So, I have been following PZ Myers’ blog at Pharyngula for some time and it always makes me smile when he comments on some of his email correspondance. Well, I had a bit of a mention in a news story last weekend which looked at the control of feral cat populations (see the Ottawa Citizen article). As a result, I received the following email:

Dear Sir:

On the weekend I read an article by Graham Lanktree for the Postmedia News and I am very disappointed that someone of your stature would say such irresponsible things about TNR programs. I am not officially connected to any animal rescue group but while working on a construction project for more than three years I became involved with a feral cat colony. It started out by me feeding a litter of kittens and ended by me trapping, neutering and returning over a dozen cats. Also, over a dozen kittens are now happily adopted in forever homes. These past few months I returned to the colony and trapped two more juveniles who where fixed and released and two more kittens that are now in foster care.

Has it made a difference? I believe it has. One of the original members of the colony I had to have euthanized. He was a unneutered male who I thought was an old cat. It turns out he was only 3 years old. The tough life of a feral aged him quickly. He had feline leukemia most likely contracted from fighting over females. One of his offspring that is still part of the colony is a healthy cat that looks like he could be somebody’s pet. All of the cats recently trapped are disease free. Has it made a difference? Yes it has.

You contend that more research needs to done. I could not agree more. Perhaps someone with your education and position could undertake it instead of further denigrating the work of others.

Sincerely, [redacted]

I was pleased that someone had taken the time to get in touch with me about this, because too many people might have unquestioningly accepted the “scientist’s” view.  I have had a similar exchange about a paper I published on IQ which was initiated by someone on Google+.  It really is great to have interactions with people who want to learn more or clear up uncertainties!

Now my receiving an email in response to this article shouldn’t have come as too much of a surprise given the emotionally charged debate that rages over the control of feral cats. The research isn’t particularly thorough up to this point which makes most positions largely based on extrapolations from small numbers of studies or arguments from gut instinct. That said, I felt the need to respond (particularly to the accusations of being “irresponsible” and “denigrating the work of others”). Also, it gives me a chance to reference some of my claims (which is sadly lacking in the media…):

Dear [redacted],

Thank you for taking the time to get in touch with me about TNR schemes and I am sorry that you find my opinions “irresponsible” and “denigrating”. Let me take a few minutes to briefly justify my statements (taken from the Ottawa Citizen story):

“Yet, community groups seeking to fill the vacuum by stepping in with TNR programs are wasting their time, says Chris Hassall, a conservation ecologist at Ottawa’s Carleton University.”
This is a direct quote from a paper that evaluated the use of TNR to control feral cat populations in Rome (Natoli et al., 2006). They neutered over 8,000 cats from 103 colonies and found a marginal (16-30%) decline in cat numbers over that time. They conclude that “…all these efforts without an effective education of people to control the reproduction of house cats (as a prevention for abandonment) are a waste of money, time and energy.” Note that I was paraphrased, not quoted, in the “wasting their time” section. I was citing the aforementioned study.

“One of the main things you notice when you look at the research literature around trap-neuter-return is how poorly we understand these feral cat colonies,” he says.
I think we probably both agree with this.

“I’m skeptical of the role TNR could play. There are lots of emotional arguments and little intensive research to back it up.”
I think I was correct here. There is no evidence that TNR schemes can work in large populations of cats. Along with the Natoli et al. (2006) study, an even larger study looking at the effects of two TNR schemes in the USA (Foley et al., 2005) stated “results of analyses did not indicate a consistent reduction in per capita growth, the population multiplier, or the proportion of female cats that were pregnant.” There does seem to be some efficacy in smaller populations (on the order of 100 animals), but success was only achieved by removing a substantial number of animals through adoptions (Levy et al., 2003). This is not sustainable at larger scales, as humane societies are killing dozens of cats per week already due to lack of homes.

That’s not to say feral cats don’t pose a significant concern to public health and local wildlife, Hassall says. “We know that, given the opportunity, they will eat reptiles, amphibians and that 20 per cent of their diet are birds.”
There have been a number of studies of prey preference in feral cats. If you are interested, those studies are: Barratt (1997), Coman and Brunner (1972), and Paltridge et al. (1997).

“In an urban environment, we’re already looking at an ecologically desolate place and that additional pressure can have a big impact.” There’s also the fact that 80 per cent of rabies shots are given in the U.S. because of contact with infected cats, he adds.
I stand by my diagnosis of the urban environment as “desolate”. The environmentalist Aldo Leopold once wrote that “One of the penalties of an ecological education is that one lives alone in a world of wounds. Much of the damage inflicted on land is quite invisible to laymen.” Such is the situation with the urban environment, with its parks, gardens and lawns. The rabies paraphrase was slightly incorrect. 80% of rabies shots in the US are given due to contact with cats, but there are very few cases of rabies in cats.

