TPWD News Release — Dec. 18, 2009
DALHART, Texas — State and federal officials are investigating the deaths of about 2,000 geese and ducks discovered this week near Dalhart in the northwest Texas Panhandle. Preliminary results of lab evaluations indicate naturally-occurring avian cholera is a factor.
Avian cholera poses no threat to human health and while the die-off could affect local waterfowl populations, wildlife officials say isolated events like this are not uncommon for the area.
On Tuesday, Dec. 14, Texas Parks and Wildlife Department biologists and game wardens observed about 1,000 dead geese on Lake Rita Blanca, a 500-acre impoundment on the outskirts of Dalhart. An additional 1,000 dead geese and ducks were found on a nearby wetland.
TPWD officials suspect the die-off event likely began during the first week of December when temperatures in the area dropped to near zero for lows and stayed near or below freezing during the day for about a week. Flocks of about 30,000 geese were on Lake Rita Blanca when temperatures plummeted, causing the lakes to freeze up.
Biologists theorize the near zero temperatures triggered stress in the geese, which often gives rise to disease outbreaks. In this case, preliminarily signs suggest avian cholera as a likely bacterial agent involved.
Fifteen specimens of waterfowl collected from the site by TPWD were shipped to the U.S. Geological Service’s National Wildlife Health Center in Madison, WI, for clinical evaluation to determine the cause of death. USGS Wildlife Disease Specialist Dr. LeAnn White advised TPWD that a preliminary examination of the specimens were suggestive of a cholera outbreak, but cultures of the causal agent will not be ready for several more days. A formal report will be sent to TPWD at that time.
According to the Wildlife Disease Action Plan established to handle such problems and coordinated between TPWD, the U.S. Fish and Wildlife Service and USDA Wildlife Services, once a disease outbreak has been documented proper precautions are taken to protect wildlife and human health. Precautions should be taken when handling dead birds, such as wearing protective gloves.
Avian cholera is highly contagious among most birds and can spread rapidly. Prompt action is often needed to prevent and minimize the spread of the disease. In addition to monitoring the situation, during severe outbreaks dead and sick birds may be picked up and incinerated to slow the spread of diseases.
While most birds can become infected with avian cholera, the species most commonly affected are ducks and geese, coots, gulls, and crows. Avian cholera does not pose a threat to human health, according to the USGS Wildlife Health Center, but common sense precautions should be used when handling wild fowl.
Geese can carry the organism without active disease symptoms showing until severe stress gets involved, triggering active symptoms.
The bacteria can be transmitted by bird-to-bird contact, contact with secretions or feces of infected birds, or ingestion of food or water containing the bacteria. Aerosol transmission may also occur. The bacteria may survive up to 4 months in soil and water.
Death may be so rapid that birds literally fall out of the sky or die while eating with no previous signs of disease. Sick birds appear lethargic, and when captured may die within minutes. Other signs include convulsions; swimming in circles; throwing the head back between the wings; erratic flight, such as flying upside down or trying to land a foot or more above the water.
The Texas Panhandle has long been known for small and occasionally large disease outbreaks of avian cholera in waterfowl when severe cold begins to stress the birds. TPWD waterfowl biologist Bill Johnson said he has seen these problems on an annual basis when the right conditions come into play, "but we are fortunate that severe cold usually does not last too long and the problems are usually relatively small."
"Temperatures in the area have been moderating for the past week and the frozen lakes are rapidly thawing. There does not seem to be new birds being added to the die-off," said Johnson. "Signs indicate the event is about to run its course, but we will continue to monitor the situation, especially if severe cold returns to the area."