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There are a number of ways of assessing grazing pressure. It is important to factor in the additional DSE’s that other species are contributing to your total grazing pressure, so that you are aware of the impact of other grazing species on your country, and avoid any shortfalls that might come about from your calculations.
Tactical Grazing Management (NSW Agriculture, 2000) bases part of this estimate on the different dung that allows different species to be identified. The manual provides a method for estimating the relative grazing pressure of sheep and kangaroos. Based on the comparative levels of dung, an estimate of the kangaroo population (average number for the previous two months) can be obtained if the number of sheep in the paddock is also known. A ‘step – point transect’ process is used to assist in this process.
Total grazing pressure is determined by attributing a DSE rating to the different species:
- Kangaroo = Has generally been estimated as 0.6 - 0.7 DSE, however recent research (Dawson and Munn, 2016) suggests that in arid rangeland areas, competition is not normally an issue in good seasons and that 0.4 DSE appears to be a better estimate in poor seasons.
- Goat = 1 DSE
- Rabbit = 0.1 DSE
Tactical Grazing Management also provides the option of assessing:
- Rabbit numbers based on the density of rabbit warrens and the average number of
open/active entrances:
- Rabbit number = Number of warrens per paddock x average number of open or active entrances per warren x 2.4 (rabbits per open entrances).
- Feral goats numbers based on sightings:
- Number of goats compared to number of sheep noted during paddock inspections allows a proportional estimate of goats.
Grazing pressure can also be determined by conducting:
- Spotlight survey at night for kangaroos, goats and rabbits
- Aerial survey for kangaroos.
Once the numbers of these animals are determined and the additional grazing pressure is determined, then decision can be made as to whether a control program is required to reduce this additional grazing pressure to a sustainable level. This can be achieved by:
- Rabbit control: baiting, fumigation and warren destruction
- Goat control: mustering, water-point trap yards, shooting programs
- Kangaroo control: obtain a permit for control by a licensed shooter, with meat ideally being used for pet food or human consumption.
Lookup: Glovebox Guide to Tactical Grazing Management, NSW DPI.
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