Two large-scale studies of TNR programs in California and Florida, Hassall says, showed no decline in the population of feral cats because gains were offset by people introducing new animals into the area.
These two studies were described in the Foley et al. (2005) paper, although the problem with new introductions was more the focus of the Natoli et al. (2006) paper.

To create an effective TNR program, he says, would require thorough monitoring and complimentary efforts, such as adoption and vigorous public education campaigns.
I think we both agree with this as well.

If there are specific claims that you take issue with then I would be more than happy to discuss them with you. Also, I wondered whether you might agree to my publishing your email (without your name, of course) on my blog? I think it is important that this issue is more widely discussed. My involvement in this issue has made me more interested in possibly pursuing TNR as a research project, although that will be limited by availability of grant funding (as all academic work is). I understand that people often become emotionally involved in these issues and I hope that you realise that the opinions that I was asked for (and offered) were those based on the peer-reviewed science,

Yours sincerely,

Chris Hassall

References:
Barratt, D.G. (1997) Predation by house cats, Felis catus (L.), in Canberra, Australia. I Prey composition and preference, Wildlife Research, 24: 263-277.
Coman, B.J. and Brunner, H. (1972) Food habits of the feral house cat in Victoria, Journal of Wildlife Management, 36: 848-853.
Foley, P., Foley, J.E., Levy, J.K. and Paik, T. (2005) Analysis of the impact of trap-neuter-return programs on populations of feral cats, JAVMA, 227: 1775-1781.
Levy, J.K., Ggale, D.W. and Gale, L.A. (2003) Evaluation of the effect of a long-term trap-neuter-return and adoption program on a free-raoming cat population, JAVMA
Natoli, E., Maragliano, L., Cariola, G., Faini, A., Bonanni, R., Cafazzo, S. and Fantini, C. (2006) Management of feral domestic cats in the urban environment of Rome (Italy), Preventive Veterinary Medicine, 77: 180-185.
Paltridge, R., Gibson, D. and Edwards, G. (1997) Diet of the feral cat (Felis catus) in Central Australia, Wildlife Research, 24: 67-76.

Now, I have seen the tone that some of these discussions can take but I felt that I had handled it fairly and with as much scientific rigor as I could muster. I didn’t expect my correspondent to check any of those references and he probably wouldn’t be able to get access to the papers, anyway (but don’t get me started on access to scientific literature…). There were three ways this could have gone: (i) silence, (ii) an angry response, or (iii) the Canadian response:

Dear Chris:

Thank you for the reply and please call me [redacted]. My initial concern with your comments had to do with the statement “wasting their time.” I appreciate you clearing that up. The Italian study was never mentioned and the “wasting their time” quote was attributed directly to you. You can understand my confusion. This is actually lazy reporting or an attempt to stir the pot by this reporter. That being said, I do not agree that 16 to 30% is a marginal success rate. Perhaps the study was more concerned with getting rid of the cats rather then their welfare. I understand that. Everybody has their own agenda.

I agree 100% that education is needed, however; people being people I’m not sure this will ever be achieved. The colony that I mentioned in my previous e-mail was started by some irresponsible relatives of an elderly lady that had passed away. She had numerous cats and they were just turned out when her house was cleaned up. I realize the population of this colony is not significant (10 -20 cats) but I have spent a lot of time observing their interaction. When I first came upon them they were all individuals, scared and very wary of each other. As I got the colony under control through TNR they became tamer. I even saw them sitting in the sun with neighbourhood pets and some even started to travel in pairs or small groups. I was glad to see that.

As for you scepticism re TNR. Again you clarify by saying “large populations.” This was never mentioned in the article. My concern is that there are people out there like myself that are making a difference in smaller populations may read this article and abandon their efforts due to these quotes. I sincerely hope I am wrong.

I have absolutely no problem with your contention re the predatory nature of cats. I have two of my own and they are indoor animals as I believe all should be.

The premise that TNR does not work because of immigration is a mystery to me. If you have 50 cats and you neuter them all and then someone introduces 10 “new” cats to the colony is this still not progress? Doing nothing and having 60 unaltered cats doesn’t seem to be an argument against TNR.

I am happy to hear that you are considering this as a study. Good luck with your funding. And if you want to use my previous or this e-mail on your blog please be my guest. The only thing I request is that you forward me a link so that I might read it. And further comment if there is a forum.

Regards, [redacted]

I don’t see the need to add much more to this. My correspondent and I differ in our aims with regards to TNR. He sees merit in improving the lives of feral cats while I see the lives of feral cats as a potential problem for other wildlife.  I think that the precautionary principle should apply and we should reduce feral cat colonies to the lowest possible levels.  I did a fair amount of reading and I’ll be drafting a more comprehensive review to demonstrate why I feel this way over the next few weeks.