Why Does Hawaii Not Have Squirrels?

why does Hawaii not have squirrels

Among the many animals that Hawaii does not have are squirrels. They also don’t have lions, tigers, or bears, oh my. They don’t even have squirrels. But why? It’s not for lack of habitat: squirrels live across most of the world in almost every habitat imaginable. So, why does Hawaii not have squirrels?

Hawaii has never had squirrels due to the distance between continental North America and these islands being too great for squirrels to swim, and humans have never introduced them. Therefore, if you see an animal resembling a squirrel in Hawaii, it is a small Indian mongoose, an alien invasive species.

You may be used to squirrels being all over the place and a downright pest, especially in cities that deliberately introduced the eastern gray squirrel. 

If so, it will probably surprise you that no one ever introduced squirrels to Hawaii, and these islands are still squirrel-free. However, humans did, unfortunately, introduce the small Indian mongoose, which has become a severe pest on the islands.

The Origin Of Squirrels And Why They Never Made It To Hawaii

The small fluffy-tailed rodents we know as squirrels (and their family members, such as ground squirrels, flying squirrels, and chipmunks) first evolved in western North America in the late Eocene, some 36 million years ago. The first squirrel looked somewhat like a modern flying squirrel.

From North America, squirrels arrived in Eurasia some 30 million years ago via a land bridge between North America and Eurasia and diversified into the different squirrels that live there now. 

They reached Africa and diversified into the modern African species when that continent collided with Eurasia some 18 to 20 million years ago.

Squirrels diversified explosively in South East Asia when sea levels dropped dramatically around 11 million years ago. South America seems to have had no squirrels until 3 million years ago when a land bridge was established (the Isthmus of Panama), and squirrels migrated southward from North America and diversified.

As you can see, squirrels have made it to just about every continent, except for Australia (where humans have recently introduced them) and Antarctica. While Antarctica would be too cold for them anyway, there’s another reason why squirrels have arrived where they have and haven’t gone other places: land bridges.

Squirrels can cross if one continent is connected to another by a land bridge. But they don’t swim nearly well enough to make it across if there’s no connection. 

The 2000 miles of ocean between the Hawaiian islands, formed by a volcanic hotspot and have never had a connection to any continent, are far too great a distance for squirrels to cross without human help.

The Squirrel Craze Never Brought Squirrels To Hawaii

Beginning in the late 1840s and intensifying in the 1870s with the proliferation of public parks designed by individuals such as Frederick Law Olmsted across American cities, people began reintroducing eastern gray squirrels to urban areas where humans had exterminated them.

People introduced these squirrels because they thought they were cute. In addition, individuals such as Ernest Thompson Seton, who co-founded the Boy Scouts, believed that it would be good for children’s moral character to practice charity by feeding them.

However, no one ever decided to introduce squirrels to Hawaii, and Hawaii has therefore never had squirrels in the wild (although zoos may have had one or two specimens). But you may think you saw a squirrel in Hawaii. What was that creature? 

The answer is a small Indian mongoose. It is about 2 feet in length and has become one of the main pests in Hawaii.

Let’s take a closer look at it. 

Why There Are Small Indian Mongooses In Hawaii

In the 1800s, the main crop in Hawaii was sugarcane, and the local economy was heavily dependent on this crop. 

However, the harvest was prone to severe depredations by rats, from the Polynesian rat introduced by the Hawaiian people to Norway rats and roof rats introduced by white settlers. These rats gnawed at the sugarcane to access the sweet juice, destroying a large portion of the crop.

Some people read a newspaper report about how sugar farmers in Jamaica managed to control rat numbers by introducing mongooses from India.

Some Hawaiian sugarcane farmers decided importing mongooses from Jamaica would be a good idea. Despite other individuals counseling that they should do more research to see whether the mongooses were affecting rat numbers in the Caribbean, the planters brought them anyway.

Initially, 72 mongooses were brought from Jamaica and released on the Hamakua Coast of the Big Island in 1883. Their offspring were shipped to the other islands: Maui, Molokai, and Oahu. 

None were shipped to Lanai, and although the farmers sent them to Kauai, they didn’t establish themselves there because someone drowned them on arrival. 

Reports differ as to whether the residents didn’t want them on the island and drowned them in the harbor or whether a dock worker was bitten and threw them overboard in anger.

With no natural enemies in Hawaii, and plenty of food, the mongooses thrived, and their populations exploded. Unfortunately, it turned out that the planters had imported them in vain. 

They’re active exclusively during the day, whereas rats are nocturnal. The mongooses ate hardly any rats, and improvements in poisoning ended the rats’ damage to the sugarcane fields.

The Devastating Effects Of Small Indian Mongooses In Hawaii

Although the mongooses didn’t eat rats, they found plenty of other things to eat: birds, reptiles, eggs, insects, plants, and fruits. They prey on the eggs of endangered sea turtles and the eggs and hatchlings of ground-nesting birds.

The females are ready to reproduce at ten months and can raise up to 3 litters of 2 to 5 pups per year, meaning that populations of mongooses snowball if not controlled.

It is significant that the largest population of the Hawaiian state bird, the goose known as the nene, was found on Kauai. However, with the recent establishment of mongooses on this island, nene numbers are declining.

Final Word

So now you know: there are no squirrels in Hawaii because the islands have never been connected to the mainland, and squirrels cannot swim across the ocean. 

Humans have also never brought squirrels to the islands. However, humans have brought mongooses, which have turned out to be serious pests.

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