Wild Animal News

The issue of invasive species is a problem world wide. Creatures are brought from their native habitats intentionally or by accident and the results can be anything from beneficial to disastrous.

Recently we have written about invasive hippos in Colombia, domestic cats (gone feral) in Australia, and spiders in the United States. Of the three highlighted, the Joro spider so far is the least damaging. Australia estimates that there are six million feal house cats in the country and they are devastating unique wildlife. Cats are superb hunters and flightless birds and small animals are no match for them and are being driven to extinction. The hippos in Colombia, like Burmese pythons in Florida, are also disrupting local wildlife and may drive some creatures to extinction. Once established. invasive creatures can be very hard to control.

In Alaska the problem is a small opportunistic mammal that almost every one hates: rats.

Rats are one of the most damaging invasive species in the world and are difficult to control because they are commensal. The word comes from Latin and refers to sharing the same table, which is what rats do. They live very close to humans and depend on human negligence and waste for their existence. They are legendary disease bearers and they destroy far more food than they eat. The rats in Alaska came with sailors from other countries and have a toehold in the state. The weather is a big help in trying to keep them at bay because the extreme temperatures are too much for them. There are native rodents, including muskrats, but they are adapted to the climate unlike the invaders.

Alaskan authorities are recommending the same control measures recommended everywhere: deny them food and shelter. If you watch your crumbs, keep an eye on your pet’s food and contain your garbage they will have little to eat. If you clean your house, and seal cracks and entrances they will have nowhere to live. Outdoors, cold weather and abundant predators will soon eliminate them.

Meanwhile, Anchorage appears to be rat free and hopes to stay that way. Scientists can point to one great success story: Hawadax Island. The small island in the Aleutian Chain was colonized by rats after a shipwreck. Rats proliferated and took over the island as they were the top predator in the locale. in 2008 a consortium of federal, state and conservation groups set out to eliminate them.

They used poison, which worked well but had some collateral damage. The island has been rat free for ten years and the benefits to the island appear to outweigh the collateral damage which probably included a few eagles as well as other animals that ate the poison. Birds have rebounded because the rats aren’t there to eat their eggs. Kelp appears to have rebounded too. The birds are back and their lifeways contribute to growth of kelp. Scientists say a rat free island is noisy with birds, an island with rats is silent because there are few birds.

It is the stuff of an arachnopobes nightmare: large as a human palm and spreading a huge web – it is the invasive Joro spider and it appears to have colonized Georgia and seems likely to spread throughout the eastern seaboard.

The joro spider is native to Japan. It began showing up in Georgia recently but there isn’t much to worry about according to The Alabama A&M and Auburn Universities Extension. They say Joro and similar spiders have been in the U.S. for about a decade and have not displaced native species. They have venom, most spiders do, but it is not medically significant. Their jaws are also adapted to biting soft-bodied insects, making bites unlikely.

Although it is so far benign in its impact -except to prey species – it is a non-native species and is being watched with care. Invasive, species, those that disrupt eco systems, are causing havoc all over the world. Many are far bigger than spiders. We have reported on a number of cases including hippos in Colombia. The hippos were brought to Colombia by drug lord Pablo Escobar and abandoned after his death. They are multiplying and may have to be killed to prevent all sorts of environmental damage. Also, There are numerous invasive species in Australia. Many of you are probably familiar with the invasion of Florida by Burmese pythons and the major efforts underway to fight them. Florida has been struggling for years, offering bounties, trying to find recipes and even importing snake hunters from Asia. A recent news article about a bobcat eating python eggs has been taken as a sign that native species are fighting back.

But humans are inventive and there is a never ending effort to control ongoing invasions by any means available. Recently, major advances in the war against dangerous insects point the way toward control of other invasive species. We recently reported on a major advance in the war on ticks, In the United States alone ticks are responsible for 14 dangerous diseases. Researchers at the University of Nevada have announced that they have found a way past tick defenses to modify their genes. Meanwhile, billions of genetically modified mosquitoes are to be released in Florida and perhaps California to drive down the population of the biting insects. This is similar to the very successful efforts eliminate screw worms by releasing sterilized flies. The federal government has approved the pilot program. Disease carrying mosquitoes have arrived in the US carrying yellow fever, dengue fever and Zika virus. The release, which has met with opposition, is designed to reduce the number of mosquitoes. The mosquitoes are male, which do not bite. They are designed to mate with females who will then produce a generation of females that do not survive to maturity, thus breaking the reproductive cycle.

Genetic modification can be done on large animals as well, but is likely to be even more controversial. Australia is plagued with 6 million feral cats which are annihilating native species. So Australia is considering bioengineering methods to destroy the cats, The methods under study include similar controls imposed on insects. One idea is genetically modifying the cats so that only one gender is born. This would quickly lower the population. Other options include making the animals more susceptible to disease. One thing is likely – there is likely to be more public concern about genetic assault on larger animals than there is on ticks, fleas, mosquitoes, flies or even, potentially, spiders.