[obol] Migration counts

[Alan Contreras]

Migration counts are difficult for the reasons set forth by Dave Irons and
others.  However, the main issue with NAMC is not that people don't get good
data (birds counted on a given day produces good data for that day, even
though it doesn't cover the bulk of migration), but that the results seem to
disappear into space.

Ideally, a migration count would involve counts conducted on four or five
dates over time: in fall that time is enormous, essentially July through
October.  Even that period excludes a lot of waterfowl (don't get here until
November) and some male Rufous Hummingbirds (moving south on montane ridges
by June). Spring is the same way.

There is nothing to prevent Oregon birders from developing our own protocol
that results in a meaningful movement-over-time picture for Oregon in spring
and fall.  Such a survey need not even require that all observers use the
same dates, because it is a survey of movement peaks, not of population size
in a location.

Most birders, myself included, rarely keep track of numbers of what we see
in the field, except for more unusual species or those that interest us.  It
is the "count" aspect of these events that provides useful data, and it is
counting that is largely a matter of habit.

-- 
Alan Contreras
EUGENE, OREGON
acontrer at mindspring.com