The Problem of Feral Cats

Feral cats kill about 1 million native animals per day in ecosystems which didn’t evolve to cope with cats. How should we deal with the problem of feral cats? I hear a lot of ‘kill ’em all’ [1]. When in HK I noticed a lot of cats with one ear slightly smaller.. then found out that there were vans of vets capturing then de-sexing cats, marking them by taking a small slice of their ear, then releasing them. I thought that this was a compassionate approach, though may have cost more to do than just killing the cats.
This issue raises some interesting fundamental questions that humans often seem all to ready to answer with our amygdalas – it’s hard not to, it’s in our nature. Though we do realize that us humans have had the largest impact on the ecology – and that it’s our own fault feral cats are here. Despite it being humanity’s fault, the feral cat problem still remains. As long as there are a population of human pet owners won’t be 100% responsible for their cats, the feral cat problem will always exist. A foolproof morality pill for humans and their pets seems quite far off – so in the mean time, we can’t depend on changing cat and human behaviour.

To date, feral cat eradication has only been successful on small islands – not on mainlands. Surprisingly, it was accidentally found that low-level culling feral cats may increase their numbers based on observation in the forests of southern tasmania – “Increases in minimum numbers of cats known to be alive ranged from 75% to 211% during the culling period, compared with pre- and post-cull estimates, and probably occurred due to influxes of new individuals after dominant resident cats were removed.”

A study by CSIRO, which advocates considering researching and eventually using gene drives, says:

So far, traditional controls like baiting have not been effective on cats. In fact, the only way land managers have been able to stop cats from getting at our native animals is to construct cat-proof fencing around reserve areas, like those managed by Australian Wildlife Conservancy, then removing all the cats inside and allowing native mammals to flourish. This isn’t considered sustainable in the long term and, outside the fences, this perfect storm of predatory behaviour has continued to darken our biodiversity landscape.

The benefit of gene drives is that it can reduce and even eventually eradicate feral cat populations without killing the cats, but by essentially making it so feral cat offspring all end up male.

…there is hope on the horizon—gene drive technology. Essentially, gene drives are systems that can bias genetic inheritance via sexual reproduction and allow a particular genetic trait to be passed on from a parent organism to all offspring, and therefore the ability of that trait to disperse through a population is greatly enhanced… Using this type of genetic modification (GM) technology, it becomes theoretically possible to introduce cats into the feral populations to produce only male offspring. Over time, the population would die out due to lack of breeding partners.

Research into gene-drives and broader genetics can help solve a lot of other related problems. Firstly I don’t assume we should just assume that future tech will be able to solve all our problems, though if we sequenced as much species as possible and kept highly accurate and articulate records of ecosystems, this may help to rejuvenate or even revive species and their habitats at some time in the future – and genetics (esp gene-drives and CRISPR) research has proven to be very powerful – so from the point of view of wildlife / ecosystem preservation, a catalog and revive strategy is surely worthy of serious consideration. One might see it as restoration ecology + time travel.

There are a myriad of considerations but what are the fundamental, ultimate goals of mitigating the negative impacts of feral cats? Two goals may conflict – species preservation and overall suffering reduction. Should we see single goals as totalizing narratives – in practice perhaps not – but great fodder for thought experiments:
1) Species preservation: If this is the ultimate goal, acknowledging that the most upstream cause of feral cats are humans, we could impose staggeringly huge fines on people for not being responsible pet owners – and use that to fund studies and programs for ecosystem preservation – given current technology we can’t resurrect long gone species, though we can try to more deeply catalog species genomes and ecosystem configurations with the hope that one day once we solve human irrationality, perhaps we can then be in a position to choose to engage in efficient comprehensive re-wilding programs – incidentally we may wish to curb the population of pet lovers (for the record, that’s a joke :))
2) If Suffering reduction is the ultimate goal then that really changes things up – there is a ridiculous amount of suffering in the wild, as both David Pearce and Richard Dawkins show. Should we eradicate nature? I’ll stop there.

The total amount of suffering per year in the natural world is beyond all decent contemplation. During the minute that it takes me to compose this sentence, thousands of animals are being eaten alive, many others are running for their lives, whimpering with fear, others are slowly being devoured from within by rasping parasites, thousands of all kinds are dying of starvation, thirst, and disease. It must be so. If there ever is a time of plenty, this very fact will automatically lead to an increase in the population until the natural state of starvation and misery is restored. In a universe of electrons and selfish genes, blind physical forces and genetic replication, some people are going to get hurt, other people are going to get lucky, and you won’t find any rhyme or reason in it, nor any justice. The universe that we observe has precisely the properties we should expect if there is, at bottom, no design, no purpose, no evil, no good, nothing but pitiless indifference.Richard Dawkins, River Out of Eden: A Darwinian View of Life

Interview with David Pearce on ‘Wild animal suffering – Ethics of Wildlife Management and Conservation Biology’

David Pearce advocates for a benign compassionate stewardship of nature, alleviating suffering in the near and long term futures using high technology (assuming that ultimately the whole world will be computationally accessible to the micromanagement needed for benign hyper-stewardship of nature).