[mou] Re: Henslow's Sparrows

[Brad Bolduan]

Jim,

I was just talking about this with someone else today.

I just had a few points which you probably already know.  Then a few
additional questions.

This is not isolated to Minnesota.  It has also been reported in the other
two state listserves which I monitor (Iowa and South Dakota).  A recent post
on one of these lists stated that the species is much more common than it
was several years ago in at least one location in Illinois as well (I don't
know if this was a gradual increase).

I am sure a good share of the increase is real, although certainly some
records were found by people looking to expand on the numerous reports this
year.  I happened to hear Henslows this year before the reports started
rolling in and I did not go looking for them.

In a situation like this I usually assume that a portion of the population
made a temporary shift north or northwest.  But then someone should have
fewer birds than usual.  Does anyone have a good feel for the extent of this
perceived increase?  Is any part of their core range experencing fewer
reported birds than usual?

It would also be very interesting to get a feel for what habitat these birds
are using.  The birds I have seen this summer have been in or near native
prairie which had not been burned in several years (perhaps their expected
habitat).  However, as Dennis Martin mentioned the birds at Bashaw (assuming
we saw the same birds) are using the WMA (native prairie) as well as the
adjacent CRP field (planted natives).  [The birds I saw were in CRP east,
not west of Bashaw.]  I believe the birds at Holthe SNA, Jackson County were
also using planted natives as well as "true natives".  If I recall
correctly; Henslow's has often been found in exotic grasses (such as brome),
but it has been proposed that it selects habitat with fairly dense, tall,
dead vegetation - including song perch sites.  For that reason it apparently
avoids recently burned areas.

The birds I have seen seemed to be associated in areas containing dead sweet
clover stems from last year(and alot of sedge wrens).  Do these associations
seem to hold true in other areas?  If not are the birds in areas with other
relatively tall dead perches?  I would assume no birds are being seen in
areas which were burned in 2004 or 2005?

I hope I didn't get too carried away.  Thank you for starting the discussion
Jim.  It will sure be interesting reading the coverage this "invasion" gets
in The Loon and North American Birds.


Brad Bolduan
(In the prairie part of the state and liking it)
Windom, MN


-----Original Message-----
From: mou-net-admin@cbs.umn.edu [mailto:mou-net-admin@cbs.umn.edu]On
Behalf Of Jim Williams
Sent: Monday, July 04, 2005 17:06
To: Williams, Bob
Cc: mou-net@cbs.umn.edu
Subject: [mou] Re: Henslow's Sparrows


Can anyone offer insight into the very large number of Henslow's
Sparrows being reported in Minnesota this summer? More birds? Why? What
changed? Or, more birders? Do we simply find more once we begin
looking?
Jim Williams
Wayzata