Species Richness Variation

Chris Raper triocomp at dial.pipex.com
Sun Jun 15 04:38:38 EDT 1997

On Sat, 14 Jun 1997 21:46:01 -0700, "Roger C. KENDRICK"
<kendrick at hkusua.hku.hk> wrote:

>Here in Hong Kong, during the last two weeks I have run a moth trap
>three or four days (well, nights!), weather (i.e. thunderstorms)
>permitting. On the overcast, humid (>90% r.h.), calm nights, with the
>temperature around 26 to 280C and occasional rain, the total number of
>species seen (not including some "micro" moths) was in the region of 60
>to 90. On the two nights were there wasn't a cloud in the sky, with
>relatively low (around 70 to 80% r.h.) humidity (for Hong Kong in
>summer), similar temperatures and little wind, the species counts
>(excluding the same "micros") were 260 and 225 species!! No prolonged
>extremely heavy rain was recorded during this period of time, a factor
>that is known to cause a major drop in species numbers caught.

Hi Roger,

I have trapped in South America once or twice and have always thought
that overcast (even drizzly rain) increases the catch by blotting out
the moon, keeping air temperatures higher and diffusing the moth

In French Guyana we trapped on a perfect night (overcast, hot &
humid), using a combination of one 500W MV and two 150W MV bulbs, and
caught 1000's of moths of all kinds. Using the same apperatus
(all-be-it at a different location) a few nights later on a moon-lit
night we caught 5 Hawks and a few wasps and flying ants.

Chris R.

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