Question

Sneaky snakes

During the 1940s, military ships from the South Pacific accidentally introduced brown tree snakes from Australia to the island of Guam. These snakes eat birds, lizards, and small mammals in their native range of Australia. Since no species on Guam eats the snakes, their population has grown rapidly. Researchers estimate that two million tree snakes now inhabit the island. So far, 10 species of birds and 5 species of lizards have disappeared from Guam; small mammals have also decreased in abundance.

Use this information and your knowledge about biology to answer questions 11-15.

11. Since the brown tree snake is a keystone species (albeit an invasive one which harms the local population) in Guam, it must also be a keystone species in Australia.

True

False

Question 12

Native predators of birds on Guam likely decreased in abundance after brown tree snakes arrived.

True

False

Question 13

If birds on Guam usually disperse seeds, brown tree snakes likely had a negative indirect effect on plants.

True

False

Question 14

Since more prey and fewer predators occur on Guam than in Australia, the density of brown tree snakes in Guam likely exceeds the density in Australia.

True

False

Question 15

If some species of the extinct lizards used to eat bird eggs, brown tree snakes had a positive direct effect and a negative indirect effect on birds.

True

False