The Hawaiian Islands (work in progress!)

This pages summarizes a recent trip (Dec 2019) to Hawaii that focused on some of the natural history aspects of the islands.  We hope the reader will find it useful in deciding whether the islands are worthwhile visiting.  While much of the information presented below can be found from internet sources, we believe some of our observations and certainly our opinions will be unique.  We encourage the reader to explore this material.

This page has developed into something much larger than originally anticipated.  Thus we have broken it down into different pages that can be more rapidly accessed via the links below.  Each link takes you to a specific part of the page.  This should save tedious scrolling down of a single page.

1.  Geographical setting of the Hawaiian Islands.  Where they are, overview of the main islands.  An quick summary of their geological and climatic setting.

2.  Geology of the islands, especially the Hawaii (commonly termed the “the Big Island” to avoid confusion with the entire state of Hawaii).  This material is especially useful for those interested in the volcanic landscapes.

3.  Climate of the islands.  For those seriously planning to take advantage of their time on the islands you will benefit from a better appreciation of the island’s climate.

4.  Vegetation of the islands and some examples of restoration efforts.

5.  Wildlife of the islands – mostly focused on birds, since there are no native land mammals or reptiles or amphibians and we don’t know much about groups like insects.

6.  Summary  of where to go, what to see.  Our biased opinions.

Some basic facts about the Hawaiian Islands first.  They are all volcanic, ranging from the youngest in the southeast (Hawaii, at less than a half million years) to the oldest in the far northwest (Kauai being the last large island – at about 5 million years).  They have been colonized by organisms and plants over millions of years and within the last 1000-1500 years by humans from Polynesia.  More recently, in the last several hundred years, western influences have introduced innumerable other organisms that are not native to the islands.  These have created major environmental problems on the islands.

The islands are not uniformly green, despite what tourist information might try to lead potential tourists to believe.   Nor are the surrounding oceans uniformly good for skin and scuba diving.  Never-the-less, there are many interesting aspects of the islands for naturalists.  For example, diversification of the fruit fly genus Drosophila has been extreme – there are something like 500 species found in the islands.  Likewise, there are about 160 species of ferns found in the islands – of which almost 80% are endemic to the islands.  Many other plants have diversified within the islands, with the result that the native flora has a high rate of endemism.  This is similar to other remote island ecosystems.  It might be mentioned that the Hawaiian Islands are generally considered the remote islands anywhere on Earth – depending on how this is defined.  They are approximately 2500 miles away from the nearest continental land.

While there are no native terrestrial mammals (there is one native bat), no native reptiles or amphibians, (there are introduced herptiles (mostly geckos) and a few frogs (mostly introduced Coqui’s (Eleutherodactylus coqui) from Puerto Rico) there are a number of native birds, especially “Honeycreepers”.  Unfortunately, perhaps 50% of these small endemic birds have gone extinct in the last century – mostly due to avian malaria from introduced birds.  Most native birds have little immunity to this disease.  Thus, a birder seeking endemic Hawaiian species will be disappointed, since they are unlikely to find more than a dozen species even with considerable effort.  However, there are a number of land-nesting pelagic birds that are perhaps easier to see in Hawaii than elsewhere.

Sadly, one is likely to see many more non-native (introduced) birds in Hawaii than native birds.  Thus, with some exceptions, the Hawaiian Islands would not be a birder’s first choice of destinations for a given travel budget.

Some of our opinions are likely to be at odds with conventional touristic advice.  We discuss the islands as a potential destination for seeing fascinating aspects of natural history.  Enjoying warm water in mid-winter, sunbathing on the many fine beaches, or enjoying the numerous (high priced) resorts don’t factor into our discussion below.

Basic Geography of the Hawaiian Islands

The Hawaiian Islands are viewed as a result of a “hotspot” in the upper mantle – visualized as a sort of heat source in the upper mantle of the Earth over which the North Pacific tectonic plate has been moving for millions of years.  As the thin oceanic crustal plate has been moving northwestward, it has passed over a relatively stationary heat source in the upper mantle.  This, in turn has generated magma, that due to its lesser density, has migrated towards the surface resulting in occasional volcanic eruptions.  This simple conceptual model doesn’t answer many questions (like why are there discrete islands rather than one continuous ridge), but it is understandably hard to make direct measurements in the interior of the Earth.  The best source about the Hawaiian volcanoes and their monitoring is the United States Geological Service Hawaiian Volcano Observatory website.  The entire site has interesting information, at varying levels of detail, but sufficient for nearly all natural history travelers.

