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North America > Texas Whooping Cranes and Fresh Water Inflows
The last naturally occurring population of Whooping Cranes in the world, 247 individuals, breeds at Wood Buffalo National Park in Canada and then migrates over 2,500 miles to spend the winter on the coastal wetlands near and within the boundaries of Aransas National Wildlife Refuge (NWR) in Texas. Reduced to only 16 individuals in 1941, the Whooping Crane has made a slow but remarkable comeback from the brink of extinction. 
The U.S. Fish & Wildlife Service listed the Whooping Crane as threatened with extinction in 1967 and endangered in 1970. Intensive cooperation between public and private sectors of the United States and Canada has resulted in the gradual recovery of wild populations. Click here to view a table of current and historic Whooping Crane numbers. The Whooping Cranes’ primary food source on their wintering grounds in Texas is the blue crab, comprising 80-90% of the cranes’ diet. The coastal wetlands of Texas provide excellent habitat for blue crabs if the salinity of the water remains within 5-15 parts per thousand (ppt). This range in salinity is determined by the amount of fresh water entering coastal wetlands as rain or inflow from streams. 
The majority of the freshwater inflows to the San Antonio Bay come from the Guadalupe and San Antonio Rivers. Historically, the Guadalupe and San Antonio Rivers have supplied almost 80% of the total freshwater inflows into this estuary. If fresh water input is reduced, the salinity in coastal wetlands may reach levels as high as 50 ppt. Blue crabs are intolerant of such high salt levels. As a result, during periods of drought and reduced freshwater inflow, there are fewer crabs available to Whooping Cranes. In such cases the physical state of the cranes is weakened, and is reflected by higher mortality in Texas and low reproductive success on the breeding grounds in Canada the following spring. In 2008-09, as a result of drought and water diversion, the Guadalupe River did not deliver enough fresh water to the coastal wetlands where the Whooping Cranes spend the winter. Availability of the blue crabs declined, and the increased salinity levels also forced the cranes to expend energy searching for new sources of fresh drinking water away from their territories. The Whooping Cranes suffered, with 23 birds dying over the winter. Normal mortality of the cranes on the wintering grounds is approximately 1%--last winter an alarming 8.5% of the population perished. As the human population grows in Texas, the demand for fresh water is also increasing. If more and more water is taken from the Guadalupe River basin, the salt content in coastal marshes will continue to increase, especially during droughts, and blue crab numbers will decline. Thus, the endangered Whooping Cranes may be unable to reproduce well enough to sustain the small population that winters in Texas. To address these critical issues, ICF is a member of and supports The Aransas Project (TAP) in its efforts to protect the health and ecology of the Aransas area, including endangered and threatened species such as the Whooping Crane. In 2002, ICF supported a three-year research project studying Whooping Cranes, blue crabs and freshwater inflow at Aransas NWR. To raise public awareness and support for the conservation of cranes and fresh water resources, ICF participates in the annual Whooping Crane Festival at Port Aransas, Texas, and provides a variety of educational programs and materials. CLICK HERE to make a donation to this important conservation initiative. Click on the links below to read more about Whooping Cranes and freshwater inflow issues in Texas:
ICF Bugle article, Volume 35, Number 3
ICF Bugle article, Volume 29, Number 4
ICF Bugle article, Volume 29, Number 3
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