Winter Summary

The beaches I visited this late winter season stretched from the Northwest shore down to the Southeast shore. I didn't get a chance to see the Northeast part of the island but hopefully I can rectify that soon. So, as winter is over I wanted to do a quick comparison of the beaches I visited so far.

Major differences:
There weren't as many big differences as I was expecting. Naupaka, koa haole, and a few birds I saw were at each site. The variety of species tended to change from beach to beach. For example, Ka'ena and Sandy were where I saw the most birds. I saw many native and endemic species at Ka'ena Point. This makes sense since the location is primarily a reserve. However, there were still quite a few introduced/invasive species. The other beaches were more recreational, so people weren't there to experience the coastal habitat, so many introduced species are allowed to roam around or grow, such as pigeons and koa haole.

The environment itself changed from beach to beach. Ka'ena Point and Yokohama are both dry, hot places. Waikiki and Sandy beach are somewhat dry, but no as much as Ka'ena or Yokohama. Makapuu was the most lush environment out of all the beaches I visited. This was most apparent when comparing the naupaka that grew at each beach. The Naupaka at Makapuu and Waikiki were very green, but I have a feeling that the naupaka at Waikiki get watered.
Similarities: 
There were several species that I found at all the beaches or at several of them. Naupaka, koa haole, pigeons, and red-crested cardinals were the most common. Individuals from common species found around the island may be found on all of these beaches, but I cannot say for sure since I did not find them myself.

Naupaka at Ka'ena Point

 Naupaka at Waikiki

 Naupaka at Sandy beach

 Naupaka at Yokohama

 Naupaka at Makapuu

What about niches?
I found that these beach habitats were primarily occupied by low-lying shrubs and very few trees. Most of the beaches also had hilly/mountain terrain adjacent to the beach area, so there weren't many wetland-type species. Many of the plants, as far as I could tell, were succulent or adapted to dryness in some way. For animals, I saw that the representative bird species were ground-dwelling species, with a couple exceptions. Birds such as pigeons or the cattle egret that are most often found walking on the ground rather than perched on branches/fences/etc. I didn't see too much else in terms of animals, but the monk seals from Ka'ena are an example of a mammal that fits into the coastal ecosystem as a foraging predator.
   
Acknowledgements:
I wanted to give a quick shout-out to the people that drove me around to each of these beaches: Calder Atta, Kelly-Rose Lariosa, and Dr. Brenden Holland!

Makapuu Beach

Makapuu Beach is found at the Southeastern end of O'ahu.  The beach is not very large but there is dense foliage located behind the sand dunes of the beach. The climate is not as dry here and the plants growing on the beach are very green. This is not notable in the naupaka that usually have yellow leaves in drier parts of the island. (Please excuse the quality of these photos, I only had my gopro on me during this trip and I didn't notice my finger was in all the shots until I got home)

Here we have an establishing shot of the beach with some Coconut trees (Cocos nucifera) growing on the edge.

Of course, there is an abundance of Naupaka (Scaevola sericea) on the beach. However, at this site Tree Heliotrope (Tournifortia argentia) is also very abundant. The next 5 photos illustrate this point.

While the photo here is a bit blurry, the narrow leaves and clustered white flowers make me confident that this plant is the Kipukai (Heliotropium curassavicum) which is a native plant that can grow along coastlines or in salt flats.

Here we have the two non-native plants Spanish Needle (Bidens pilosa) with white flowers and Chinese Violet (Asystasia gangetica) with the purple flowers.

I believe this low-lying shrub is a Pa'uohi'iaka (Jacquemontia ovalifolia) that is endemic to Hawai'i. The cup-shaped, white-violet flowers would give it away but I didn't see any during this trip. The plant's name means "Skirt of Hi'iaka" based on a legend where the plant covered Hi'iaka (the younger sister of the god Pele) to protect her from sunburn.

