Hi Tweets,

Rob Conway writes:

(snip)
>I think it was Richard Rowlett who
>suggested that this was likely due to the large areas of alder forest
>which produce cones/seeds that these birds are attracted to. Preditors,
>competitors, vegetation, food sources, micro-climates and other
>ecosystem factors probably all contribute to this "weird" distribution.

Interesting that in Jericho Park in the western side of Vancouver BC there
are still pretty much the same trees, alders and hawthorns, which used to
host anything up to ten or twelve Purple Finches Carpodacus purpureus every
winter. It's been several years since I've seen any there at any time.
Likewise in Stanley Park there are trees near the tennis courts and pitch 'n
putt course which used to support a few wintering Purps. None there now
except the odd northbound migrant, and I can say that on the basis of
regular monitoring of that area. So, I'm wondering if the process or
processes that over the last decade have changed the Purple Finch from a
fairly common resident and common wintering bird to an uncommon migrant is
or are at play regionally, and what it or they might be.

Michael Price A brave world, Sir,
Vancouver BC Canada full of religion, knavery and change;
mprice at mindlink.net we shall shortly see better days.
Aphra Behn (1640-1689)