The brief history of humans in North America pales in comparison to that of sandhill cranes (Grus Canadensis). For many years and as many springs, waves of the large gray birds have sailed north on thermal winds, set their wings and slowly descended into the nurturing flows of the shallow Platte River.
In fact, at a geologically young estimated age of only 10,000 years or so, the Platte River itself is a relative newcomer when compared to how long cranes have been visiting what we now know as Nebraska.
A nearly 10-million-year-old fossilized wing bone believed to be from a late Miocene-era crane was found in Nebraska in the 1920s. Although that discovery is often used to substantiate the record of Grus canadensis in the state, ornithologist Dr. Paul A. Johnsgard said, “The fossil is not distinguishable from modern sandhills, but it might have been an earlier species of Grus.”
Although it is difficult to narrow down just how long sandhill cranes have been here, Dr. Felipe Ramirez-Chavez, executive director and an avian ecologist with the Platte River Whooping Crane Maintenance Trust Inc., said, “The fossil record for the sandhill cranes are primarily from the Pleistocene (up to about 3.5 million years ago), but there are records from the Pliocene which means the oldest known fossil is somewhere between 3.6 and 5.3 million years ago.”
At Ashfall Fossil Beds State Historical Park near Royal, Neb., the fossils of a species of crowned crane known scientifically as Balearica exigua have been exhumed from the ash bed. These remains, along with those of barrel-bodied rhinoceros, saber-toothed deer, giant land tortoises, bone crushing dogs, five species of ancient horse and three species of camels, have been dated to 12 million years ago. Although this species of crane is now extinct, two related species of crowned crane from the same genus persist in Africa today.
No story about cranes in Nebraska would be complete without mentioning the regal whooping crane (Grus americana). Nebraska is one of a handful of states fortunate enough to host the most common crane on Earth (the sandhill crane) as well as the whooping crane—the rarest of the world’s cranes.
In the 1940s, the number of these large white cranes reached a low point of 15 birds. Through experimental captive breeding programs and reintroductions, the wild population has neared 300 but continues to suffer setbacks.
While watching a juvenile whooping crane feeding in a field with several hundred sandhill cranes near Doniphan in early 2009, Karine Gil, Ph.D., an ecologist with the Platte River Whooping Crane Maintenance Trust, became emotional when describing the horrible conditions she witnessed in Texas where whooping cranes spend the winter. Drought and lack of food more than erased the previous year’s gains.
Hard work and a little luck are welcome in conservation. Recently, Karine remarked, “We have good news. There are 264 whooping cranes in Aransas this year [winter 2010]! Last year the final number was 249!”
The term sandhill crane encompasses six different subspecies—three that are nonmigratory and another three that migrate through several flyways in America. All of the migratory subspecies pass through Nebraska in late winter and early spring.
The Florida, Mississippi and the Cuban sandhill crane are all nonmigratory varieties with small ranges. Grus canadensis pratensis, the Florida sandhill crane, numbers between 4,000 and 6,000 individuals in the wild. Due to alteration of habitat and overhunting, this population that once inhabited the southeast United States has been fragmented and largely reduced. Today, the adaptable Florida sandhill crane lives in a few protected areas but also in backyards and on the ever-spreading edge of development. Though considered stable now, how far can this subspecies be pushed before the breaking point is reached?
The Cuban sandhill crane, Grus canadensis nesiotes, is reclusive and spreads out over less than a dozen small populations. Recent estimates, based on limited fieldwork and study, vary widely in the literature and indicate a population numbering somewhere between 100 and 700 individuals. Only in recent years have American researchers infiltrated the political stalemate between the U.S. and Cuba.
A comprehensive study, the first of its kind in regards to the Cuban sandhill crane, was conducted in cooperation between the Cuban National Agency for the Protection of Flora and Fauna and American researchers between 1994 and 2002. The cooperative effort found that some populations that were reported no longer existed. In addition, other populations of cranes were discovered.
As its common name implies, the Cuban sandhill cranes exists on the island of Cuba and also on a few other islands in the Cuban archipelago. Cuban sandhill cranes occupy drier habitats than the other subspecies, preferring to forage in open rangeland and savannas dominated by both palm and pine trees. After the research was compiled, it was estimated that 526 Cuban sandhill cranes inhabit the Cuban mainland and surrounding islands.
