Bay-breasted Warbler fare

[DAVID A LEATHERMAN]

I made the pilgrimage down to Boulder's Bay-breasted Warbler, to see the bird, of course, and to hopefully figure out the "why" of this event.  The answer was very straight forward: zillions of aphids in that pine tree closest to Center Green Drive (essentially none, at least down low where one could check, in the other pine).  I collected several (they are on every needle, at least a half dozen per) and believe they are quite possibly Eulachnus rileyi ("The Powdery Pine Needle Aphid").  To see these, all one has to do is basically stand under the tree for a minute and you will be crawling with them.  To see even more, gently take one of the lower boughs and look closely.  I suspect you will first see the needle surfaces shining from a coating of "honeydew", the sticky sweet, clear excrement of the aphids (they suck the sap from needles, remove nitrogenous and other compounds for their growth and development, secrete the sugary carbohydrates they don't need).  Look even closer and you will see various stages of the aphids themselves, in huge numbers.  They are a few mm long and in various shades of gray and brown.  I have photos if anyone would want to see them.

I believe the pine tree is a Ponderosa (slight chance it is an Austrian).  I say Ponderosa because the buds are somewhat orange, not pure white like Austrian usually shows.  The foliage is darker than typical Ponderosa but maybe the tree is fertilized. 

As long as the weather holds, I see no reason why this bird will leave.  Its visit is not about maintenance, this is an opportunistic bulk-up-I'm-in-tall-cotton-and-gotta-long-ways-to-go stop.  During the several hours I watched this delightful bird today, it nitpicked aphids by the hundreds (thousands?), rested for a few minutes in a state of literal food-processing (calm in one posture but occasionally twitching and very gently quivering), went back to feeding.  It moved all over the tree, apparently out of habit, because it surely didn't have to move to find food.  Twice I saw it flush a yellowjacket (which are also in this tree because of the aphids, in their case to glean honeydew).  The warbler energetically pursued and consumed the wasps.

Awesome situation we are all fortunate to witness.

Dave Leatherman
Fort Collins