Where have all the critters gone?

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By Bob Mount

Janie and I had a house built in the country and moved in 28 years ago. Critters of numerous kinds were common on the property. Snakes of the non-venomous kinds were abundant, including eastern kingsnakes.Rattlesnakes were rarely encountered, and copperheads were also rare, possibly because they are among the favored prey of kingsnakes.
Cottontail rabbits abounded in the open areas of the property and swamp rabbits were common in tha switch cane thickets along the creek in back of the house. At night numerous southern flying squirrels were attracted to my bird feeder, and I could often hear the calls of Screech Owls. During the warm season, beginning around April 15, several Chuck Wills Widows would begin serenading me with their pleasing calls each night. Each morning and early evening, Wood Thrushes would issue their beautiful, plaintive calls from the surrounding woodlands.
I made a small garden close to the house, but was unable to harvest any crops until I erected a rabbit-proof fence around the garden to prevent the cottontails from eating the sprouting seedlings. The only critters I expected to see frequently but did not were gray squirrels. Apparently, the former owner or his friends were squirrel hunters and kept the population down. It wasn’t long, however, before the population exploded. The rascals would raid my bird feeder and in short order would eat all the seeds.
Meanwhile, flying squirrels no longer visited and I rarely heard a Screech Owl. I attribute this to the gray squirrels’ appropriating the tree cavities that provided nesting sites for the flying squirrels and owls. I decided to take some remedial action and during the past several months I have trapped and relocated 18 gray squirrels. I hope the flying squirrels and Screech Owls will again make an appearance. Only time will tell.
The first coyotes appeared in our area in the 1960s. Their numbers have increased since then. I strongly suspect that coyote predation is the major reason for the declines of the rabbit populations.
I now hear no more than one Chuck Wills Widow each spring and as often as not, none at all. Two reasons have been advanced to explain why these birds are so scarce. First, their overwintering habitats in the tropics have been degraded, and insecticides are increasingly being used there. In their breeding habitats in North America, the numbers of large, night-flying moths and beetles that constitute most of the birds’ prey are not as abundant as they used to be. The declines in Wood Thrushes, Purple Martins, and quite a few other migratory birds are thought to be the result of a deterioration of their tropical overwintering habitats.
Armadillos appeared in eastern Alabama in the 1980s and quickly became abundant. About three years ago, their numbers began to decline, and now they are scarce. I see no more than one armadillo each month, when a few years ago I would see two or three each week. Some have postulated that the decline may be the result of a disease epidemic, whereas others attribute the decline to coyote predation.
Coyotes are known to catch and eat armadillos.
In a recent column I surmised along with others that the disappearance of common black tumblebugs was because they were being poisoned by the chemical ivermectin in the manure deposited by livestock being treated with the chemical. An article in “Mother Jones” written by Richard Conniff lends support to my contention that dung beetles, including the black tumblebug, are adversely affected by ivermectin, which is widely used on livestock. In the 2015 issue of “Scientific Reports,” an article states that between 62 and 98 percent of every dose of ivermectin administered to livestock ends up in the recipient’s droppings, which are eventually consumed by dung beetles.
Elizabeth Nichols, a Swarthmore College biologist, states that a healthy dung beetle population rapidly reduces standing dung heaps in pastures where livestock graze. By one estimate, according to R. Conniff , where ivermectin ‘knocks down’ the population of dung beetles in a cattle pasture, an extra 312 pounds of dung pile up on every acre every year. He adds that worldwide nearly 8 billion acres are now being used to graze livestock, which means ‘the great pile up is happening everywhere.’
Ivermectin is used not only on livestock. It is also used to treat and prevent a number of human ailments, including river blindness, elephantiasis, and head lice. It is also used to prevent dogs from getting heart worms. Over 30 years Merck & Co. has distributed ivermectin free of charge to treat human diseases. Last year, the developers of ivermectin earned a share of the Nobel Prize in Physiology and Medicine for its contribution.
Merck was involved in a study to determine whether a formal environmental impact study of the effects of ivermectin was warranted. The study reported that it was not, because the chemical and related compounds did not adversely affect humans. It did, however, acknowledge that it and they can interfere with the activity and survival of dung beetles.
Bob Mount is a Professor Emeritus with the Department of Zoology and Entomology at Auburn University. 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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