Tag Archives: Midway

Ghost crabs keep low profile along atoll’s sandy beaches

Published February 8, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
The horn-eyed ghost crab, the larger of Hawaii’s two species of ghost crabs, is known to dig M-shaped burrows. ©2016 Susan Scott

The horn-eyed ghost crab, the larger of Hawaii’s two species of ghost crabs, is known to dig M-shaped burrows. ©2016 Susan Scott

While walking a beach at Midway recently, I noticed a lot of ghost crab holes with flat smooth sand around them, no mounds, sprinklings or claw prints in sight. Ghost crabs (also called sand crabs) are famous for building large, complex burrows. So what, I wondered, had these crabs done with their sand?

You can see ghost crab holes on nearly every tropical, subtropical and temperate beach on the planet. But good luck seeing the holes’ architects. The world’s 22 ghost crab species make their mansions mostly at night and hunker down in them during the day. Ghost crabs use their burrows the way we use houses. The dwellings provide refuge from predators and bad weather, are a private place to change clothes (in the crab’s case, to molt), and when the time is right, they’re love shacks. A crab hole generally has a funnel shape at the top leading to a tunnel that ends in a chamber. Depending on species, ghost crab burrows look like the letters Y, J, I and U. The larger of Hawaii’s two species, the horn-eyed ghost crab, sometimes digs M-shaped burrows. This is usually the result of a new resident re-excavating an abandoned burrow.

The side branches of Y and M shapes are either escape routes or places to hide from predators that dig, such as coyotes, foxes, mongooses and dogs. How deep a crab’s tunnel goes depends on the sand’s moisture. The drier the sand, the deeper the burrow, because ghost crabs have lungs and gills that both need water to absorb oxygen. When we see ghost crabs taking dips in the surf zone, they’re wetting their breathing organs.

Here in the main islands, ghost crabs often leave evidence of their quarries, either throwing excavated sand willy-nilly or piling it in mounds. During the reproductive season, Hawaii’s horn-eyed males build copulation burrows in an S shape. To advertise their bachelor pads to females, males shape their scooped-out sand into pyramids.

Scattered sand, mounds and pyramids, however, are like arrows directing predators to a crab’s location. And that’s where those Midway crabs’ holes with no tailings make sense. To mask their whereabouts, ghost crabs sometimes trample their excavated sand, expertly erasing all traces of digging.

In addition to eating dead plant and animal material that washes up, ghost crabs are ecosystem engineers. Their burrows create passageways for air and water to mix sand, bacteria, soil and sediment, crucial factors in maintaining healthy beaches.

Besides being useful, ghost crabs are fun to watch and beautiful to behold. Please be kind to these native species. Our beaches need them.

Workers find plenty to like about their feathery friends

Published January 4, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
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Albatrosses at Midway are curious about volunteers on the atoll, but because they evolved without land predators, are unafraid. ©Susan Scott

MIDWAY ATOLL >> Why do 18 people with a range of backgrounds pay their own expenses to count albatrosses on a remote atoll over the holidays? We’re nature lovers, of course, but we have another link: We think living with albatrosses is fun.

Everyone marvels at the goose-size birds’ boisterous songs and delirious dances, but albatrosses have nearly endless endearing behaviors. When I asked each of my five team members to name their favorite, the response was the same: “I have to pick just one?”

Martha chose egg talk. Every once in a while a brooding bird stands up, lowers its beak to the egg and murmurs, “Eh, eh, eh.” No one knows what this means, but it’s likely voice recognition between parents and offspring, crucial when mom or dad return with a meal to a colony of hundreds of thousands of wandering, identical-looking chicks.

Craig likes shift change. For the 63-day incubation period, albatross couples take turns keeping their egg warm, the on-duty bird sitting for up to three weeks. Yet even though the sedentary bird’s digestive tract is empty after the first few days, the sitter hates to quit work. The resulting circling, murmuring and nudging by the relief partner goes on for so long that witnessing the actual transfer is a noteworthy event.

Ann-Sheree is fond of the way couples groom each other’s feathers in affectionate nibbles with those big sharp beaks. The recipient closes its eyes and turns its head and neck as if getting a massage. Then it’s the other’s turn for a tender feather fix.

Breck and Luke picked as their favorite behaviors some albatrosses’ show of utter indignation when annoyed. Each bird has its own personality, and a few are quick to issue a snappy bill-clacking warning to back off when a bird dances too near a nest or a human steps too close. A few plucky individuals deliver a peck.

These seldom connect, but when they do it’s a pinch of a pant leg or, at worst, a scratch on the skin. Afterward the bird looks smug, as if to say, “Well, I warned you.”

As for me, I love that albatrosses, lacking natural land predators, aren’t afraid of me. When I sit on the road taking pictures, young walkers often stop by and gently touch my shoe, shirt, camera or arm. What are you? I imagine them thinking as they stare up at my face. Looking into the eyes of an albatross as it calmly gazes back makes me happy to be alive. I know I speak for us all when I say that working at Midway is the privilege of a lifetime. It’s also really fun.

