Rats, dogs, and poison

[Guest guest]

Apparently I rattled a lot of folks' prized assumptions with

a couple of brief notes from the floor at the recent Asia for Animals

conference.

 

On the first day, after the opening session of a day-long

session on how to deal with burgeoning populations of urban macaques,

I pointed out that macaques had become able to proliferate in Asian

cities because removing street dogs from the respective habitats had

opened the food sources to macaque invasions.

 

Until then, everyone was talking as if the macaques just

suddenly materialized from nowhere, with no ecological change

allowing their presence.

 

Just about everyone belatedly acknowledged that yes, dogs do

chase macaques, and yes, the macaque arrivals tend to follow the

decline of street dogs, whether as result of sterilization or

poisoning campaigns.

 

As this phenomenon was first noted in India at least by 1933,

albeit that cause and effect were not connected, I don't claim any

particular originality for mentioning it; but it does need to be

acknowledged and understood, if efforts to limit either street dog

or macaque populations are to be successful.

 

On the second morning, I warned a plenary session that

before people go trying to eliminate street dogs, or feral cats,

from any habitat, they need to consider what happens next,

including whether they are creating much bigger welfare issues than

those they purport to be eliminating.

 

We have certainly seen many such examples, including the

proliferation of feral cats almost everywhere that street dogs have

been greatly reduced in numbers.

 

I reminded the audience about the macaques, & then pointed

out that rats are actually the most prolific beneficiaries of

removing dogs.

 

I also pointed out that in terms of reducing animal

suffering, if you replace a population of 10,000 dogs who are at

constant risk of being poisoned with a population of a million rats

who are poisoned equally aggressively, there is no net reduction of

animal suffering.

 

In fact, the suffering is multiplied exponentially.

 

If you want to reduce net suffering, you have to reduce the

carrying capacity of the habitat; and have to consider which animals

will be best tolerated in the habitat that remains.

 

This begins with looking at the food source.

 

You can't control the population of any species if you keep

making more food available to it.

 

In the case of street animals, you have to be aware that

unless you reduce the amount of food waste and rodents at large at

the same time you reduce a population of dogs, cats, macaques, or

whatever, you are making more food available to other species, who

will proliferate in place of whatever animals you are eliminating.

 

Population reduction is a two-way street: reducing fecundity

and reducing the food supply.

 

If you reduce the food supply without reducing fecundity,

you get famine -- the " natural " population regulating mechanism.

 

If you reduce fecundity without reducing the food supply,

you open habitat to other species.

 

If you reduce both, you get the present situation in most of

the U.S. and western Europe.

 

Only if you reduce both fecundity and food supply do you get

any net reduction in animal biomass.

 

 

Part of the problem I addressed is that quite a few

dog-oriented activists think of reducing suffering only in terms of

reducing dog suffering, & forget all about the feral cats,

macaques, rats, pigs, et al.

 

My argument is that one must consider the big picture.

 

Are the streets a better home for three cats, instead of one dog?

 

Or for a pig instead of a dog?

 

Will macaques be better tolerated than dogs?

 

We know that the streets may be the perfect home for 100 rats

instead of one dog, but we also know that rats will be killed by any

means possible, no matter how cruel.

 

On balance, if the habitat supports street animals, dogs

are usually the species most likely to be tolerated and most likely

to occupy the habitat in the fewest numbers.

 

If it is understood and accepted that eliminating dogs means

more rats, macaques, jackals, et al, & the public is willing to

accept that consequence, eliminating street dogs is an approach that

can be taken.

 

Yet the more likely approach to succeed, in most of the

developing world, is replacing the present rapidly reproducing,

short-lived dog population with a mostly vaccinated, mostly

sterilized, dewormed, generally healthier and less rapidly

self-replenishing population of dogs who -- because they live longer

-- are more likely to gradually morph into the pet population, &

less likely to become disease vectors, or (because they have been

fixed) pack up & scare people into killing them.

 

In places where there are no other species nearby to reprise

the refuse-and-rat-eating roles of street dogs and feral cats, most

often the result of effecting a reduction of numbers will just be

faster reproduction of the remaining dogs and cats, since it is just

about impossible to kill them faster than they breed.

 

Sterilization can greatly reduce the pace of reproduction,

but if the carrying capacity of the habitat remains high, dogs &

cats -- being already there -- still have a huge advantage over

wildlife, especially in the inner parts of cities that are

relatively far from current wildlife habitat.

 

I emphasized that in terms of reducing net animal suffering,

if you replace a population of 10,000 dogs who are at constant risk

of being poisoned with a population of a million rats who are

poisoned equally aggressively, there is no net reduction of animal

suffering.

 

In fact, the suffering is multiplied exponentially.

