I first remember being introduced to the field of island biogeography in a dark, empty lecture hall at Oregon State University in an advanced biology course. This theory explores and explains the factors that impact the richness and diversity of species on island habitats. Robert H. MacArthur and E. O. Wilson first coined this concept in the 1960s. However, it has been altered to use the term ‘insular’ rather than island to include habitats and species that are isolated in other ways than by vast expanses of water. They showed that the richness and diversity of species depends on a few factors, including proximity to the mainland and the size of the island, which impact the rate of colonization and extinction of species.
In the birding world, this theory relates to island biodiversity. Classic examples of islands ranking high in biodiversity are the Galapagos finches and Hawaiian honeycreepers. Both had ancestral species that landed and then diversified to fill habitat niches. Not all islands offer a vast diversity of species because they might be too small to provide adequate habitat for many would-be colonizers, or perhaps they are too far for possible founders to fly from.
Regardless of size, bird composition, and proximity to mainland areas, I love traveling to islands. Here are a couple of islands on my short list for future trips:
1. Christmas Island, Australia – This island first came on my radar reading Isles of Amnesia: The History, Geography, and Restoration of America’s Forgotten Pacific Islands by Mark Rauzon, in which he details his experiences in island restoration. The island itself has a high level of endemism. Humans didn’t inhabit the island until the late 19th century, so our influence is relatively minimal. The island is approximately 12 miles x 9 miles, with almost 90 miles of coastline. Over 60% of the landmass is protected as a national park, and it has a tropical rainforest and a healthy coral reef skirting the shoreline – great for nature explorers of all disciplines.
The island is world-famous for its annual red crab mass migration as they move towards the sea to spawn. But for me, I want to see the seabirds. Three species of booby (Red-footed, Brown, and Abbott’s), frigatebirds (Christmas and Great), noddy, and tropicbirds. Other endemics like the Christmas Thrush and Christmas Imperial Pigeon would also be great to seek out.
2. Chatham Islands, New Zealand—There are so many fascinating things about this island, one of which is that it has its own time zone, which is 45 minutes ahead of New Zealand. The island chain consists of the two largest islands, Chatham and Pitt, and 12 other islets. The coastlines comprise cliffs, dunes, beaches, and lagoons, providing diverse habitats for several species.
The island has a high number of endemic species, including 50 plant species that are adapted to cold and consistent winds. There are 18 endemic bird species still found on the island, and several others have become extinct. The remaining species are in decline, and recovery programs are underway to conserve several of them, such as Magenta Petrel and Black Robin (which happens to have inspired a gin).
3. Nicobar Islands, India – Located on the eastern edge of the Bay of Bengal are the Andaman and Nicobar Islands. These islands were created by a collision of the Indo-Australian plate Plate with Eurasia, also resulting in the life of the Himalayas. It is warm and tropical and receives over 10 feet of rain annually from monsoons. These are perfect conditions for developing the mangroves and rainforests that host endemic species. Unlike the other islands mentioned, this one has been inhabited for thousands of years, including European colonization, so it has received much human influence.
One island, the Great Nicobar Island, has been designated by UNESCO as one of the World Network of Biosphere Reserves – so you know it has to be good! Some endemic species can be found here, including the Nicobar Imperial-Pigeon, Nicobar Megapode, Nicobar Sparrowhawk, Nicobar Parakeet, and many others.
4. Isla Robinson Crusoe, Chile – Another island introduced to me in a book, The Glitter in the Green: In Search of Hummingbirds by Jon Dunn, depicts his adventures seeking out the hummingbirds of the world. One fascinating specimen is the Juan Fernandez Firecrown, a critically endangered red hummingbird found only on this island. Isla Robinson Crusoe is the largest of the Juan Fernandez Islands, almost 500 miles west of San Antonio, Chile. It was home to Scottish sailor Alexander Selkirk, who was marooned for five years at the beginning of the 18th century. His story is said to have been an inspiration for Robinson Crusoe. It has mountainous terrain with a peak of 3,000 feet, and erosion creates steep ridges and valleys down to the sea.
Another World Biosphere Reserve, this island is of scientific importance with many endemic plant families and other wildlife. Besides the firecrown, the Juan Fernandez Tit-Tyrant and Masatierra Petrels make this island worth a visit.
5. St. Paul, Alaska, USA—One of the last spots where wooly mammoths roamed, St. Paul is the largest and furthest north of the Pribilof Islands. You would not think many folks have this spot on their bucket list with just one school, one bar, one store, and around 400 people.
Although this island has no endemic species to seek out, it is a birding haven. It is part of the Alaska Maritime National Wildlife Refuge, with extensive seabird cliffs hosting millions of breeding seabirds. It is also a depository for off-course birds, including Siberian vagrants. Also worth seeing is the critical nesting habitat for many seabirds, including Red-legged Kittiwakes, puffins, murres, auklets, and murrelets.
I hope to visit many places in my life, and hopefully, I can secure an eBird listing for some, if not all, of these spots! What are some of your favorite islands?
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