Official Site of the Aransas National Wildlife Refuge Complex

Research

1. Voice Print Characterization to Identify Whooping Crane Pairs at Aransas National Wildlife Refuge and Wood Buffalo National Park. A project involving voice print analysis to identify whooping crane pairs at Aransas and Wood Buffalo was initiated in 1999 by Dr. Bernhard Wessling, a German chemist and crane vocalization expert. The project attempts to identify individual crane voices from computer analysis of digitized sonograms. The technique seems very promising in being able to track individual pairs in summer and winter without having to band them.

Whooping crane unison call recordings continued to be taken on the summer nesting grounds by Canadian Biologist Brian Johns. Dr. Felipe Chavez-Ramirez of the Platte River Whooping Crane Habitat Trust in Nebaska obtained grants from the Houston Endowment, The Magnolia Trust and the Whooping Crane Conservation Association to do recordings at Aransas. Nick Antich, a biological technician with Platte River Trust spent two months at Aransas obtaining recordings. In 2003 and 2004, technician Colleen Satyshur obtained additional recordings. She was able to record two-thirds of all wintering pairs at Aransas (46 of 69 wintering pairs). Dr. Felipe Chavez-Ramirez visited Aransas twice to get Colleen started with the voice printing project and also did some work trying to document crab movements in the marshes with video cameras.

2. Human Disturbance of Whooping Cranes at Aransas and Matagorda Island NWRs. Former graduate student Thom Lewis completed data analysis and began writing a report on his study of human disturbance of whooping cranes at Aransas and Matagorda Island. Thom completed his fieldwork in 1991, but never wrote up project results. The data is needed and the Refuge continued to encourage Thom to write the contracted report. We understand progress is continuing. In May 2005, T. Lewis did submit a draft report on his research.

3. "Linking Freshwater Inflows and Marsh Community Dynamics in San Antonio Bay to Whooping Cranes" will provide a significant amount of information regarding the role of freshwater inflows in maintaining critical elements of the habitat and food sources for the endangered whooping crane at the Aransas National Wildlife Refuge. This study is part of the Lower Guadalupe Water Supply Project and is a joint project sponsored by the Guadalupe-Blanco River Authority (GBRA), the San Antonio River Authority (SARA), and the San Antonio Water System (SAWS), Texas Agricultural Experiment Station, and USFWS. The goal of the Lower Guadalupe Water Supply Project is to provide a significant source of water for San Antonio, the Bexar County community and the surrounding region, while protecting inflows to the San Antonio-Guadalupe bay and estuarine system. The study evaluates the relationship between freshwater inflows into San

Antonio Bay and the health of the whooping crane population at the Refuge. The research includes studies of macrophytes and blue crabs in the saltwater marshes of the Refuge. Researchers are evaluating behavioral responses of whooping cranes to changes in food availability (primarily blue crabs), abiotic factors, and human-induced disturbances associated with the Refuge. The research will produce a simulation model that describes and predicts(1) effects of changes in temperature, salinity, dissolved oxygen levels, and water levels on blue crab availability and abundance; (2) macrophytic responses and rates of litter decomposition; and (3) Whooping Crane behavior and habitat use at the Refuge. Reseachers include Danielle Rutka and Kristin LaFever who are focusing on whooping crane behaviorial patterns and foraging patterns on territories along with dynamics and population studies of their main food source, the blue crab. Erin Li, George Gable, Carrie Miller, and Rachel Butzler are part of the Marsh Ecosystem Team focusing on water quality and connectivity of hydrological forces (tides, inflows, runoff, etc.) on materials exchange, inundation regimes, and vegetation dynamics. They conduct monitoring of water levels and sampling of productivity, nutrient cycling, phytoplankton, zooplankton, and biomass. This study will be conducted over a 6-yr. period at a cost of approximately $2M.

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