Biological Control Gone Wrong
Indian Mongoose / Donald Hobern
This blog post was originally an email series in September 2019
We couldn’t talk about the Cane Toad as an invasive species without mentioning the most notorious of them all, the Indian Mongoose.
Here’s an excerpt from ‘Rats and the Mongoose in Jamaica’ from the book Glimpses of Jamaican Natural History Vol 1, by C.B Lewis published in 1945 by the Institute of Jamaica.
“The European brown and black rats probably reached Jamaica by the earliest ships. In any case these prolific rodents, along with the equally prolific cane-piece rat, have always been a tremendous problem on sugar estates, and for several hundred years estate owners have found it necessary to expend large sums for rat catching....”
“The ‘bull frog’ (Bufo marinus) was introduced by Mr. Anthony Davis in 1844 also to destroy the young rats. It is not known whether the “ bull frog “, which is really a toad, was ever even locally effective in this respect, in any case the rats were as abundant as ever.....”
“In 1816, in Hortus Jamaicensis, Lunan suggested the introduction of the mongoose from India. The mongoose, being an animal with a natural antipathy to rats, might probably, to quote Lunan, “ extirpate the whole race of the vermin.”
“Around 1872 many animals were imported by a number of different estates, but all of these animals were obtained from London, having been bred in captivity. They proved to be useless when it came to catching rats, for, as one estate owner put it, “ they were literally afraid of a rat.” Mr. W. B. Espeut, of Spring Garden Estate, Portland, was the first to import some animals direct from India. Probably all of the animals on the island to-day are descendants of the four males and five females which he liberated on his estate in 1872....”
“ The introduction and complete naturalization of an animal possessing such strong predatory habits and remarkable powers of reproduction, must have an important influence on all indigenous and introduced animals capable of being affected by it.”
The natural food of the mongoose is birds, snakes, lizards, rats, mice and, last but not least, the eggs of both birds and reptiles.
The depredations of these animals on poultry and other domestic animals were soon noticed, particularly by the peasantry.
By 1882 scientists noticed the rapid diminishing of ground nesting birds, sea and water fowl, the yellow snake, which was itself a good rat catcher, and ground lizards....”
The bullfrog mentioned above is none other than the Cane Toad.
“The introduction of any animal into a new habitat involves certain important and highly complicated biological principles and interrelationships. In any long established, undisturbed area the native plants and animals exist in fairly constant proportions—a natural balanced condition. The balance of populations fluctuate slightly from year to year and may, over a period of years, gradually change ; but if a highly prolific predatory animal is introduced into a community, which will provide no natural enemies, it is obvious that the natural balance of the community will be greatly upset.
The unfortunate introduction of the mongoose into West Indian islands is cited the world round, and will continue to be cited as an example of ill-advised tampering with established natural conditions. The mongoose was introduced without consideration of its habits, other than its antipathy to rats. Eventually the mongoose will assume its place in a new balance of the wild life community, but in the meantime certain species of animals will have become extinct and many others will have become reduced in numbers and changed in habits.”
The mongoose has played a role in declining species populations leading to the possibly extinction or extinction of five Jamaican endemic species ; two birds: the Jamaican Petrel and the Jamaican Poorwill, an amphibian : the Giant Galliwasp, a mammal: the Jamaican Rice Rat and a reptile: the Black Racer (snake).
All natural food of the mongoose including the eggs of birds and reptiles
The Jamaican Petrel is a critically endangered, possibly extinct seabird endemic to Jamaica, last positively identified in 1879.
Read more about the Jamaican Petrel here