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Posts Tagged ‘seabird’

Hello friends, Hallie here from Petit Manan Island!

Life here on Petit Manan is going so well. Our tern chicks are hatched and getting close to fledging, our pufflings are fluffier and plumper than ever, and we even have our first black guillemot and razorbill chicks.

One of the cool things about working on such a small island like this is when you have a new avian visitor, you notice. We are up to 110 bird species recorded on Petit Manan Island this season, which is remarkable in itself. We have had everything from warblers to short-billed dowitchers to even a least bittern, a small bird that you typically find in marshlands on the mainland. And as well, we have had a lot of birds with interesting plumage show up to the island — like this Common Murre.

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Leucistic Common Murre next to Razorbill and Atlantic Puffin

Common Murres are usually a dark chocolate brown, which is produced by melanin. This bird,  however, is silvery-grey — a result of a genetic mutation that inhibits melanin production. This result is called leucism, which is similar, yet very different to albinism. Regardless, it makes up for a stunning result — this bird very well may be one of the more beautiful I have ever seen. Whether or not male or female common murres also think so is up for debate — hopefully this bird’s unique plumage will not inhibit it from procreating in the future.

Melanin is one of many ways birds color themselves. The laughing gulls here use melanin to create that dark mask during the breeding season, which they use to deter other laughing gulls from their nests. You also often see birds with darkened wing-tips, like the terns, in which the melanin is used to strengthen the feathers and make them more durable.

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Adult Atlantic Puffin showing the orange-red carotenoid coloration in the bill and eye

But what other colors do we see here on PMI that have significance in birds?  Since we have been catching puffins this last week, I have been captivated by the bright orange feet and bills that the puffins display during the breeding season.  Puffins, and many other birds, get this rich orange-red color from carotenoids — a color they metabolize directly from their food. Puffins use the intensity of this color to show potential mates and rivals how fit they may be. The brighter their bills and feet, the better at fishing and raising a chick they may be! You can also see melanin in the feet and the mouths of black guillemots!

Next time you see a color in a bird, its worth asking exactly why it is that way. Often even the most subtle of colors on a bird have such an immense meaning. I will be doing the same — sitting here wondering why we get tern chicks in two different colors. Any ideas?

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Common Tern chicks from the same nest showing the two different plumage colorations

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A new breeding season has begun here on Petit Manan Island. You take a step out the front door on a chilly morning, and the sky and ocean are filled to the brim with life. Little yellow songbirds- like Magnolia Warbler (Setophaga magnolia) and American Goldfinch (Spinus tristis)- are darting around the grasses. You hear a familiar song from a Savannah Sparrow (Passerculus sandwichensis) broadcasting his availability to the available females. A white bird swoops towards your head with a sharp call – it’s a Common Tern (Sterna hirundo), establishing its territory and assuring a predator free environment for its young.  And you look out at the sea – it is covered with little charismatic birds: Atlantic Puffins (Fratercula artctica), Razorbills (Alca torda), and Black Guillemots (Cepphus grylle) – the poster children for the island breeding colonies across the Atlantic.

My name is Hallie, and I have lived far from any form of civilization for quite a long time. I have been working with birds for a little over 5 years now, often in locations so remote that your best company often becomes the wildlife around you. Petit Manan, in a way, is my first time living in a metropolitan area in years – but instead of humans, its birds. There is the main crazy downtown here – Puffin Point, as we call it, which would be the avian equivalent to Manhattan. And then there is the lawn – Puffin Point’s suburbia – where you will find all of the terns scattered about fiercely guarding their nests. And out in the more rural suburban zones, you get the Laughing Gulls (Leucophaeus atricilla) and various songbirds. There is even a community underground: Leach’s Storm Petrels (Oceanodroma leucorhoa) which burrow deep down underneath the soil, right next to the roly-polies and the salamanders. The island is hustling and bustling with life, even at the dead of night, just like Times Square.

Puffin Point 

Here in bird city, love is in the air. I have quite enjoyed watching all of the different species of bird court one another. The terns are very playful – one will come back with a fish and flash it off to all of the birds around it, enticing them to chase it during a magnificent display of airborne agility. Sometimes the bird will give it to a potential mate, or sometimes it will devour the fish for itself.  The puffins are gentler – you will often see two mates nuzzling their bills against one another’s, or a male trying to catch the attention of a female by nodding his bill within her sight. And then there’s the guillemots, which will race around the female, dive head first into the water, and make high-pitched, almost song-bird like calls.

