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FORT SMITH
Whooping cranes from Wood Buffalo National Park are facing serious environmental challenges on their wintering grounds in Texas.

A whooping crane eats a blue crab at the Aransas National Wildlife Refuge in Texas. - photo courtesy of Aransas National Wildlife Refuge

A drought has once again hit the area of Aransas National Wildlife Refuge, where the endangered birds migrate each year.

The last time there was a drought in the area - in the winter of 2008-2009 - the whooping crane death toll was 23.

"That was related to the drought back then," said Vicki Muller, a wildlife refuge specialist at Aransas. "Typically, we have a one per cent mortality rate in the wintering grounds here, so we're only talking about a couple of birds."

So far this winter, one juvenile whooping crane has been found dead, but tests have been unable to determine the cause of its demise.

Muller said there is concern about the drought and its potential impact on the whooping cranes, but not yet to the level of concern as in the winter of 2008-2009.

"I'd say we're fairly worried," she said. "We're being very vigilant in watching the cranes as best we can and doing things that are within our power to help them out in any way that we can."

Muller noted that, although a survey has not yet been done, it is expected that a record number of whooping cranes - possibly 300 - migrated south from the NWT in the fall.

The major effect of the drought, which began late last spring or early summer, is salinity levels have risen in the bay and marshes where whooping cranes spend most of their time.

"When the salinity levels are high, the whooping cranes cannot drink that water and so it results in them having to find fresh water sources, usually more inland," Muller explained. "So they have to fly and exert more energy to get to these areas."

They would usually have to fly a few miles to find drinkable water.

The concern is the extra flying may weaken the birds before they start departing in mid-March for the 3,800-km migration back to Wood Buffalo.

Muller noted the marshes always contain salt water, but usual salinity levels can be tolerated by the whooping cranes. With the drought, not enough fresh water is flowing into the marshes to keep the salinity level low enough for the whoopers.

"Their bodies won't handle it and so they just don't drink it," Muller said. "They're smart enough to know not to drink it and then they'll look for freshwater elsewhere."

Aransas had expected the drought to continue into the winter and took a number of steps to maximize the freshwater areas for the whoopers.

Existing water wells were found and repaired throughout the summer and fall, Muller said. "Even now we're still working on some to try to provide as much freshwater as possible."

There is also concern the drought is possibly affecting the cranes' food supply, including the blue crab.

"In our observations out in the marshes, we are not seeing the numbers of blue crabs that we have in our findings typically," said Muller, although she noted biologists are finding plenty of evidence of blue crab, as well as wolfberry, in the cranes' scat. "So that's showing evidence that the cranes are finding resources within the marsh and they are utilizing them to some degree."

Muller said Aransas will vigilantly watch the water and food situations.

The refuge is doing prescribed burning this winter to increase the food supply for the whooping cranes. About 3,000 acres have been burned as of last week, and another 9,700 acres will be burned.

The birds come to the burned areas almost immediately, Muller said, noting a lot of the areas have oak trees and, when a fire goes through, roasted acorns fall to the ground for the whooping cranes.

"They absolutely love roasted acorns," she said, adding they also eat any "crispy critters" left by the fire.

Some of the tactics used this year were also used during the last drought, including prescribed burning and freshwater enhancement.

"But since we had such a heads-up this time because of the drought happening this entire summer, we've had a really good jump start to where we've been able to maximize that," Muller said.

There has also been some concern about naturally-occurring toxic algae, a so-called red tide, in the marshes. Recent cooler temperatures have decreased the red tide blooms, although Muller noted there are plenty of dead fish that the cranes could be eating, along with contaminated clams.

Stuart Macmillan, a biologist at Wood Buffalo National Park in Fort Smith, hopes the situation in Texas won't increase the whooping cranes' mortality rates.

"It seems the folks that run the refuge there are taking significant measures to ensure that the cranes have access to food," Macmillan noted. "It's not the first time that there's been some supplemental feeding for the cranes down there, so they've got experience doing this. They're certainly the experts on what the cranes need on their winter range."

Whooping crane bio

Status under SARA:
Endangered (last reviewed in November 2000).

Range:
The original flocks of whooping cranes nest in Wood Buffalo National Park, located on the Alberta-Northwest Territories border, and migrate to the Texas Gulf Coast and winter in or near the Aransas National Wildlife Refuge. An additional flock of whooping cranes nests in southeastern Idaho and winters in the middle Rio Grande Valley of New Mexico. A non-migratory wild flock lives in Florida.

Population Estimate:
Wood Buffalo National Park: 220 birds and increasing. Florida: 60 birds, stable to decreasing.

Life Span:
22 to 30 years.

Size:
Adults are 1.5 meters tall and weigh between six and seven kilograms.

- Source: Nature Canada

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