My earlier report was sent via mobile phone from the field when my fingers were
still frozen. Those of you who strangely have an aversion to "long" posts
probably loved its brevity. Go fish.
As stated, no redpolls, no Pine Warbler. Along the north and west sides of the
little pond west of the sanctuary peninsula at 8:30am were a Swamp Sparrow
(photos) and an adult White-throated Sparrow. Both were initially detected via
their calls. I did NOT hear either one of these toward the end of my visit,
which was about 10:30. They may have moved elsewhere in the general area, or
been on the move.
My main reason for going up there was to try and figure out the attraction of
this area for the special birds it has hosted of late. In past years I have
tried to do the same for special birds like Grace's Warbler (woolly aphids in
ponderosa pine), Prothonotary Warbler (catkin bugs in catkins of water birch),
Nashville Warblers (aphids on chokecherry), Black-throated Blue Warbler female
(aphids on chokecherry).
In gross terms, the Sanctuary's geography has attributes similar to other
montane bird "traps": 1) a forested area near water (both stagnant and
flowing); 2) a forested area with diverse vertical structure (big, medium, and
little trees, with a complex understory); 3) situated at the base of the
mountains where birds moving out of steep terrain might stage (rest and feed)
prior to moving downhill; and, 4) a "repository" for migrants that
intentionally or errantly wandered from the flatlands west up Big Thompson
Canyon and then were dumped out/daunted by the big bad Rockies (i.e., a
temporary "dead end").
Guesses about food details at the site:
Not finding any Common Redpolls, I can't be sure about them but would wager
birch seeds from catkins were the magnet at work with them. The majority of
those small, deep reddish-purple barked saplings (with white lenticels
peppering the bark) that have little dangly things (catkins) are water birch
(Betula occidentalis). They are the dominant small deciduous trees around the
pond and on both sides of the bike trail that runs e-w between the golf course
and the west end of Lake Estes. And, yes, there are some shrubby willows of
undermined species in the area as mentioned in reports but they are in a
distinct minority to the birches.
Most of the pines in and near the Matthews-Reeser Sanctuary (I miss Warner
Reeser, a very neat man) are ponderosa pine. Mixed with them on the peninsula
are a very few lodgepole pine. On the ponderosas I found 1) pine needle scales
(tiny white flecks on the needles, Chionaspis pinifoliae), 2) woolly aphids in
the genus Pineus (mostly clustered around terminal buds or at the needle
bases), and 3) the woolly pine needle aphid (Schizolachnus pini-radiatae)
(zillions of blackish eggs and a few gray adults lined up on the underside of
needles, only evident unless you lift up boughs, same insect as sustained the
Boulder Bay-breasted Warbler for weeks in late fall 2013). The distribution of
these three sucking insects was very localized, which is another way of saying,
most of the pines I examined were pretty clean of significant insect issues.
IF the Pine Warbler winters in this area, based on nothing other than
abundance, the scattered pines with good populations of the woolly pine needle
aphid would appear to sustain it. And if it messed around in the birch catkins
(or gathered intel by observing the other birds messing around in birch
catkins), it would also probably find the abundant catkin bugs (Kleidocerys
resedae) therein to its liking as a supplemental food.
Both juncos (several) and Mountain Chickadees (several) this morning were
spending considerable time in water birch catkins, getting mostly birch seeds
but probably not passing up discovered catkin bugs as well.
Of course, junipers, both Rocky Mountain and common, populate the M-R Sanctuary
and their berries would be staples for the juncos and maybe other birds like
robins, a migrating/wintering Hermit Thrush, solitaires, waxwings, etc. I
thought I might have heard the little aggitation "chuck" note of Hermit Thrush
today but I never saw one. The big juniper on the northwest side of the pond
might be good tree to check if anyone visits in the near future.
Dave Leatherman
Fort Collins
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