Sandhill cranes expand population

A pair of sandhill cranes stand in a partially-harvested rye field in rural Princeton’s Baldwin Township July 25.

A pair of sandhill cranes stand in a partially-harvested rye field in rural Princeton’s Baldwin Township July 25.

By JOEL STOTTRUP

Some say that once they’ve heard the distinctive unison voices of a pair of sandhill cranes, they will never forget what bird the sound belongs to.

Those sounds and the sightings of these long legged birds, sometimes seen in the hundreds in one place, have become more frequent in the Princeton area in the past several decades.

Biologists and bird watchers at the local Sherburne National Wildlife Refuge (NWF), and in  the offices of the U.S. Fish & Wildlife Service (F&WS) will attest to their numbers growing.

The sandhill crane population has really grown in the past 20-30 years, and their range has expanded, said F&WS Region 9 biologist Tom Cooper last week. He notes that the sandhills (as they are called for short) that are seen in the Princeton area are part of what is called the Eastern population of these cranes. They nest from eastern Minnesota through Ontario and then down through Michigan and have expanded into Pennsylvania, Ohio, and New York state, Cooper said. This same population migrates to Florida, Georgia, southern Tennessee and Mississippi during severe winters, but will also hang out as far north as Indiana and southern Michigan during mild winters, Cooper added.

It is the mid-continental population of sandhills that migrates to the Platte River, Cooper said.

Tom Hewitt, biologist at Sherburne NWF, who counts the sandhills at that refuge each fall, said he counted nearly 6,500 of them there last fall, and just under 7,000 in the fall of 2011. The refuge’s Fox Pool is a big staging area for the sandhill cranes during the fall before they migrate out, he said. Hewitt explained that they stay there during the night, head out to fields during the day to feed and store up fat for energy to migrate, and then fly back to Fox Pool in the evening.

Sherburne NWF allows a limited number of people to take part in a supervised watching of masses of sandhill cranes flying out from their roost during fall to forage in fields where stray grain lies after harvest.

Hewitt and Cooper talked about the swing from when the sandhill crane population was very low in the early 1900s and their climbing back up in latter decades. These, and other migratory birds were being hunted in large numbers until Congress passed a migratory bird act in 1918 that prohibited hunting these birds, Hewitt and Cooper said.

Also helping the number of sandhills rise back up, said Hewitt, is habitat improvement, such as what has been done at Sherburne NWF. Sandhills like nesting and roosting where there is water, said Hewitt.

Hewitt and other Refuge staff members, with assistance from students at St. Cloud State University, count sandhill cranes at the refuge in the spring. The sandhill crane census takers will be positioned at the refuge to make a triangular pattern and then listen and record the unison calls of the sandhills, Hewitt said. From that information, refuge personnel get an idea of how many nesting pairs are there, and this year there were roughly 31 nests, Hewitt said.

Cooper said that when the Eastern population of sandhill cranes was at its low point, there was just a small remnant population found in Wisconsin. Now the Eastern population numbers 70-80,000 cranes, he says.

Cooper estimates that the Eastern population of sandhills has been growing about 4 percent per year since census taking of them began in 1979. At that time the count was 14,385 cranes and last year it reached 87,796, Cooper said.

Cooper says sandhill cranes lay two eggs in a nest, that both will hatch, and that usually only one of the young, which are called colts, survives. It is the stronger one that lives, he said. He also noted that sandhills don’t breed until they are several years old. It is the adult sandhill crane that has the distinguished red upper part on its head, he said.

The biologists talked to for this story and some others who have observed sandhill cranes up close, agree that they have a bit of a primitive look.

Next to reptiles, birds are the vestiges of dinosaurs, said Hewitt. Some would agree that some birds, like the sandhill cranes, look more primitive than others.

The Minnesota DNR has put in place a sandhill crane hunting season for a small number of counties in northwestern Minnesota as a trial, due to the complaints of the birds effect on some crops there.

If the sandhill crane population continues to increase, it could get to the point where the hunting season for them is expanded as a way to control them, Hewitt said.

Some who have tasted the meat of a sandhill crane call them “rib eye in the sky,” while others would not call it that, Hewitt said.

Whether you like sandhill cranes or not, and many do enjoy watching their flight and their standing about, these wild birds are more strong in number now and it appears they are here to stay during the warmer months.

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