Unfortunately I could not respond to this message from Geoffrey
earlier.
In
order to address the relative proportions of rarities against the 3 abundant
species Geoffrey is referring to in our local fauna (Geoffrey's comment (3)),
one has to keep in mind:
At
Jerrabomberra wetlands any wader species (and the same applies to many other
bird species) receives a lot of attention, is seen by many observers for
whatever period it decides to stay, and is reported to the database multiple
times over that period. This contrasts with obs. from Lake Bathurst and Lake
George during the waterbird surveys which are based as a rule on 1
visit/month.
Record
summaries will have to take these different scenarios somehow into account,
although I am not quite sure what the best way may be. Certainly "(No
birds/visit/month (e.g. L Bathurst)" and "(average) no birds/visit/month (e.g.
Jerrab.)" may be one way of getting some idea of proportions??
Lake Bathurst
was for many years after 2000 dry, hence the 8 nil years for the Curlew Sp
(Geoffrey's comment (2)).
Michael Lenz
Thank you Steve. This
calls for a few comments.
1)
These are records, not
individual birds. (There certainly weren?t 25 Pec Sandpipers here in 2003,
although there might have been 25 reports of a single bird. Similarly for
the wood Sandpiper in 1994.)
2)
The NSW reports probably reflect
reports by Michael Lenz from L Bathurst etc (Surprised they didn?t go back
before 1981) These are remarkably
consistent for the Curlew Sandpiper up until 2000, after which there are 8 nil
years. Those records appear to be cumulative (monthly) presence
records, for example the ABN gives 102 Curlew Sandpipers at Lake Bathurst in
October 1997.
3)
I am interested in the
relative proportion of ?rarities? as against the 3 species that are abundant in
coastal SE Australia (RN Stint, Sharp-tailed Sandpiper, Curlew Sandpiper).
You can?t get this from the Michael Lenz numbers as presented here (eg 5 records
each of Sharpie and Pec Sand in 1989 gives no idea of relative numbers.)
>From what we know of the ACT wetlands we seem to get a few sharpies (less than
10 at once) each year. However I think the records will show that the
proportion of rarer waders here (by number) is much higher than the proportion
of rarer waders to the common 3 at somewhere like Werribee. Perhaps wader
species migrating singly or in small numbers are more likely to turn up
somewhere off the usual track than wader species migrating in large
numbers.
4)
As to this being an unusual
year, well perhaps a combination of winds and the conditions being favourable at
those local spots that get a predictably thorough scrutiny.
From:
Wallaces [
Sent: Monday, 4 November 2013
7:52 PM
To: Canberra birds
Subject: [canberrabirds] An
unusual year for sandpipers
More reports of Pectoral and Curlew Sandpiper from Kellys
Swamp today (see http://www.eremaea.com/BirdlineRecentSightings.aspx?Birdline=11)
prompted me to look at when these two species and the Wood Sandpiper have
been recorded in the same year. Below is a summary of the records from the
COG database. It shows that the three species have never been recorded in the
same year in the ACT and only in one year (1995) in the rest of the COG area of
interest. The records for 2013 are incomplete.
Steve
|
Number of
records |
Species |
|
|
|
State/Year ending 30
June |
Curlew
Sandpiper |
Pectoral
Sandpiper |
Wood
Sandpiper |
|
ACT |
6 |
25 |
11 |
|
1975 |
1 |
|
|
|
1993 |
|
|
1 |
|
1994 |
|
|
9 |
|
1995 |
|
|
1 |
|
2003 |
|
25 |
|
|
2005 |
3 |
|
|
|
2010 |
2 |
|
|
|
NSW |
138 |
35 |
3 |
|
1981 |
1 |
|
|
|
1982 |
3 |
|
|
|
1983 |
13 |
|
|
|
1984 |
7 |
|
|
|
1985 |
8 |
|
|
|
1986 |
9 |
|
|
|
1987 |
4 |
|
|
|
1988 |
11 |
|
|
|
1989 |
5 |
5 |
|
|
1990 |
2 |
|
|
|
1991 |
7 |
|
1 |
|
1992 |
8 |
3 |
|
|
1993 |
6 |
3 |
|
|
1994 |
13 |
4 |
|
|
1995 |
13 |
3 |
1 |
|
1996 |
9 |
5 |
|
|
1997 |
2 |
2 |
|
|
1998 |
8 |
3 |
|
|
1999 |
2 |
|
|
|
2000 |
2 |
|
|
|
2006 |
3 |
2 |
|
|
2007 |
1 |
1 |
|
|
2009 |
1 |
|
|
|
2013 |
|
4 |
1 |
|
Grand
Total |
144 |
60 |
14 |
