Dark Banquet - Bill Schutt [24]
A related, but less-cost-efficient, method of vampire control involves the inoculation of livestock with low doses of anticoagulants. Vampires feeding on the inoculated bovine blood suffer the same hemorrhagic fates as those grooming warfarin paste off their roost mates. While this systemic method eliminates the need to capture and correctly identify vampire bats, it does require the treatment of the entire herd in order to be effective.
In the end, both of these methods are successful because of the low reproductive rate in vampire bats. Like the vast majority of bats, vampires give birth to only one pup per year—a far cry from other mammal pests like rodents, who can crank out babies faster than a baseball player can split sunflower seeds.
Back in the slaughterhouse, Kim and I used the same colander to strain off the strange, woven clots that materialized in the barrel—squeezing out the blood they held, before discarding the sponge-like clumps in a waste bucket. After about fifteen minutes of this fun, the defibrinated blood that remained in the barrel (i.e., the blood minus the clotting factors and proteins making up the clots) was poured, still warm, into the two-gallon plastic containers we’d brought with us. By stimulating clots to form, and then removing them, we were assured that our defibrinated blood would remain liquefied and clot free during storage, and when we placed it out to feed our bats.
Although we didn’t realize it at the time, a similar method was employed between the 1820s and 1920s to defibrinate a human donor’s blood prior to transfusion. In the days before the medicinal use of anticoagulants, donated blood was collected in a bowl, whisked, and filtered before being transfused into a recipient.
Some researchers use an alternative method to facilitate the storage of blood (for vampire bat meals and other purposes). The technique involves “citrating” the blood by adding the compound trisodium citrate to it. This also prevents the formation of clots, and although we never employed this method, in hindsight it could have provided our captive vampires with a slightly more nutritious meal. This is because, unlike our whisk and filter method, the clotting proteins aren’t actually removed from the citrated blood.
After returning to our lab at Cornell’s School of Veterinary Medicine, Kim and I transferred the blood into several dozen Snapple bottles we’d collected earlier from the cafeteria (yes, we cleaned them first). We froze the blood-filled bottles, thawing one out each morning so that the liquid would reach room temperature by nightfall. That was when we fed our vampire bat colonies—pouring the blood into an ice-cube tray and elevating it with a wooden block so that the roosting bats wouldn’t have to strain themselves while they ate. As Farouk had done in Trinidad, we supplemented the diet of our white-winged vampires with a live chicken (once per week and on holidays). This turned out to be a vital step in maintaining our vampire colony, as I found out three years later.
Shortly after passing the bats off to another Cornell grad student (who had proposed a study on their digestive physiology), I received a rather frantic call from Kim. I discovered that the new researcher had not only relieved my friend of her bat-keeping duties but had decided to suspend the colony’s live chicken supplement (basically to save a few bucks each week while eliminating the far from insubstantial hassle of dealing with live chickens). Within ten days, vampire bats began dying at an alarming rate—a trend that stopped immediately after a “talk” with the grad student led to a resumption of weekly chicken dinners for the colony.
During the three years that we maintained our colonies of common and white-winged vampire bats, it’s safe to say that we saw some strange stuff, much of it relating to feeding behavior or social interactions between roost-mates. We found out later that Farouk and his Trinidadian bat crew had already noted much of what we were observing at Cornell. Their reluctance to publish,