Wednesday, 23 October 2013

Goading the Goats: Tourists trigger tension

(This is a review of a paper on animal behavior. I wrote this review for a Coursera ( course on Animal Behavior (which, by the way, is an excellent course -- I recommend without reservation that everyone take it!). I hope you like my review).

Vidya Jonnalagadda

Goading the Goats: Tourists trigger tension

Humans like watching wildlife, be it photographs, videos, or live animals.  With growing numbers of takers for wildlife tourism—observing animals in their natural settings—the question is who gains what from this activity.
Doubtless, the National Park or Wildlife Reserve gets revenue, and tourists get edutainment, but what do the animals get?
Stress, seems to be the simple one-word answer, judging by a study of Nubian ibex (desert goats) in Ein Avdat National Park in Israel.
We may believe that the goats simply munch away till they are full. But in reality, vigilance wins over victuals; time spent grazing on any spot is determined by actual abundance of food and perceived risk of predator attack.
Tadesse and Kotler [1] scored “giving up density” (GUD)— measure of food remaining in a patch after the ibex move on to another spot—to gauge the goats’ perception of risk of attack while grazing. They placed feeding trays at various locations of the Park: sites classified as cliff faces, plateaus, and garden habitats. Each tray contained a known amount of edible matter (100 g) hidden in a vast excess of nonedible plastic tubing (1.3 kg); the ibex had to dig through the mesh covering of the tray to get to the food. GUD was the amount of edible matter remaining in the trays after the ibex moved away.
The researchers noted that the food eaten from the trays was dictated by the density and distance of tourists. More tourists meant less time feeding, particularly if the tourists were on slopes above the feeding trays.
This means two things: 1. though the ibex appear habituated to humans trekking through their habitat, they are still wary of possible attacks by tourists, and 2. humans "lurking" at certain vantage points are more stressful to these goats. People moving on slopes above the ibex generate extra stress presumably because the ibex sense that their “escape routes” are cut off.
For some animals, vigilance is a function of herd size (number of animals in the herd): as expected, more the total number of eyes in a herd, less the time each individual animal spends scanning the surroundings for predators (and taking breaks from grazing). But larger herd size did not correlate with lower vigilance for these goats; showing that one may not extrapolate what is good for the goose as also good for the gander.
This point is driven home by the observation that male ibex never fed from the trays (the reason is not yet known!). Among the females feeding from the trays, adults showed the highest degree of vigilance.
While the reason for this behavioral dichotomy is not known, it opens up the possibility that the tourist-generated stress affects other aspects of caprine [2] life, such as reproductive behavior. If being watched makes a goat less likely to feed, might it also make it less likely to mate? After all, these animals are not willing participants of a reality TV show!
Tadesse and Kotler show how a simple, low-tech, easily scalable, and non-invasive method can reveal key factors governing behavior of animals in their natural habitat. Given that behavior of animals is the only indication we get regarding their mental well-being, studies such as this can provide very important guidelines to design tourism and conservation programs that minimize tourist-induced stress to wildlife.
[1] S. A. Tadesse, B. P. Kotler. (2012) Impact of tourism on Nubian Ibex (Capra nubiana) revealed through assessment of behavioral indicators. Behavioral Ecology 23:6, 1257-1262. 
 [2]relating to goats.

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