Allocating grassland resources to guanaco populations in Argentina
To help society in Santa Cruz, Argentina put together a Provincial Guanaco Management Plan, we developed population simulations to see how the number of guanacos (Lama guanicoe) may change with different amounts of land set aside for these animals.
For population simulations, we used a population matrix model tailored to the life history of female guanacos. We estimated bounds on guanaco population growth from information from the Cameron ranch (Tierra del Fuego, Chile), which contained 40 years of uninterrupted guanaco population sampling data. Simulations further included information on annual rainfall, winter temperatures, sheep densities, removal from hunting, catastrophic drought, and catastrophic snowfall.
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Comparison among annual fertility across quota values. Annual fertility represents the amount of reproduction by a single breeding adult per year.
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Trajectories for the simulated guanaco populations under a10% quota. Trajectories illustrate growth in animal abundance, where growth is initially unbounded, followed by reduced growth when populations near the carrying capacity.
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The simulated proportion of guanaco groups that get extirpated after 100 years for a range of landscape sizes (x-axis) and guanaco herd sizes (y-axis) under a 10% quota.
Comparison among annual fertility across quota values. Annual fertility represents the amount of reproduction by a single breeding adult per year.
Trajectories for the simulated guanaco populations under a10% quota. Trajectories illustrate growth in animal abundance, where growth is initially unbounded, followed by reduced growth when populations near the carrying capacity.
The simulated proportion of guanaco groups that get extirpated after 100 years for a range of landscape sizes (x-axis) and guanaco herd sizes (y-axis) under a 10% quota.
Model outputs reveal the probabilistic extent to which limiting grassland receptivity by a given quota may lead to the local extirpation of wild sub-populations. Simulated trajectories and other important demographic properties under each quota level include estimated abundances, vital rates, long-term properties, short-term properties, genetic properties, and other extinction properties.
Start the Demographics of Guanacos App
The study is entitled Rabinovich JE, Grauer JA, & Hanley BH. Allocating grassland resources to guanaco populations in southern Patagonia (In preparation).
The code for the Shiny application is in Hanley BJ, Grauer JA, & Rabinovich JE. Demographic properties of guanaco in southern Patagonia [software]. Cornell Library eCommons Digital Repository (In preparation).