Don't they serve squab in the restaurants anymore?
Yes. Have you never had a McSquab with fries?
How many of those pigeons were slaughtered when the dovecoot was abandoned and how many were turned loose to fend for themselves.
None were slaughtered, but nor were they “turned loose”. They were already loose; the dovecote worked because of the pigeon’s homing instincts. I imagine that when people lost interest in raising pigeons they simply stopped scattering grain in the dovecote to attract and feed the pigeons, and the dovecotes were gradually abandoned by the pigeons.
Do people ever complain about the free range pigeons population today? Now translate that to feral pigs, sheep, and cattle.
Feral sheep? The mind boggles.
But, again, I think this is unrealistic. A decline in demand for farmed meat will result in a decline in stock breeding, not in the mass release of excess stock. Even if the world becomes vegetarian overnight (which, so far as I know, no-one foresees) and farmers are left with stock that they cannot sell on any terms, I do not see them releasing the stock to starve. They will destroy the stock because
(a) they are not cruel
(b) they will fear adverse social consequences if they turn loose stock which trespasses on their neighbour’s land, eats their crops, damages their fences, etc
(b) they will fear legal
consequences if they turn loose stock which trespasses on their neighbour’s land, eats their crops, damages their fences, etc
It seems that killing the animals outright rather allowing them to fend for themselves and possibly starve or get hit by a lorry, would violate these animal rights.
It doesn’t seem like that to me. And, more to the point, I doubt that it will seem like that to the farmers concerned. You seem to suppose that farmers who currently kill animals in order to sell the carcass for profit will find themselves ethically unable to kill the same animals to avoid the animal dying of starvation or neglect. That doesn’t sound very plausible to me.
Or is there right the right not to be eaten as opposed to a right to life?
Farmers won’t stop producing meat because the animals have a “right to life”; they’ll stop producing meat because people will stop buying it. And they’ll stop buying it because, as the world population grows, the relative cost of using productive land inefficiently to raise meat rather than efficiently to raise food crops will make meat more and more expensive.
Meat-eating won’t disappear altogether. There will be the idle rich, for whom meat-eating will be a form of conspicuous consumption. And there will be meat that is hunted in the wild, which doesn’t involve an opportunity cost in terms of food plant production foregone.