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Archive for the ‘Ship Island 2020’ Category

We can finally say what we have been hoping for this entire summer: Ship Island has chicks!

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A freshly hatched chick and a pipping one!

We first spotted cracks in some eggshells on the 10th and two days later, we found our first hatched Common Terns! With the late season egg laying and colony abandonment, we were relieved to hear the small, raspy peeps from the nests.

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“Feed me!”

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A worried parent perched on my head while I banded their chicks

Ever since, we’ve been working non-stop. Already, there are over 70 chicks banded! We have productivity plots set up across the colony that we check every other day. Inside, we keep track off all the eggs in each nest and weigh the chicks every other day to monitor their growth. In just one week, chicks can weigh 6 times heavier than their hatch weight! We also begun provisioning watches to see what food is being brought to the nest, who is being fed, and who is feeding it to them. This data is important to help monitor the health of the colony and what prey species are available in the surrounding ocean.

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Comet NEOWISE

When we do have downtime, we have been fascinated by the night sky. As we are several miles from the nearest town, we have little light pollution. Across the northern hemisphere, you might be able to see comet NEOWISE in the northern sky. On the same day we saw our first chicks, Andy and I saw our first comet! The sky was completely clear giving us not only a great view of the spectacle, but also the Milky Way, Jupiter, and Saturn.

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The Milky Way, Jupiter (brightest “star”), and Saturn (to the left of Jupiter). Photo by Andy, lights by Percy

As the season continues, we hope to share more excited news with you all!

Percy

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While walking through Ship Island’s colony, I’m always fascinated by the variety of egg shapes and sizes we come across. Out of curiosity, I decided to measure and photograph some of these eggs to see how variable Common Tern eggs can be!

Eggs are developed rather quickly. After copulation, an egg can form and be laid in 24 hours! Typically, an egg can be added to the nest every 1 to 2 days. While most clutches contain 1-3 eggs, this season, we’ve found some with 4 to 5! The nest starts off as a simple scrape in the sand, gravel, or dirt. As parents spend more time around or in the nest, they’ll move twigs, vegetation, seaweed, and other objects around to create a proper nest that will keep their eggs inside.

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A Common Tern nest with 3 eggs

On average, Common Tern eggs are 42 mm long and 30 mm wide. As always, there are some eggs that do not meet these parameters. I found that lengths vary the most, ranging from 38 to 46 mm! Meanwhile, egg widths stay closer to the average, varying from 28 to 31 mm.

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These two differently sized eggs are from the same nest!

Tern eggs are subelliptical meaning they are elongated with tapered rounded ends. The widest point of the egg is off center. Like size, shape varies greatly! Some eggs have the widest point towards the middle, creating an oval shape. Others have the widest point so close to one end, the egg has a long narrow point, like a raindrop.

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A typical, subellipitcal egg

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Almost an oval-shaped egg

Sometimes, the most striking feature about the egg is its color and pattern. In just one clutch, the eggs can look wildly different. The colors can range from cream, tan, light brown, to dark brown. The shells are covered in small to large dark splotches and streaks. These markings can concentrate around the widest point, like a belt, or spread across the egg like freckles. The color and pattern is thought to help camouflage the eggs on the beach. However, we occasionally find some odd eggs that stand out. Some appear almost pure white with faint or no markings at all! Others are so dark brown that the markings are hard to distinguish.

Although Andy and I love finding these eggs, we’re hoping that they’ll be hatching soon! While there are some eggs which have been freshly laid, there are some which have survived abandonment and could be hatching any day. We look forward to welcoming the first chicks to Ship!

Percy

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While the other islands are expecting their first chicks any day, we watched as all of our terns left their eggs behind. We were hopeful this year! We had over 100 nests and over 200 eggs. Yet, once again, Ship Island has experienced a colony abandonment!

During the first week of June, we had found some predated terns, likely due to a Peregrine Falcon. Ship is located only a few miles from Mt. Desert Island where several pairs are known to nest. Our worst fears were confirmed when Andy and I both flushed the falcon on June 8. As the day went on, tern numbers decreased dramatically from 300 to 50. By the evening, they were all gone.

We weren’t just only concerned about Ship. Over on Trumpet Island, there were no gulls. A predator like a falcon wouldn’t cause the gull colony to abandon as well. We began to suspect an otter attack. Although the gulls eventually returned to the island, we visited the following day to look for predation signs. We were relieved to find nests and eggs intact. We even found some newly hatched Herring and Great Black-backed Gull chicks! However, we think we now know the likely culprit: an owl.

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We got right to work, setting up more traps and beginning all night stints. But, what do we do to encourage the terns to come back? Since terns nest in colonies, they won’t nest if there aren’t others terns around them. So, we have to trick them into thinking there are terns there already!

Currently, there are over 30 Common and Roseate Tern decoys around the nesting grounds. To complete the illusion of a lively tern colony, a solar-powered sound system has been set up. During the day and night, we play recordings of a colony on speakers.

Although we haven’t caught our owl yet, we think the decoys are working! Throughout the week, we’ve seen more terns returning and staying longer. Just today, I even witnessed courtship rituals and nest scraping! We’re doing our best to give them space to allow the colony to start back over.

Hopefully next week we’ll have some better news to share!

Percy

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