Lack of natural wildfires allows woody plants to encroach on the cranes habitat, and predators, such as feral hogs and canines as well as the introduced mongoose, threaten both cranes and their nests. As most of the Cuban populations number only a few dozen animals, occasional hunting of cranes by humans is also a significant barrier to the recovery of the Cuban sandhill crane. It is likely that some of the surveyed smaller groups of cranes are now extirpated from the island. However, the Cuban government now has established some protected areas for the cranes, and several of the small populations appear to be on the rise.
As rare as the Cuban and Florida subspecies are, there is another that is the rarest of all of the sandhill cranes. Grus canadensis pulla, the Mississippi sandhill crane, fell to only about 30 birds in the mid-1970s and wasn’t recognized as a separate subspecies until 1972. It was nearly lost. Physiological, morphological, behavioral and other variances differentiate this small population from the others. At a current level of only about 120 birds, the future is totally uncertain for this subspecies.
That it even persists today is likely the result of the 1975 court settlement that established 20,000 acres of land on Mississippi’s Gulf Coast as the Mississippi Sandhill Crane National Wildlife Refuge. They exist only here—on one refuge, in one county, in one state. Without this small parcel being so designated as a refuge, this rare member of the genus Grus most likely would have been lost forever by now. Considered critically endangered, lack of habitat prevents this subspecies from expanding outside of the refuge’s boundaries. And even if it could, the pine savannah habitat that these cranes use is also endangered. It once stretched from Louisiana to Florida—a wet, coastal grassland savannah interspersed with longleaf pine trees. Today, this are,a still vibrant with a high diversity of plants and animals, has been reduced to a mere shadow of itself—95 percent of it has been destroyed. Along with it, Mississippi sandhill cranes and many other species have suffered as the savannah has been, and continues to be, developed into oblivion.
The modest increase in numbers is due to an intense captive breeding program where birds are released to augment the “wild” birds, about 90 percent of which were born in captivity. What little natural reproduction that does take place is not enough to compensate for birds that are lost to naturally occurring predators and to the many feral dogs that enter the refuge. A structured regimen of prescribed burns keeps areas open as Mississippi sandhill crane habitat.
Nature photographer, author and advocate of cranes Michael Forsberg spent time at the Mississippi Sandhill Crane National Wildlife Refuge as part of his research for his book “On Ancient Wings: The Sandhill Cranes of North America.” He said, “The Mississippi Sandhill crane has probably only survived into the 21st century because of the teeth of the Endangered Species Act, the guts and good graces of a handful of dedicated scientists and conservationists that have championed for their existence and sheer luck by surviving the ravages of Hurricane Katrina. It surprises some people to no end that the Sandhill crane, for now the most successful of crane species on Earth, contains a nonmigratory subspecies which has been flirting with extinction since the 1970s.”
Of the three subspecies of sandhill crane that frequent Nebraska, the lesser sandhill crane (Grus Canadensis Canadensis) occurs here in the highest numbers. Approximately 80 percent of the world’s population of this subspecies funnels through the Platte River valley each spring.
Along with the lesser sandhills, there are greater sandhills (Grus canadensis tabida) and the Canadian sandhills (Grus canadensis rowani). Depending on conditions, human visitors can see thousands or tens of thousands of cranes in a single morning or evening, at a time when there may be several hundred thousand along the shallow confines of the Platte River.
Dr. Gary Krapu of the Northern Prairie Wildlife Research Center said, “With regard to numbers of cranes coming though Nebraska in spring, our best estimate is about 600,000, with 500,000 coming through the Central Platte Valley and 100,000 along the North Platte.” The cranes typically begin arriving by mid-February with most of the cranes gone by the second week of April. This gathering of cranes is the largest to be seen anywhere else on Earth among the planet’s 15 species of crane.
Each individual bird spends three to four weeks in Nebraska feeding on waste corn in fields adjacent to the river and also eating invertebrates and small animals in the few remaining wet meadows near the river. While in Nebraska, cranes may add on 20 percent to their body weight. These nutritional resources are vital to cranes; when they return to the Arctic to breed, spring is often yet to arrive, meaning that food resources are rare or nonexistent for some time.
