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Posts Tagged ‘Ship Island’

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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This past week on Ship has been very similar to what has been going on at Metinic and PMI. Most of our days have been pretty dreary. On these foggy and rainy days we spend our time reading (A+ to Morgan for reading 8 books so far), eating snacks, catching up on sleep, writing letters, drawing, and staying updated on what’s going on in the real world. It is relaxing, but we’re anxious to get back out there and get a closer look on how our terns our doing.

When it’s not too foggy out, we are able to sit outside and watch the colony. We don’t sit too close because we don’t want to surprise or scare them. We’ve been doing this frequently to deter the Peregrine Falcon who has been stopping by from the island.

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Sunset view while watching for predators

Before the bad weather, we spent most days attempting to re-sight bands, making productivity plots, and trapping adult terns to band, measure, and weigh. To trap the terns we use a Treadle Trap. We first need to replace the eggs with fake eggs. This prevents the tern from damaging their eggs once he/she is trapped. After this we place a wired box over the nest with one end open. When the bird steps through the opening onto the pad, the door will shut and the tern is unable to escape. We quickly retrieve the bird to collect our data, put back the original eggs, set him free, and repeat. It was pretty cool when I got to hold and release my first tern!

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One of our productivity plots

The results from our GOMSWG census indicated that we have about 620 nests in total. Hopefully we’ll start seeing some chicks soon!

-Amanda

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This weekend the Ship Island crew headed over to Pond Island to take part in a beach cleanup along the shore. Morgan and I, as well as several other volunteers, collected dozens of trash bags filled with lost buoys, cans, bottles, and more. This year is the first year the group will be able to actually recycle the plastic that was collected. Through the company, TerraCycle, our collection of plastics, no matter how dirty or broken they may seem, will be sent over to be thoroughly cleaned and re-purposed. Typically, most objects made out of recycled plastic only consist of about 30% reused material. Though it doesn’t seem like a lot, or maybe even not enough, if the concentration is increased then the new object becomes closer to the end of its lifespan and can no longer be reused. It was good to get off the island and spend some time with others working to keep our environment clean, but we’re glad to be back on Ship with our terns!

 

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Section of a boat that was found washed to shore. We needed all hands on deck to carry this one over!

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Beach Cleanup Volunteers

Back home on Ship, we’ve had problems with other birds predating on our Common Terns and their eggs. Currently, Great Black-backed Gulls, Herring Gulls, American Crows, Peregrine Falcons, and Northern Harriers are our main concerns. Almost every day we spend two hour shifts in the blinds to observe the tern behavior and keep an eye out for any of these predators that might pass by. During the evening we’ve been marking nests with predation sticks so we can notice if any eggs have gone missing. By doing this we are also able to get a good idea on how many terns we really have on the island. It doesn’t look like it, but so far we have counted over 500 nests, which means we have over 1000 terns! So far so good! In a few days we will be doing a GOMSWG census which will give us an even closer estimate on our tern population size. We’re excited to share the results with you next week!

-Amanda

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COTE gettin trapped

An unsuspecting common tern parent walks calmly into a trap to incubate a clutch of wooden dummy eggs.

As the summer starts to pick up so does the tern activity here on Ship. At the end of last week we had some visitors from the Student Conservation Association  come to help us put up new productivity plots before our island is overrun with new tern chicks. The productivity plots contain 6-11 nests of varying sizes in different areas throughout the colony. These are put up so that when the chicks hatch we will be able to monitor their growth for the rest of the season. As of today we have a total of 6 productivity plots!

 

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Adult common tern  in one of the productivity plots.

This week we’ve also been trapping adult terns for banding and or recapturing. This is done by swapping out the eggs in nest with fake wooden eggs (we don’t want a parent to accidentally break their own eggs). We then place a wire treadle trap over the nest and set the trap. To set the trap we stick a wire attached to the treadle into the sliding door. Then we go hide (usually in one of our blinds) so the terns don’t see us, but so we can also see the trap. You can tell if the terns can see you because they will give you dirty looks and yell a lot.  From there its a waiting game. Some trapping stints were more successful than others, just like some birds were more cooperative than others.