Check out volunteer opportunities at Get Involved.

Mystery of Midway kolea remains unsolved for now

Published January 11, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
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Some Pacific golden plovers, or kolea, spend their winters on Midway. ©LUKE HALPIN

I’m home from Midway, where I learned a lot about albatrosses. But one highlight of my visit came as a surprise: a flock of kolea.

I knew a few Pacific golden plovers wintered on Midway, and saw the occasional bird hopping around our living quarters. What I didn’t know is that they sometimes graze together there in large numbers.

Every day, kolea gathered among morning glory vines growing over a stretch of cement rubble that lies between runway and ocean. I wondered what the birds found so tasty in that one spot. And because our Oahu plovers so ferociously fight other birds with the nerve to trespass on their territory, I was also curious about how close together these individuals foraged. I rode my bike to the place to find out. The kolea had other ideas. From 100 to 200 birds immediately rose up and flew off together toward the ocean. Having never seen a flock of plovers in flight before, I was thrilled. But I needed to see birds on the ground.

I sat down and waited. And waited. After an hour not one bird had come back. Clearly, to see what these kolea were up to, I would have to be sneaky.

The next day, I stopped my bike far from the area and walked toward the vines. As I drew closer, I could make out the birds’ busy heads bobbing among the rocks and leaves in that stab-run-stab gait so familiar to us Hawaii residents.

I slowed my pace, taking one small step every 15 seconds, figuring the birds wouldn’t notice that I was drawing closer. Wrong. One danger call — “CHU-EET!” — and they were all gone.

The following day, after again flushing the birds, I sat atop sharp cement shards and leaned against a naupaka bush staying as still as I could. One kolea landed on the rusty breakwater, then another and another. Gotcha, I thought. But as I raised my camera for a picture, a bird raised the alarm. Gone again.

The next day, I dressed in dark clothes and took with me a padded beach chair that I nestled inside the branches of the little naupaka. Not a single bird landed in the vines, the slabs or even atop the distant breakwater. I sat there so long I nodded off; when I awoke there was still not a single bird in sight.

Before I admitted defeat, I crawled on hands and knees among the green vines and cement chunks but didn’t see a single living grub or insect, or evidence of anything eating the leaves or flowers.

The mystery of the morning glory plovers remains unsolved, but my efforts weren’t entirely in vain. The Midway birds’ wariness made me appreciate even more our Oahu plovers’ remarkable adaptation to human presence in urban settings. At the beach park next time, I’ll thank them.

Midway’s like a dance floor for amorous albatrosses

Published December 28, 2015 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2015 Susan Scott
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Albatrosses, which mate for life, return to the same spot year after year to nest. Couples are affectionate in the nesting grounds. ©2015 David Dow

MIDWAY ATOLL >> For the holidays, Craig and I are working 16 days in sweltering sun, driving rain and gusty wind. At the end of each day, we are dirty, stinky, tired and hungry. Yet we agree that this is one of the best Christmas gifts we could give ourselves. As volunteers for the U.S. Fish and Wildlife Service, we’re counting albatrosses at Midway.

Consisting of 2.3 square miles of land, the atoll lies near the end of the Northwestern Hawaiian Islands, 1,260 miles from Honolulu. Human history here tells of shipwrecked sailors, telegraph workers, travelers, hunters and war. Today, though, Midway belongs to the birds.

Seventeen seabird species nest here, but our focus these two weeks is on albatrosses. Starting in November, about a million Laysan albatrosses return to the atoll to raise chicks, creating the largest albatross colony in the world. In addition, hundreds of thousands of single albatrosses also arrive on the atoll’s islands to find mates.

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DancingDuring the first three years of life Laysan albatrosses stay at sea, soaring over the waves and sitting on the water looking for fish, squid and flying fish eggs. Then, like sea turtles, the birds return to the island where they hatched.

The young, nonbreeding albatrosses turn the grounds into an avian rock concert as they sing and dance to attract members of the opposite sex. Usually the performance involves two birds, but sometimes a third and fourth join in, creating a circle of pure exuberance.

Albatross dance steps vary slightly with species, but they’re all similar and include beak touching, wing fanning, head bobbing and sky pointing, often while circling one another on tiptoes. At certain moments during the dance, each bird claps its bills like castanets, moos like a cow, honks like a horn, and neighs like a horse, all punctuated with the occasional owlish screech.

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It can take several seasons for a young albatross to bond with a mate, but when the chemistry is right the partying is over. The quiet couples kiss, cuddle and straighten feathers in touching displays of affection.

It takes eight to nine seasons of practice before a young couple successfully raises an offspring, but once they get it right, the two will breed for decades. A bird named Wisdom, at 64 the oldest albatross known, is here sitting on yet another egg.

We volunteer bird counters pay our own considerable expenses and work long hours in all weather. But if Christmas is about sharing memorable times with friends, appreciating the extraordinary life on our planet and feeling happy to be alive, well then, Midway is the gift of a lifetime.

For volunteer information: click here

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Susan in a sea of birds. Courtesy David Dow.