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Relief of the main Hawaiian Islands.  The yellow line, for scale, is 500km long (about 310 miles).

Logistics of getting to the islands

Most flights from the US mainland and elsewhere arrive to Honolulu on the island of Oahu.  Honolulu is the largest city in the Hawaiian Islands and receives by far the most tourists.  Other direct flights from the US mainland arrive to Maui, then Hawaii (hereafter termed “the Big Island” and then Kauai.  See this link for more information.  Monthly tourist statistics for the main islands are in Fig 2 and here.


Fig 2.  Hawaiian tourism facilities by month for 2018.  From this site.

The main points from this figure are that 1) tourism is fairly constant throughout the year and 2) Oahu get much more tourism than the other islands.  Given that the Big Island is larger than all of the other islands combined, the “tourist density” is very low on the Big Island – at least compared with the other islands.

Accommodations in Hawaii are very expensive compared with the US mainland.  Expect to pay $150-200 or more for low-end accommodations (B&B’s, etc) – away from the beach.  Resorts can be two to three times this per night.

Traffic can be surprisingly heavy for the population of the islands.  There is not a grid-like network of roads like on most mainland destinations.  Each island has a coastal road that circumnavigates the island and these can become very congested near rush hours, if there is construction, or if an accident occurs.  In our recent trip to the islands we experienced heavy rush hour traffic on the Big Island when entering Hilo and also along the Kona coast.  And on Kauai – “the Garden Isle” – it took us 30 minutes to go 2 miles at rush hour.

Climate of the Hawaiian Islands

Some basic understanding of the climatology of the islands is presented here.  Books (e.g. Sanderson, M., Prevailing Trade Winds: Weather and Climate in Hawai’i, 1993) have been written about the climate of the Hawaiian Islands and innumerable research studies have focused on various aspects of the weather and climate.   The best easily available source of climate information about the Hawaiian Islands is the webpage maintained by the Geography Department University of Hawaii.  Note that the most interesting page is actually that describing the rainfall of the islands.  We put more than normal emphasis on the climate and weather of the islands because we know (from our recent trip) than many tourists have only a poor understand of the geography and climate of the Hawaiian Islands.  Aren’t the Hawaiian Islands all green, warm and with Palm Trees everywhere?  The short answer is no, the long answer is the rest of this page…

Here is the latest satellite imagery animation showing cloudiness around the Hawaiian Islands.  This page is maintained by the College of Dupage.  This animation is composed of 10 min visible imagery for the latest 4 hr period.  Being visible imagery, if you decide to look at this animation when it is dark in Hawaii you will not see much…  There are other animations of different types of imagery (infrared) useful during nighttime, but interpretation of these is less obvious than the visible imagery.

Temperature on any of the islands is mostly a function of altitude.  The temperature decreases with altitude at a rate of about 3˚F per 1000 ft.  This does vary from day to day and even with the time of day, but for most visitors this is a tolerable estimate.  A “well-mixed” atmosphere on Earth displays a lapse rate (decrease in temperature with height) of about 9.8˚C per km.  Converting to English units gives a value of close to 5.4˚F per 1000 ft.  However, in Hawaii and elsewhere the average lapse rate is closer to 6-7˚C/km and varies from day to day and even the time of day.  During our last descent from 10,000 ft elevation at the top of Haleakala on Maui to near sea level, taking about 45 minutes (near sunset), we saw the temperature rise from 45˚F to 77˚F.  A great many tourists do not appreciate these changes, and arrive at the Haleakala summit with sandals, shorts and T-shirts.  With the wind, many visitors who were coming to see the sunset (a popular tourist attraction – one that we don’t favor) were scrambling to get inside the upper visitor center or back into their vehicles.

Hawaii ECMWF 29 DEC 2019 fcst 950 mb - about 2000 ft.

