florida (these are endangered), others are no longer migrating further south than Tennessee, although they also fly north in the spring. It is unusual to have cranes living in Northern New Mexico, although I understand from local fishermen that a few have occasionally remained here throughout the winter. I recently learned that Sandhill Cranes have even been seen in parts of Maine.

 

Their normal migration routes take them from Mexico as far northwest as Siberia into the Canadian Shield and Alaska to breed with one major stopover in Nebraska at the Platte river where 600,000 cranes meet to rest themselves before making the last leg of their arduous and dangerous seasonal journey (another group that settles further northeast makes a stop in Mississippi). In the fall all northern populations will make the trip south for the winter because of inclement weather and lack of food.

 

New Mexico and Texas have the dubious distinction of being the first states to legalize crane slaughter and now every state along their central flyway except Nebraska engages in spring and fall hunting. We can thank the state Fish and Wildlife organizations for “managing” the crane population by issuing licenses to kill these magnificent birds to bring in even more money when these organizations are already extremely well supported financially by the NRA and our taxpayer money. A Caveat to those that don’t know: All State Fish and Wildlife agencies, that purport to support wildlife have a deadly hidden agenda: to kill birds and animals at their discretion.

 

When I first began to hear the cranes I never imagined that I would start to see them or watch them make gracious descents into a neighboring field at all times of the day, every day for months. Watching them cup their wings, drop their long legs and spread their tails as they parachute to the ground is a gift that I have never taken for granted. A solitary musical rolling rill, a haunting cry that raises the hair on my arms is a sound that now lives on in my mind and body.

 

Spring migration has begun and the largest aggregations of cranes are moving north. Some days the bowl of blue sky feels too empty, but some small flocks are still visible especially during the early morning and again at dusk. I noted the sudden loss of large flocks just before this last full moon and wondered if these birds also migrated at night. Further research confirmed that Sandhill cranes sometimes do migrate after dark during the week before and after full moons.

 

A few days ago the core of engineers opened the dam raising the river and the protected riffles below my house disappeared, so during this last week in February I am without the morning joy of listening to nearby pre-dawn murmuring, but can still see and hear some cranes flying by. According to my friend Barbara R. some flocks remain at the Bosque del Apache, so hopefully we will be hearing their haunting cries for a while. It isn’t until April that all Sandhills reach the Platte River …

 

Pueblo people say that humans were once Cranes who lived in the clouds… they came to earth and danced for joy in the rain… Cranes also watched over ceremonies and remain a part of some Indigenous rituals today. Sandhills also act as Guardians for the People easing transitions from life to death and beyond….

 

Cranes are Elders in every sense of the word, ancient relatives and they continue on, some adapting, others following unknown scripts or patterns that stretch back to antiquity. The way they live, migrating out of seasonal necessity, returning to home – places, celebrating through community and song in life and death is a way of being that embodies flowing like a river… And for that, their magnificent beauty and inherent wisdom, I thank them.

 

I close with a Zuni prayer about the relationship between Cranes, Water and the Rebirth of Spring.

“When our Earth Mother

is replete with living waters,

When spring comes

The source of our flesh –

All the different kinds of corn

We shall lay to rest in the ground.

 

With their Earth Mother’s

Living waters,

They will be made into

New Beings…

 

That our Earth Mother

May wear a fourfold green robe

Full of moss

Full of flowers

Full of pollen,

 

That the land may be thus

(S/he has made you)

I have made you into living beings.

 

 

 

What is Migration?

Migration is the process or act of migrating, i.e. the movement of animals and birds from one region or place of habitat to another. Migration occurs in all major animal groups – birds, mammals, fish, reptiles, amphibians, insects and crustaceans. (Migration may also occur at the cellular level). The triggers for migration are complex and poorly understood. Climate variability, availability of food, seasonal changes, and reproduction, are some reasons that animals migrate.

Like scientists, I have been captivated by this process especially since we know so little about how animals know what they know, and because whatever capabilities they have developed over millennia are being interrupted by Climate Change (cranes for example have been in their present form for 30 million years.).

Studies have shown that migrating species appear to use a wide variety of mechanisms to navigate, including the stars, the sun and the moon, olfactory (chemical) cues, and Earth’s magnetic field. Some birds like cranes that normally migrate during the day also migrate at night a week before, during and after the full moons. Many species learn their migration routes by first traveling with experienced individuals, but others are able to migrate and navigate successfully without prior experience, an ability that still perplexes scientists and keeps me attached to field theory as a possible explanation. Field theory postulates that each animal has access to its own morphic family field and can tap into that field for information and guidance. This would explain why some animals are also able to find their way over thousands of miles without parental assistance. Migration requires a lot of energy and many individuals die during migration. Despite these heavy costs, the potential benefits of migration are great, which is why migration behavior has evolved in so many species.

One of the driving factors that leads to migration is the season. Many animals move from one place to another at certain times of the year or during a particular period of their life cycle. Some animals migrate only once during their lifetime, often just before they reproduce like the salmon do. Other animals, including many species of birds and many marine animals, such as sea turtles and whales, migrate long distances to their breeding grounds many times during their lives.

In other instances, animals are forced to leave an area when conditions in their environment deteriorate. Many bird species that nest in Canada and the northern regions of the United States and Siberia like the Sandhill cranes do migrate south as winter approaches because they seek a warmer and more hospitable climate. Another critical reason that birds migrate south is because their food supply disappears during the cold months. However, it must be said that some birds normally begin migrating south before their food supply has disappeared, and often even before it has begun to decline.

Approximately 1,800 of the world’s 10,000 species of birds migrate each year in response to the seasons. Many of these migrations are north-south, with species feeding and breeding in high northern latitudes in the summer, and moving some hundreds or thousands of miles south for the winter.

Birds probably utilize circadian rhythms (internal twenty four hour clocks) to regulate their migrations in both the fall and the spring. Apparently the changing length of the days may stimulate hormonal and behavioral changes that also result in migration. Scientists believe that natural selection favors birds that use predictable environmental cues, like the seasonal change in day length to initiate migration before their food source disappears.

The tilt of the earth’s axis is shifting because Greenland’s ice melt is causing sea level to rise. In general, the redistribution of mass on and within Earth affects the planet’s rotation but this effect is sudden and more extreme and seasonal migrators are struggling to adapt.

Seasonal migrators must migrate every year. For other animals, migration is less predictable. For example, the Snowy owls that live in Canada have to move south when the lemmings crash.

Irregular (non-cyclical) migrations called irruptions also occur under pressure of famine, overpopulation or other unknown influences but are not considered to be true migration.

The shifting range of the Sandhill cranes is a source of fascination to me and appears to be a result of global warming. These birds once migrated into Mexico each winter. Now some populations only fly as far south as Tennessee, and others remain in Florida. At one time these cranes were mostly found in the Midwest before they moved north or northwest to breed, but since the year 2000 they have been seen in south central and western Maine.

We may not know how migration works, but we do know the patterns of migration are changing and that Climate Change is a reality. My fervent hope is that somehow most species, who are all our “elders” – humans, after all have only been around for 200,000 years – (plants for 450 million years, animals for 350 million years) – may possess strategies that we can’t even imagine to survive the damage that we have brought upon all living things including ourselves.

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