Arctic Feeding Frenzy

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Gulls and kittiwakes feeding in the intertidal zone of a lagoon on the Chukchi Sea coast north of Kotzebue, Alaska. Photo Kevin Rodriguez.

Arctic terns flew with effortless precision, as they plunged into the outflow of an Arctic lagoon, catching their prey and returning to their nesting sites just a few hundred yards away. Glaucous gulls and black-legged kittiwakes flocked amongst the terns, while the parasitic jaegers continuously harassed these birds until they dropped their catch, swooping in to intercept the prize midair. For the three of us researching the fish of arctic lagoons, it was great to be welcomed back to camp after a long day of fish research by such a beautiful display of a productive Arctic ecosystem – the sun projecting over the sides of the nearby mountains casting a smooth orange glow on the gravel beach and the cast of characters that had congregated there to feed.

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An arctic tern plunges into the water in seek of prey. Photo Kevin Rodriguez.

 

This commotion was not only attracting the attention of seabirds. Many marine mammals and fish also cued in on what was unfolding that night. Off in the distance, bearded seals swam stealthily with nothing but their heads exposed. Alert to our presence; they skimmed the surface of the water to maintain constant visual contact with us as we watched from the gravel beach. Groups of juvenile and adult Dolly Varden char cruised the shore, taking advantage of the seemingly never-ending supply of food. But we had yet to see what was causing this confluence of different organisms. It was not until small fish began riding the waves onto the shore that we realized the identity of the lead performer in the amazing ecological drama that was unfolding before us. Capelin, a smelt species that is an important forage fish in the Pacific, Atlantic and Arctic oceans, were “rolling” onto the beach, attracting hundreds of birds and marine mammals, and countless predatory fish. Capelin, as evidenced by the feeding frenzy, are important prey items for a host of top marine predators and act as a critical link between zooplankton and higher trophic levels. Although generally associated with pelagic (offshore) habitats in the marine environment, on this day, a huge school of capelin had chosen this small section of beach above the Arctic Circle to spawn – breeding while laying innumerable eggs along our beaches.

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An arctic tern flies off carrying a male capelin snatched from the beach. Photo Kevin Rodriguez.

The sizeable swell washed the capelin up on shore by the thousands, stranding the capelin for mere seconds until the next crashing swell washed them back into the water. Capelin could be seen forming dark amorphous schools as they swam a few feet offshore, apparently waiting to fulfill their biological need to spawn while simultaneously avoiding all the hungry onlookers. Capelin are part of a group of forage fish, including other smelt and sand lance species, which spawn on beaches. Although intertidal spawning is rare, capelin are only one of two marine fish (along with the grunion, so well-known in California) that fully emerge from the water to spawn. With each successive wave, more capelin purposefully washed themselves high and dry, allowing them to deposit and fertilize eggs at the high waterline.

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Capelin spawning on the beach of a lagoon on the Chukchi Sea Coast. Capelin were seen spawning like this over a period of three weeks in June 2016. This event may be a new phenomenon in this area. Photo Kevin Rodriguez.

We examined the fish washing ashore and determined that most (about 95%) were males in breeding condition, distinguished by the presence of an elevated ridge of scales along their lateral ventral edges and longer pectoral fins. Why were there so many males compared to females? The literature suggests that one to three males may accompany a female onto the shore, but our sex ratio was far more skewed. How extensive are these spawning events on this coast, and how important are they to marine predators? Our collaborator, Alex Whiting with the Native Village of Kotzebue, was surprised by the event and suggested that this could be a new phenomenon in Kotzebue Sound. Alex had never encountered reports of beach spawning capelin from the subsistence fishing camps. These beaches lie within the Cape Krusenstern National Monument and our work adds to the understanding of this coastal treasure. We couldn’t have asked for a better end to an already beautiful day of Arctic lagoons research, but as always, we go to sleep with more questions that we will need to find answers to in order to understand and protect this unique Arctic environment.

Written by Kevin Rodriguez, National Park Service and WCS Research Technician. July 2016.

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Remnants of Winter

A month ago, on the 29th of May, I spent a day collecting the thirteen motion-activated cameras that we deployed on wolverine snow-holes this spring, not knowing anything about the photos taken in our absence. Across the tundra, most of the snow was gone, patches remaining only in drainages and cut banks where it had drifted during the winter.

