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This is a difficult question because many birds
are pretty good at hiding and no survey is perfect. The results from the COG
Garden Bird Survey show this for a 3 hectare site by month continuously for 18
years. Of course there are problems of undercounting and one needs to consider
the method. It also shows species diversity over the same scale. All this stuff
will be in my report on the GBS, which is being worked on now. That level of
detail is not in the Birds of Canberra Gardens book, although that book
does show and describe averages over time (by month and long term - 17 years)
individually by species, for most of the about 100 most frequently recorded
species.
The quick answer is the total number of individual birds of
all species combined, per average observer-week (the sample size is 46,222
observer-weeks) was in the vicinity of 75.6 birds for an approximately 100 metre
radius plot. It is the consistency and the variation around that range, by
month, year, by habitat and by observer differences and appreciating how those
factors work, that is the interesting bit. All will be revealed.
-----Original Message-----
From:
<>
To:
<>
Date:
Thursday, 6 July 2000 11:20
Subject: [BIRDING-AUS] RFI birds
per hectare
Here's a tricky question - what's the
average number of birds per
hectare in Australia?
Somebody at
Uni asked me and I didn't know. All I could find in a
quick literature
search was about 15 per hectare for woodlands. Does
anyone know of any
figures for other habitats in Australia? I realise
it is going to vary
depending on seasons, but I just need approximate
figures.
Cheers,
Lainie Berry
Birding-Aus is on the Web
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