Assessing the Effectiveness of Tuberculosis Management in Brushtail Possums (Trichosurus vulpecula), through Indirect Surveillance of Mycobacterium bovis Infection Using Released Sentinel Pigs

Table 1

Predicted (CKRI) and actual (residual TCI, CCI, and WTI) measures of the relative abundance of possums before and/or after aerial 1080 poisoning in four study blocks on Molesworth Station, 2008.

	Normal coverage blocks (𝑛=2)		Reduced coverage blocks (𝑛=2)
	Precontrol	Postcontrol	Precontrol	Postcontrol
Predicted CKRI	Both > 5%	N/A	Both > 10%	N/A
Residual TCI	—	0.8%, 0.4%	—	1.8%, 1.1%
ChewCard index (CCI)	163%, 68%	3%, 0%	224%, 190%	18%, 11%
WaxTag index (WCI)	75%, 22%	0%, 0%	87%, 79%	7%, 6%

Each index represents a measure of possum relative abundance. CKRI: capture/kill-rate index (proportion of possums trapped and/or killed by cyanide paste relative to trap/poison frequency, as described previously [34]); TCI: trap-catch index (proportion of possums trapped relative to a standardised trap frequency and spacing pattern, as described previously [35]); CCI and WTI: ChewCard or WaxTag indices (possum interference/detection devices to detect possum presence and activity, as described previously [36–38]).