[obol] Re: Spring Arrival Dates: Long and likely annoying for some
- From: Mike Patterson <celata@xxxxxxxxxxxx>
- To: obol@xxxxxxxxxxxxx
- Date: Fri, 25 Apr 2014 08:08:37 -0700
Actually, I been very specifically studying migration patterns of
riparian species in Clatsop Co. since 1989. I have an 8 year dataset
from the South Jetty of the Columbia willow patches (1989-96), a
dataset from Neawanna (1999 to 2009) and am currently building a
dataset for Stanley Marsh. If I've done the math correctly, that's
25 year (geez, I'm old).
I ran the Neawanna data, because it was easy to get to. I could have
added SJCR and Stanley, but it wouldn't have changed anything.
My phenology list for Clatsop (which includes sight records) shows an
earliest arrival date for Swainson's Thrush of April 25 and an average
first arrival of May 9 and a peak movement around May 21.
We all have a tendency to rush spring because we're excited about it,
but there are good reasons to take the timing of migration seriously and
show due diligence for getting our ID's correct. If bird species are
changing their migration patterns in response to global climate change,
we want to be able to track that change with a rigor that will be hard
for the deniers to argue with.
On-line data collection sites like eBird can be powerful tools, but they
are only as good as the data that gets entered. We cannot and should
not assume that just because it's on eBird it must be true. The folks
who built eBird don't make that assumption. The stuff you see on an
eBird distribution map is a second order approximation (data that got
past the regional editors who vary in skill, background and willingness
to be hard-asses). Those maps are quite accurate at their statistical
centers and become increasingly blurry when you get to the edges. When
eBird data is applied to more sciency things by folks with lots of
letters after their names, it gets cleaned up even further through
statistical filters that are probably tossing most of those early April
reports as outliers and statistical noise.
Don't be statistical noise. Learn phenology. Take the time to document
those outliers. Attach the details to your eBird reports. Then you can
thumb your nose at the OBOL know-it-alls with a well earned righteousness.
Mike Patterson–Mike has been birding in Oregon since the early
1970's (at least). He has been the Oregon CBC editor for North
American Birds for about two decades and he has been banding along
the Oregon coast (Swainson's Thrush central) for 11 years.
--
Mike Patterson
Astoria, OR
Some assembly required
http://www.surfbirds.com/community-blogs/northcoastdiaries/?p=1888
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