Here we have some type of weed (I'll hazard the common yard weed Bermuda grass but the leaves don't look thick enough to me) that is growing between some Pohuehue (Ipomoea pes-caprae).

 Another Pohuehue growing between an 'Akia (Wikstroemia uva-ursa) plant.  The 'Akia produces a substance that was used to paralyze fish in tidepools by Hawaiian fishermen.

There were some young Ironwood trees (Causuarina equisetifolia) growing near the lifeguard station.

 Chinese Violets and an Aloe plant (Aloe vera).

I managed to get a blurry photo of this June Beetle (Oxygrylius ruginasus) crawling along the ground. ID: Bug Guide

A Chinese Violet with white flowers.

A field of Kawelu grass (Eragrostis variabilis) that is characterized by its yellow seed-head or inflorescence.

 This appears to be Kawelu too, but with greener seed-heads.

For these last two plants I could not find a good match in the field guides I am using. In the first one it looks like it is getting ready to flower so had the flowers been out I might have had an easier time with that one.

Summary:
Rating: 4/5
The beach itself was not crowded and is a good spot to wade in the water. There were some interesting plants here during my visit but the majority of plants were naupaka and tree heliotrope. I also enjoyed the scenery of this beach over the other beaches I've gone to so far, so I have to give it points for that. There is also a small island known as rabbit island, named after the rabbit farm that used to exist there. Now it is managed as a seabird sanctuary as seabirds use the island for nesting (source).

Web Sources:
Brown, Mark H. "Reddish June Beetle - Oxygrylius Ruginasus - BugGuide.Net." Reddish June Beetle - Oxygrylius Ruginasus - BugGuide.Net. Iowa State University Department of Entomology, 8 Oct. 2013. Web. 26 Mar. 2016.

"Rabbit Island." Rabbit Island, Oahu. To-Hawaii.com, n.d. Web. 26 Mar. 2016.

Yokohama Beach

Yokohama beach is on the Northwest shore of O'ahu. It is fairly popular among both locals and tourists alike and the climate here is much drier than at the other beaches. Even Ka'ena from the North side wasn't as dry as the approach from the West side. This is due to the West side being "shielded" by the volcanoes from the trade winds that help create condensation on the windward side of the islands. Condensation builds up as the trade winds blow clouds up and around the volcanoes on each island. However, the trade wind inversion, the altitude where trade winds stop rising over the volcano, prevents the clouds from reaching up over the whole island, so the windward side gets the majority of the rainfall. This is well-illustrated through mean annual rainfall collected in the Hawaii Rainfall Atlas. 

I began my trek on the West side near the Lower Makua Cave. I hope to get a chance to go exploring in there at some point in the future!

On the coast opposite the cave, the landscape is very rocky with some shrubby/succulent plants. I will go into describing these to the best of my abilities.

Grasses are very common here. Depending on whether there are people watering it or not, the grasses  are either lush and green or dried out and yellow. Here I closed in on some Fountain Grass (Pennisetum setaceum) that appears almost completely dried out but has strands at the top that resemble wheat. Among them are small 'Ala'ala wai nui (Plectranthus parviflorus) shrubs. These plants are in the mint family but have lost their minty aroma, which serves as a defense in nature, possibly due to lack of predators.

More fountain grass that hasn't completely dried out yet.

I spotted this plant among more grass, which I believe could be an 'Ala'ala wai nui that is flowering. However, the leaves make me think it is something else entirely that I do not see in my guides.

This little guy here is an Pigweed/Purslane (Portulaca oleracea). These plants are invasive to Hawai'i. It can be used in medicines, but it displaces native species.

 I believe this is an Alena plant (Boerhavia repens). It is a native plant that is used medicinally. The flowers are supposedly pink but I didn't see any on the plants that I saw.

The closest ID I could find for this tree was the Noni (Morinda citrifolia). This is based primarily on the flowers that are pictured on the left side of the plant. The plant has a number of uses in Hawai'i ranging from dyes to medicines.

