The finches on the Galápagos Islands were different from those in Ecuador. Their beaks were suited for how they got their food on each island. Beak shape, Darwin realized, was an adaptation that helped the finches survive.

For example:

Green warbler‑finches have thin, sharp beaks. They use them to spear insects.

Medium ground finches have short, stubby beaks. They use them to eat seeds on the ground.

Common cactus finches have broad, curved beaks. They use them to nibble on plants.

medium tree finch
(Camarhynchus pauper)

large tree finch
(Camarhynchus psittacula)

mangrove finch
(Camarhynchus heliobates)

woodpecker finch
(Camarhynchus pallidus)

green warbler‑finch
(Certhidea olivacea)

Cocos finch
(Pinaroloxias inornata)

small ground finch
(Geospiza fuliginosa)

medium ground finch
(Geospiza fortis)

large ground finch
(Geospiza magnirostris)

sharp‑beaked ground finch
(Geospiza difficilis)

common cactus finch
(Geospiza scandens)

Española cactus finch
(Geospiza conirostris)

vegetarian finch
(Platyspiza crassirostris)

small tree finch
(Camarhynchus parvulus)

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People began to introduce new plants and animals to the islands as they arrived. Goats, pigs, dogs, and plants were brought to the islands to make life easier for settlers. We call them introduced species. Other living things not from the islands— rats, insects, and weeds—probably arrived on ships.

Cats are not from the Galápagos. A cat can harm native and endemic wildlife.

Wild boars, or wild pigs, now roam the islands.

Most Galápagos plants and animals weren’t exposed to things from other places. So, outside organisms put them at risk for disease or even attack. We call these invasive species. They cause damage to the islands.

Blackberry plants grow and spread quickly. They take up space native plants need to grow.

Plant Invaders

About 700 of these invasive species are plants. One plant, the wild blackberry, has been a cause for concern. It was introduced in the 1970s. It quickly spread across the islands. The blackberries crowded out the Scalesia forests on Santa Cruz and three other islands.

Scalesia plants are giant members of the daisy family. They can grow up to 15 meters (49 feet) tall. These forests are homes to a variety of bird species, including the woodpecker finch. The berries have taken over a lot of land.

Farmers consider the blackberry a weed. It turns farms into wastelands by choking out other plants. Fighting blackberries is hard work. Destroying it by hand can be back‑breaking. And killing it with herbicides is too risky. The poisons could harm other plants.

Before you read

Life Science

Ecosystems and Introduced Spieces

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This grassland was once covered by thick forest.

Between Man and Goat

Invasive species include animals, too. There are 13 introduced species of mammals in the Galápagos.^✻ The one that has caused the most damage is the goat. Whalers, pirates, and fishers brought goats to the islands in the 1850s. By the late 1990s, the total number of goats reached six figures.

Goats are known for their appetites. Over time, they ate their way through large patches of land.

^✻ Bats and rice rats are the only mammals native to the Galápagos Islands.

Taking Back the Islands

Once an invasive species takes over, how do you get rid of it? Galápagos farmers fight the blackberry one plant at a time. They rip them out by hand.

The goats were another matter. Their grazing threatened the survival of rare plants and trees. In 2004, Project Isabela was enacted. Goats were killed, so plant and animal life could come back.

a herd of goats on Isabela Island

Invasive species pose a real threat to the islands. Each must be monitored and managed to protect the islands.

Goats eat plants like prickly pear cactus, which is food for giant tortoises, land iguanas, doves, cactus finches, and mockingbirds.

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