Design of aerial surveys for population estimation and the management of macropods in the Northern Tablelands of New South Wales, Australia

Abstract

As part of a kangaroo management program, eastern grey kangaroos (Macropus giganteus) and common wallaroos (M. robustus robustus) are harvested from three kangaroo management zones in north-eastern New South Wales, Australia. To set sustainable harvest quotas, it is necessary to obtain reasonably accurate estimates of the sizes of the populations of these two species of macropod. Recently, this has been done on two occasions using helicopter linetransect surveys. For the most recent of these surveys, conducted in 2004, each management zone was subdivided into three strata of increasing kangaroo density and the surveys were designed in relation to this stratification using an automated survey design algorithm. The results of the surveys were that eastern grey kangaroo densities were estimated as 8.11 ± 1.81 km -2 in the Glen Innes zone, 10.23 ± 2.41 km -2 in the Armidale zone and 4.82 ± 0.87 km -2 in the Upper Hunter zone. Wallaroo densities for these three zones were 3.06 ± 0.73 km -2 , 5.68 ± 3.45 km -2 and 4.40 ± 1.01 km -2 respectively. The wallaroo densities were determined by multiplying the initial estimated densities by a correction factor of 1.85. Across the three kangaroo management zones, eastern grey kangaroo densities did not change in any significant way between the two surveys. This was also the case for wallaroos in the Glen Innes and Armidale zones. Wallaroo density in the Upper Hunter zone, however, increased significantly between the two surveys. Over a decade before these surveys were conducted, a series of ground surveys using walked line-transect sampling were undertaken. The density estimates derived from the helicopter surveys proved to be broadly comparable to those derived from the ground surveys, suggesting that conducting helicopter line-transect surveys designed using the method deployed here is effective in producing population estimates for the purpose of kangaroo management.

Detection probability in aerial surveys of feral horses

“…It may be warranted to replace observers after 3 hr of survey time, though given the variation in observer performance, any change of personnel should be directly addressed in modeling efforts. Surveys designed to optimize detection based on crepuscular wildlife behavior have the added benefit of mitigating observer fatigue by using short flight times interrupted by a long midday break (see Choquenot 1995, Cairns et al 2008, for example).…”

Experimental Evaluation of Shark Detection Rates by Aerial Observers

“…Aerial surveys using helicopter and fixed-wing aircraft have been used to estimate the presence and abundance of terrestrial and marine animals for many years. Terrestrial surveys have focused on large quadrupeds such as moose, oryx, elk, deer, horses and zebras [1] – [6] , although abundances of smaller animals such as kangaroos, goats, emus and smaller birds have also been assessed [7] – [11] . Numerous factors affect the ability of observers to sight terrestrial species, including group size, individual activity and the frequency at which animals are obscured by vegetation [4] , [12] , [13] .…”

Prevalence and gross pathology of liver fluke in macropods cohabiting livestock farms in north eastern NSW, Australia, and diagnosis using cELISA

“…The Common wallaroo are comparatively sedentary within their habitat ( Croft, 1991 ) preferring mountain and rocky landscapes ( Taylor, 1984 ) which are areas less likely to support the habitat of the intermediate snail host. Furthermore, the density of Eastern grey kangaroo (26.4 kmˉ 2 ) in the Northern Tablelands region of NSW is higher than Common wallaroo (7.4 kmˉ 2 ) ( Cairns et al, 2020 ) which would further increase grazing pressure within their habitat during periods of low rainfall and pasture growth.…”