Subject: Bluebirds (mountain bluebirds this time)
Date: Oct 5 09:29:27 1995
From: Roger Hoffman - Roger_Hoffman at nps.gov


While the collective tweeter brain is thinking about bluebirds and population
trends, I thought I would ask for opinions on another declining bluebird
population (where the starling definitely cannot be blamed):

The numbers of mountain bluebirds reported in the Olympic Mountains (of NW
Washington State) have declined from "fairly common" in the 1940's to nearly
absent today (there are still occasional summer sightings -- especially from
the NE corner of the Olympic Mountains).

In his _Birds of the Olympic Peninsula_ (1949) Kitchen describes the mountain
bluebird as fairly common (at least locally). Other records from the Deer Park
and Hurricane Ridge areas suggest that they were rather common during the
1940's. There are few if any records of mountain bluebirds in these
well-visited areas from the last couple of decades. By the way, starlings are
generally not present in these areas :-) .

There are a couple of competing (and possibly intertwined) hypotheses that I
(and others) have been considering:

1) The effect that fire suppression in the National Park and National Forest,
reducing both the number and extent of fires, has had on available nesting
cavities (snags). Not only are fewer snags produced because of the reduced
fire activity, those trees that are ignited (ie. struck by lightning) are often
cut down during the fire suppression activities

2) Regional climate changes. Fred Sharpe (_Olympic Peninsula Birds_ -- Draft
Manuscript) has hypothesized that regional cooling (and related wet springs)
from the 1940's to the 1970's may have reduced the abundance of flying insects
in the subalpine areas which of course would have a dramatic effect on the
success of nesting mountain bluebirds. These climate changes may have also
affected (negatively) the natural fire frequency absent any human-influence.

I pose these questions to the group:

1) What opinions and comments do you have regarding these hypotheses?

2) Do you know of any research that might support or refute either
hypothsis?

3) What other hypotheses come to mind?

4) Have similar declines in other areas been documented?

Roger_Hoffman at nps.gov
Olympic National Park
Port Angeles, WA. USA