[mou] robin disappearance - revisited

[Thomas Maiello]

Okay, I have had some very good feedback on my noticing of the scarcity 
of robins in my yard last week when I returned from out of state.  I am 
thrilled to say that they are back - although not in the numbers they 
were before.  I thought the molting explanation sounded feasible since I 
have found with birds and anything in life that I do not know 
everything, will not know everything, and, when open, I can learn 
something if I just listen.  So here are a few comments I received, 
observations, brief research results and strained conclusions I have 
made since my original post.

Dueling comments:

    * Robins molt this time of year and hide out because they can't fly
      very well.
    * The dry conditions caused the robins to move to greener pastures.

Observations:

    * When I returned the area was still suffering from an extended heat
      wave and dry spell that has lasted since spring.
    * Even though I had people helping me water my yard in my absence,
      upon my return the grass was the one element that did suffer and
      the underlying ground was hard and dry.
    * The soil in the area where I live is primarily sand - not really a
      cornucopia of earthworm or grub habitat and nourishment.
    * I did notice the robins in the bushes and a few in the yard but
      they were not flying well or much.
    * Earlier in the year I noted that the robins were excessively
      feeding on my suet and grape jelly and practically wrestling me
      away from earthworms I uncovered for fishing.
    * My abundant crop of crab apples littered the ground during the
      heat wave covering the vegetative areas of my yard with slowly
      rotting fruit.
    * Since the delightful rains we had, the robins have returned but
      not in as great of numbers.

Web research (at which I am well practiced):

    * No reports or articles about robin immobility or decreased flying
      ability during molt.
    * Robins were often given as examples of typical molting patterns
      and hold to assumed numerical feather molt patterns.
    * Articles reported Robin distribution and foraging success related
      to food abundance and diversity.

Historical experience with robins in Oklahoma:

    * Robins do indeed seem to prefer to ground forage for food.
    * Robins will eat rotting, fermenting fruit until they are so
      intoxicated that they sit on the ground struggling to hold their
      head erect and their heads often loll about like a rag doll's. 
      These birds were easily captured and didn't seem to even know it.
    * Robins seem to eat other foods out of convenience and might eat
      from feeders out of scarcity of foragable food or to supplement
      their diet.

Non-scientific conclusions:

    * The robins in my yard were likely off to greener pastures such as
      parks or municipal green areas where grassy areas were watered,
      the ground softened and foragable invertebrates were available -
      although I did not see any postings for robin Woodstocks observed
      at area parks.
    * The observations of robins eating grape jelly and suet practically
      in excess over the first part of the summer could have been an
      indication that the near drought conditions were making it tougher
      and tougher to forage for preferred food.
    * The lack of food diversity as the heat wave hit the 100's heat
      index could have dried and hardened the ground and forced
      subterranean invertebrates to burrow deeper into the the ground. 
      This lack of access to the bird's primary natural food source
      (invertebrates and fruit) could have finally begun to effect their
      health and they were forced to find better areas to supplement
      their diet.
    * The holdout robins I spotted in the bushes could have been blind
      drunk from relying on the fermenting crab apples and simply forgot
      how to fly - could also explain the one that kept running into
      branches as it skirted away from me in the shrubberies.
    * I am arrogant enough to think that I might even have an idea of
      what I am talking about and, in reality, this is all a pompous guess.

Surely there is some graduate student needing a topic for a master's or 
doctorate.  Or perhaps Mythbusters could take it on.  Anyone got their 
number?

Thomas Maiello
Spring Lake Park