Showing posts with label island wildlife. Show all posts
Showing posts with label island wildlife. Show all posts

Wednesday 24 November 2021

Hawaiian government procrastinates about how to deal with their 'cat problem'

US News today reports on a male Hawaiian monk seal dying after a five-week battle with toxoplasmosis. It has prompted another discussion about how Hawaii should deal with both domestic and feral cats. The argument is that the toxoplasma oocysts which are shed in both feral and domestic cat faeces (once) somehow make their way to the sea where monk seals ingest the oocysts and become infected with toxoplasmosis.

Comparison of size of Hawaii 4 main islands with UK
Comparison of size of Hawaii 4 main islands with UK. Image: MikeB from

They tried to save this seal but, as mentioned, it died. The seal, known as RW22, was treated at the Marine Mammal Center. They called on cat owners to keep their pets indoors and to dispose of faeces in cat litter in the trash. It's another instance of where putting cat litter down the toilet is a bad idea. It has to going to landfill. However, I guess oocysts can still make it to the sea from landfill under certain circumstances.

But the point of this article is that in 2016, five years ago, there was a report of eight monk seals dying for the same reason. The symptoms in the infected seals vary but they included lesions in the brain, adrenal glands, diaphragm, lymph nodes and spleen. In the case of RW22, the seal showed signs of partial facial nerve paralysis and a corneal ulcer which they believed were symptoms of toxoplasmosis.

So there is an ongoing problem if the experts are right in Hawaii of feral and domestic cat faeces making their way to the ocean around the four main islands. And little or nothing has been done about it, it seems to me, over the intervening five years and I presume longer.

They are constantly moaning about a feral cat problem on Hawaii with the cats attacking precious Hawaiian birds. There's been report about that as well. They appear to be scratching their heads about how to deal with the problem.

I think the real problem is a lack of leadership in the Hawaiian government. This is combined with a lack of commitment in dealing with this problem.

One website tells me that there are TNR programs on Hawaii run by volunteers which is very normal but that the government opposes them. They don't think it works. That too is quite normal. Some people support TNR and others disagree with it. It is too slow for some and returning the cats to where they came from doesn't make sense to some people.

However, the 4 Hawaiian main islands are about 1/15 the size of the UK. The point is that it is not a huge geographic area and it makes me believe that the government could successfully operate widespread TNR on the three smaller islands to start off with. 

They could support the volunteers and formalise TNR programs to make them more widespread and therefore more effective. Currently it is the only way to deal with feral cats humanely. You have to deal with the cats humanely because people put them there. And killing them is ineffective due to the vacuum effect. 

RELATED: Kerala, India: High Court orders registration of companion animals

In parallel with that there should be more determined approach to managing domestic cat ownership and raising standards. You'll find quite a lot of discussion in other parts of the world on obligatory micro-chipping, spaying and neutering and on occasions curfews either during the night to keep the cats inside or even mandating keeping cats within the bounds of the owner's property full-time. 

I'm not saying that that is the way to go but with a manageable human population size it may be feasible to operate obligatory registration of domestic cats and from there to make micro-chipping and spaying and neutering obligatory as well. The hard part is effective enforcement of mandatory pet registration laws.

This would improve domestic cat ownership, reduce the number of unwanted cats, reduce the number of feral cats in parallel with TNR which will gradually over a period of say 20 years reduce the population of feral cats. It's a long-term project. There is no other way. But if they'd started this 20 years ago they would have made some progress by now.

Friday 23 July 2021

Extinction of mammals on islands by introduced domestic and feral cats

When the predation of wildlife by feral and domestic cats is raised as a topic the devastating impact of cats on islands is invariably a major issue. Wildlife species on islands are particularly vulnerable because they are isolated from many of the diseases, predators and parasites that plague mammals on the mainland.

Stewart Island
Stewart Island - Photo: Getty Images / tsvibrav

Dr. Bradshaw states that island species account for 83% of all documented extinctions of mammals. However, scientists can only implicate feral cats in the destruction of wildlife on these islands in about 15% of such extinctions. And further, within that 15% of such extinctions to which the blame is only the feral cat, other introduced predators should take their share of the responsibility according to Bradshaw in his book Cat Sense.

He says that mongooses, cane toads and especially rats are equally if not more devastating than feral cats on wildlife predation. Black rats a.k.a. ship rats, it is claimed, can do more damage than any other introduced predator. It is ironic, therefore, that it may be beneficial or there are at least some benefits to not slaughtering feral cats because cats are reasonably effective hunters of black rats according to Dr. Bradshaw.

If you attempt to exterminate feral cats (as is currently the objective of Australian legislatures) you might find that the outcome is far worse than imagined in terms of the population of black rats. He cites the example of Stewart Island off the coast of New Zealand. On that island feral cats have existed for more than 200 years with an endangered flightless parrot called the kakapo (owl parrot Strigops habroptilus). The cats mainly fed on the introduced species of the brown and black rat. Those species of rat have been held responsible for the extinction of several other species of birds in the same area.

Removing the cats in these places might lead to an increase in the rat population which in turn might lead to the extinction of the kakapo.

That's just an example because sometimes eradicating cats from an island can lead to a dramatic recovery in the population of certain vertebrate species. Bradshaw cites examples such as iguanas on Long Cay in the West Indies. Also, deer mice on Coronado Island in the Gulf of California.

Although, there is no doubt that the sheer number of feral cats in most places must have a significant impact on wildlife. The difficulty, as I see it, is quantifying that impact and the way that ornithologists and their organisations latch onto biased or estimated predation rates in rather poor studies to further their agenda which is to in effect kill large numbers of cats.

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