Above is an snapshot of an animation that shows the flow around the Hawaiian Islands on a December day.  Every day is somewhat different, but this shows the important impact of the topography on the wind field – here at 950 mb (about 2000 ft above sea level).  Note the strong winds south and north of the Big Island and the return flow (lee-side eddy) behind the island.  To a somewhat lesser degree these eddies are present on all of the islands.  To visualize the daily forecasts of the winds from various weather prediction models see this link.

An average of mid-day cloudiness around the islands is shown in the figure below.  The first image shows what you might see with your eye if you could average the satellite imagery over a few years. Over the ocean brighter areas are where there is more cloud cover, darker areas are less cloudy.  Over land the land brightness complicates the interpretation, though cloudy areas are still apparent.  The lava flows from Mauna Loa on the Big Island are evident.  The second image shows the average cloudiness with the color table going from very frequent cloudiness (red) to minimal cloudiness (white ).  A grayscale version of the same data is shown in the third image.

The average cloudiness does not exactly correspond to the actual rainfall distribution – some areas of equal daytime cloudiness receive different annual rainfall.  This can be due to the clouds not raining equally, or the twice daily satellite imagery doesn’t represent well the rainfall at other hours – especially at night.  Annual rainfall maps prepared by the Geography Department at the University of Hawaii are the most useful estimate of precipitation on the islands.  See their online atlas here.

Our opinions of where to visit

After visiting the three islands of Hawaii, Kauai and Maui we formed some definite opinions on what might be most productive for nature tourists.  Our first choice to visit is the Big Island, followed by Maui and then Kauai.  This is based mostly on the nature and condition of the natural vegetation and the opportunities for walks.  But there caveats to this statement.  We discuss the different islands below.  As we did not visit Oahu on this most recent trip (MD has, but almost 40 years ago!) we do not discuss nature observing possibilities on Oahu.

The lower elevation moist forests near sea level on all of the Hawaiian Islands have been greatly modified by humans as they are most suitable for agriculture.  However, on Maui, Hawaii and Kauai there are large tracts of moist forest that are nominally protected – mostly in State forests or other watershed protection areas.  However, few of the natural forest tracts are easily accessible, and some are closed to entrance.   Large tracts of higher altitude land on the Big Island and Maui have been converted to cattle pasture, replacing the original moist or dry forests.  Attempts are being made to promote regeneration of the natural forests to help support the endangered bird species.  This will be discussed below under each island.

Personal comment by Mike: I first visited the Hawaiian Islands in 1981 during a stop-over on return from India, to visit a friend in the Navy.  We flew from Oahu to the Big Island to explore for one day, and this was my first exposure to the Big Island.  I returned for a specific trip to the Big Island and Maui after Christmas 1982, and was there for the beginning of the longest-lasting (in recent history) eruptive phase of Kilauea that started on January 3 1983.  I also hiked to the top of Mauna Loa and spent New Year’s Eve on the Park Service cabin on the eastern rim.  Since that experience I had wanted to return, remembering the unique view of the caldera with frost in the early morning and the sky glow from the 1982 El Chichon volcanic eruption in southern Mexico 8 months earlier.

In my opinion, the main reason for visiting the Big Island is to see the landforms associated with fluid, basaltic volcanic eruptions.  Such eruptions produce relatively low-slope shields and a host of associated volcanic features like lava tubes, pit craters, fissures and spatter cones.  These are not associated with the continental volcanoes with more viscous lava that produce steeper volcanic cones.  Fluid basaltic lava flows are found in many continental areas, such as the Craters of the Moon National Monument in Idaho and Valley of Fires Recreation Area in New Mexico, but the very recent nature of the eruptions in Hawaii makes seeing the volcanic features easier, as they are less eroded by weather elements.  And there is nothing elsewhere in the world quite comparable in size to Mauna Loa.  There are similar oceanic shield volcanoes in the Galapagos Islands, the Comoros Islands of the Indian Ocean, and elsewhere, but these are not nearly as accessible as those in Hawaii.

Of course, as we discuss below, the Hawaiian Islands do have unique flora and fauna.  Of course, this comes far down the list of attractions that are advertised by the Hawaiian tourism authorities or commercial websites.

