Wayne et al.,

I used to do the Issaquah route in King County but abandoned it in favor of
a new route further east that runs from Duvall through Carnation to near
Snoqualmie Falls. At some point the traffic got to be so continuous, even at
5 AM on Sunday mornings, that your 3 minutes window to hear birds singing is
reduced to 5 seconds of semi-quiet or less. In such conditions whatever data
you might gather is worthless in any case and hardly comparable to what
would have been recorded at that spot 20 years before or at some other more
tranquil roadside.

Gene Hunn

----- Original Message -----
From: "Wayne C. Weber" <contopus at telus.net>
To: "Kelly Cassidy" <lostriver at completebbs.com>; "TWEETERS"
<tweeters at u.washington.edu>
Sent: Tuesday, July 25, 2006 1:45 PM
Subject: Re: [Tweeters] Breeding Bird Survey population trends


> Kelly and Tweeters,
>
> As I mentioned, determining population trends from BBS data is a
> complex process.
>
> Abandonment of routes (or creation of new routes) is potentially
> a problem in determining population trends. Other than the Point Grey
> route in Vancouver and West Vancouver, which I covered from 1974
> to 1994, I am aware of only two other routes in BC which have
> been abandoned due to heavy traffic, both in the Greater Vancouver area.
>
> I'm sure that several routes in rural areas have been abandoned as well.
> Most roads in BC are logging roads, and tens of thousands of miles
> of these have been abandoned over the last 40 years or more. I'm
> sure that several BBS routes have become undriveable because of bridges
> washing out, roads deteriorating, etc. I know at least one route that was
> covered for 2 or 3 years, then abandoned because river noise
> interfered so much with observations that useful results could not be
> obtained.
>
> BBS coverage in Canada is usually based on one route per degree-block
> (a chunk of land measuring one degree latitude by one degree longitude--
> about 4000 square miles, depending on the latitude). In more
> heavily-settled
> areas of southern BC, there may be 2 or 3 routes per degree-block.
> When a route cannot be covered and must be abandoned, another route is
> assigned in the same degree-block. The location of new routes is
> determined using random numbers, to try to avoid strong biases toward
> or away from certain habitat types.
>
> In the analysis of BBS data, I believe that results are weighted, such
> that
> routes in degree-blocks with 2 or 3 routes "count" for less than those in
> blocks with only one route.
>
> However, all these measures attempt only to ensure that habitats covered
> are a reasonable sample of roadside habitats in a large area (e.g. a
> state or a province.) This is achieved incompletely at best on the BBS,
> because roads are always biased in favor of some habitats (farmland, urban
> areas) and away from other habitats (forests, wetlands). Selection of
> routes has little if any effect on the analysis of year-to-year population
> changes. The main effect that dropping or adding a number of
> routes might have in an area the size of Washington would be to
> affect which bird species had a large enough sample (i.e., number of
> routes) to give meaningful estimates of population change. It would
> have little if any effect on the direction or magnitude of those changes.
>
> Wayne C. Weber
> Delta, BC
> contopus at telus.net
>
>
>
>
>
> ----- Original Message -----
> From: "Kelly Cassidy" <lostriver at completebbs.com>
> To: "'TWEETERS'" <tweeters at u.washington.edu>
> Sent: Saturday, July 22, 2006 6:11 PM
> Subject: RE: [Tweeters] Breeding Bird Survey population trends
>
>
>
>> [mailto:tweeters-bounces at mailman1.u.washington.edu] On Behalf
>> Of Wayne C. Weber
>> Sent: Saturday, July 22, 2006 4:39 PM
>
>> most years since 1980 (and 2 of them since 1974). (In
>> addition, I did one route in Greater Vancouver from 1974 to
>> 1994, but have since abandoned it since traffic makes it
>> nearly impossible to cover properly now.) The long-term
>
> Wayne's comment about abandoning a route due to traffic brings up
> something
> I've wondered about for a long time. Are routes more likely to be
> abandoned
> if they are in developed areas? Are new routes more likely to be situated
> in non-ag and undeveloped areas? Does a non-random abandonment of routes
> or
> placement of new routes skew the results? If routes are abandoned more
> often in developed areas and new routes more likely to be established in
> less-impacted areas, wouldn't that make the numbers for birds that don't
> do
> well in ag or urban areas look better than they really are as urban areas
> expand? Is there any sort of "correction" for these possible biases?
>
> Whatever biases BBS has, however, the methodology is far better than for
> the
> CBC.
>
> Kelly Cassidy
> Pullman, where it's hot and dry. The wheat in the surrounding
> fields smells like it's roasting.
>
>
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