By Yuval Zukerman
Recently, due to the COVID-19 pandemic that is keeping everyone inside their houses, wild animals are increasingly being observed within cities and settlements. The lack of human activities associated with the COVID-19 virus poses an opportunity for animals to enter and utilize the abundant artificial resources found in human-dominated areas. Yet this phenomenon is not new at all. The world's human population is growing rapidly and consequently, the overlap between humans and wildlife is rapidly increasing as well. Some wild animals get repeatedly exposed to human activities, leading some species to modify their behavioral responses, and in many cases causing a substantial decrease in their response toward humans. This high tolerance to humans may provide increased opportunities in the form of readily available and easily accessible resources (for example, garbage piles that provide plenty of available food), but may also entail risks for both animals and humans.
In my research, I study these behavioral changes of one amazing species- the Nubian ibex. Nubian ibex are iconic desert ungulates. In the past they ranged widely in North Africa, throughout the Gulf and into the Levant. Now they are threatened throughout most of their range with only ~2500 individuals left, two-third of them inhabiting the deserts of Israel. Some ibex populations in the Israel have become extremely tolerant towards humans, and can be found deep within local towns and villages, and while I feel lucky when I wake up in the mornings and see ibexes outside my door, it also makes me wonder – how is this tolerance to humans affects ibex behavior, and in the long run, its evolution. The main goal of my MSc research is to find out whether ibex tolerance to humans influences other behaviors towards non-human stimuli (for example, predators or novel objects).
How do I achieve this? I scare ibex! I spent most of my last summer walking toward male ibex until they decided to escape. The distance between me and the ibex at that moment is called the flight initiation distance (FID), and I measured the FID of males from six different sub-populations that are found in in six different areas in the Negev Desert, varying in their levels of human disturbance.
I found large differences between the FIDs of the sub-populations, even more than I thought. In the areas that are highly disturbed by humans (i.e. settlements), the FID was very low, (sometimes less than 1 meter). One time I was so close to the ibex that eventually I was the one to escape while the ibex stayed put. In contrast, in the most natural and low-disturbed areas, FID was much higher, sometimes even more than 200 meters.
This summer I intend to continue my research and measuring FID of males in the same sub-populations but with other types of approaching stimulus: a dog with a human (representing a predator associated with humans), a leopard model (representing a natural predator) and a novel object. Then I will compare the results and see if exposure to human influences ibex behavior even when facing non-human threats.
Ibex in Midreshet Ben-Gurion