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Forwarded message:
Subj: OSFL STATUS
Date: 97-01-15 18:38:18 EST
From: Alt8bird
To: TWEETERS at u.washington.edu

In response to Michael Brown's question regarding the staus of the
olive-sided flycatcher...

This information is part of a status review on the species I am preparing on
the species for the U.S. Fish and Wildlife Service:

Indeed, the olive-sided flycatcher is declining based on Breeding Bird Survey
data, and the declines are relatively CONSISTENT and STATISTICALLY
SIGNIFICANT throughout the species range.

Some of the numbers based on BBS data through 1995 (approximately 25-30
years):

North America (all of the species breeding range) -4.1 %per year
Western North America -4.3 % per year
Washington -3.1 % per year
Oregon -5.2 % per year
California -4.1 % per year
British Columbia -5.6 % per year
and on... and on...

What is even worse is that the declines are increasing in the last 15 years
over those recoded in the first 12-15 years.

The olive-sided flycatcher is a bird of the conifer forests, but not a forest
interior bird. It is most often associated with forest openings (man-made
and natural) and forest edge where there are tall trees or snags for singing
perches and foraging perches and adequate air space around these trees to
sally out and capture flying insects. Tall, remant trees within older
forests that stand out above the canopy are also used (often residual trees
not killed in long past forest burns). It is also frequently associated
with forest burns - which in effect create openings in forest, leave large
snags and adequate air space for foraging, and create edge with live forest
particularly where burns are patchy and many stands of live trees remain amid
the burned forest.

So why the declines? Well, its all speculation since NO work has been done
to indentify causes, and in fact this is probably our most poorly known of
the forest flycatchers, despite its high level of detectability. A lot of
speculation has focused on the wintering grounds since the declines are so
consisitent throughout the species range. Principal wintering grounds are
mid-elevations in the Andes Mountains of South America (particularly
Columbia). Tropical deforestation in these habitats has been high and it is
very likely that loss of wintering habitat may be contributing to the
declines.

However, often times there are multiple factors at play when declines are
this pronounced, and it is likely that problems are also occuring on the
breeding grounds (in migration to for that matter). There is an interesting
dichotomy on the breeding grounds in that in the last 25-50 years we have
SEEMINGLY created more habitat for the olive-sided flycatcher. That is,
forest mangement has resulted in more forest openings and more forest edge
habitat through increased fragmentation of forests. But there is much
thought that these forest openings may be "ecological traps" that attract
birds in because of the appearance as suitable habitat, but in fact are
unsuitable and reproductive success is poor due to any number of factors,
including limited food resources and/or high rates of predation or
parasitism.

It has been specultaed that the olive sided flycatcher (and likely other
species) may have evolved with historical forest burns, particularly the
large infrequent stand-replacement fires, and if so, then the species has
likely been adversely affected by fire suppression/control policies of the
last 50 years.

Hope this helps, but clearly this is all speculation. Keep in mind that
specific instances of a pair of birds no longer seen around places you work,
live, bird etc. may or may not have anything to do with what I have
described. I am speaking to the "big picture". We are initiating work this
summer on the species in the northern Cascades of Oregon. More will follow
as agencies become more aware of the declining status of this species.

Bob Altman
Avifauna Northwest
18000 SE Vogel Road
Boring, Oregon
503 658-2537