Summer 2009 - Guadalupe-Blanco River Authority
Summer 2009 - Guadalupe-Blanco River Authority Summer 2009 - Guadalupe-Blanco River Authority
Research Gives New Insightsinto the Needs of Whooby Joel WilliamsAn extensive study of the habitat, behavior and diet ofwhooping cranes at their wintering grounds on the TexasGulf Coast found, among other data, that the endangeredbirds can obtain nutrition from a variety of food sources available, andare not dependent on any one type of food for survival.Researchers from Texas A&M University initially reported thefindings on April 29 in Seguin at a joint meeting of the boards ofdirectors of the Guadalupe-Blanco River Authority (GBRA) and the SanAntonio River Authority (SARA).“The goal was to evaluate the relationship between freshwaterinflows and the health of the whooping crane population,” said R.Douglas Slack, regents professor of the Texas A&M Department of“The goal was to evaluate the relationship betweenfreshwater inflows and the health of the whoopingcrane population.”Wildlife and Fisheries Sciences, one of the lead authors of the studytitled the “San Antonio Guadalupe Estuarine System” (SAGES)study, and a report based on it, “Linking Freshwater Inflowsand Marsh Community Dynamics in San Antonio Bay toWhooping Cranes.”Other authors of the report included two other principalinvestigators, Dr. William E. Grant and Dr. Stephen E. DavisIII, along with Dr. Todd M. Swannack, Dr. Jeffrey Wozniak,Danielle M. Greer, and Amy G. Snelgrove.Whooping cranes winter at the Aransas National Wildlife Refugeon San Antonio Bay, which is affected by the Guadalupe and SanAntonio Rivers.The research team found in the seven-year, $2 million study thatthe impact of inflows and other stimuli on the whooping crane andits diet is complex, and that additional study would provide a morecomprehensive evaluation of the effects of altered freshwater inflows.Among other findings, the study concluded that the blue crab is theoptimum food source for whooping cranes, but that “cranes are veryadaptable and they can switch to other types of food,” Slack said.Clams and wolfberries, among other foods, provided importantsources of biomass for the cranes, the study found.The SAGES study was primarily funded by the GBRA and SARA.The sponsors were interested in assessing impacts from the LowerGuadalupe Water Supply Project (LGWSP) in which GBRA waterrights would have been leased to San AntonioWater System (SAWS) and SARA, andwater would have been diverted fromnear GBRA’s Salt Water Barrier inthe lower basin, which is about11 miles from San AntonioBay. In considering whetherthe water diversioncould affect the bay,the entities involvedin the LGWSPinitiated theSAGES studythroughTexas A&MUniversity’s Department of Wildlife andFisheries Sciences.10When the LGWSP was canceled in 2006, SAWSdiscontinued its funding of the SAGES study. SARAand GBRA continued to fund the study, recognizingits importance and the potential for other watersupply projects and future growth, economicdevelopment needs as well as the lack of basicresearch on the crenes needs on their winteringgrounds. Other monetary funding and in-kindsupport for the SAGES study was provided by
ping Cranesthe Texas Water Development Board, the U.S. Fish and Wildlife Service,and the U.S. Geological Survey.Additionally, SARA and GBRA entered into an agreement withresearchers with the University of Texas at Austin to study the SanAntonio Bay estuary system, known as the Estuarine Responses Project“This research will be very valuable in the futureas we look at state water planning andenvironmental flows.”(ERP), headed by George Ward, research scientist and associatedirector of the Center for Research in Water Resources.The Texas A&M team investigated the diet, behavior and habitatof whooping cranes at their wintering grounds and evaluated therelationship between freshwater inflows feeding San Antonio Bay andthe health of its endangered whooping crane population.This research will be very valuable in the future as we look at statewater planning and environmental flows,” said GBRA General Manager“Bill West. “We understand that it is important to complete additionalresearch to accompany the SAGES results, but there is no doubt thatDr. Slack and his team have provided significant insights into thefeeding habits and needs of the whooping crane.“GBRA gets its fair share of both praise and criticism for its role inmanaging the Guadalupe River Basin,” West said, “but I hope GBRA’sparticipation and leadership in seeing this study through fruition showsjust how important protecting the environment is to us as we go aboutmanaging our water resources.”Steve Raabe, director of Technical Services for SARA, added, “Thesignificance of this study is it is the first time that a full ecosystemmodel has been developed for an ecosystem as complex as we haveon the Gulf Coast. It’s a very good leap forward, but it’s still just thefirst step.”Lee Wilson, president of Lee Wilson and Associates, anenvironmental consulting firm retained to ensure the study’sindependence, said that the team operated from the premise thatlow fresh water inflows, such as water coming from the river, wouldincrease the salinity of the bay, have an adverse impact on blue crabsand lead to increased crane mortality.The SAGES research, however, did not findthat salinity adversely affected the crabs orthe cranes.The study found that while in the salt marsh,thewhooping crane diet consisted of wolfberry fruit, blue crabs,clams, snails, insects, fiddler crabs, snakes and fish.Wolfberry plants tend to reach their peak fruit bearing seasonabout the time the whooping cranes beginarrivingin October.