The Population Ecology of Wild Horses in the Australian Alps

More documents

Recommendations

Info

Table 4: Summary of horses caught by brumby-runners in the Alpine National Park, Victoria. *Not all horses caught were recorded in 1999-2000. Year Total caught Stallions (%) Colts (%) Mares (%) Fillies (%) 1998-1999 224 9.4 29.9 43.8 17 1999-2000 78* 7.7 37.2 41 14.1 2000-2001 174 9.8 25.9 36.2 28.2 2001-2002 207 7.7 36.2 33.3 22.7 The assignment of wild horses caught into categories of stallion, mares, colts and fillies can be misleading for interpreting age of horses, particularly males because males (3-6 years old) can be called colts while the classification of 3-year-old females and older as fillies is less common. I would recommend that any data collection should include an estimation of age in the future to address this. This was done between 2000 and 2002 and the data was used in comparisons with the Cowombat, Big Boggy and Currango wild populations. Brumby-runners did not select for males or females when all age classes were combined for the analysis, however they did select for adult females over adult males. They also showed a preference for younger animals (
Predicted Popu latio n S ize 4500 4000 3500 3000 2500 2000 1500 1000 500 H=0 H= 50 H=100 H=150 H=200 H=250 H=300 H=350 0 0 10 20 30 40 50 Time (Years) Figure 4: Predicted size of the Alpine National Park wild horse population at different levels of harvest (H) per year. The model assumes logistic growth with intrinsic rate of increase = 0.2, initial population size = 2000 and carrying capacity = 4000. This model assumes a non-selective harvest. Harvesting that targets younger animals means that more animals have to be removed to achieve the same population reduction, while selectively harvesting adult females will lead to a sex bias in the population and less animals would have to be removed to achieve the same target. Modelling shows that although brumby-running is a form of recreational harvesting, it can suppress populations below carrying capacity and can be used as a management tool. Its effectiveness as a management tool will depend on the management objectives in each circumstance. I recommend that if it is used as a management tool in the future it should be accompanied by population and/or impact monitoring, as should any form of management. Key management messages • The maximum observed rate of spread of wild horses in the Australian Alps between Dyring’s (1990) study and the maps presented here is remarkably low (< 4 km per year). • Wild horses do not occupy the full extent of their potential range. • Humans appear to be the most important factor influencing wild horse distribution. The presence of horses in an area can usually be traced back to an introduction event, and control efforts have removed them or reduced their range. 13
Page 1 and 2: The Population Ecology of Feral Hor
Page 3 and 4: seen to be a problem during last ce
Page 5 and 6: Humans appear to be the most import
Page 7 and 8: methods simultaneously and assessed
Page 9 and 10: Kosciuszko National Park and the Al
Page 11: Managers that target adults (surviv
Page 15: Walter M. J. (2002). The population

The Population Ecology of Wild Horses in the Australian Alps

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?