So glad you posted this as I was wondering why there have been so many dickcissel sightings this year. Really interesting stuff.
Thanks very much!
Ann C. Pettigrew, V.M.D.
Sent from my iPad
> On Jun 23, 2017, at 4:15 PM, Robert Mulvihill <robert.mulvihill...> wrote:
> The recent spate of Dickcissel sightings across PA may have to do (as it
> did during the big summer invasion of Dickcissels in 1988) with extreme
> drought in the northern plains, specifically, North and South Dakota:
> From the National Climate Report (May 2017):
> "...it was dry across much of the Dakotas during the spring, and
> precipitation deficits accumulated quickly. According to the U.S. Drought
> Monitor, drought spread rapidly across the Dakotas in May as impacts became
> more apparent. Below-normal spring temperatures delayed planting and slowed
> crop growth in this region. During the month of May, the percent of topsoil
> moisture rated short to very short increased from 7 percent to 36 percent
> in North Dakota and from 12 percent to 38 percent in South Dakota. This is
> something to watch closely as we head into summer."
> For those who may be interested in reading it, I published an article
> almost twenty years ago now about the likely relationship between
> Midwestern spring droughts and the historic and recent invasions of
> Dickcissels in Pennsylvania Birds:
> http://www.pabirds.org/PABIRDS/BackIssues/PBV02N3.pdf >
> It will be interesting to see how this year's influx compares to 1988's.
> Robert S. Mulvihill
> National Aviary
> 700 Arch Street
> Pittsburgh, PA 15212
> <Robert.mulvihill...> <Robert.mulvihill...>
> *The National Aviary <http://www.aviary.org> works to inspire respect for
> nature through an appreciation of birds.*