 An Aloe plant (Aloe vera) growing among some non-native grass.

These trees were common at this location. Another is pictured above by the cave entrance. They are called Kiawe or Mesquite (Prosopis pallida). These trees generally have thorns on them when they are young. It was introduced in the early 1900s as a commercial plant with many uses, but it heavily threatens native plants by shading them out and absorbing any available water quickly.

I found this plant growing between lava rock. I was not able to confidently ID this plant. It looks like it could be several species in my guides and I don't know enough to call it one way or another.

A Spanish Needle (Bidens pilosa) plant.

 The next four images are of Koa Haole (Leucaena leucocephala). These plants were all over the place once I made it to Yokohama Beach proper. That and grasses, which were primarily the fountain grasses that were pictured above.

 Here we have some Naupaka (Scaevola sericea) that is found everywhere on the island.

A Pohuehue (Ipomoea pes-caprae) that I found on the beach itself. These plants are native to Hawai'i.

Summary:
Rating: 2/5
I didn't see much diversity in this location on my brief survey. A large amount of the flora here is comprised of either grasses, koa haole, or the kiawe trees. The dryness of the site itself also makes for a poor beach experience as you get blasted by the sun. If you hike up to Kaena from this side of the island, you can see tide pools along the way that people like to cool off in. This spot is also popular for surfers and fishermen, so this beach could be worth your while if you are coming for one of those or similar activities. However, as a recreational beach I wouldn't recommend this beach first, especially if you aren't already on this part of the island.

Citation:

Giambelluca, T.W., Q. Chen, A.G. Frazier, J.P. Price, Y.-L. Chen, P.-S. Chu, J.K. Eischeid, and D.M. Delparte, 2013: Online Rainfall Atlas of Hawai‘i. Bull. Amer. Meteor. Soc. 94, 313-316, doi: 10.1175/BAMS-D-11-00228.1.

Sandy Beach Park

Sandy Beach Park is located on the South Shore of Oahu. This spot is great for body-surfing and surfing at a more intermediate level. The first thing you'll notice when you arrive is that all the plants look like they are maintained and hedged. The grass is green and the trees are spaced out for shade over benches. On the beach itself, the flora looks a bit more natural. There are some species that I saw at the other previous sites, and some that I haven't seen yet.

There was a ton of Naupaka (Scaevola taccata) on the beach. These plants were everywhere. I'm starting to really get an idea of just how common they are in coastal areas. 

This tree is one of the plants I couldn't identify in Waikiki at the "In-between". After talking to a friend who knows some botany, I learned that this is called the Norfolk Pine (Araucaria heterophylla). These trees are closely related to the Cook's Pine (Araucaria columnaris) and they can be mistaken for each other on the Hawaiian Islands. Both are non-natives and you can tell them apart based on some morphological features that are well presented here.

 Pigeons, or Rock Doves, (Columba livia) were very common at Sandy Beach. They could be found on the grass by the parking lot and on the sand of the beach. Here in Hawai'i, the pigeons are commonly either grey (just like in mainland US cities) or white. These differences in color are known as morphs. Concerning safety, a study by Oshiro & Fujioka (1994) found that pigeon feces and mongoose feces can contribute to high bacteria levels in the water (The study was conducted at Hanauma Bay but it is possible that the same applies to other beaches such as Waikiki), so it is probably a good idea to wash your hands after going in the water.

Coconut palms (Cocos nucifera) could be found on the beach around life guard towers and in the grassy field behind the beach. I talked about them a bit in the "In-between" post, so you can learn about them there. They are not native to Hawai'i.

Koa Haole (Leucaena leucocephala) is common all over the island and I saw it before at Kaena.

Another banana spider (Argiope appensa) like the ones I saw at Kaena. This is a female here. The banding isn't as clear on this individual but there are some white-grey bands that can be seen on the legs if you look closely.

