In article ,
"BAC" writes:
|
| 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?

There are circumstances under which that is the case. It is true for
red deer in many parts of the Highlands. I cannot say whether or not
it is true for wood pigeons in the UK.


Regards,
Nick Maclaren.