The Big Island (Hawaii)

We spent 7 nights on the Big Island – all in the small community of Volcano – at the entrance to Hawaii Volcanoes National Park.  This small town/village area is at about 3500 ft elevation so it is cool compared with coastal locations.  In addition the trade wind flow ascends this side of the Big Island and it is very frequently cloudy with light rain.  Annual precipitation is near 140 inches per year, resulting in verdant landscapes.




The Big Island showing historical lava flows from Mauna Loa (only) and some of the times it took for various flows to reach the ocean or their maximum extent.  One flow had a flow rate of 12 million cubic meters per day (about 400 million cubic ft per day)!  The reddish color indicates the slope; note that Mauna Loa has shallow slope compared with Mauna Kea or Hualalai.


Hawaii Volcanoes National Park is our favorite area in the Hawaiian Islands to experience natural environments.  The combination of extensive trails through volcanic landscapes and sharp transitions between moist and dry forests, along with coastal and high mountain environments, allows for one to experience relatively natural and relatively uncrowded environments.  Because the Park’s attractions are quite distant (at least 80-90 miles) from the main touristic resorts on the Kona coast (west side) of the Big Island, fewer tourists visit the park, and those that do visit mostly as day trips or as part of tours.  The lack of current volcanic activity (ending in late 2018) also may have reduced visitation.


Current map of Hawaii Volcanoes National Park provided at the entrance gate upon arrival.  Click for detailed view.


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Hawaii Volcanoes National Park “backcountry” trail map.  Click on map for larger view.  NOTE: some trails are closed due to the 2018 eruptions and earthquakes.


After the Big Island, Haleakala National Park on Maui is our next favorite area for observation of natural Hawaiian environments.  While there are fewer trails at Haleakala, they are more strenuous and they pass through relatively natural high-altitude landscapes.  Most people who make long walks do so starting at the top (almost 10,000 ft elevation) and walk downhill, ending near 8000 ft.  However, there is a nearly 1000 ft climb near the end (from about 7,000 to 8,000 ft) near the trail’s end, making this hike a long 11 mile day trip or an overnight hike.  While there are parking lots at both ends of the hike, unless your group has two vehicles you must hitch-hike back up to your vehicle (this is one park where this is allowed).

Other than the above mentioned downhill hike, most other hikes are not loops, so you walk out and back on the same trail.  Some of the trails are very rocky and require sure footing, while trails in the crater tend to be on ash and cinders and are smooth.  Vegetation is more dense at lower elevations, with many interesting berries.

Haleakala National Park is a long drive from the resort areas on Maui.  It is about 40 miles to reach the main visitor center that is at 7000 ft elevation.  It is another 3000 ft altitude gain to the upper visitor center and entrance trail into the main “crater” of Haleakala.  The road is very winding, with many curves – especially before reaching the national park.

We did not extensively explore Maui, especially the moist areas on the eastern part of the island – the “infamous” road to Hana.  Nor did we visit the West Maui mountains (Io’s Needle).  However, finding natural moist forests on Maui (or on any of the islands) is not simple.  All Hawaiian Islands have forest reserves managed by the state of Hawaii.  These reserves may include introduced trees and are not managed to be natural landscapes.  Hunting is allowed on weekends.  The relatively recent Hawaiian State Natural Areas are attempting to protect natural landscapes but these are often closed to public entry.

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Trail map for Haleakala National Park.   Click for larger image.


We only spent 3 days on Kauai, so we could not sample all interesting natural areas.  However, the Alakai Swamp trail at 4000 ft elevation, known as the best birding location on the island and with unique wet bog plants, was not feasible to access due to the condition of the trail (muddy).  And the Kilauea Point National Wildlife Refuge, while mostly known for its historic lighthouse, is known among birders for being the best spot in all of the (main) islands for seeing seabirds.  These include Laysan Albatross, White-tailed Tropicbirds, several species of Boobies and Frigatebirds.  The Nene is also conveniently seen here.


We did not visit Oahu – other than a short stop to transfer planes on our flight from Hilo on the Big Island to Lihue (Kauai).  However, more tourists visit Oahu than any other island.   As such, it has more visitor facilities, including botanical gardens, than the other islands.

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