[CT Birds] owl movements

Nick Bonomo nbonomo at gmail.com
Mon Dec 10 10:31:49 EST 2012


There is a significant movement of Barred Owls in progress this
autumn/winter, something that may have been masked thusfar in
Connecticut by listserv rules. But the Barred Owl(s) reported recently
from downtown New Haven fit right into that pattern. Judging by eBird
and listserv reports around us, the volume of this movement is rather
large. So keep an eye out for these birds and, better yet, log them
into eBird so this incursion can be better monitored.

Another one to watch for is Boreal Owl. Banders in Ontario noted a
southward movement of this species earlier in the season, and
apparently it has resulted in one bird being found in Massachusetts
last month. It's been a while since we've seen one of these in
Connecticut, but perhaps this is the winter to find one. Many of you
might recall the bird that wintered in Central Park a few years ago
that was enjoyed by hundreds. There are also multiple records for
Boston, so city parks are certainly worth checking too.

Searching for day-roosting owls can be a tedious task, but maybe this
extra motivation will get more of us looking this winter. If you do,
please take care to avoid disturbance when searching. Be careful and
deliberate. Of course, communal roosts of Long-eared and Northern
Saw-whet Owls are rather sensitive and should not be posted publicly
to this listserv, as repeated disturbance could cause flushing and
eventual abandonment of the roost.

Speaking of northern vagrants, a Boreal Chickadee was recently
reported from northern Massachusetts.

Below I've cross-posted a more detailed noted from Marshall Iliff
regarding the owl movements. Check it out.

Nick Bonomo
Wallingford, CT

Subject: Barred Owl influx of 2012
Date: Fri Dec 7 2012 11:05 am
From: miliff AT aol.com


The below is a bit long, and is an email I sent to friends in Cape May who
were discussing the Barred Owl record from Cape May Point SP (where they
don't breed) that is shown here: http://cmboviewfromthecape.blo...

In response, Sam Galick pulled some eBird maps to demonstrate that the Cape
May bird may fit a wider pattern. I built on the discussion using more
eBird maps and the comparison is pretty neat. Since this is all going down
in Boston and Massachusetts, I thought I;d share it here.

Of course, if you have seen Barred Owls this fall (or any other), sharing
your sightings on eBird would help your records to add to these patterns
shown in eBird output.

Below is what I wrote. Be sure to click the map links which are striking:

Movements in Barred Owls are very hard to detect, but some areas where they
do no breed are good places to detect their movements when they do occur.
Cities are often the best for this, since we know they don't breed there.
My yard in Annapolis, MD, was a place to detect Barred Owl movements too: I
had singles in January and March, up until this year when a pair bred
there. Obviously, Cape May Point is another such place to detect Barred
Owls on the move.

Barred Owls do not breed in Boston (=Suffolk County) at all. Sam's map
links from Oct 2012 and Nov-Dec 2012 showed that the bulk of the movement
this year has happened in Nov and Dec, but the Oct records on his first map
were already showing that Barred Owls were on the move. The county bar
chart shows that their occurrence here is *always* this phenomenon of
dispersal, which happens Oct-Dec:


Time will tell whether this year's birds spend the winter successfully.

To see that this year is significant you simply have to play with the year
selector in eBird. I expanded to Aug-Nov to illustrate the below pattern.

Here's a a few more years--focus on records from Suffolk County, which
essentially follows the city limits of Boston:

2011 (one record from Suffolk County,

12-2012&byr 11&eyr 11

2010 (one record -- same bird plotted from two different hotspots):

10&eyr 10

2009 (GOOD YEAR -- four records!)

10&eyr 10

2008 (zero records)

2007 (zero records)

So...compare all that to 2012 (at least 17 individuals; some folks have had
four different birds on their roosts during the day)

12&eyr 12

Added to this, there have been high numbers of road-kills in Massachusetts
as well as two or three records from Cape Cod (one in eBird) and Plum
Island, both places where they do not breed. My interpretation is that this
is a clear influx related to the same rodent crashes that are bringing
Boreal Owls south (one photographed in Marblehead in mid-Nov).

Cities are very good places to detect them because: 1) someone is bound to
notice them; 2) sparse habitat makes them conspicuous; 3) high rodent
populations may mean that they stay for a while. Outside of cities they are
much harder to detect and when one finds one it may well be a local bird;
but given what is seen in the cities there must be hundreds of Barred Owls
on the move statewide in Massachusetts, and again, the elevated roadkills
in fall 2009 and 2012 support this. I do expect that young birds are
disproportionately represented in flights like this, but I do get the
impression that some of these are longer-distance dispersers.

So, I would view an out of place record in Cape May in the light of this
pattern to the north, which I think was Sam's point. eBird is giving us the
tools to understand things like this much better, but it does require
knowing where to look and what the reporting biases are etc.



PS - those of us in Massachusetts should be on *high alert* for Boreal Owls
this winter, especially in cities (especially in Boston!). If a non-birding
friend finds a small owl roosting during the day, make sure they show it to
you--it may be a Boreal! Of course, please do not disturb it if you find
it, as it is surely food-stressed (the cause for this year's southerly
influx of Boreals)

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