SPINNER DOLPHINS

Dolphin Research Project

The first day on Midway Island the researcher explained the goals of the spinner dolphin research project was to determine habitat use, the abundance and distribution of dolphins,  group size and composition, social structure of the dolphin schools, social affiliation patterns between individual dolphins, to develop a photo-identification file for the dolphin population and develop year-round baseline activity patterns.

Such information will impact the development of boat usage in the atoll. The aim is to disturb the dolphins as little as possible in order to keep them in the area and not to disturb them enough to leave. Is the population  transient or residential? Do sub-groups exist and if so how stable they are.

No research/documentation had been done yet on dolphins in an atoll habitat. Midway is a perfect place for such a study as the shallow clear waters of the lagoon allow for detailed observation below the water as well as above it.

Spinner dolphins, Stenella longirostris, receive their name from the frequent activity of leaping from the water and spinning in the air. Apparently spinning is done solely for fun but, it may also serve as a signal that feeding is about to begin. It is significant that spinning activity peaks in mid-afternoon before the group spreads out at dusk to forage for dinner. Aerial activity is used in socialization and is believed also to be used in communication. Some scientists speculate that aerial activity also serves to remove ectoparasites from the dolphin bodies.   Spinners can reach a height of about 3 meters when they spin and can make a maximum of four revolutions. Spinner dolphins swim mostly in deep waters, but occur in regions where there are shallow platforms or islands.

The schools of dolphins on Midway are larger than those around the other Hawaiian Islands, very likely because there are fewer sheltered land and resting areas. There is a large shark population in the area so the lagoon provides a safe and quiet place to rest. They typically live in tropical waters, but may range into temperate water with a worldwide distribution.

The average spinner is 5 ½ -6 ½ feet long. Calves at birth are generally 30 inches long weighing 33 pounds. Gestation is 10 ½ months and females will lactate for a period of 1-2 years. Typically, males are bigger than females. Female spinners sexually mature between 4-7 years and tend to have one ovulation  period each year. Males mature later, usually between 7-10 years. Mating is promiscuous with peak activity during summer and fall. Lifespan for spinners is about 20 years. Only 1% of females have been documented to reach post-productive status. Although spinner dolphin society is highly promiscuous, family units are apparent.

Contact is an essential ingredient in spinner dolphin society where touching, nuzzling, and stroking occur frequently among the animals in the group even though the composition of the group changes. Many dolphins are day feeders, but spinners feed at night in deep waters on fish, squid, and shrimp. They have been documented to dive to depths of 200-300 meters while feeding.

For most dolphin species the dorsal fin is used for identification because it can be photographed from the surface of the water. Nicks and marks in the trailing edge of the fin are most often used for identification because they are relatively permanent and change little over time. 

We used a 23 foot pontoon boat for water surveys which were conducted at random in five transects of the lagoon. It was great fun to watch the dolphins bow surfing with us. The schools sometimes contained some small animals.

This was a fun 10 days to say nothing of being educational and interesting.

WAITOMO CAVE and WATER BALLETS

                                              A New Zealand Natural Wonder

Waitomo  Cave, known as the glow worm grotto/cave, is derived from two Maori words, wai meaning water and tomo meaning cave. The Waitomo River eventually vanishes into the hillside.

On this fascinating and unusual visit we learned from a docent that a New Zealand Mountie and a British surveyor discovered the cave in 1887. They rafted down the river but could go only half way into the cave. Two weeks later they discovered the present entrance and in 1889 the first tour took place.

The glow worm is different from a firefly  The light from a glow worm is less than from a firefly but when multiplied by thousands the sight is spectacular. The life span of the glow worm is eleven months and there are four stages. First is the egg which turns to larvae, then to a cocoon, and finally to a fly---similar to a butterfly. The glow comes from the larvae suspended from the ceiling. It snares its prey by dangling filaments of sticky beads. Chemical oxidation creates the glow.

