Emails received so far result in the following list of plants we know Common
Redpolls in Colorado like, or could be predicted to like:
1) Shrubby Cinquefoil (Pentaphylloides floribunda (also goes by the scientific
name of Potentilla fruticosa) seeds - tall shrubs south of Lily Lake.
2) Wood's Rose (Rosa woodsii) - the photo by the observer at Lily Lake shows
the bird very near the fruits (rose hips) but it was unclear whether the
redpolls were actually picking at the hips (they are too big for the birds to
consume in one gulp) or possibly removing the less-conspicuous buds (which
would not be red but rather more the color of the stems)
[Both of the above plants are in the Rosaceae family, which may be helpful in
predicting other plants to which these birds might be attracted.]
3) Birch (Betula) seeds from catkins - two people commented on seeing redpolls
in the past back East (Michigan, etc.) associating with birch catkins. This
was one of things that seems logical for Lily Lake, although I didn't notice
any of these trees while walking its south and west shores. Of course, nearby
on the peninsula and shore of the west end of Lake Estes (Matthews-Reeser
Sanctuary), River Birch (Betula fontinalis) (also called "Water Birch" - B.
occidentalis, by authors other than Weber) is abundant and has been the source
of bird interest in the past, but seemingly more so by migrant insectivores
seeking insects like Birch Catkin Bugs, which in turn are interested in the
birch seeds in the catkins.
4) Thinleaf Alder (Alnus incana subsp. tenuifolia) would be another logical
tree in which to find redpolls, having catkins that are very similar to birch.
5) Additional reports were received of feeding on seeds of Wild Sunflower
(Helianthus annuus) on the prairie.
6) As stated earlier, I have seen them in the past in Colorado Blue Spruce
(Picea pungens) and Engelmann Spruce (P. engelmannii) getting seeds from
attached cones.
7) They are also known to occur in deciduous trees feeding on buds (probably
flower buds preferentially). It would be nice if observers could flesh out
which species of deciduous trees (or conifers other than spruce) over the next
several months.
Thanks again to Steve for the suggestion and to those who have contributed
observations. In the future if you see them on a plant you don't recognize,
take a sample and send it to me (612 Stover Street #7, Fort Collins, CO, 80524)
and I would be happy to try to figure it out (or take it to a botanist who
actually could).
Dave Leatherman
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