Calculations for: Detector dog work assessing probability of detection for Yellow crazy ant

The use of detector dogs within environmental programs has increased
greatly over the past few decades, yet their search methods are not
standardised, and variation in dog performance remains not well quantified
or understood. There is much science to be done to improve the general
utility of detector dogs, especially for invertebrate surveys. We report
research for detector dog work conducted as part of yellow crazy ant
eradication. One dog was first used to quantify probability of detection
(POD) within a strictly controlled trial. We then investigated the search
patterns of two dogs when worked through sites using different transect
spacings. Specifically we quantified their presence within set distances
of all locations in each assessment area, as well as the time they took to
assess each area. In a GIS we then calculated the relative percentage of
the entire search area within six distance categories, and combined this
information with the POD values to obtain a site-level POD. The calculated
relationship between distance and POD was extremely strong (R2 = 0.998),
with POD being 86% at 2 m and 28% at 25 m. For site-level assessments
conducted by the two dogs, both dogs achieved highest site-level POD when
operated on the lowest transect spacing (15 m), with POD decreasing
significantly as transect spacing increased. Both dogs had strong linear
relationships between area assessed and time, with the area assessed being
greater when the transects had greater spacing. The working style of the
two dogs also resulted in significantly different assessment outcomes. In
one hour one dog could assess approximately 9.2 ha with transects spaced
20m apart, and 6.8ha with transects spaced 15 m apart, whereas the second
dog could only assess approximately 6.9 ha with transects spaced 20 m
apart, and 4.9 ha with transects spaced 15 m apart. Our study provides
insight into the ability of dogs to detect yellow crazy ants, and sets the
basis for further science and protocol development for ant detection. With
the lessons learnt from this work we then detail protocols for using
detector dogs for ant eradication assessments.