Nature Does Indeed Know Borders

Written by Arieh O’Sullivan
Thursday, December 03, 2009

How man-made phenomena along the borderline have made Israeli rodents more cautious than their Jordanian neighbors.

The old adage is that nature knows no borders, that species don’t recognize any map demarcations and that they will develop equally on both sides if climatic conditions are shared.

But new research from the University of Haifa in Israel argues this isn’t always the case.

According to the study, Israeli rodents are more cautious, the ant lion more ambitious and reptiles less diverse than their Jordanian counterparts.

The Israeli-Jordanian border is demarcated by the Jordan River, Dead Sea and then a straight line southward to the Red Sea. The climate is virtually identical on both sides. But it turns out various man-made steps have caused the fauna to develop and behave differently.

“The boundary is indeed a virtual marking that appears on the map and is not capable of keeping these species from crossing the border between Israel and Jordan,” said Dr. Uri Shanas, head of the Israeli team that carried out the research at the University of Haifa. “But the line does stop humans from crossing it and thereby contains their different impact on nature.”

The study began as an anthropogenic study of various Western-style agricultural practices on Israel’s wildlife, mainly rodents, reptiles and insects. The Jordanian side was to serve as a sort of control since the land had been less cultivated and primarily based on nomadic shepherding and traditional farming.

“After a few sampling events we started to see something strange and note differences the border itself caused,” Shanas told The Media Line.

He said they were working in conjunction with a Jordanian team made up of Jordanian researchers and students, often within shouting distance of each other as they examined identical landscapes.

“The funny thing was for example, with rodents,” Shanas said. “We were catching mostly gerbils. Many times we came to our sites and the traps were empty. We didn’t catch anything. I would call to my Jordanian colleagues on their mobile phones, sometimes just over the fence, and ask them how many they caught. They were happy to say they caught lots of gerbils. So we started to think that there was something else going on here.”

The researchers at the Department of Environmental and Evolutionary Biology determined that the Israeli gerbils were more suspicious, cautious and vigilant since they developed leeriness to the red fox who hunt them.

It turned out the red fox was much more abundant on the Israeli side since there were more food sources from the agricultural fields and garbage dumps. By contrast the Jordanian side was mainly an untouched wilderness.

“The foxes put pressure on the gerbils and that made them more vigilant on the Israeli side,” Shanas said, adding that on the Jordanian side the gerbils allowed themselves to be more carefree.

Another study found a greater presence of the funnel-digging ant lions on the Israeli side.

“The reason we find lots of ant lions on the Israeli side is because there are gazelles,” Shanas said. “The gazelles are well protected on the Israeli side while they are not protected by law or practice on the Jordanian side. The gazelles break the soil crust and that enables the ant lions to build their funnels on the Israeli side.”

“We call the gazelles ‘ecological engineers’,” he said. “So this is another way in which the cultural differences across the border affect several species and their distribution across the border.”

The study also found that the number of reptiles is similar on both sides, but that in Jordan the variety of species was greater. This was mainly due to fewer farming fields and greater wilderness continuity in Jordan.

It was clear that the impact on nature was directly or indirectly man made. Researchers expected culture would impact on diversity, but were surprised it also impacted on behavioral differences.

“This study might be able to show the Jordanians which way they are going in terms of changes in biodiversity on their side,” Shanas said.

The results of the study could serve as a potential window for Jordan as a demonstration of how their fauna might change on the border region.

“We both have to learn from each other and maybe this is the bottom line,” Shanas said. “They can learn from our experience but we can also learn from their experience.”