Because of this, biologists have theorized that even though the sandhill cranes that migrate through Nebraska spend less time here than any other place they visit, the Platte River is the most important habitat for those cranes. Why? Because the resources available to them in Nebraska (waste grain, calcium and protein from invertebrates) enable them to wait out the end of the Arctic winter and improve their chances to then nest successfully.
The lesser sandhill crane is the most diminutive of the migratory sandhills. In its journey from its wintering grounds in Texas, New Mexico and northern Mexico to its nesting grounds in Canada, the Yukon Territory, Alaska and even Siberia, a lesser sandhill crane can make a one-way trip of seven thousand miles!
The three migratory subspecies vary in height from 3 to 3 1/2 feet and 5 to 7 pounds up to 5 feet tall and 10 to 14 pounds. Of those measurements, of course, the lower values are attributed to lesser sandhill cranes and the larger values to greater sandhill cranes, with the Canadian sandhill crane registering size and weight in between those extremes but closer to that of the lessers. Wingspans range 6 to 7 feet.
The sexes are difficult to determine with the naked eye except that, in a mated pair, males tend to be larger.
The unison call
There is another time at which the casual observer can differentiate between the sexes of sandhill cranes. Biologists say that the unison call is a way for a pair of cranes to reaffirm their bonded status. During this call, the male’s bill is pointed almost straight up into the air. At the same time, the female’s is at an angle to his. They call rapidly together in what many have referred to as a symphony of nature, an icon of nature, a true honor to witness.
Dam it—The changing Platte
Historically it is believed that sandhill cranes used a portion of the Platte River in Nebraska about 200 miles in length. As land and waterway was altered, the portion of river used by the cranes has dwindled to about 70 miles, much of which is considered to be marginal habitat at best.
In the last century the Platte River has been dammed, diverted, siphoned, polluted and degraded to the point where it no longer functions naturally like a river at all. The users of the Platte’s water are many. It is taken for the ever-expanding front-range area of Colorado, irrigation, other agricultural uses, development, industry, city well fields and hydroelectric plants (to name a few). Man has reduced its flows as much as 70 percent by some estimates, and as a result, the violent spring floods and ice jams that kept her sandbars clear and clean rarely happen now. Why does this matter to cranes?
Sandhill cranes prefer to spend the night in the Platte’s shallow current for various reasons. The aquatic roost is a good defense or at least a deterrent against many predators. It is easy to picture a coyote, bobcat or other mammalian predator raising a river full of the birds as it splashes toward the flock. The river course itself provides a wide field of view—the wider the better for wary cranes to see approaching predators.
As those historic spring flows have been eliminated, the river channel has narrowed, filling with shrubs, trees and grasses. These forested islands provide great habitat for deer, raccoon, beaver and coyote but not for cranes. Cranes will avoid these areas, which provide cover to predators.
Helping the Platte help cranes
The pioneer anecdote that the Platte River was “a mile wide and an inch deep” is well known but not entirely accurate. Actually, the various channels, punctuated in between with wetlands, meadows and riparian areas, were as large as 15 miles wide in places. The aforementioned factors have transformed the once powerful Platte into a usually tame waterway.
Since man altered the river, he is charged with managing it for all, mankind and wildlife alike. But how do government agencies, wildlife managers, environmental groups, landowners and others mimic Mother Nature so as to provide habitat for the sandhill cranes and the millions of ducks, geese, shorebirds, fish and other animals that rely on the Platte?
In several stretches of the Platte River in Central Nebraska heavy equipment is used to plow up woody growth—small trees and shrubs that sprout on sandbars. These same areas are then disked, effectively providing roosting sites for cranes for another season. Government agencies partner with wildlife groups, such as Audubon’s Rowe Sanctuary, to fund this expensive process.
Some summers along the Platte the river actually runs dry. Sometimes the flows disappear for several months. Another aspect of habitat management for the entire river involves controlling invasive species of plants that steal huge quantities of water from the river and associated groundwater. Non-native varieties of phragmites and purple loosestrife are species being targeted by river managers because they crowd out desirable native plants and because of their huge thirst for Platte River water.
Salt cedar is another growing river management issue. Like many invasive species, it was imported (from Eurasia in the mid-1800s) to be used in landscape plantings. It is estimated that an acre of salt cedar sucks up 2.9 million gallons of water in a year’s time. One mature plant can use 200 gallons per day! With water being the valuable commodity it is and with the threat of drought almost constant in the Midwest, managing this plant is not only vital to sandhill cranes and other wildlife but also to the humans that rely on its water.
