Bird deaths and Bogong Moths

[David Rees <>]

John

I think your Park Ranger is a bit confused.  This particular moth mainly breeds, inland, not on the coast - on the plains from northern Victoria to southern Qld.   Don't know which plant 'corn' is  Wheat or Maize.  Maize is not grown much in Australia - mainly here and there as an irrigated summer crop, with a small amount of customary production in summer rainfall areas southern Qld. which mostly goes into Australian made cornflakes.  Important thing is that it is a summer crop, i.e. the moths are tucked up (should be) in their caves when this stuff is growing. There are other moths that are bad on this, related very similar species but not the same.

Lets look at wheat, its a winter crop in Australia and certainly NOT grown on the coast.  The amount of pesticides put onto Australia's dryland wheat is low and not getting higher. Chemicals allowed these days are non-persistent in the environment.  Herbicides are used, mainly for preparation and pre-crop emergence, the most popular one is Glyphosate. This use cuts down hugely on diesel used for heavy cultivation and reduces risk of soil blow as stubble can be left intact and the new crop drilled into it, with control of emergent weeds.  Glyphosate breaks down quickly with contact with soil and does not accumulate in animals ( insects, mammals etc. etc).

In the 'good old days' pesticides such as arsenic, DDT, etc were used to deal with catapillars that would accumulate in the environment and could act in the way your range said.  Its just that individual you spoke to is a few decades out of date with his/her thinking.

The main threat to this system is not agriculture, it is the effects of climate change that will bring more severe droughts and hot periods such as we are in right now. If there is no winter rain, there is no growth and therefore no food for caterpillars and therefore there are no moths to fly to the mountains, its pretty simple...  Furthermore, higher summer temperatures mean that the temperature in the bogong caves will go up. this is also detrimental to moths survival as they will be more active and use up their fat reserves before they have chance to fly back to the breeding grounds in autumn.  This system is finely tuned and climate change could cause it to collapse, quite quickly.  We might be seeing that happen right now before our very eyes.

David

On Thu, Jan 17, 2019 at 7:00 AM John Harris <> wrote:

A sad postscript to the current thread about low numbers of Bogong moths is that they breed on the coast often on farmland where corn etc is grown and they absorb Agicultural chemicals. They carry these chemical residues to the mountains where a Park Ranger told me that increasing bird deaths of insectivorous species were attributed  to ingesting hebicides, pesticides etc. from eating the moths. Same must apply here in the ACT now I think about it.....