Re: [CALBIRDS] Dan Murphy's Allen Hummingbird Sighting in N. CA: Today......
- In a message dated 1/31/2010 9:23:51 AM Pacific Standard Time,
Did other folks in central and n. CA see Allen's returning recently, too?
At Santa Cruz County the average arrival date for the 1st reported migrant
Allen's Hummingbird during the 40-year period 1969-2008 was Jan 15 (standard
error +/- 10 days), and for the more recent 10-year period of 1999-2008 the
average arrival was Jan 10 (+/- 7 days). 1st arrivals have shown a highly
significant trend for earlier dates over 40 year period. I believe this
year's 1st arrival for SCZ was Jan 11. You can see a plot of the arrival dates
for SCZ for Allen's and a number of other spring migrants here:
A number of species have exhibited notable changes in the timing of
arrivals over recent decades, most especially for species that arrive in late
winter or early spring. The info cited in the Marin County breeding bird atlas
may not well reflect the more recent situation for some species of migrants.
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