In article ,
"BAC" writes:
|
| The grey squirrel reference was a joke, of course.

Of course :-)

| The increase in collared dove population is an interesting point, because
| they are relative newcomers, and there does seem to be a correlation between
| their establishment here and the sparrow decline, although that may merely
| be coincidence. What is the 'realistic causal chain' you have in mind,
| though?

Winter and early spring feed. With the major reduction in fields left in
stubble over winter, the number of horses etc., seeds are in limited supply.
Pigeons are much larger than sparrows, and bully them out of the way (as
well as eating much of what is available). It's one of the many plausible
speculations.


Regards,
Nick Maclaren.