Horse Number Calculations Following aerial surveys in Autumn 2014, preliminary results from a draft report released at the end of August indicate the number of horses in Kosciuszko National Park is between 3886 and 7862 animals. There were between 2777 and 5893 in northern Kosciuszko, with a 17% rate of population increase, and between 1109 and 1969 in the Pilot area of southern Kosciuszko, with a 6% rate of increase. Although research is insufficient to know how many horses die each year, Theile and Prober suggested that on average, 20% of horses in the Victorian high country die of starvation, dehydration or from eating poisonous plants (http://www.australianalps.environment.gov.au/publications/research-reports/pubs/feral-horseimpacts-pt2.pdf). Quite likely these deaths occur unevenly over the years (http://www.esajournals.org/doi/abs/10.1890/07-1153.1) but, for our calculations, we assumed a 20% death rate. It would be unrealistic to use a constant rate of population increase, because population increase is linked to population density. We therefore assumed that the growth rate increases to 20% (http://theaustralianalps.files.wordpress.com/2013/12/2009feralhorsealpssurvey.pdf) as the population size decreases from the starting value to half that initial value. On the other hand, we also assume that the growth rate declines to zero as the population size increases from the starting value to twice that value. The starting values are set at the lowest estimate (3886 in total) or the highest estimate (7862 in total) in different scenarios. The number of horses removed by trapping is set at either the average number removed per year (186), or the maximum number removed in any one year (664) (http://www.environment.nsw.gov.au/resources/planmanagement/final/130067KNPImp1112.pdf). Thirty percent of these horses are rehomed and seventy percent end up at the abattoir. In scenarios where the number of horses remaining in the National Park is less than the number planned for removal, we reduced the number that can be trapped to half of the number of remaining horses. To consider aerial culling, we assumed that half of the feral horses remaining in any year could be destroyed. We made separate calculations for the Pilot and Northern Kosciuszko and added the results to get one value for the whole park.