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To: |
Brian Fleming <> |
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Subject: |
Bird Numbers |
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From: |
Harvey Perkins <> |
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Date: |
Thu, 31 May 2001 13:30:10 +1000 |
Further to Wynton's and Anthea's comments, I have found a similar situation
at the ANU campus.
I have done a survey of birds seen on walks across campus over the past 2
and a half years, between the Biochemistry building and the John Curtin
School of Medical Research. The route taken would be something like 800m
each way (slightly different there and return routes) and includes a
section of Sullivans Creek which attracts a variety of water birds and
others associated with water.
The stats are:
Total of 60 surveys over the two and a half years.
Total number of species recorded so far during these surveys is 64 (add 3
more for species seen on campus but not during the surveys).
Mean number of species recorded on any survey is 22.8 (sd 4.1).
Highest number of species recorded for a single survey is 34 (on 8.11.2000).
64/34 = 1.88 (cf 1.89 stated by Wynton for his two sites).
Harvey
>>
>> Hi Birders,
>> Being a numbers man i could not resist giving some input re local bird
>> lists.
>> For about 25 years i have been recording birds at North Lake and Blue
>> Gum Lake near Perth.
>> At North Lake the total is 104 and Blue Gum is 72. The highest daily
>> counts have been 55 at North Lake in Jan. and Feb. and 38 for Blue Gum
>> Lake in Feb.
>> This is expected due to the summer migrants and the westwards pull to
>> the coast as the inland lakes dry out.
>> The interesting relationship is that the total number of species is
>> almost twice(sorry to get into accountant speak but both ratios
>> are1.89 ) the highest individual count conducted when it is likely the
>> max. numbers could be expected.
>> This rule of thumb could prove very useful when time ( such as 25
>> years! ) does not allow a very long and exhaustive survey to determine
>> the total numbers of species. It is of course based on surveying the
>> same area over and over and on a relatively small area based around a
>> Lake.
>> I would be interested to see if this ratio is consistent with other
>> surveys as it could be used for conservation and other reasons to
>> estimate the total number of species based on only a few visits.
>>
>> Regards Wynton
>I would agree with this statement. I have been noting the number of
>species seen at local parks here in the Heidelberg area (suburban
>Melbourne with Yarra and wetlands) for about 30 years. The total score
>for a walk round the local park is usually 28 to 32, say 30. (When I
>started, early 1970s, it used to be around 35). But it's seldom the same
>30 on successive days. The total number of bird species seen in our
>local park over the year would probably be well over 60, and again would
>vary from year to year, depending on continental and local conditions.
>
>Anthea Fleming in Ivanhoe, Vic.
.........................................................................
Dr Harvey D. Perkins :: Editor, :
Divn Biochemistry & Molecular Biology :: Canberra Bird Notes, :
Australian National University :: Journal of the Canberra :
Canberra, ACT 0200, Australia :: Ornithologists Group (COG) :
ph +61 2 6125 2693; fax:+61 2 6125 0313 :: 42 Summerland Circuit, :
and: :: Kambah, ACT 2902 :
Pest Animal Control :: Ph: (02) 6231 8209 :
Cooperative Research Centre (PAC CRC) :: mobile: 0438 869 990 :
.........................................................................
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