Feeds:
Posts
Comments

Posts Tagged ‘tern’

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!

IMG_2734.jpg

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

IMG_2660.jpg

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

Advertisements

Read Full Post »

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!

DSCN0099.JPG

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.

DSCN0098.JPG

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!

DSCN0096.JPG

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.

IMG_2322

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

 

Read Full Post »

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.

received_1208456342518222.jpeg

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.

IMG_3440

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.

IMG_4038.JPG

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

IMG_3921

 

Read Full Post »

Photo by Wayne MacCabe

Photo by Wayne MacCabe

This is the Captain, who lives on the walkway in front of the house. What makes him so special to us is he was rescued from freezing rain when he was still inside his egg. One rainy day the area where Captain’s nest was got flooded with collecting rain water. The whole nest and the three eggs inside it were completely submerged in the water and were floating around. The parent was hovering over the nest, unsure of what to do. After seeing this I quickly ran outside and scooped up the nest and re-located it to a nearby high-elevated area. Seconds later Captain’s mother was back on her nest. I was relieved to see this because terns can be sensitive to any slight change to their nest and can be spooked away if they feel something is wrong. Unfortunately, I still didn’t have high hopes for the chick’s survival. I didn’t know how long the eggs were floating in the cold water, they could have passed away from the cold temperatures or from the water sealing up the pores on the egg which lets the chicks breath oxygen from the air. But, to my surprise about a week later Captain hatched and soon after so did his brother, Sailor. I named the chicks this because the nest was floating around like a ship at sea. Now, both Captain and Sailor are fledging!

We have over 2,000 chicks on the island and just our presence here increases the survival rate for these chicks. This is because we deter predators like greater black back gulls, peregrine falcons, herring gulls, and more which will make a quick meal out of the fledging terns and chicks. Realistically, we can not 100 percent stop predation from these species, but we work hard to keep fatality numbers low. Without us working here on the island these birds would likely take over and would have a devastating blow to the tern population. It made me so happy to see that Captain had made it but I noticed I gained a lot more than just satisfaction from seeing him survive, I gained a new understanding of my time here on the island. This event encouraged me because it really showed how my time and work on the island present on the island.

-Laura Bollert

Read Full Post »

Greetings from Ship Island! As one of the researchers normally stationed on Petit Manan Island, I had the privilege of island-sitting Ship island for just over a week while the regular crew had their break and visited Petit Manan. Visiting other islands gives us new insights into seabird biology as each colony behaves in their own way slightly different from all the rest. Plus, who wouldn’t want to check out the Puffins?! In 2013 I spent the summer here, so when I stepped out onto the warm, sandy shore, it was a bit like visiting an old friend.

Lazy sunset on the beach.

Lazy sunset on the beach.

With me came Shelby, a young student just learning the ropes of being a biologist. We had a fun time learning what birds, plants, and insects live on the island. Every morning we went “birding” to conduct the morning bird count, learning where each bird family lived and what theirs songs sounded like.

Common Yellowthroat with a little morsel for his chicks.

Common Yellowthroat with a little morsel for his chicks.

Spotted Sandpiper

Spotted Sandpiper “defending” his nest as we attempt to find it.

During our time here the chicks started hatching en masse, so Shelby also got to band quite a few birds! Banding is a very delicate process so first we practiced in the house several times, but she did great.

Shelby banding one of her first chicks!

Shelby banding one of her first chicks!

We even got a bonus with this adult Tern I caught out of the air.

Adult Tern caught by hand!

Adult Tern caught by hand!

Tomorrow we go back to where we belong – me to Petit Manan, and Shelby to her home on the mainland. It has been a great week on Ship with beautiful weather and many laughs but we are ready for whatever’s next!

– Julia

Our favorite sandy-color chick.

Our favorite sandy-color chick.

Read Full Post »

Last week, John and I trapped and banded our first terns! We were thrilled to finally have the opportunity to see and work with these birds up close. But these amazing up close interactions did not come without a lot of hard work and preparation.  The process of trapping and banding is very detailed and a complete understanding is needed to keep the terns happy and healthy.

Before we could start banding, Julia and Wayne had us practice on dummy birds. These dummy birds were composed of cardboard toilet paper rolls for bodies, Q-tips for legs, and duct tape for heads. Julia and Wayne informed us of the methods of handling and banding terns when out in the field and with their help we simulated banding on our dummy birds by using old bands. After we felt comfortable with banding we learned how to collected measurements from our birds. When a tern is captured we recorded the weight, wing length, and head and bill length of the tern. We got to see and use all of the tools used to take these measurements.IMG_8528

In preparation for trapping, we laid out all of our equipment out on the lawn and checked to make sure all of the traps had all their components and were functional.  John and I spent some time getting used to setting up the traps and gripping the idea of the little quirks that makes the trapping process run a lot smoother.  Once we were quick and efficient with setting up out traps we were ready for the real deal!

Laura & Julia setting up their trap

Laura & Julia setting up their trap

Our first trapping day was nerve racking and exciting! We had to find a balance when trapping and banding our terns that would enable us to work fast but also be gentle and thoughtful when handing the terns. As much as we wanted to take our time and soak up all the beauty, we had to act quickly and efficiently when banding the terns to minimize the amount of stress placed on the birds. I felt uneasy going into my fist banding experience; this wasn’t like the dummy birds we practiced on, the terns move around a lot more than the dummies and one wrong pinch on the band could harm the tern. But to my surprise banding my fist bird came natural to me and it went smoothly. I got to trap and band many more terns that day and I hope to do some more in the next few days.

John and his tern

John and his tern

So far we have trapped 19 COTE (common terns) and 16 ARTE (arctic terns) our goal is to have a total of 20 COTE and 100 ARTE by next week! Trapping and banding terns is important because it shows sight fidelity and survival rates of juveniles and adults.

– Laura Bollert

Read Full Post »

We’re up to our elbows in chicks out on Metinic. In my last post, I mentioned that our tern chicks have started to hatch. A week later, our little fluffy friends are growing up fast.

Arctic Tern Chick

Arctic Tern Chick

We can often see our older chicks testing out their wings, although they are still a long way from being airborne.

An Arctic Tern chicks, stretching its wings

An Arctic Tern chicks, stretching its wings

Our resident Savannah Sparrows also have chicks of their own. These buzzy-sounding birds build a classic cup-shaped nest in grass on the ground. It can be easy to miss until you see the five squawking mouths.

A nest full of Savannah Sparrow chicks

A nest full of Savannah Sparrow chicks

Spotted Sandpipers are Metinic’s only nesting shorebird this year, and our first sandpiper chicks have made an appearance. Despite their small size and their resemblance to a cotton ball standing on a pair of toothpicks, these chicks are up and running around by day one. They do have a parent around to keep them out of trouble though!

Spotted Sandpiper adult (left) and chick (right)

Spotted Sandpiper adult (left) and chick (right)

Finally, we found our first Black Guillemot chicks. It’s hard not to love these little black puffballs. Guillemots are also the only alcid to lay two eggs at once, so guillemot chicks usually come in pairs.

Our first pair of Black Guillemot chicks

Our first pair of Black Guillemot chicks

Of course, Syd and I didn’t want to miss out on the fun of Guillemot Appreciation Day, so we celebrated in the most delicious way we could!

Our tasty guillemot cake

Our tasty guillemot cake

More updates as our chicks continue to grow!

 

-Amy

Read Full Post »

Older Posts »