Many other invasive and exotic plants are increasing their presence along the Platte and other waterways. Herbicides, grazing, mechanical removal and prescribed burns are some of the ways habitat is managed, and in some instances, it is how it is reclaimed. Restoring habitat for cranes helps man and animal alike.
The spring migration
Perhaps the ultimate salvation for cranes and crane habitat will come from the people that love the large gray birds. In a mass migration of their own each spring, thousands of people flock to the Platte valley to see the cranes. They are a varied lot. Some of them are lifelong birders. Others are general appreciators of wildlife, and some are simply tourists coming to see them because they are there. Besides the cranes, they all have something in common—they spend their money here.
Figures vary by source and by year, but generally the thousands of people that come here to see the birds infuse millions of dollars into economies along the way. Estimates range from 10 million dollars to over 50 million. It would be hard to hit the figure on the head because every shop, gas station, restaurant, hotel and other business they visit along the way—whether it is between Omaha and Kearney or New York City and Grand Island—benefits each time a “bird” person stops to spend money. With many communities, businesses and families having financial difficulties today, the value these birds represent is a powerful reason for conservation.
When those bird people make it to Nebraska, and more specifically, the Platte River valley, they seek out places to see the birds and the river.
Near Alda, a facility seeks to provide the birding public a place to see the cranes. Formerly known as Crane Meadows, today it is known as the Nebraska Nature Center. Over the years it has struggled to keep going, but current director Brad Mellema was optimistic when he said, “We’ve got 20 years of history here, but we’re kind of starting from scratch now. Now, we are focused on the visitors.”
Through partnerships with other organizations, the Nebraska Nature Center has blinds available for crane watching as well as a foot bridge where the sunset can be seen in its full glory as cranes fly from every direction. Mellema added, “Educating people about cranes and this accumulation of birds—we want to tell that story.”
Other viewing areas flank the river in several places in the Grand Island, Alda and Gibbon areas. These are near cornfields and give visitors an opportunity to see the cranes feeding.
More than 35 years ago, what has become one of the most popular and well-known places to meet fellow “craniacs” and to see and learn more about their feather friends began along the banks of the Platte near Gibbon.
The National Audubon Society’s Lillian Annette Rowe Bird Sanctuary began in 1974 as a sanctuary for wildlife, initially with about 800 acres of protected habitat. Today, more than 1,900 acres are protected. Bill Taddicken has been with Audubon for more than a decade and serves today as Rowe’s executive director. He said, “Our mission is ‘To conserve the Platte River ecosystems for cranes and other wildlife through conservation and education.’
We want to maintain a Platte River ecosystem that is viable for wildlife and people. We partner with private individuals from all over the world, including local farmers and landowners. We also have active partnerships with the U.S. Fish and Wildlife Service, NGPC, FSA, NRCS, the Platte Valley Weed Management Area, Central Platte NRD, UNK, Kearney Visitors Bureau, ESU 10, Kearney Public Schools, Minden Public Schools, Minden Chamber of Commerce, The Platte River Whooping Crane Maintenance Trust, the Platte River Recovery and Implementation Program, and many more.”
Educational programs are ongoing at Rowe all year long, but “crane season” is Rowe’s busiest time. Educational sessions, kid’s games, a family crane carnival and special events are part of crane season activities, but the big draw is the morning and evening field trips to see the cranes from riverside blinds.
Volunteers from all over the country lead most of these field trips. Visitors may end up at one of their three regular viewing blinds, but there are others that may be used depending on where the birds are hanging out.
Since 2003 when Rowe’s Iain Nicolson Audubon Center was completed, attendance has swelled to about 15,000 each crane season. Rowe’s long history of habitat preservation/ restoration means their several miles of river property provide sanctuary for many species and tens of thousands of cranes each night. As a result, birders from around the state, country and world converge there in the spring.
One sentence from Forsberg’s “On Ancient Wings” regarding Mississippi sandhill cranes applies equally well when considering the survival of all sandhill cranes in general. He said, “One thing is for sure. If this place one day has no cranes, it will have lost its spirit, and the soul of this remnant landscape will wither.”
For more information on the annual crane migration, visit http://www.nebraskatravels.com/sandhill-crane-migration.html.