[CT Birds] mockingbird trends

Chris Elphick elphick at sbcglobal.net
Mon Mar 26 18:23:29 EDT 2012

As a few people on this list, Chris Field and I (by which I mean "mostly Chris, 
with the occasional word of encouragement from me") have been working on a 
project to better describe the trends of Connecticut's birds.  The effort has 
partly involved expanded analysis of existing data sets, such as the counts 
available from Breeding Bird Survey routes - but analyses of those data already 
exist and our version has, at best, minor analytical improvements.  The main 
focus has been on developing better ways of illustrating the data so that a wide 
variety of users - not just geeky scientists - can see what is going on.  

Given the discussion about mockingbirds at the end of last week, I asked Chris 
if he could post the mockingbird results on-line.  If you click on the link 
below you will see two animated graphs.  As the animation runs, the one on the 
right (with the photo in the background) will plot the trend over time from the 
mid-60s to 2009.  You'll see that numbers start really low, increase to a peak 
in the early 90s, and have declined since then.  This is a similar pattern to 
that in the CBC data posted last week.

If you look at the animation on the left, you will see that it starts with a 
grey horizontal line, which shows the average number of birds seen on a route 
when the survey began in the mid-60s.  As the animation proceeds a blue line 
bounces up and down, showing how the average changes from year to year - this 
mirrors the blue dot on the trend line of the other animation.  

You'll also see a bunch of black bars going up and down - these are the 
individual counts on each survey route (one bar per route) and illustrate just 
how much variation there is from place to place within the state as well as from 
year to year (and note that a BBS route involves multiple points over quite a 
large area - so data from individual points would be even more variable).  The 
inclusion of these individual routes, and the variation they illustrate, shows 
why you can't just take counts from one location (e.g., my yard) and use them to 
draw general conclusions about regional patterns.

If you want to stop the animation there is a play/stop button bottom left.  You 
can also modify the speed with the button bottom right.  The link is:


Finally, many thanks to Mark Szantyr, for use of his (as always) killer 
mockingbird photo.


 Chris Elphick
Storrs, CT
elphick at sbcglobal.net

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