I actively looked for first migrants at New River, Coos starting back
around 2000. I also kept records of my earliest observations on my data
base. In addition, I started keeping field notes for the south coast in
2007. I have attached an excel spreadsheet with the first arrival date
info I have for Rufous Hummers in Coos. Based on these data the average
arrival date is 9 February for the 2000-2019 period (excluding 2018 for
which for some reason I have no data) and the average arrival date is 10
February for the period 2006-2015 that the Crotty article analyzed. The
chart in the Crotty article shows the average arrival date for the period
of 2006-2015 in Coos Bay as day 70.9 which equals 12 March. This is a
month different from the observation data I have! No matter what sort of
analysis was used to produce the early arrival dates in the Crotty article,
the output seems really off. In fact, the peak of the Rufous migration
is around mid-March most years based on my experience (give or take a
week), not about the time the first arrival occurs!!
Happy hummingbird migration,
Tim Rodenkirk
Coos Bay
On Thu, Mar 21, 2019 at 9:12 PM Mike Patterson <celata@xxxxxxxxxxxx> wrote:
I first started monitoring Rufous Hummingbird migration reports
back in 2000 via regional list. I collected data vigorously until
2005 when other responsibilities made it too difficult for me to
devote the kind of effort it was taking.
Since there seems to be some interest in this subject, I will try
to compile a summary with graphs and stuff over the next couple
days, but I will toss out a couple of tidbits for folks to chew
on.
1. Most people, prior to the time Anna's Hummingbirds became ubiquitous
did not put out their hummingbird feeder before mid-March...
2. "Experts" in the region were remarkably dismissive of reports claimed
before mid-March back in the early 00's...
3. First detection reports need to be analyzed in the regional aggregate
to parse out meaningful information.
4. Peak migrational density is a better indicator of Rufous Hummingbird
phenology than first arrival.
--
Mike Patterson
Astoria, OR
Bald Eagles - a gateway bird
http://www.surfbirds.com/community-blogs/northcoastdiaries/?p=3709
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Chart.xlsx
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