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Helen Chmura uses a radio tracker near the Colville River to locate collared wolverines. Photo Tom Glass.

In keeping with what we know about wolverines, most (though not all) of the sites where they had created holes still had some snow, where we found evidence of how they had used the area. It is the relationship between wolverines and spring snow that drives many of our research questions.

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A snow filled drainage as we approached the study area. Photo Tom Glass.

Upon reviewing the photos from the cameras, we discovered that five of the holes were associated with kits. At three of these, we found substantial latrines – piles of scat about a foot in diameter and several inches tall. We collected these as evidence, hoping to more fully examine their diet, and possibly to obtain a genetic sample from the kits, which would allow us to follow family relationships if we catch them again later as adults.

At many of these sites, we were also able to see the remains of the tunnels that the wolverines had excavated and used. These were extensive, sometimes stretching as much as forty feet from one end to the other. At one site we found beds, where the wolverine had apparently brought moss into the den for insulation and comfort, which were now suspended on pedestals, all other snow having melted around them.   Many sites also contained food remains, like caribou hooves, bones, and hair.

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A latrine inside a natal den (left side of frame). The sticks and debris leading away to the right likely mark the location of a tunnel. There was also a partially consumed caribou leg in this latrine. Photo Tom Glass.

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A moss bed, formerly inside a wolverine snow structure before the snow melt.Photo Tom Glass.

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Looking down a partially collapsed tunnel. Scat and bones litter then length of this section. Photo Tom Glass.

Upon approaching one site, an adult wolverine fled into a remnant tunnel in the snow. One of our primary questions is when and why wolverines leave the snow structures, so it was fascinating to observe this individual still using the site. After some deliberation, we decided to approach cautiously to retrieve the camera. When we arrived, we found two kits – both dead – on the snow near the entrance of the tunnel. A necropsy found no obvious wounds to either (though one was partially consumed), and the intact kit was severely underweight for its age. From this, our best guess is that the mother was killed (either by a predator, like a wolf, or by hunters), and the kits were left to fend for themselves. This leaves the question of the adult wolverine we observed at the hole – possibly the father, or simply another interested party. Unfortunately, our camera did not stay standing long enough to provide any evidence.

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The adult wolverine fleeing into a hole as we approached. Photo Tom Glass.

At one hole, a natal den, we captured nearly 4,000 pictures of the mother, kits, and presumed father coming and going from the area. Among these, there is a series which depicts the mother nursing the three kits, at the entrance of the den, while the male observes from a distance. In another set, the mother arrives at the den and drags in a caribou leg. In others, the kits tumble playfully around the entrance. These are fascinating windows into the lives of these creatures, about whom we know so little. In most cases, snippets like these create more questions than they answer, providing the impetus to get back out there, don the parka, and keep searching.

Written by Tom Glass, WCS research technician. June 2016.

Peard Bay Special Area

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View of Peard Bay from the decommissioned Distant-Early-Warning (DEW) Line Site.

Peard Bay, on the Chukchi Sea Coast, is the newest BLM-designated Special Area within the National Petroleum Reserve – Alaska. This area is relatively unknown to scientists, but well known to nearby residents who have used the area for millennia. Located between the villages of Barrow and Wainwright, the bay is sheltered by barrier islands and hosts high densities of polar bears and ringed seals, nesting eiders, and in the fall, migrating waterfowl and shorebirds.

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En route to the Seahorse Islands to search for nesting common eiders.

As at Kasegaluk Lagoon, where we are currently studying eider nesting success, we are concerned with the inundation of eider nests and increased predation in this rapidly changing environment. However, we must first fully understand where on the barrier islands the eiders are nesting. WCS personnel recently spent time at Peard Bay searching for nesting eider ducks. On the Seahorse Islands we found a colony of at least 50 common eider nests, some nesting so close together that the nests were touching each other. Other interesting observations included a northern fulmar, a small group of crested auklets, and a nesting red-throated loon.

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This eider made its nest amongst the flotsam washed up by the tide. Eiders were nesting as few as 20 m from the water’s edge.

 

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Red-throated loon nest found on a small lake slightly inland at Peard Bay.

Written by Sally Andersen, WCS Conservation Coordinator. June 2016.