After touring the cave we boarded boats and floated quietly though the grotto where thousands of worm larvae hung suspended from the ceiling. It was a rainbow of color, like none any man could create. There was no picture taking, so I bought a postcard.  We were all as quiet as church mice as we slowly floated down river. It was the most fantastic sight!

 

ORCHID GARDENS

Today water ballets   and displays are quite common and I’ve seen many in many different locales. However, the Orchid Gardens in Rotorua, New Zealand were my first.

The gardens and flowers were lovely, but the water organ/ballet was spectacular.

A local guide told us, “The gardens were built in 1985 at a cost of 1.3 million dollars. The water organ contains 700 pipes and 14 pumps. This set of pipes was made in Germany at a cost of $250,000, and there are only another four or five sets like these in the world.”

Water shot dramatically from the pipes simulating a ballet and the whole performance was set to computerized music.

When the water show was over I said, “I’d really like to sit through that again.”

My traveling companion agreed and we did. It was a marvelous performance!

THE GREEN MACAW

     Beautiful Birds

           

The owner of our hotel in Sarapiqui, Costa Rica belonged to a volunteer organization trying to save the green macaw.

She told us, “Because of deforestation and rapid colonization, the habitat of the Great Green Macaw has been reduced from 12,460 hectares to 529 hectares. Five years ago there were only 25 mating pairs, now they have increased to 100 pairs.

           “The Great Green Macaw is still endangered. On the black market one sells for $3000.  That is a great deal of money to someone making $300 a month.”                

The bird mates for life. They live exclusively in the almond tree in the tall canopy of the forest. The almond tree grows 30-50 meters tall. As the leaves fall from the tree, it creates a natural cavity for the bird. The nut is very hard, but the macaw has a very strong beak and can crack the nut.

She continued, “Almond wood is very hard and a desirable building material. People cut the trees on their property to sell the wood. Our organization has started paying property owners an annual sum      to take care of and nurture their almond trees and not  cut them down. It seems to be working.”

            A macaw reproduces at five years of age and has one to three chicks a year. They can live to be 60 years old. Owls and the African bee are the predators of the macaw chicks.

She concluded, “It is recommended that 1000 trees per hectare is ideal. Seven years ago this ten acres was pasture land. We have planted every plant on the grounds. We also planted many almond trees, and it is our hope that someday macaws will be all over this area.”

We saw many green macaws during our visit.  Our Chachagua hotel had a resident green macaw. Her mate had died and she was a cantankerous little bird. Well, she wasn’t very little. She would perch on the dining room rail during meal times. She was cranky enough to make visitors aware to keep their distance. She was lovely to look at though and you couldn’t help but feel sorry for her.

MIDWAY’S GOONEY BIRDS

A CRAZY BIRD
When Kelly called me about doing a couple of research projects on Midway Island, I figured why not. It turned out to be a fantastic three weeks.We went to help with both spinner dolphin and Hawaiian monk seal research projects, but the big bonus was the gooney birds.

Our first day we were surprised at how excited the residents were   when the first gooney flew in. The second day there were about 5 birds, then 15, and after that they were too numerous to count. We spent a lot of time on the beach watching them come in---it was busier than the busiest airport.

Every morning when we got up the first thing I did was look out the window to see how many birds were out on the lawn. After ten days the ground everywhere was covered not only with Laysan Albatross but also Black Footed Albatross. Eventually a half million mating pairs had returned home. The inn was full, and we no longer could walk a straight line anywhere!

Midway has the largest colony of Laysan Albatross in the world . Seventy percent of the world’s population of this beautiful, sometimes comical,  bird lives here. I did not know the gooney goes to sea in July for four months returning in mid-late October. We couldn’t have timed our visit any better. I really would have been disappointed if we were there while the birds were all at sea

They are absolutely beautiful gliding in the air. The underside of their wings is a beautiful white with black accents and trims. In the air they are most graceful. When landing into the wind, the landing is graceful and upright, but when they misjudge and land with the wind they often make a nosedive landing and the antics are funny beyond description. They were a lot of fun to watch and we spent many an hour observing not only the above but also their intricate mating rituals.

Details about the gooney will follow another day.