Alder trees are right up there with the birches for producing seeds that attract Pine Siskins and I have seen Common Redpoll feeding along with them. By late summer the leaves of Alders look pretty ratty and are full of holes from all of the small caterpillars feeding on them. During migration we watch warbler and vireos flocks glean small green "worms" from the leaves as they move through our woods. Alders also make great and easy to split firewood, are used to make printer/copy paper and improve the forest soil with their decomposing leaves and wood as well as having nitrogen fixing nodules on their roots like alfalfa or other legumes. They are short-lived trees, the ones on our place are dying out at about 70 years old and make great nest snags for woodpeckers etc. Wilson Cady
Columbia River Gorge, WA
---------- Original Message ----------
From: "D&J Nunnallee" <
nunnallee at comcast.net>
To: <
tweeters at u.washington.edu>
Subject: [Tweeters] Alder Trees and birds
Date: Sun, 29 Nov 2020 15:57:03 -0800
Hello Tweets,
I grew up in Washington long believing that alders are 'junk trees', weedy
trees which spring up unwanted everywhere. And indeed they are everywhere
that deciduous trees grow in this area.
This Fall I have been impressed by the large flocks of Pine Siskins
frequenting alders in our front yard, surely to glean insects I surmised.
But then the leaves fell and still the birds returned in large numbers. I
studied the trees with my binoculars and saw that there were green drooping
catkins, small oval green cones and small oval brown cones. I checked the
Internet and found that alders produce their new (female) cones and new
(male) catkins this time of year; the catkins will release their pollen next
spring to fertilize the cones.
Ok, so I studied the flocks of siskins more closely, and discovered that the
birds are frequenting *only* the brown cones. Hmm, those are the old cones
from last year which have not yet fallen. So I gathered a few cones, each
roughly the size of a fingernail, and some catkins to study under my
dissecting microscope. I was surprised to find that the brown cones dropped
numerous seeds with the slightest jostling. The seeds are flat and are found
in the narrow flat recesses of the cones. The green cones by contrast have
visible seeds, but they are tight, not yet matured, and are difficult to
remove. The hanging catkins of course have no seeds, and are of little
interest to the birds.
So now it is clear what the birds are seeking, and it is also apparent how
important the alders are for our small seed-eating birds. I will not think
of alders as 'junk trees' again.
Dave
David & Jo Nunnallee
Sammamish, WA
nunnallee at comcast.net
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