and device coverage and spacing
To achieve high kills it
is important that all individuals in a population are put at
risk from the control operation.
Individuals can survive operations by being located in gaps
resulting from incomplete aerial coverage or in gaps created when
ground-laid devices (traps, baits,
bait stations) are too far
To avoid gaps in aerial
operations, all operations must use aircraft (helicopters or
fixed-wing) fitted with Global Positioning System units.
If and when available, flow meters should also be used to
ensure baits are being sown along all transects.
Swathe width must be determined for each aircraft taking account of both aircraft
speed and height, and hopper (bait spreader) used.
For ground operations,
spacing between trap or bait lines should not exceed 100 m.
To put all
individuals at risk, lines should be left for at least 8
nights (see Fig.).
and placing traps and baits closer together on the line may
enable greater spacing between lines, but spacings of
greater than 200 m should be avoided.
Graph showing the relationship between
percentage kill over time with three different between-line
spacings (100 m, 150 m, and 200 m).