Every species of bird here establishes themselves differently: but they all have the same goal in mind. Right now on Petit Manan Island, its finding a mate, finding a place to nest, and getting started securing the future generations of their species. It is quite a magical time, and as chaotic as a metropolitan area can be, the island with its seabirds has its charm.

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It has already been over two weeks since the Great Horned Owl roamed the surface of Ship Island looking for a late-night snack. You would think that over time, the terns would settle down and begin to behave “normally.” But that’s not the response we’re seeing. Even today most of the colony begins to sweep high above the island soon after sunset, then disappear quietly out over the ocean. It seems that small numbers do come back to warm their chicks and eggs, but the majority aren’t seen again until sunrise.

The owl caused full colony abandonment during the nights on the island. This occurred for over a week straight, which might have led to some long-term effects on chick physiology. Many of the eggs didn’t end up hatching since they weren’t incubated during the nights. But, some eggs were still able to make it. Typically, eggs hatch after 21-23 days of incubation. With the owl disturbance, incubation length increased, which is why our chicks arrived slightly behind schedule.

Although we have many healthy chicks all around the island, there are a select few that are showing what we assume to be the negative consequences of this over-exposure to the cold and wet nights on a Maine island. When terns incubate, they are constantly rotating the eggs around. This allows for even nutrient and heat distribution throughout the egg as well prevents the embryo from sticking to the shell, allowing it to float in the middle and develop successfully. Without this constant rotation, it’s possible that the chicks could have developed certain physical defects.

 

Not only are we seeing odd chick appearances, but we are also seeing a huge change in colony behavior. The terns have been extremely sensitive to any presence that might seem or sound threatening. This even includes species that are not considered predators. In order to protect themselves, terns often mob, dive-bomb, or attack the predator. They also might flee, just as they did with the owl. Their actions depend on the level they feel threatened themselves versus how threatened their young are. We’ve observed terns going after Common Eiders, Dowitchers, and Harbor Seals. They were even frightened by the sound of a nearby fishing boat. Although we can see that these species are here to do no harm, it’s still good to see the terns working hard and being extra protective.

These actions displayed by the tern colony isn’t uncommon among populations who are or were at risk of nocturnal predation. In fact, it has been witnessed in several other Common Tern studies where owls were present. Looking at a well-known colony observed by Monomoy NWR in particular, you can read how they experienced very similar results years ago (Nisbet and Welton, 1984).

It’s amazing how a single bird can influence an entire colony in only a few days. This owl left an impression on the terns to last the entire season. The fate of this years fledgling was greatly altered and we can only hope that next year the colony works to make up for this years loss.

On a better note, we’re still waking up to a few more chicks every day, and we’ve already seen a few fledge! Based off of our provisioning efforts and weight measurements, our current chicks are growing at a steady rate and being fed a healthy diet, which mostly consists of Atlantic Herring. Some chicks are being fed so much that they actually have to lose weight in order to lift themselves off the ground and fly! We’re glad to finally start seeing our chicks transform into successful adults!

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One of my healthy provisioning chicks. Not quite ready to fledge yet!

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Chicks that were recently born. Only a couple days old!

Only one more week until the island closes. This season really flew by! I’ll keep you updated on any more unusual or exciting events happening on Ship!

-Amanda

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This past week on Ship Morgan and I both took our short breaks off the island. While Morgan was away I was joined by Kelby from PMI to work on predator control, productivity plot management, chick banding, and more!

We’re starting to see more and more chicks every day! Usually when we’re checking the productivity plots we can see when they start pipping. This is when their little beaks start to break open the egg. This lets us know that the next day we will definitely have some new arrivals to weigh and band if they’re dry and ready.

Before we start provisioning, we still have some time to re-sight birds from previous years. Typically, they will have a small silver BBL band on their ankle which contains either 8 or 9 numbers. We can use a spotting scope to see these numbers and enter them into a database where we can learn more information about that bird, such as it’s age. To make re-sighting easier, we put up posts for them to perch on so they aren’t being covered by the vegetation and are closer for us to see. While I was re-sighting from the blind, I spotted a tern that hasn’t been re-sighted in 19 years! I also found one with an orange band. This means that it was banded all the way in Argentina, which I thought was pretty cool.

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An example of a BBL band that can be found on the leg of a Common Tern. As you can see they are very small, which makes them difficult to read.

