Yard bird lists again

["Philip Veerman" <>]

Looking at bird results by suburbs from GBS data, as distinct from individual GBS sites adds another whole level of variability. Tonya's question could be taken as referring to sites or to suburbs. Martin would have used a system that groups by suburb to get the data he mentions. And Martin's 2 questions are quite valid, which is why the use of answering the question in terms of GBS sites is useful. And why I provided data by individual year (i.e. one chart) and over all years and examined and described in detail the issue about how the time period relates to number of species recorded, in the sites that had contributed every year, in sites in general and the total survey as a single unit.

 

There is no doubt though that people have been variable in the way they interpreted the GBS site geographic restrictions (what is a yard?), especially in the early years when the instructions were vague and inconsistent.

 

Yes there would surely be some true variability in bird species richness between suburbs. However there are big biases operating in getting that data from GBS results. There is a big difference in the number of GBS charts contributed between suburbs. Data showing this is given in Appendix 5 of The GBS Report. Not only that but in the years this has happened. Also Canberra suburbs differ in size (Kambah is about twice the size of most other suburbs) and Kambah has had many GBS Sites - the most by far, at least within the first 21 years and this is unlikely to have changed.

 

About Curtin, it largely comes down to the features of one site (GBS Site 230) with a good observer - actually more than one - for several years, in an area on the edge of the suburb, adjoining an open area, so a flyway for many species passing through and especially with a creek adjacent, that gives scope to a wide range of species that would not occur within the middle of a suburb. Beyond that, the internal parts of Curtin are hardly likely to have more species than most other suburbs.

 

Philip

 

-----Original Message-----
From: Tonya Haff [
Sent: Thursday, 21 April 2011 8:39 PM
To: martin butterfield
Cc: Canberra Birds
Subject: Re: [canberrabirds] Yard bird lists

Wow, thank you Martin, that's a really interesting
summary. I had no idea that some suburbs had such high species lists! 
Looking on a map, it doesn't make intuitive sense to me why some suburbs (say,
Curtain) would have had so many more bird species come through than others; do
people think this is due to observer bias, because dedicated twitchers live in
some suburbs, but not in others?  

I'm North American, and all the
twitchers I know there keep 'yard lists', which is simply all the species one
sees or hears while directly in one's yard. It's kind of fun, though rather
silly - if you see a cool bird down the street, you have to run back to your
driveway and try to see it from there. Consequently, I've always followed this
tradition.  Honestly, in the middle of O'Connor, I'm really not sure how
many more species I'd pick up by walking 100m in any direction!  But the
GBS sounds like a good idea - maybe I should start keeping both
lists.

Then I could actively hunt for
owlet-nightjar!

Cheers,

Tonya

On Thu, Apr 21, 2011 at 7:09 PM, martin butterfield <> wrote:

I rate Tonya's question as interesting since it immediately raises the questions of:

• what is a yard? and
• over what time period?

Milburn's observation, which stimulated Tonya's post, seems to have have been clearly within his property (or at least visible from there).  That is probably a rather more restricted definition that the GBS definition of a site equivalent to a radius of 100m from the property (ie about 3Ha).  However, one could say that if it is within a 3Ha area including the yard the birds are quite likely to be seen in or from the yard.

I will leave to observers to talk about individual, identified, sites but have put up some data at the suburb level in the attachment.  To explain the shorthand of the column headings a tad, taking Aranda as an example:

• over the 29 years of the GBS 127 species have been recorded at least once on one or more of the GBS Charts from that suburb ; and
• the maximum number of species recorded from any one site in that suburb (over a number of years) is 83.

On the first measure Aranda rates 6th, while on the second it comes in at #9

Martin

On Thu, Apr 21, 2011 at 10:05 AM, Tonya Haff <> wrote:

Hi all,

Just curious if anyone has tallies of yard birds for suburbs around Canberra?  I just moved to O'Connor from Aranda, and I'm curious what other people have as typical and high-number bird lists for their yards in town.  A tawny frogmouth in the front yard yesterday brought us up to 35 species since December.

Cheers,

Tonya