[TN-Bird] Re: thoughts on Bill Pulliam's BBS data graphs of Wood Duck and Black-throated Green Warbler
- From: "Roger Applegate" <Roger.Applegate@xxxxxx>
- To: "TN-birds" <tn-bird@xxxxxxxxxxxxx>, "littlezz@xxxxxxxxx" <littlezz@xxxxxxxxx>,<tboves@xxxxxxx>
- Date: Thu, 13 Oct 2011 09:37:11 -0500
Than
The range shift issue is one of the reasons that looking solely at BBS is
problematic. Having "permanent" routes that are used year after year can cloud
that fact that changes in habitat specific to the route can show a declining
trend while all that has happened is that the birds have moved to another
location. This location could just be far enough from the route that they are
no longer detectable on the route, but they are still there and trend may
really be stable or increasing.
Roger D. Applegate
Wildlife Biologist and Coordinator
Bobwhite Ruffed Grouse, Cottontail, Tree Squirrels
Wildlife Diseases
Human Dimensions Surveys
Tennessee Wildlife Resources Agency
Ellington Agricultural Center
PO Box 40747
Nashville, TN 37204
PH: 615/781-6616
FAX: 615/781-6654
Email: roger.applegate@xxxxxx
UPS Address: 440 Hogan Road
Nashville, TN 37220
FedEx Address: 5107 Edmonson Pike, Nashville, TN 37211
>>> "Boves, Than James" <tboves@xxxxxxx> 10/13/2011 9:12 AM >>>
Interesting to think about these local patterns in comparison to range-wide
patterns. Are global patterns the same or different to TN changes? How many TN
changes represent range shifts vs. true declines/increases? For instance,
American Redstart has shown no change range-wide (1966 - 2008) vs. Bill found a
65% decline in TN. What do these differences mean?
I've attached a recent paper that summarizes rangewide BBS results from
1966-2010.
Than Boves
Knoxville, TN
From: tn-bird-bounce@xxxxxxxxxxxxx [tn-bird-bounce@xxxxxxxxxxxxx] on behalf of
Bill Pulliam [littlezz@xxxxxxxxx]
Sent: Thursday, October 13, 2011 9:05 AM
To: TN-birds
Subject: [TN-Bird] Re: thoughts on Bill Pulliam's BBS data graphs of Wood Duck
and Black-throated Green Warbler
It's interesting to me that the discussion here has been entirely about
declining species, and especially about a species whose decline is already
well-known. Of course the species that are in trouble are a major concern.
But the biggest message I got from the BBS data in total was about the
increases. Raptors have skyrocketed. The non-neotropical migrant forest birds
have increased dramatically as well. The median for all 104 species that had
enough data to give meaningful statewide trends was an increase of 66%. Let's
not forget the good news!
About the declines -- I found some surprises in the list of species that had
dropped sharply. Four of the top five are well known: Bewick's Wren (-100%),
Loggerhead Shrike (-90%), Golden-winged Warbler (-89%), and Northern Bobwhite
(-78%). But nestled among these is also Yellow Warbler at -87%. Nine more
species showed drops of greater than 50%: Common Nighthawk (-78%), Gray
Catbird (-71%), House Sparrow (-70%), American Redstart (-65%), Eastern
Meadowlark (-61%), Northern Flicker (-58%), Common Grackle (-58%),
Whip-poor-will (-52%), and Orchard Oriole (-52%).
And again to keep the context, while 14 species showed drops of greater than
50%, 37 species showed increases of more than 100% (i.e. double). One native
species was almost entirely extirpated (Bewick's Wren), one native species
became a widespread new member of our breeding avifauna (Tree Swallow).
Bill Pulliam
Hohenwald TN
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