Now that the owl is gone, we are starting to see more birds come back to the colony. Many of them left during the time he was here and abandoned their nests. Thankfully now they’re starting to scrape the ground and re-nest. Chick age distribution around the island will surely be scattered, but at least they’re not giving up!

Now that I’m back on the island, there’s a lot more chicks running around and much more work to do!

-Amanda

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So far around the island we’ve come across Common Eider, Mallard, Savannah Sparrow, and Spotted Sandpiper chicks. Although a little behind schedule, we were beyond happy to finally find our first Common Tern chicks! Soon we will start banding them and taking measurements. Hopefully we will start seeing more every day!

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Our first Common Tern chick!

Our terns have been acting different than normal. Rather than settling down to incubate, many of them appear to be much more active flying around and leaving the island. We grew suspicious that there might be an owl around. In order to make sure it doesn’t disturb our terns, we set up a total of 17 foothold traps covering all sections of the island. When we placed the traps, we put them in areas that seemed suitable for an owl to land. If the owl lands on the platform that contains the trap, its leg will be caught. This trap doesn’t hurt the owl because it’s padded, but it allows us to capture it so it can be relocated. Though our minds were focused on an owl, we didn’t forget about our frequent Peregrine Falcon visitors. To prevent any unintended capture, we made sure to set off the traps during the day.

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The sign is lined with chicken wire at the top making the post with the trap the only suitable place to land

Only a few days after setting the traps, we caught the owl! Morgan and I noticed the terns were once again acting strange during our night stint, where we took shifts watching the colony between 6:00 PM and 12:00 AM. The next morning the terns were dive-bombing at the ground, and I could see through my binoculars that the trap wasn’t on the post anymore. It seemed unlikely that we caught an owl, especially since we weren’t completely sure we even had one, and last year it took over 2 weeks to catch it! We walked over expecting to find something like a gull caught up in our trap, but to our surprise it was a Great Horned Owl! We safely caught the owl, covering its head so it would stay calm, and removed him from the trap. It already had a band on its leg, so we suspect that it might be the same one from last year. The owl will be brought to a rehabilitation center to make sure it isn’t hurt, and it will be released somewhere far from our terns! We are so thankful we caught it in time, especially now that our eggs are hatching!

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Morgan about to cover the infamous Great Horned Owl with a blanket to keep him calm

 

Outside of bird research, we enjoy watching the Harbor Seals bask in the sun and swim around with their pups. The seals can be found on two adjacent islands. One pup decided to visit us on Ship this week. We were nervous when we didn’t see the mom around, but we were taught that after 3 weeks the pups begin to live on their own.

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Curious pup visiting our island

Ship has been very busy this week. We’re hoping to continue to wake up to new surprises every day, but only good ones!

-Amanda

 

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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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Petit Manan Island is well known for its seabird inhabitants, most notably our Atlantic Puffins and Arctic Terns. However, a total of eight species of marine birds return yearly to nest on Petit Manan Island. Most of these birds have conspicuous nests, such as the terns and Laughing Gulls which lay their eggs on the ground’s surface. The Alcids, such as Puffins, Black Guillemots, and Razorbills, lay their eggs in burrows or rock crevices, but the adults are still easily observed on the rocks and surrounding waters. But Leach’s Storm-Petrels, the smallest seabird denizen of Petit Manan, are a little bit trickier to detect.

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Jimmy holding an adult Leach’s Storm Petrel that was grubbed from a nearby burrow

Leach’s Storm-Petrels differ from the other seabirds on PMI in a variety of ways. Taxonomically, they are the only species representing a group of seabirds called the Tubenoses to be found on PMI. Also, they are nocturnal and nest in often long, twisting sod burrows.  The burrow entrances are smaller than the size of a fist, and tucked underneath rotting logs, debris and rocks. These life history traits make observing storm-petrels quite the challenge, and prevent accurate estimations of breeding pairs on nesting islands.

This summer we have been testing a new methodology to s
urvey for active storm-petrel burrows. Instead of just reaching as far into each burrow to feel for birds and eggs, we have been playing a recording of storm-petrel vocalizations outside of each potential burrow entrance. The results have been extremely exciting! The birds have been responding with their strange, goblin-giggling call from deep within their burrows. But more importantly, this method has allowed us to find more birds than just by feeling in the burrows. In fact, 63% of the storm-petrels we located only because we heard them – their burrows did not allow us to reach them. Overall, 93% of the adults we located using both methods responded to playback. Hopefully this monitoring technique will provide new insights into Leach’s Storm Petrels nesting on Maine coastal islands!

-Jill

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