Practice Test: Reading Comprehension - 21 | 100 RCs for GMAT PDF Download

Directions: Read the given passage carefully and answer the questions as follows:

Despite its 1989 designation as a threatened species under the federal Endangered Species Act, the desert tortoise, Gopherus agassizii, has declined in numbers by ninety percent since the 1980s. Although federal protection made it illegal to harm desert tortoises or remove them from the wild of the southwestern North American deserts, this measure has been insufficient to reverse the species’ decline, and further intervention is required.
Recovery has been slow, partly due to the desert tortoise’s low reproductive potential. Females breed only after reaching full size at fifteen to twenty years of age, and even then may only lay eggs when adequate forage is available. Although the number of eggs in each clutch varies, and each female might lay a few clutches in one season, the average mature female produces only a few eggs annually. From these precious eggs, hatchlings emerge wearing soft shells that will harden slowly into protective armor over the next five years. The vulnerable young are entirely neglected by adult tortoises, and only five percent ultimately reach adulthood.
Predators are blamed for most tortoise deaths; ravens, specifically, are estimated to cause more than half of the juvenile tortoise deaths in the Mojave Desert. Tortoise eggs and juveniles, with their delicate shells, can fall prey to many birds, mammals, and other reptiles. For protection from predators, as well as from desert temperature extremes, tortoises of all ages burrow into the earth.
However, if rabbits and rodents are scarce, larger mammalian predators may dig tortoises out of their burrows, devouring even mature tortoises despite their hardened shells.

Even with current protections from human interference, the desert tortoise faces a tough recovery, so additional measures must be taken. First, the limited habitat of desert tortoises, with soil suitable for their burrows, must be protected from development. Next, urban expansion often has the unintended effect of increasing raven populations, so aggressive measures to control the birds are necessary to increase desert tortoise hatchling survival rates. Finally, released captive tortoises typically perish, and can pass upper respiratory tract disease into the wild population with devastating consequences, so continuing education of pet tortoise owners is essential.