Tawny frogmouth Deaths
Mon, 31 Mar 2003 15:30:23 +1000
Last November, I put up a request for information on what was causing the die-
back of Sydney?s Tawny Frogmouth population at the end of every winter and a
possible relationship / implications when compared to a recent discovery that
Bogong Moths where transporting arsenates from their wintering grounds the High
Plains where they are a major food source for the Endangered Mountain Pygmy
Possum and a possible additional risk to their survival.
The response that I got was overwhelming for a general inquiry and it is one of
the reasons why I am only putting up a response now with a summary of what I
found out. The others being recent work loads and laziness.
Thankyou to everybody that replied. In the summary I have not included peoples
names as the responses where made to me in private and I want to try and keep it
The majority of the information pointed out that the deaths of Tawny Frogmouth
was caused by Organo-chlorides. These are stored in body fat and are harmless
until the bird becomes stressed through lack of food etc and draws on this fatty
tissue top of the of the food supplied. Many organo-chlorides where outlawed in
the 70?s. I believe that it is possible that they could be picked up from
insecticides like ant sprays and similar household products. A couple of
mentions of rat sack where made. I found this a little confusing as I do not
believe that Tawnies would feed on mice and rats.
Nobody was able to discount the possibility of arsenates contributing to Tawny
Frogmouth Deaths, eventhough the deaths occur at a similar time to the Bogong
Moths migration, however the research seems to have been thorough to pick this
as a possibility.
An interesting point of relevance to this and to the Pygmy Possums is that in
general biologically-incorporated (organic) arsenic is less toxic then inorganic
arsenates. Depending on the types of arsenic being transported, it may be
possible that there is no risk of mortality to mammals and birds.
A lot of responses questioned why Bogong Moths where a suspect. In brief after
very heavy rains a few years back around Kosciousko, the snow grass outside of
caves and protected areas was found to have died. This followed natural
lines and could be traced back to the source. The caves etc where tested and
dead Bogong Moths where found to contain very large levels of arsenates in their
systems. This did not break down when the moth died and the rains washed it
When I last spoke to anybody on this issue (last November) it was yet to be
determined if any impact was occurring on animals that fed on Bogong Moths.
A large part of the research occurring the issue was trying to trace where the
moths where coming from, was it more then 1 site and how where they coming into
contact with the arsenates. I only have an interest in Pygmy Possums and are
part of the research that is currently occurring in this area.
If anybody has any further information or queries, please do not hesitate to
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