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Researcher's Report

Wildlife Ecology in San Guillermo National Park

The findings from the data Emiliano has shared gives an insight to the relationships that exist between pumas, vicunas and plant growth in the San Guillermo ecosystem under study.

Using those results, Emiliano described how pumas might influence vegetation height by preying on vicunas.

Guiding Questions:

How heavily do pumas prey on vicunas?
What evidence do you have to support your answer?

There are two lines of evidence that suggest that pumas heavily prey on vicunas at San Guillermo National Park. The first comes from results already reported by other researchers. These researchers found that vicunas represent 80% of the diet of pumas. The second line of evidence comes from the results of research question 2: pumas are responsible for almost 78% of the total baby vicunas that died. So, based on previous and new information, it could be concluded that vicunas suffer a heavy predation pressure from pumas.

How do vicunas respond to puma predation?
What evidence do you have to support your answer?

We have established that pumas exert a strong predation pressure upon vicunas. From what we know about puma hunting strategies this predator takes advantage of places where it can hide to stalk, ambush and kill its prey.

The behavioral observation data reveal that vicunas are most vigilant in tall grass habitats, which presents features that pumas could use to conceal themselves. This line of evidence, therefore, connects vicuna behavior with habitat type and puma predation pressure.

How does vegetation respond to decreased vicuna grazing pressure?
What evidence do you have to support your data?

Vegetation clearly responded to a decrease in vicunas grazing pressure. The experiment conducted in the field, where several plots were fenced so vicunas could not graze on them showed that vegetation height was 3.4 times higher than in the plot where vicuna were allowed to graze.

Puma Predation on Vicuna and Its Influence on Vegetation Height

Pumas prey heavily on vicunas. Eighty percent of the puma’s diet is made up of vicuna, and seventy-seven per cent of the vicuna of the vicuna who do not survive to their first birthday fall victims to pumas.

Pumas are ambush hunters so vicunas are more vulnerable in habitats that present features where pumas can hide. Vicunas risky habitats spend more time vigilant and therefore less time feeding.

When vicuna do not graze as heavily, plants respond by increasing their height.

Puma predation on vicunas causes vicunas to spend less time feeding and more time alert in risky habitats. This, in turn, decreases the grazing pressure and allows plants to grow higher in risky habitats.

Send Emiliano your questions or your suggestions to guide further research.

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