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General Discussion

MORGAN. Could you say how confident you are with a 40 m spacing between baits to overcome contagion?

JANE. Reasonably confident. You usually get contagion where a single animal has gone along a line, probably a larger animal.

MORGAN. Have you done any night observations at bait lines?

JANE. No I have not had the time. I gather from your own night observation work that random encounters may be involved rather more than the possum specifically following along the lines. J. Jolly mentioned earlier the scent signals left by animals, and this could draw them back to the same bait station later on.

WOOLLONS. Unless you can show the location of baits is purely random, all those equations could unfortunately be very, very biased, either way.

JANE. I think the night observation work probably helps interpretation regarding randomness. Are you worried about the successive nights being different from the initial night?

WOOLLONS. I'm worried about the basic model which you really have not changed. You have certainly made the operation far easier and that is a very good thing, but does the basic model hold? I don't think you have shown this.

JANE. Well I admit I have some rather limited data. I have incorporated bait interference lines on which are only 20 bait stations. This I feel is far too few and one probably requires nearer 100. To my mind if one carries out an operation a little more precisely, then we can probably get back to getting a reasonable linear relationship between bait interference and trapping estimates.

ANONYMOUS. In other words you are relying on trapping as your calibration. That raises the question of how reliable is trapping?

JANE. True.

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