The Hawaiian Island Chain has erupted from the bottom of the ocean and risen to create new land over millions of years. Lifeless lava was colonized by wandering organisms that happened to find the islands in the vast Pacific Ocean. New species have been arriving, adapting, and thriving in the Hawaiian Islands for millions of years. The isolated location of Hawai‘i means that it’s very difficult for new species to arrive in the islands naturally.

When an organism exists in a place without human intervention, it is called indigenous. An indigenous organism may be found in many different places around the world. An endemic species is an organism that can be found in only one place. Organisms can come to the Hawaiian Islands naturally by wind, wing, and waves.

Strong trade winds can sweep small airborne seeds, insects, and birds far out into the Pacific Ocean, where they might be lucky enough to find the Hawaiian Islands. An example of wind borne arrivals are spiders. They can travel long distances by releasing silk threads into the air that catch the wind like a kite and carry them away. Microscopic fern spores can also drift on the wind over long distances.

Flying animals like birds, winged insects, and bats can be blown toward the Hawaiian Islands by chance. Many birds frequently come to the Islands, but don’t migrate there regularly. Some birds that arrived in the Islands stayed and developed into endemic populations. The Hawai‘i State bird, the nēnē (Branta sandvicensis), is closely related to the Canada goose, but is a distinct species. Unlike its continental cousin, it doesn’t migrate and only flies short distances.

Birds can also carry small seeds stuck to their feathers, or in their guts. Birds like the kōlea, Pacific golden plover, migrate to Hawai‘i from Alaska every winter. The raspberry and blueberry probably arrived with a bird like the kōlea. These plants from North America slowly adapted to their new home in Hawai’i to become the endemic ‘ākala and ‘ōhelo plants.

Many organisms arrived from the ocean as well. Some plants disperse seeds that can float on the ocean for years. Sometimes large storms and floods wash plants and animals into the open ocean where they form floating rafts of debris that can carry plants and animals across the ocean. Fish and marine mammals can swim to the Islands as well. The Hawaiian monk seal,¹ is an example of an endemic Hawaiian marine mammal.

Variety of Ecological Zones

Newly arrived organisms found a wide variety of climate and soil types. They were able to spread out and adapt to all of them. Some endemic species were able to expand from older islands to newly formed ones in the continuously growing island chain. Even though the island of Hawai‘i is less than half a million years old, the location has an ecological history that stretches back many millions of years.

Some Hawaiian endemic species have evolutionary lineages older than the islands they live on. Generations of lobelias have lived near the Hawaiian volcanic hotspot for millions of years. They were able to spread to new islands rising from the ocean depths and continue their lineage, even though their original home islands eventually eroded away beneath the waves.

Kaua‘i is the oldest of the main islands in the Hawaiian Archipelago. Kaua‘i is estimated to be 5 million years old. The last common ancestor of endemic Hawaiian lobelias and continental lobelias arrived in the Hawaiian Island around 13 million years ago. This suggests lobelias arrived in the area at least 8 million years before Kaua‘i was formed.²

The arrival of new organisms and their adaptation was a slow process. The isolation of the Hawaiian Islands only allowed an estimated 600 or less different indigenous species to establish permanent populations. The average time between new species establishing in the Hawaiian Islands was about 100,000 years.

Hawai‘i has more endemic species than most places

Extremely isolated islands like Hawai‘i have more endemic species than most places. The Hawaiian Islands provide more opportunities for a limited number of species to adapt to a broad range of different ecosystems. When an organism population changes from its ancestors and becomes so specialized that it can only be found in one place, it is called an endemic species.

Isolation is a key factor to stimulate accelerated specialization. When a population is isolated, there are fewer choices for food sources and mates. The organism evolves to improve its ability to use the limited resources available.

For example, the Hawaiian honeycreeper birds are a group of more than 50 birds that evolved from a common Asian finch ancestor. The original Asian finch ancestor arrived in the Hawaiian Islands millions of years ago. Over time, different populations of the bird spread out to inhabit different ecological zones. Each population became more specialized at exploiting a different food resource.

Evolution is when an organism population slowly adapts over many generations to take better advantage of a particular environment. Every individual in a population is unique, no two organisms are exactly the same.

An individual finch might have a beak that is slightly better shaped to get more of a particular food source than other finches. The more successful birds can have more offspring and pass along the special traits that make it more successful. Less successful birds do not have as many offspring, and their traits gradually become less common. Isolated populations gradually become specialized at exploiting specific food sources over multiple generations. Each new generation has slightly more birds with slightly more specialized characteristics. Over millions of generations, birds developed radically different beak shapes, and colors from their ancestors.

Some finch populations became specialized to drink nectar from particular flowers, and others to eat fruit, or snails.³ Some plants also co-evolved to have their flowers pollinated by specific birds,⁴ and their seeds dispersed by different birds.⁵ The various bird populations found different sources of food in each unique ecological zone. The process of one species spreading out and adapting to different specialties is  called adaptive radiation.

Adaptive Radiation

The process of adaptive radiation happened for each of the 600 indigenous species that arrived in the Hawaiian Islands. Plants and animals formed mutually beneficial relationships that allowed them to inhabit every different type of ecological zone. The diversity of different ecological zones, and the isolation of the Hawaiian Islands, led to one of the most biodiverse ecosystems on Earth.

Plants and animals were able to evolve into a diverse community that worked together. Every organism had a different role to play in the ecosystem that supported them all. Resources were divided amongst the different organisms so that they did not compete with each other too much.

A mature ecosystem has several plants and animals that fill the same role. The mature ecosystem has enough variety to continue functioning if one, or a few, species is lost or severely degraded; and yet, not too many species are competing for the same resources.

People adapted to the Hawaiian Islands in ways similar to wildlife, and differently as well. Similar to other organisms a very small number of families came to settle the Hawaiian Islands. The people spread out into different ecological zones and set up communities where people had different specializations. Some people were farmers, some fished, some built canoes or houses, etc. People, like the honeycreepers, specialized in different skills. People adapted their behavior and culture to make the best use of different environments.

Culture is a way for humans to adapt to an environment without having to change the shape of our beaks. Like with evolution, change starts with individuals. Individuals share and mix their beliefs and behaviors with people around them, to create a community. A community with common beliefs and customs over generations becomes a culture. A successful culture is able to support a diverse community that works together. Each individual has a special role in supporting the community’s continuation.

Continue reading about cultural adaptation in Hawaiian History