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Posts Tagged ‘Arctic Tern’

It has been a very busy week for the Petit Manan crew as well as all the tern parents on the island. Our first chicks hatched on June 15th and more and more have been hatching each day. These little fluff balls are absolutely adorable but that cuteness comes at price! Like any good parents, the adults have become very protective of their young and are willing to do anything to ward us researchers off which include pecking us and pooping on us. Now that there are chicks out and about the research team has added on a few more tasks to our days. Every day we must check productivity plots we set up around the islands. These plots are basically giant tern baby play pens each containing 6-15 nests. In these pens we track the hatch date of every egg and track the progression of each chick as they grow. In the end, it will give insight on the entire hatching and fledgling success of the tern colony. We weigh the chicks and also band them; that way, when they start running around we can tell who is who.  We also are beginning food provisioning surveys in which we record what the adults are feeding their chicks. We’re hoping to see lots of herring, hake, pollock, sandlance! It’s a fun time to be on Petit Manan and we’re hoping for lots of healthy chicks that grow up ready to migrate down to South America or further this fall.

‘Till next post,

Chris

Pictures: Top L to R; Lance weighing a chicks, an Arctic tern chick, an Arctic tern chick sporting some new bands. Bottom L to R; Kate searching the productivity plot for chicks, a tub full of common tern chicks waiting to be weighed

 

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We’ve got tern fledglings on Metinic! After a few breezy days of large chicks jumping up and flapping, some have finally gotten airborne. While not as sleek or acrobatic as their parents, the somewhat pudgy fledglings are still capable fliers. They are still returning to their nests to get fed, but then fly off instead of running into the grass with the smaller chicks. Even as our first chicks take to the air, more chicks keep hatching, so we’ll continue to be busy for the next few weeks.

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These arctic tern chicks are from nests 5 feet apart. One is ~18 days old, the other ~3 days old. Arctic terns fledge at around 21-24 days.

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An arctic tern flies in with a small hake for a small chick.

As if to make up for the splendid weather we’ve had most of the season, the dreary fog and rain has finally been keeping us inside. It’s best to keep off the tern colony when it is cool and wet so the parents can keep their chicks warm and dry instead of flying at us. The weather has given us a good opportunity to catch up on data entry and stay warm around the wood stove, at least whenever we aren’t heading off persistent colony-bound sheep.

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The wood stove is a welcome sight upon returning from chasing sheep in the rain.

During breaks in the dismal weather, we’ve gotten out to check on our growing guillemot chicks. They’re starting to get pretty big and hiding deep enough in their burrows that it has become a bit of a challenge to get some of them out to weigh them and measure their wing chord. While wedged in the rocks with my arm deep inside an active guillemot burrow, I spotted our first whimbrels of the season on the beach. That brings our island species list up to 95 with a passing puffin spotted during provisioning. We’re hoping to reach 100 species before the end of the season, and it certainly seems within reach.

Until next time!

-Mark

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Petit Manan Island is in peak hatching season! The small, delicately speckled brown tern eggs are disappearing and being replaced by similarly patterned fluffy chicks. The oblong, white-brown spotted black guillemot eggs are opening up to reveal all-black downy chicks. Where once we were seeing large, gleaming white puffin eggs, now chicks with long grey down and white bellies are hiding quietly in their burrows. We even have found one razorbill chick (see photo below)! The only seabird still solely in the incubation stage are the Leach’s storm-petrels.

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One question that I often get asked is, why do some seabirds only ever hatch one chick (think puffins, razorbills, storm-petrels), while others can rear multiple chicks (terns, guillemots, etc)?

In general, seabirds have small clutch sizes compared to birds of other groups like most waterfowl, game birds, and some perching birds. This is because seabirds, unlike the groups mentioned previously, tend to have long life spans. This means it is not quite as critical for seabirds to have a successful nesting season their first breeding season or every year of their life in order to replace themselves in the population. Other bird species may only get one chance to successfully reproduce if annual adult survival is low due to high depredation of adults and/or other factors.

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But why lay only one egg instead of two or even three? There are multiple factors that influence seabird clutch size, and still many questions to be answered. Chick rearing is very energetically demanding for the parents, from egg formation to providing enough food for growing chicks. Right from when birds arrive on the breeding grounds, food availability is critical. After long migrations or rough winters, seabirds need to be able to find enough resources near their breeding colony to allow them to be in proper condition for breeding. Limited food resources during this period of time can cause birds to lay smaller clutch sizes, or even not nest at all.