 

As it happens, quite a lot of comparative data exists to

demonstrate the difference between how poisoning and predation affect

animal populations, especially rat populations.

 

The gist of it is that poisoning produces a boom-and-bust

cycle. Typically poison is put out when rats reach the cultural

carrying capacity of the habitat, i.e. when people become

intolerant. Poisoning then kills the rat population down to

invisibility. Then the poisoning stops, until the rats are again at

a high ebb.

 

While the rats are seldom seen, abundant food is available,

so they breed quite prolifically. The result can be oscillations

between populations of hundreds and populations of millions, several

times per year.

 

Predators rarely kill a prey population below the level at

which it can rapidly replenish itself, as if they do, the predators

starve. The upper end for successful predation is consumption of

about two-thirds of the prey population over the duration of the

breeding cycle.

 

Predation usually runs a lot lower than that; but, combined

with other mortality, predation does tend to have the effect of

stabilizing the population of the prey species within relatively

stable limits. There is still seasonal oscillation, but unless

there are unusual weather patterns, boom and bust cycles even out.

 

The net effect is that if you have a gross carrying capacity

of about five million rats in a city, and a cultural carrying

capacity of about 3 million rats, a dog population of about 1,500

will hold the rat population at or below the cultural carrying

capacity by consuming about a million rats per year.

 

A poisoning campaign sufficient to keep the population below

three million would probably kill about six times as many rats, at

minimum, and might also bring a mouse population explosion, since

rats are the leading predators of indoor mouse pinkies, chiefly in

their role as a nest predator.

 

 

One person lamented to me that all of the above contradicts

the common humane teachings about keeping pets at home.

 

This is actually a misunderstanding.

 

" Keep your pets home " applies to pets; " pets " does not

include all dogs & cats, nor even most dogs & cats in most of the

developing world.

 

Neither does " Keep your pets home " have anything to do with

reducing or eliminating the populations of street dogs & feral cats,

who mostly were never pets in the first place, & mostly have never

had ancestors who ever were pets, since the whole concept of keeping

pets in a home in the modern manner is barely 200 years old.

 

Before that, practically all pets roamed, practically all

of the time.

 

Part of the confusion about this issue is that street dogs

and feral cats are commonly called " strays, " but are not.

 

The word " stray " means " out of place. " Street dogs and feral

cats are in the habitat niche they have always occupied, since the

dawn of civilization. A pet who has lost a home is a stray, but a

street dog or feral cat is in the habitat niche that their species

have evolved to fill.

 

Someone also contended that I was undermining the theme of

anti-rabies campaigns that have as a stated goal the elimination of

free-roaming dog populations.

 

There is not much I have encouraged for longer than

eliminating rabies. I saw my first rabid cat at age five, & have

never forgotten her.

 

Many anti-rabies laws around the world have eliminating

free-roaming dogs as a goal, but it is a fundamentally unrealistic

goal until the habitat conditions that favor street dogs are

eliminated.

 

It is, however, quite possible to vaccinate enough street

dogs to eradicate rabies, as was done in Argentina, Brazil, and

Uroguay nearly 25 years ago.

 

Incidentally, there is no model anywhere, other than

possibly on small islands, for eliminating rabies by killing or

otherwise eradicating the host species. This has been formally

recognized by the National Association of Public Health

Veterinarians, among others, since 1973.

 

Rabies -- in any species -- has been eradicated only by mass

vaccination, whether of dogs, foxes, raccoons, or any other

ground-dwelling host.

 

Rabies has never been eradicated in a bat population,

unfortunately, because no one has ever figured out an efficient

method of vaccinating bats.

 

Finally, someone objected that not eradicating street dog

populations is not an option, because dogs at large will be

poisoned, otherwise abused, and sometimes eaten.

 

Whether you sterilize & vaccinate street dogs or not, the

same things will still happen to them, and their numbers will remain

whatever the habitat supports, no matter how many are killed or how

many are sterilized until you get to 70%; but if you sterilize &

vaccinate the street dogs, while leaving them in their habitat

niche, you can gradually overcome the fear of dogs and give dogs

some value, that they don't have when reproducing uncontrolled and

going unappreciated for their contributions to civil well-being.

 

If you just try to eliminate street dogs, but fall short of

sterilizing 70%, you may encourage proliferation to replenish the

habitat niches, where the food sources permit; and you will

contribute to the widespread misperception that dogs are an

undesirable species.

 

If perceived as unfit to exist on the street, dogs will

certainly be perceived by most of the non-dog-keeping public as unfit

to live in a home.

 

 

 

--

Merritt Clifton

Editor, ANIMAL PEOPLE

P.O. Box 960

Clinton, WA 98236

 

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Fax: 360-579-2575

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