“Wolfberry fruit and snails and insects were consumed in thehighest quantities and required the least effort during foraging,and generally were associated with the most efficient foragingbehavior,” according to the Executive Summary of theSAGES Report. “Blue crabs were the most optimal food in relationto protein, and clams were a significant source of biomass. Whoopingcranes foraged most efficiently during the winter of 2005-2006 whenwater levels were lowest.”The population of whooping cranes at ANWR increased from 133 in1994 to 270 before 23 of them died over the winter.Only a few bodies were found, including one with a broken leg, onewith a parasitic infection, and one that appeared to have been eaten bya predator.Fieldwork for the SAGES study was completed before thewinter 2008-09.There was speculation that the drought, low freshwater inflows, andan increase in salinity in the marsh may have led to the high mortality“We understand that it is important tocomplete additional research to accompany theSAGES results.”rate by reducing the number of blue crabs available. Slack said he hadnot seen any evidence that a lack of nutrition caused the deaths.However, critics of the SAGES study contend that it ignorespreviously conducted research, and is incomplete because it did notcover this winter, when so many cranes died in the midst of a drought,when the marsh would tend to be salty due to lack of fresh water.11
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ping Cranesthe Texas Water Development Board, the U.S. Fish and Wildlife Service,and the U.S. Geological Survey.Additionally, SARA and GBRA entered into an agreement withresearchers with the University of Texas at Austin to study the SanAntonio Bay estuary system, known as the Estuarine Responses Project“This research will be very valuable in the futureas we look at state water planning andenvironmental flows.”(ERP), headed by George Ward, research scientist and associatedirector of the Center for Research in Water Resources.The Texas A&M team investigated the diet, behavior and habitatof whooping cranes at their wintering grounds and evaluated therelationship between freshwater inflows feeding San Antonio Bay andthe health of its endangered whooping crane population.This research will be very valuable in the future as we look at statewater planning and environmental flows,” said GBRA General Manager“Bill West. “We understand that it is important to complete additionalresearch to accompany the SAGES results, but there is no doubt thatDr. Slack and his team have provided significant insights into thefeeding habits and needs of the whooping crane.“GBRA gets its fair share of both praise and criticism for its role inmanaging the <strong>Guadalupe</strong> <strong>River</strong> Basin,” West said, “but I hope GBRA’sparticipation and leadership in seeing this study through fruition showsjust how important protecting the environment is to us as we go aboutmanaging our water resources.”Steve Raabe, director of Technical Services for SARA, added, “Thesignificance of this study is it is the first time that a full ecosystemmodel has been developed for an ecosystem as complex as we haveon the Gulf Coast. It’s a very good leap forward, but it’s still just thefirst step.”Lee Wilson, president of Lee Wilson and Associates, anenvironmental consulting firm retained to ensure the study’sindependence, said that the team operated from the premise thatlow fresh water inflows, such as water coming from the river, wouldincrease the salinity of the bay, have an adverse impact on blue crabsand lead to increased crane mortality.The SAGES research, however, did not findthat salinity adversely affected the crabs orthe cranes.The study found that while in the salt marsh,thewhooping crane diet consisted of wolfberry fruit, blue crabs,clams, snails, insects, fiddler crabs, snakes and fish.Wolfberry plants tend to reach their peak fruit bearing seasonabout the time the whooping cranes beginarrivingin October.“Wolfberry fruit and snails and insects were consumed in thehighest quantities and required the least effort during foraging,and generally were associated with the most efficient foragingbehavior,” according to the Executive Summary of theSAGES Report. “Blue crabs were the most optimal food in relationto protein, and clams were a significant source of biomass. Whoopingcranes foraged most efficiently during the winter of 2005-2006 whenwater levels were lowest.”The population of whooping cranes at ANWR increased from 133 in1994 to 270 before 23 of them died over the winter.Only a few bodies were found, including one with a broken leg, onewith a parasitic infection, and one that appeared to have been eaten bya predator.Fieldwork for the SAGES study was completed before thewinter 2008-09.There was speculation that the drought, low freshwater inflows, andan increase in salinity in the marsh may have led to the high mortality“We understand that it is important tocomplete additional research to accompany theSAGES results.”rate by reducing the number of blue crabs available. Slack said he hadnot seen any evidence that a lack of nutrition caused the deaths.However, critics of the SAGES study contend that it ignorespreviously conducted research, and is incomplete because it did notcover this winter, when so many cranes died in the midst of a drought,when the marsh would tend to be salty due to lack of fresh water.11
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