"Nick Maclaren" wrote in message
...

In article ,
Malcolm writes:
|
| If the birds weren't shot, the mortality would go down and their
| life-expectancy up.

That is extremely unclear, and might be the converse of the truth. It
will depend very much on how close they are to overpopulation at the
stressful times of year.

It is quite possible that stopping shooting them would cause an increase
in their population, and a consequent increase in their mortality rate
and a reduction in their life expectancy. That is what often happens
to prey species with effectively no predation - as is the case for
wood pigeons in many parts of the UK.


Are you saying that, for a given ecosystem, only a certain maximum number of
a population of birds can be expected to survive the winter, regardless of
how many more than that number started the winter?