I read a recent blog post highlighting the feral cat problem in Hawaii (http://rumpydog.com/2014/08/14/so-hawaii-wants-to-kill-cats/). The post mentioned a paper published in Conservation Biology which indicated that Hawaiian residents preferred euthanasia over trap-neuter-release (TNR) programs when it came to feral cat management (http://onlinelibrary.wiley.com/doi/10.1111/cobi.12201/abstract;jsessionid=FB4AAB1970A118DB0073E69D40924627.f01t04?deniedAccessCustomisedMessage=&userIsAuthenticated=false). This study was criticised as being flawed and its findings erroneous by Vox Felina, a group that supports TNR (http://www.voxfelina.com/2014/08/a-response-to-lohr-and-lepczyk/).
Whether or not the Conservation Biology study is flawed is irrelevant. What the residents of Hawaii prefer in this regard is also irrelevant. The fact remains, feral cats should not be present on Hawaii. They were introduced in the 1800s and have caused untold destruction to the native bird life since then. These species, like the birds of New Zealand, evolved without the presence of predators and are ill equipped to deal with them. Neutered cats kill just as many birds as cats that have not been neutered.
The debate over TNR and euthanasia only occurs because we have an emotional attachment to cats that has evolved over many hundreds of years. No one appears to be advocating TNR programs for the possums of New Zealand, the rabbits of Australia or the brown tree snakes running rampant on Guam. Why the inconsistency? All four groups of animals are feral and cause untold damage to their new environments, environments which will only recover properly if these animals are completely removed. The only way the New Zealanders were able to successfully reintroduce any of their endangered birds to their offshore islands was to remove every last cat.
As well as the predation issue cats also carry toxoplasmosis. This disease is caused by a small parasite that needs cats to complete its life cycle. It causes no disease in cats but has killed alala (Corvus hawaiiensis), nene (Hawaiian goose; Branta sandvicensis), red-footed boobies (Sula sula) and even the endangered Hawaiian monk seal (Monachus schauinslandi). Toxoplasmosis is also a zoonosis, posing health risks for pregnant women and immunocompromised people (http://www.usgs.gov/ecosystems/pierc/files/factsheets/cats.pdf).
Unfortunately as long as there are feral cats running around the Hawaiian Islands, its bird species will be at risk of extinction. No TNR programs will remedy that. The only remedy is to remove the cats from the environment. Anything else is nonsensical.
Dr. F. Bunny