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This still does not answer our question why puffins and other species only lay one egg, in both good and bad food years. For species with one egg clutches, it is more beneficial for the long-term survival and breeding success of the adults to raise only one chick at a time. Raising two chicks would probably not be impossible during good food years, but the energetic costs on the parents might make this not worthwhile in the long run. So puffins, razorbills, and many other seabirds prefer to take things slow, laying only one egg per season.

Currently, we have found 17 black guillemot chicks, 15 Atlantic puffin chicks, one razorbill chick, and a few hundred tern chicks!

-Jill

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It’s been a beautiful week on Metinic, with the warm sun providing for excellent hatching weather. More tern chicks show up every day in our plots and some of the older ones are getting their first wing feathers. Of the dozens of chicks in our plots, the color and pattern can vary considerably from sandy tan chicks with only a few black spots to almost snowy white speckled with dark streaks.

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We call these arctic tern chicks the “Silver and Gold Siblings”

We made the most of the weather early in the week to continue our trapping efforts, with a special focus on one particular bird. In 2010, Refuge staff placed geolocator data loggers on the legs of several arctic terns to track their annual journey from breeding grounds in Maine to their winter range in the waters around Antarctica. The geolocator measures the amount and timing of sunlight to determine the location of the bird. Most of the loggers were retrieved in 2011 or 2012, but a few were still missing. Luckily, Helen and I spotted this bird in May, and figured that it was breeding here. On Wednesday, Refuge staff Brian, Michael, Linda, and Sara came out to the island to locate and catch the bird. Between the six of us, we sat in our five blinds and watched for the bird. We quickly found the bird and its nest, but trapping efforts were to no avail. After a fruitless attempt on Thursday, Brian and Michael came back out on Friday and finally managed to catch the bird after a few hours of waiting with a bow net. It appears that the nest is being attended by three adult terns, which is unusual, but may account for the difficulty of catching the bird if it’s only spending a third of the time on the nest. The geolocator was removed and the bird released. Hopefully, the data on the geolocator can be retrieved and we can see where the bird has been!

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The geolocator on the tern’s leg before it was removed

While the Friday tern trapping stint was ongoing, Helen and I went out to check on black guillemot burrows on the northwest side of the island in advance of hatching. June 27th is International Guillemot Appreciation Day, traditionally around when the first chick hatches. Guillemots, relatives of puffins, nest in rock crevices all along the Maine coast. We located several rocky burrows with eggs and a few with adults attending. Between the burrows, a few gull chicks were running around near their nests atop the rocks.

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An adult black guillemot incubates its eggs in a rock crevice

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Herring gull chick. Both herring and great black-backed gulls breed on Metinic.

At the southern end of the cliffs, we were checking a last couple of rocks when we were surprised to find our first guillemot chicks a few days early!

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Black guillemot chicks are covered in dark gray downy feathers

Have a happy Guillemot Day!

-Mark

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The beginning of the week started out slow and rough as the weather was not cooperative.  High winds made it so we could not go out to the tern colony as we wanted the adults to stay on their eggs and keep them warm from the howling winds.  Finally the weather broke Tuesday afternoon and we were able to do some trapping and banding of adult terns.  We do this by selecting a couple of nests, replacing the eggs with wooden ones so they do not get damaged, and placing a chicken wire trap over the nest with the door open.  When the adult walks into the trap, they step on a trigger platform that closes the door.  As the adult sits in the trap incubating the wooden eggs, we walk up and take it out of the trap through a hole in the top.  The adult is then placed in a bag where it is weighed using a spring scale.  We then band the bird and measure its wing chord and head-bill length before it is released to return to incubate its eggs which we have switched back to the real ones.

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A common tern checking out the trap

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Measuring wing chord length

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Measuring head-bill length

Wednesday we headed over to Matinicus Rock to help them with their tern census.  It was nice to get out to another island to see what was going on there; plus we got to see Atlantic puffins, razorbills, and common murres, three species that do not nest on Metinic.

