Just a few thoughts on the migrant trap issue.

1) It may be more than latitude. The vagarants on the east coast could
be carried by the prevailing winds. The ones on the west coast have to
migrate in the wrong direction, and are probably reverse image migrants.
At our latitude we would not expect to see any reverse migrants, and
on the west coast we wouldn't expect any weather related migrants.

2) Many of our vagrants are not true vagrants but are individuals pushing
the edge of their species limits. They are quite common just to the east
in Montana or to the north in Canada. There are not enough of these
to produce the huge numbers of vagrants that seem to be following
reverse migration routes through southern Oregon and into California
to be discovered on the coast or in the desert.

3) There are just a lot of vagrants moving through Caifornia. Too many
to say they just have the right geography.

4) We might expect to pick up more Eurasian vagrants than we actually
do. It may just be the number of birders, but a lot of birds seem to
skip Washington and end up in California. Witness records of Wheatears,
Brown Shrikes, Red-throated Pipits, and Skylark. These must have flown
past our coast. We do alright, or almost alright, on the waterbirds,
but where are the landbirds?

From: Jerry Tangren, Wenatchee WA
<gsw$en at wsuvm1.csc.wsu.edu>