COTE release

After banding, the tern is released to resume tending its nest– now with the real eggs safely back in the nest bowl!

 

Wednesday was the Gulf of Maine Seabird Working Group (GOMSWG) census day and our friends from the Student Conservation Association came to assist us in that as well. It was a successful census and a gorgeous day to do it on. During the census we also had a visit from a peregrine that we’ve been seeing on a regular basis. It came earlier this week and hung out on the back of our island. The peregrine allowed us to get fairly close, which was when we noticed it was pretty badly injured. Even though peregrines are a predator of common terns we hope it is able to recover.

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The peregrine falcon (Falco peregrinus) is a listed as an endangered species in Maine.

Finally one of the most exciting things began to happen yesterday as were putting up our last productivity plot. Yes that’s right, you’ve probably guessed it, its what we’ve all been waiting for. WE HAVE TERN CHICKS!! Two chicks hatched while we were putting up the final plot yesterday. This morning during our nest checks we found four more healthy chicks that were fully fluffed out and we were even able to band them!

We hope to have even more babies running around our island within the next few days!

Till next week.

Kelby Leary @ Ship Island

 

 

 

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hoppin on

A banded common tern (Sterna hirundo) returns to the nest for incubation. This image was remote-triggered on a hidden camera, toward which the terns are very tolerant!

Common tern activity levels on Ship have made an about-face, going from mostly quiet to positively booming! For the past 10 days or so, the birds have been active virtually all day long, courting their partners and tending their nests. At the time of writing, well over 150 nests have been established on the island. Of 100 nests being monitored for early-season predation, only 4 have been lost– and 3 of the 4 were taken out by the highest tide of the month. If you’re more of a visual learner, check out the figure below; a legend is available by rolling your mouse over the chart. If you want, you can even click to zoom in on any of the images.

In simple terms: things are going well. Breeding savannah and song sparrows have begun to hatch, as have the common eiders, gulls, and double-crested cormorants on our neighboring islands. It should be a matter of days before our nesting spotted sandpiper fathers will escort their chicks to safe foraging, as well.

 

Between seal pups, tern eggs, and the numerous fuzzy chicks emerging all around us, we have plenty to observe at Ship. Later this week we hope to establish our productivity plots for the season and begin adult trapping efforts in order to band new birds recapture known individuals. Our projected first hatch date is June 19th, so knock on wood and stay posted for the big news in a couple of weeks!

fuzzy COEI peeps

A fuzzy creche of six common eider (Somateria molissima) chicks escorted by two hens! We hopefully theorize that the small number of adult birds escorting this creche is due to rampant nesting success of all the other eider hens out there on Trumpet and East Barge Islands.

As if all these babies weren’t enough, spring migration somehow persists on Ship. Our long-awaited Nelson’s sparrow (easily identified by its song, which sounds remarkably like a match being lit) has finally taken up residence on the island, along with an alder flycatcher that can be heard singing daily; the vocalization (a burry “fee-beeoh!”) of this bird is just about the only thing that sets it apart from its doppelganger, the willow flycatcher.

 

In birding parlance, focusing in on a single area to frequently document its species is known as “working a patch”, and that’s certainly what every Maine Coastal Islands seabird crew does. Because a daily birdwalk is part of our essential duties, we become very familiar with what species to expect on a daily basis and can quickly recognize oddities. In working our teensy patch called Ship Island, we have managed to document some 68 birds, including such bizarre wintertime lingerers as long-tailed duck, Bonaparte’s gull, and even a single black-legged kittiwake! And that isn’t even mentioning all of the freshly-molted warblers that continue to stream through in their alternate plumage.

That’s the news from Ship Island this week. Hopefully our industrious tern colony will continue to grow despite gloomy weather! In the meantime, we’ll be counting birds and huddling in the warmth of our tiny cabin when it gets too miserable out.

 

Bonus bird fact: did you know that the scientific name of the common eiderSomateria  molissima, literally translates to “very soft woolbody”? An apt name, considering how the seaducks are prized for their luscious down! And if you’ve ever had the pleasure of feeling an eider’s feathers, you’ll know this to be true.

 

Until next time!

Meredith Miles @ Ship Island

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