Tortoises are on the decline because they rely on drip pools. Drip pools form when there is dense foliage to collect water out of the thick fog. Unfortunately, the forests are gone on the island of Isabella due to a huge goat population. These goats are non-native and were introduced by pirates, traders, whalers, and privateers who stopped in the Galapagos to replenish supplies
goats reproduced quickly and had no predators, so they essentially ate the forest, leading to a huge decline in tortoise populations.