The Zebra Dove (Geopalia striata) is a common sight in urban areas. They can be found pretty much wherever pigeons are found. It's no surprise that they would be near a popular beach like Sandy.

This tree gave me some trouble. Using the guide books I have, my best guess is that this is a larger example of the Milo (Thespesia populnea) like the one I saw at the In-between. However, the leaves are not quite as heart-shaped as the leaves from the other plant I saw before. In the second picture below is another plant that I believe resembles the milo more than this one, but I am not completely sure about that one either.

In the background are some Chinese Violets (Asystasia gangetica) and in the foreground is a fuzzy plant that I couldn't identify. I haven't seen anything like it anywhere else on the island so far.

The Ironwood or Australian Pine (Casuarina equisetifolia) is not a true pine, but it has become a fairly common plant, according to the Ecotourist guide. I haven't seen too many myself, but this is a good example of one that can be found here at Sandy Beach.

 Taro (Colocasia esculenta) is probably one of the most common plants on the Hawaiian Islands. It is a staple food crop that is used for local poi, which is like a taro paste. It is delicious when it is fresh but gets to be a bit sour tasting after a while. Taro is also a common flavor in many sweet foods such as frozen yogurt, bubble tea, etc.

Hala (Pandanus tectorius) is a tree or shrub that is indigenous to Hawai'i. The fruits of these trees resemble pineapples. Their long, drooping leaves are their defining characteristic.

Mallard Ducks (Anas platyrhynchos) can be found on all the islands near ponds and marshes much like on the mainland. Here they like to hang around shower area probably because it is the nearest source of freshwater.

Cattle Egrets (Bubulcus ibis) are common on Manoa campus and in marshes or agricultural areas. These guys are probably here for the freshwater from the shower area much like the ducks.

The Spanish Needle (Bidens pilosa). This is a weed that originated from the tropical Americas characterized by it's large white pedals and yellow flowers.

This appears to be a young False Kamani (Terminalia catappa) growing up on the beach. Another one is pictured below near a bench with the more characteristic brown/yellow leaves mixed in with the green.

This plant is known at the nehe (Melanthera integrifolia). It is a native plant.

Pili grass (Heteropogon contortus) can be found in patches at Sandy Beach. This is a native grass to Oahu.

I saw some more Red-crested Cardinals (Paroaria coronata) foraging near the beach in patches of grass. Previously, I saw this species at Kaena, but not at Waikiki. I'm not gonna say that they don't go to Waikiki, but perhaps the heavily maintained grounds by the hotel are not a good habitat for them.

Green algae covers lava rock out on the beach. I have heard that turtles like to eat this algae and so it is possible there may be turtles about wherever this algae is found. I didn't see any turtles, so I don't know how much truth there is to the story.

Summary:
Rating: 5/5
Sandy Beach Park was a nice place to spend the afternoon. There are a number of endemic/native species here, but there are also tons of non-natives/invasives. I encountered many of these species either at Waikiki or Kaena. I'm starting to see that the coastal strand on O'ahu is somewhat homogenous with some subtle differences depending on the location. So far the presence of coconuts and pigeons seem to be restricted to popular or "touristy" beaches as there weren't any at Kaena. I will have to see if that holds up as I continue onwards. Better than Waikiki but not as unique and interesting as Kaena. This spot is great for relaxing or getting in the water if you are a strong swimmer. It is recommended that you use fins to swim or body surf since the waves and current can be strong.



Journal Citation:

Oshiro, R., & Fujioka, R. (1995). Sand, soil, and pigeon droppings: Sources of indicator bacteria in the waters of Hanauma bay, Oahu, Hawaii. Water Science and Technology, 31(5–6), 251–254. http://doi.org/10.1016/0273-1223(95)00275-R

Web Citation:

"The World´s Tree Species: Norfolk Island Pine vs. Cook Pine." The World´s Tree Species: Norfolk Island Pine vs. Cook Pine. Blogger, Dec. 2007. Web. 10 Mar. 2016.