Is West Nile Virus killing our crows and blue jays?

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For the past three years or so, each week-day afternoon when I attend the meeting of the Geezers at Hardee’s on Marvyn Parkway, I bring some food scraps and drop them on the parking lot. Between three and six crows would be expected to immediately descend for an afternoon treat. Then, one day about four weeks ago, no crows showed up, and it’s been that way since. I began to suspect that a disease of some sort may be affecting the crow population, so I began paying attention to the number of crows I would see driving around and to the number on and around my property. I observed a few, but not nearly as many as in the past. I also noticed an apparent decline in the blue jay population.

Could it be that the crows and jays are contracting West Nile Virus? The disease is known to affect birds of the corvid family, which includes crows and jays, much more severely than numerous other birds known to be reservoir hosts of the mosquito-transmitted disease. In one area where the disease is endemic, the crow population declined by 90 percent. In some other areas studied, WNV killed between 30 and 60 percent of the resident crows.

The disease is increasing in Alabama. Six cases have been reported in humans in Montgomery County; three in Mobile County; and one each in Baldwin, Tuscaloosa, and Jefferson counties. Some people who contract WNV are asymptomatic, and in others the symptoms are so mild that they do not seek medical attention. In a small percentage of the affected people, the virus spreads to the central nervous system resulting in encephalitis or related disorders and may cause death. One patient died in Montgomery County.

Last Friday, I was told that a patient at EAMC had tested positive for WNV, but the State Department of Public Health has not confirmed the report. The department has reported that WNV has been detected in 14 wild birds in Lee County. An avian pathologist with the State Veterinary Diagnostic Laboratory in Auburn told me that “several crows” brought to the laboratory had tested positive for the disease.

Birds are the main reservoir hosts for another mosquito-borne disease, Eastern Equine Encephalitis. The EEE virus can be contracted by a wide variety of animals, but horses seem to be more susceptible than most others. Humans can be infected, but human cases are rare. EEE occurs in Lee County horses and the disease can be fatal. Dr. Kim Bond, an Auburn veterinarian, told me she recommends that owners of horses vaccinate their animals against both EEE and WNV. Vaccines are unavailable to prevent humans from contracting EEE or WNV.

Because both these diseases are endemic to Lee and surrounding counties, residents should take measures to avoid being bitten by mosquitoes, which are most active from late afternoon to early morning.

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It’s Monday evening and I’m hoping and praying Isaac will deliver us some badly needed rain this week. It will be too late for the white oaks on my property to produce a crop of acorns. Five years ago, the trees produced a healthy crop. During the ensuing three years none were produced, and this year, the drought-stressed trees are dropping immature pea-sized acorns on my deck, meaning another bad year for deer, turkeys, and other critters that rely heavily on acorns for food.

I’m wondering what the ground-dwelling critters in my woods are doing to satisfy their thirst. Both brooks on the property have been bone dry for at least two months. My pond still has some water, but small animals that rely on the pond water for drinking must leave their protective forest cover and subject themselves to increased risk of being killed by predators.

Speaking of predators, researchers at the University of Georgia attached video cameras to 60 free-ranging house cats to determine what they were killing during daylight hours. Snakes, lizards, and frogs made up 41 percent of the kills; small mammals, 25 percent; and birds, 12 percent. George Fenwich, of the American Bird Conservancy, says, “Based on a U.S. cat population of 74 million, cat predation is one of the reasons why one in three American birds are in decline.” (USA Today, Aug. 7)

Since the Observer received this column, there have been even more reports of West Nile Virus affecting humans including at least one still unconfirmed case in Opelika.

Bob Mount is a Professor Emeritus with the Dept of Zoology and Entomology, Auburn Univ. He is also chairman of the Opelika Order of Geezers, well-known local think tank and political clearing house. He writes about birds, snakes, turtles, bugs and assorted conservation topics.

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