FULTON, UNITED STATES // Scientists warned a devastating drought in Texas could threaten the world's only remaining flock of whooping cranes.
The birds eat blue crabs and berries during their annual migration to the Gulf of Mexico coast. The high-protein diet is supposed to sustain North America's tallest bird through the winter and prepare it for the nesting season in Canada. But this year, the drought has made food and water scarce.
The lack of rain has made estuaries and marshlands too salty for blue crabs to thrive and destroyed a usually plentiful supply of wolf berries. In addition, a long-lasting "red tide" - a toxic algae that blooms in salty water - has made it dangerous for the birds to eat clams, which retain the algae's toxin and can pass it along the food chain.
"We're very apprehensive, very concerned, monitoring the population very closely to see what it is the reaction might be," said Dan Alonso, the manager of the Aransas National Wildlife Refuge, the winter home of about half of the 300 remaining cranes.
In 2009, when Texas last suffered a severe drought, an estimated 23 whooping cranes died between November and March, when they typically head north to nest in Wood Buffalo National Park in northwestern Canada. Tests indicated some had contracted rare diseases and were undernourished. Scientists believe some died of starvation.
This year, at least one crane has already died, Mr Alonso said.
Scientists are alarmed because they don't normally see dead birds so early in the season. Usually, only 1 per cent - or about three birds - die over the winter.
"I think we're going to lose a bunch again this year," said Tommy Moore, the captain of a skimmer boat that takes tourists and bird lovers to view the cranes in Texas' shallow wetlands.
"The only thing I've seen them eat, period, is dead fish off the side of the channel ... there's just nothing here to eat," said Mr Moore, who observes the birds nearly every day.
A century ago, the whooping cranes' 1.5-metre frame and mournful call were common across the Texas shoreline and as far away as the East and West coasts. But by the 1940s, the pesticide DDT and disappearing habitat decimated the population, leaving only 14 birds in the whole country.
The eventual ban of DDT and efforts by scientists and Gulf coast residents who view the cranes as a part of the tranquil landscape helped bring the population up to the current estimate of 300 birds.
Unlike other birds, the cranes don't stop to eat while flying back to Canada so the nutrition they get in Texas is especially important. In addition, the high-protein diet is key to a successful nesting season. The cranes only produce one chick per season, so there is little room for failure.