PLANET EARTH Deserts
To get there, they have to cross the Sonoran desert. But the desert is so big that for most of the year they would be unable to cross it. Now, with the saguaro in bloom, they can refuel on the way. So the saguaro's success in developing a way to store water is now crucial to most of the animals that live or even travel through this land. The scarcity of rain（降雨不足） determined the shape of this icon of the desert but water, scarce thought it is, has also, like the wind, shaped the land itself.
In the deserts of Utah（犹他） ancient rivers flowing across sandstone country steadily widen their canyons until now the land between them has been reduced to spires and pinnacles. With little or no soil to retain the water on the surface of the land life here is scarce indeed. And when resources are limited, conflict is never far away. These are Nubian ibex（努比亚野山羊） and they are squaring up for a duel（争斗）. And when trouble starts, a smart ibex knows that the best thing to do is to gain higher ground.
These are actually subordinate male ibex, but their fights are nonetheless serious. Losing one might mean never getting the chance to breed ever. When competitors are evenly matched as they are here, duels can last for an hour. In this heat the effort is truly exhausting. But victory here will gain important ranking points on a male's way to the top. There's so much at stake that not all play fair.