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Atlantic puffins on Matinicus Rock

The next day it was our turn to census!  With the help of a few guests, we were able to count 608 nests in our colony of arctic and common terns!  We did this just in the nick of time as we came across multiple hatched chicks with more popping up every day!  The rest of the week was spent securing our productivity plots which are circles of fencing surrounding a number of nests.  When the chicks within the plots hatch, we record the hatch date and band them.  Every time we visit the plots, we weigh the chicks and keep track of how they are doing until they fledge.

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Pipping arctic tern egg

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A hungry chick waits to be fed

Throughout the week we have also come across savannah sparrow chicks and fledglings, and spotted sandpiper chicks running around on the rocks.  An identifying characteristic of spotted sandpipers is they bob their rump up and down as they walk; it is funny to watch the tiny fuzzy chicks do this as well!  We are looking forward to more chicks showing up in the upcoming weeks!

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A tiny spotted sandpiper chick

Until next week,

Helen

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The nesting season is ramping up on Metinic! We found our first tern egg on Wednesday and more nests have popped up every day since.

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Two egg Arctic Tern nest atop a boulder

 

Elsewhere on the island, we’ve found Common Eider, Herring Gull and Great Black-backed Gull nests. Some of the island’s birds are further along and already have chicks. At least one eider clutch has already hatched, with the three ducklings sticking close behind their mother as she cut through the waves. On our first trip to the southern end of the island, we came across half a dozen Killdeer chicks darting around the marsh while several Canada Goose goslings swam across a protected cove with their parents.

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Killdeer chicks can run soon after they hatch. They also look like cotton balls on stilts.

Metinic is unusual among Refuge seabird islands in that it hosts a permanent terrestrial predator: garter snakes. Though generally small, these snakes could pose a threat to diminutive tern chicks, so we do our best to catch any near the colony. When caught, they often release a musky smell that fades from clothing after a few hours. These snakes then take a one way trip to the mainland, where they can get their fill of rodents, away from nesting seabirds.

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This snake and two others are now spending their days near Rockland.

Between stretches of fog and steering sheep away from the tern colony, we managed to find some time to continue our shorebird monitoring efforts. People up and down the Atlantic coast are curious about shorebird numbers and movement, so we do our best to keep an eye out for birds on the rocks and beaches. It’s also a good way to get our species list up. Two American Oystercatchers and a Purple Sandpiper helped to get our list up to 81 this week.

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Shorebirds can often be found in mixed-species flocks. This Purple Sandpiper was noticeably smaller than the Black-bellied Plovers and Ruddy Turnstones it was with.

Until next time!

-Mark

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Hi all!  Helen here!  My first week with the seabirds on Metinic Island has been full of exploring, birding, and learning new things!  We started out the week by rounding up all of the resident sheep and driving them to the southern end of the island where we put up an electric fence to keep them out of the tern colony for the season.  We did this just in time as both the arctic and common terns have returned and are actively seeking out mates and nesting sites.  We have begun observing the terns from the blinds and have watched them settling in throughout the week.  We have seen the terns landing on the ground, evaluating various potential nesting sites, and showing courtship behaviors such as the males presenting the fish they caught to females.

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Common terns checking out the area! 

The terns aren’t the only ones settling in for the season, the black guillemots are courting and seeking out burrows in the rocks as well.  We have also observed a number of common eider nests with eggs!  We even saw one hen with three ducklings today, which is early for them.  We are expecting to find many more eider nests in the coming weeks as they are still displaying courtship behaviors.  To prepare for the arrival of the chicks, we have begun setting up snake plastic as a means of predator control.  Metinic has a population of garter snakes who enjoy feeding on the seabird eggs and hatchlings, so we set out black plastic that the snakes will be attracted to because they create a warm place for them to hide.  We will periodically check the plastic and gather any snakes into a bucket to release them on the mainland.

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A hen common eider on her nest, they have excellent camouflage!

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Freshly laid eider eggs

Along with setting up and preparing for the upcoming season of seabird chick monitoring, we have been keeping track of our other feathered friends on the island.  Every day we start out with our morning point counts then spend the day exploring around and recording any additional bird species seen/heard, and we end the day with shorebird counts right before sunset.  So far, Mark and I have recorded 71 different species!  Metinic is a great location to support a variety of birds as the island includes rocky coast, open field, forest, wetland, shrub, and pond habitats.  We are looking forward to adding to our list as the season progresses!

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Black-throated green warblers are very common in the island forest!

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Ruddy turnstones on the shore

 

 

Until next week,

Helen

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