Interesting discussion about bluebird winter flocks. I have lived in Ohio
only about 12 years, but in this state I've never seen Eastern Bluebirds in
winter flocks larger than about 10 or 15 birds. Farther south, such as in
northern Florida and near the Gulf Coast, I've sometimes seen flocks of 20
to 30 Eastern Bluebirds. Sometimes they forage on the ground in mixed
flocks with a few Pine Warblers, which makes for an interesting color
combination. In these situations, presumably they're feeding on insects. In
Ohio in winter they're not going to find enough insects to sustain a large
flock, and they often concentrate in areas where there are many small
fruits, such as poison ivy berries. Although I haven't seen any studies
supporting this, I suspect that food availability is a factor limiting the
size of winter flocks here.

In the western U.S., where I lived and birded for many years, the largest
flocks of Western Bluebirds in most areas seem to be of about 20 to 30
individuals, but there are exceptions. In my experience, Mountain Bluebirds
often form larger concentrations. This is especially true in Arizona. There
are places in the foothills of central Arizona where hillsides are covered
by vast woodlands of junipers, and when the junipers have a heavy fruit
crop in winter, fruit-eating birds can be numerous there. Major flocks of
American Robins are often present, and many individual Townsend's
Solitaires, but the bluebirds steal the show. Occasionally I've seen
hundreds of Mountain Bluebirds and scores of Western Bluebirds swirling
over the hillsides. The largest concentrations seem to consist of multiple
smaller flocks -- i.e., we're seeing several flocks of dozens each, not one
flock of hundreds -- but they're all in the same area at the same time.
Again, the presence of an abundant food source appears to be the key to
making these concentrations possible. It would be interesting to know if
our native juniper in Ohio (eastern redcedar) ever has large enough fruit
crops to attract big numbers of Eastern Bluebirds.

Kenn Kaufman
Oak Harbor, Ohio


On Mon, Jan 8, 2018 at 11:27 AM, [log in to unmask] <
[log in to unmask]> wrote:

> I have had the same experiences as Jon. Usually 12 to 25 or so Eastern
> Bluebirds. Also similar numbers with Mountain and Western Bluebirds on
> frequent trips West. Now Eastern Bluebirds are visiting feeders and heated
> birdbaths and spending more time foraging for insects in the woods.
> I would be in awe to see such numbers. Especially if it were a sunny day
> and their blue was flashing about like beacons.
> Ohio Bluebird Society has their annual meeting in Columbus at GIAC on
> February 24. Hope to see some of you there.
> BestDarlene SillickPowell, Ohio(A bluebird nut)
> Sent from my Verizon LG Smartphone
> ------ Original message------From: Jon CefusDate: Mon, Jan 8, 2018 10:19
> AMTo: [log in to unmask];Cc: Subject:Re: [Ohio-birds]
> Bluebird flocks in winter
> In my limited experience so far the largest groups I’ve seen have been
> 10-20 birds.  During extreme cold, as we’ve recently experienced, they seem
> to flock more to forage for food.
>
> Jon Cefus
>
> Sent from my iPhone
>
> > On Jan 8, 2018, at 10:02 AM, Ken Andrews  wrote:
> >
> > This is a question for birders who live near or go birding in open
> fields or farmland in the winter. Have you seen flocks of bluebirds?
> >
> > I have seen small groups in the Cuyahoga Valley in winter. I have seen
> around ten together at once near Jaite where there are open areas of
> fields. I have seen them in pairs in the spring and summer all along the
> railroad tracks there.
> >
> > The reason I ask is that, my friend in the SF Bay area posted a photo of
> Mountain Bluebirds. He said he saw well over 80 in one spot just on some
> power lines. There were more in the fields below. (It was at s place called
> Cedar Mountain Winery.)
> >
> > I read on the Cornell website that Eastern Bluebirds flock like this in
> rural areas with large open fields in groups that could exceed 100. Has
> anyone seen flocks with numbers like this in Ohio?
> >
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