sampling techniques

Two techniques for assessing possum (Trichosurus vulpecula Kerr) diet from stomach contents ("point-sampling" and "layer- separation") are described and compared. Point-sampling involves sieving stomach contents, systematically selecting fragments from the retained material then, identifying and weighing these. Layer-separation involves separation, identification, and weighing of the discrete layers apparent in most possum stomach contents. In 41 of 43 stomachs examined, we were able to separate discrete layers that nearly always comprised a single food item.

Distance sampling and fixed-width strip-transect counts were compared as methods for estimating population trends of the tomtit (Petroica macrocephala) from late September / early October to early November 2004, before and after aerial 1080-poisoning for control of the brushtail possum (Trichosurus vulpecula). Two observers independently recorded the distance and compass bearing to tomtits detected along 36 transect lines in each of two forests (one prefed with non-toxic bait and one not prefed).