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Posts Tagged ‘Common Tern’

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(A few of our first of hopefully many eggs on Ship!)

Hi folks!

Bobby from Ship Island here, as the cleverly constructed title suggests, we have eggs here on the island! A total of 13 eggs in 12 nests, which gives us hope that the birds are willing to nest for the breeding season on the island. Whenever Colin or I find a nest with an egg, we turn the egg to stand up, that way when we check the egg later on we can tell if it has been incubated (the egg falls back on its side from the tern sitting on it) or if it has not (egg is still standing up).  However, the number of terns that have been showing up since the last blog post has not been ideal. We have not seen more than 50 terns at once on the island for the past week and a half, at this time last year for contrast, there were 519 breeding pairs. It has become crunch time as we are using our final method to attract the terns back, creating our own tern colony.

This is done with two simple props, audio of a tern colony through multiple speakers, and using wooden decoys of terns (bird manikins essentially). These both simulate that a real colony is on the island and that it is safe to nest for the breeding season. Although it reminds me of The Truman Show in some ways, this method is the best bet to have the terns stay and nest immediately to allow them to be raising young in time for their migrations later in the summer. To paraphrase Princess Leia from Star Wars, the tern decoys may be our “only hope left”, but Colin and I are waiting confidently for our feathered friends to return. Don’t stop believin’ in Ship Island!

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(Terns and the decoys, can you spot the difference?)

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Good evening everyone!

Nesting is well under way here on Metinic. While all the terns are pairing up, it is possible to see a few that are trying to be the envy of the whole colony. How you might ask? Well they flaunt some forage fish of course!

I enjoy watching as a tern will bring a fish onto the point and move all over the place, showing it off to as many other terns as possible. They really know how to make their neighbors jealous!

Forage fish are the main food source for terns. What are forage fish exactly? Well they are species crucial to the connection of the marine food web. Sometimes referred to as “Wasp-waist” species, these fish connect the abundance of zooplankton and phytoplankton in the ocean to the abundance larger predatory fish. Basically forage fish eat the small stuff (zooplankton and phytoplankton) and then larger fish (and seabirds) eat the forage fish. Without forage fish, there would be a large gap in the marine food web.

Monitoring forage fish species that the terns are bringing to their chicks will be crucial once they hatch. A few years back, there was a low abundance of Atlantic Herring (their favorite food), and instead a large abundance of Butterfish. The only problem was that the tern chicks were not capable of swallowing the Butterfish. Despite the large abundance of fish, sadly many tern chicks starved that year.

In recent years, especially in Maine, forage fish abundance has been a widespread issue. Outside of the seabird world, Atlantic Herring and other forage fish are used by people in various ways. However, the most common use for these fish is as bait, especially for Lobster. Many Lobstermen will tell you that while there are other baits that work, Atlantic Herring works the best as lobster bait. That has created a competition between Lobstermen and the seabirds for herring.

There are several papers that have been posted on the important role that forage fish play in seabird producivity. However, one paper has rung true for many seabird species across the globe. The motto of that paper is “One third for the birds”. Basically, one-third of the maximum prey (forage fish) biomass should be saved for the birds to consume. Increases in human uses of forage fish has made this a complicated situation. If you would like to read the paper for yourself here is the link: https://archimer.ifremer.fr/doc/00056/16770/14307.pdf

With all that being said, fish are key to seabird survival! Therefore we need to monitor which species the terns are bringing back to their chicks. (There is a whole other rabbit hole to go down about how we can use seabirds as indicators for the health of fisheries but I’ll save that for another time).

By the way, I have marked a total of 25 eggs so far, with 6 nests identified as Arctic Terns and 5 as Common Terns (one of which has 2 eggs!). I am hoping to have the rest of the nests marked by species in the next few days.

All the best,

Mary

(Photo below: Common Tern with Hake)

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(Photo below: Common Tern with Hake)

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Hello everyone!

It’s Mary again. I am excited to announce that we have been seeing more and more eggs! Today I found the most eggs we have seen yet: a total of 10 new eggs!

While walking around I have also seen many scrapes. It is interesting to find an egg laid next to an old Popsicle stick, because that means there were eggs in that same spot last year. I am curious if it is the same birds laying in the same spot, or if it is two separate birds that had the same idea of a good laying spot.

Another exciting announcement is that I saw my first tern sitting on her egg. Finally I was able to mark an egg with a flag to begin working on the species ratio. This egg was marked with a blue flag, as it was a Common Tern sitting on this egg. If it is an Arctic Tern sitting on the egg, then we mark it with an orange flag.

We have had a relatively constant number of terns on the island the last few days – our estimates are around 550 to 650 terns (they are really tough to count). We still only have Common and Arctic Terns but we are hoping to see a few Roseate Terns!

We finally had some sun today, which meant it was laundry day for me! If you are curious how I wash my clothes with no running water, an old refrigerator drawer and a 5-gallon bucket, let me know! I am happy to post about what it is like living on the island and accomplishing little tasks like laundry, showers and dishes.

Check in soon to hear how many more eggs we find!

Best,

Mary

(Photo below: Common Tern sitting on her egg)

IMG_4402 (Photo Below: Ever wonder how small a tern egg is? Check out this gorgeous little egg!)

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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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This week, we banded our first adult Common Terns, set up our first productivity plots, have our first Spotted Sandpiper chicks, and saw our first Common Eider creche.

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We have been busy trapping and banding terns. So far, we have trapped 9 adult terns with 2 recaptures. One banded as a chick on Petit Manan Island in 2009 and the other banded in Buenos Aires, Argentina!

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Productivity plots are used to monitor chick productivity. Each plot includes 8-10 nests and is monitored daily until chicks hatch. Once all chicks in the plot have hatched, they are banded and weighed every-other day.

Earlier this week, we conducted the Golf of Maine Seabird Working Group (GOMSWG) survey here on Ship Island. We found a total of 498 Common Tern nests, a few even had 4 eggs!

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We cannot wait for our chicks to start hatching!

Your 2018 Ship Island Crew

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We found our first Common Tern nest, and couldn’t be more excited! Since finding our first nest, we have marked over 50 nests and have been monitoring them daily for signs of predation. We have taken note of close to 100 nests in our little colony, while keeping a close eye on any signs of unusual activity that could result in predation. We have been observing more and more terns visiting the colony and spending the night with us.

Yesterday, we headed over to Trumpet Island with refuge staff to conduct a census. While on the island, we walked 3m apart and counted all gull (Great Black-backed and Herring) and Common Eider clutches observed. Not only did we census Trumpet, we also got to observe a Great Black-backed Gull chick hatching!

Although the gull chicks were adorable, we cannot wait for our tern chicks to start hatching!

Your 2018 Ship Island Crew!                                                                                                                 ~Olivia and Bailey

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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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