They’re back! The shearwaters, that is

Hi folks, CoCo here! Last weekend, I got to camp out on Managaha. Just as I was just settling in to sleep, I heard this bloodcurdling scream! It sounded like a baby crying, or like a babui being slaughtered. Now, I KNOW there are no babies or pigs on Managaha, so you can imagine how scared I was. Fortunately, my good friends from the Division of Fish and Wildlife were able to reassure me that I wasn’t going crazy, I was just hearing the cry of the wedge-tail shearwater, or lifa’ru. They told me I was actually really lucky to hear the call, as you have to be in the right place at just the right time.

And what exactly IS the right time? Well, it’s good you ask! According to DFW’s Shelly Kremer, wedge-tail shearwaters are pelagic, meaning that they live much of their lives out at sea, eating mainly squid and small fish. Then, around April, they head to land (Managaha) to begin courtship and digging tunnels.

Tunnels? What on earth are birds doing digging tunnels? Well, the shearwaters actually dig their nests and lay their eggs in these tunnels. Some of the tunnels are as long as 5-6 feet, but many are quite shallow, just below the surface of the earth. They dig with their feet, pushing out the sand behind them. Around mid-June, the birds will lay just one egg. The parents take turns incubating the eggs and going out to feed. 6-8 weeks later, about half of the eggs laid on the island will hatch (the others are infertile), and out pop some fuzzy chicks! After they are born, the parents will go out during the day to feed, leaving the chicks unattended, and return at night to feed their young. Once the chicks have all of their flight feathers, the parents stop coming back. When the juveniles get hungry enough, they leave the island and start fishing for themselves. This usually happens around December. Amazingly, the juveniles will not return to land until they are ready to breed, a full three years later!

So, what do we know about our local shearwaters, exactly? Well, not a whole lot. Nobody knows exactly how far out to sea they go, how long they live, or much else, for that matter. A local fisherman told me that he often sees lifa’ru out at sea, but typically quite far out, maybe ten miles from land. So far, though, there are not much scientific data about their movements. A related species, the streaked shearwater, was found to have traveled 1000 kilometers away from land just to eat, so it’s possible that our birds go very far as well!

At Managaha, DFW biologists have been extensively studying the birds since 2003. They count the nests, eggs, and how many chicks hatch. They also monitor the growth rate of the chicks until they fledge, or get their flying feathers. Young birds are banded right before they fledge, at about six months of age. Adults are caught and banded during mating season in April or May. By putting a unique ID on a metal band around their legs, the scientists can tell what percent of the birds return to Managaha. Over the last two and a half years, a total of 275 birds have been banded! Of course, none of the juveniles banded in 2003 have returned yet (we won’t expect them back until 2006), but we have seen some of the adults returning. In time, with the banding data, we will be able to find out how long the birds live and how many survive to adulthood.

One of the biggest problems facing the shearwaters used to be ground-based predators. Like most seabirds, shearwaters have legs that are so far back on their bodies that the birds tend to be quite awkward on the ground. Also, their nests are in the ground, making them vulnerable to cats and egg-eating rodents. Fortunately, all of the cats on Managaha were removed before the 2003 breeding season, and most of the rats are also gone. Consequently, we’ve seen a huge increase in the number of chicks hatched over the two years that we have collected data. In 2003, only 15 chicks hatched, but last year, in 2004, 31 hatched! Keep an eye on this page around August to find out how many hatch this year.

Predators are not the only problems facing the shearwater, however. Because their nests are underground, it can be hard to know where they are. Anyone walking through their nesting area might accidentally step on the shallow burrows, crushing the eggs inside. Also, if you’ve ever been to Managaha, you’ve probably noticed that the island is experiencing erosion on the western and southwestern end, while sand is gathering on the northwestern end. Unfortunately the erosion is occurring in the same area that the shearwaters like. They prefer nesting in grassy areas and under large shrubby bushes, and they like living on the outer edge of the island, not the interior. The largest concentration of nests tends to be on the western side of the island. (Stay tuned to this page for a feature on beach erosion on Managaha and Saipan).

So why should we care? Managaha is the only known nesting site of the wedge-tail shearwater in the CNMI! This is a unique resource, so we need to make sure that they will continue to survive. Also, shearwaters, like all other migratory birds, are federally protected under the Migratory Bird Act. In order to even study them, DFW needs to obtain a permit from the US Fish and Wildlife Service.

To combat the problem of habitat loss, DFW and the Brown Treesnake Program teamed up with TREES (Team Responsible for Environmental Enhancement of Saipan), Northern Marianas College’s Natural Resource Management Program, and the Workplace Investment Agency summer program. They re-routed the path to open up more potential habitat, re-vegetated the old trail, and made a new trail. They put up signs and ropes to keep people out of the area. Also, there are plans in the works to erect educational signs around the nesting areas, letting people know about the birds and how they can help to protect them.

Unfortunately, these protective measures are not always successful. When I went walking in the morning, I noticed with horror that a family had laid their picnic out in a nice grassy area…which just happened to be within the nesting area. I watched in shock as the parents stepped over the rope, and cringed as I imagined their feet crushing a burrow underneath, and possibly one of those fragile eggs. I ran up to the rope and called out to the family. When I explained to them about the shearwaters, they were very understanding and immediately moved their picnic outside of the ropes. Whew! A near-disaster averted by just a little bit of information.

So, what does this mean for you? Next time you’re on Managaha, and you see the signs and ropes, remember what you’ve learned about the beautiful and mysterious shearwaters. Let them have their habitat – stay out of the roped off areas, and if you see any other people in there, just let them know why the signs and ropes are there. And count yourself among the lucky ones if you hear their strange and eerie wail one night.

Coco

(The voice of CoCo was provided by Qamar Schuyler, Coral Outreach Specialist at CRM, DEQ, and DFW. She can be reached for comment at 664-8300, or email Qamar.Schuyler@crm.gov.mp.)