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Posts Tagged ‘Gulls’

It’s time to find out just what our gulls have been up to since we attached GPS tags.  In our first round of tagging, we sent out five tags on five separate Herring Gulls.  The tags we used are useful because they are lightweight, but they don’t transmit the data directly to us. Instead, we have to catch our gulls again.

We started by watching the nest. Both gull parents will help incubate the eggs, trading off throughout the day. The gull not on the nest generally heads out to forage for food. However, we only tagged one gull from each nest, so it’s important that we only set the trap up when the right gull of the pair is taking his or her turn at incubation. Thankfully, the GPS tags are easy to see from a distance.

Once we know the right gull is in the area, we set the gull trap up, just like before. We were hoping they wouldn’t get trap shy and refuse the sit on their eggs when the trap was present. Luckily, our first tagged gull was caught less than an hour after we set up the trap!

Success!

Success! A Herring Gull in a box trap

The tags were removed by cutting off the small tuft of feathers to which they were taped. Don’t worry – birds regularly replaced their feathers, so the cut ones will fall out and be replaced with new ones.

After downloading the data from the tag, what we found was pretty cool: our first gull’s foraging trips were more than 15 miles long. She stuck to the mainland coast, mostly between St. George and Rockland. Her trips sometimes took her more than four hours!

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The foraging routes of our first recaptured gull

In the end, we recovered three of the first five tags we sent out, and none of the gulls followed the same paths. One gull went straight up to Warren, ME several times over a few days. That’s a round-trip distance of almost 40 miles. We think he might have been looking for spawning alewives.

Gull 4 Map

Our second gull made a beeline for Warren every time!

The third gull stayed local and barely left the waters around Metinic Island – it looks like she preferred feasting on the spawning polychaete sand worms just offshore.

Gull 3 must have found plenty to eat in her own backyard

Gull 3 must have found plenty to eat in her own backyard

We also lost two tags – the gulls managed to pull them off, so it looks like we need to come up with a new way to attach the tags. Our next step is to design a harness for the tags that the gulls can’t rip or tear. Hopefully we’ll have more news about our wandering gulls before the season is over.

Metinic also has plenty of terns and guillemots – expect to start hearing about them soon!

-Amy

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You’ve seen them on docks. You’ve seen them on dumpsters. They eat fish, french fries, and everything in between. But where do all these gulls come from? And where do they go once they’ve finished their lunch?

 Gulls can be found just about everywhere there’s water (and plenty of places where there isn’t). There are plenty of them around, and they’ve gained a reputation as garbage-eating pests.  But there’s way more to a gull than dumpster diving.

Some gulls, like this Great Black-backed Gull, are actually quite handsome! - Photo by Zak

Some gulls, like this Great Black-backed Gull, are actually quite handsome! – Photo by Zak

First of all, gulls are actually cousins of the terns we’re working so hard to protect out on these islands, and these cousins have a lot in common. Both terns and gulls prefer to nest in large colonies, and lay their eggs in nests on the ground. They’re both strong fliers, capable of traveling long distances over the ocean (although nothing quite tops the pole-to-pole migration of the Arctic Tern).  Males and females of both tern and gull species are almost identical (although males tend to be a little bigger) and both parents work together to raise their chicks.

So why have gulls done so well when terns are in trouble? It all comes down to food. Gulls are opportunistic – they’ll eat anything. Terns are picky eaters – they generally only eat fresh-caught food they pluck from the water themselves. Like a tern, gulls also love fish. But they’ll also eat mussels, urchins, crabs, and in recent years, human refuse. They’ve learned to follow fishing boats, flock to open dumpsters, or sometimes snatch food right out of people’s hands. So gulls have thrived on these new abundant food sources, while terns have been struggling.

A Herring Gull, Metinic's most common gull - Photo by Zak

A Herring Gull, Metinic’s most common gull – Photo by Zak

But we and the Refuge have been wondering, where exactly do Refuge Island gulls get their food? Does a gull here on Metinic fly all the way to the mainland for a meal? Or do they stay local and snack in the intertidal zone? This year is the pilot year of a study to answer those very questions with the help of GPS.

So, what’s the plan?

Step 1: Catch a gull.

The best way to do this is on the nest. The setup is simple enough: the gull sits on a string tied to a wooden prop. The prop separates into two pieces and the box falls down, capturing the gull. We replace the real eggs with wooden ones so they won’t accidentally get crushed. Sounds easy enough, right? Maybe not.

Some people call gulls rats with wings – and it’s not a total misnomer. Both rats and gulls are a lot smarter than many people think.  It took us several hours of trapping to catch our first Herring Gull.

Catch me if you can!

Catch me if you can! AKA, Gulls – 3, Biologist-0

Step 2: Attach a GPS Logger

These little boxes, called igotU tags, are programmed to take a GPS reading every 3 minutes for about 4 days. To attach one to a gull, we put it in a waterproof casing then tape it to the gull’s back feathers with extra strong tape. The tag is light enough that it won’t hinder the gull when it flies, and hopefully the tape will keep the gulls from preening the tag off.

igotU tag getting taped to a Herring Gull's back - Photo by Amy

igotU tag getting taped to a Herring Gull’s back – Photo by Amy

We also band the gull and take a few measurements to determine if it’s a male or female.

Zak checks a GPS tag

Zak checks a GPS tag on a Herring Gull

Step 3: Release the gull!

Amy releasing a tagged and banded Herring Gull - photo by Zak

Amy releasing a tagged and banded Herring Gull – photo by Zak

Step 4: Trap the gull again.

To get the data from the GPS loggers, we have to trap the gull again and remove the tag. Stay tuned for Part 2 to see what we find out!

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A GPS-tagged Herring Gull on its way – Photo by Zak

– Amy

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Hello from the 2013 Metinic Crew!

There will two of us on this amazing island this year.

I’m Amy, and I’m returning for my second summer with Maine Coastal Island National Wildlife Refuge. If you’re a long-term reader of this blog, you might remember my entries from Ship Island last year.  I’m a graduate of Colby College, and this is my third summer on seabird islands (2nd with the MCINWR).

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A Common Tern on Metinic Island – photo by Amy

Joining me on Metinic Island is Zak, a student at Michigan State University. This is Zak’s first time on a seabird island, but he’s had tons of other bird-y experiences, including work in China and Costa Rica. His most recent accomplishment is almost single-handedly meeting the all-time high species count for Metinic Island in under 3 weeks (more on that in future entries).

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Our house on Metinic under the stars – Photo by Zak

Also settling in for the summer are our reasons for being here:  terns, guillemots, eider, and gulls. It was a rough summer for the terns last year – bad weather and high levels of predation caused the colony to abandon the island before their eggs had hatched. Luckily, they’ve come back this year to give it another try! We’ve seen over 150 Common and Arctic Terns hanging out on the north point of Metinic.  We hope to see eggs sometime in the next two weeks – keep your fingers crossed for us and the birds!

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Arctic Terns investigating a nest scrape – photo by Amy

In the meantime, gulls, Spotted Sandpipers, and Common Eiders are already sitting on eggs, while Black Guillemots and Leach’s Storm Petrels have been examining and excavating burrows.

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A nest of Common Eider eggs – look at all that soft down! – Photo by Amy

We’ve just recovered from a stretch of rainy and windy weather, so expect more soon!

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A Herring Gull in the rain – Photo by Amy

– Amy

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Hello again from Ship Island! Jill and I have been off the island for about 4 days as part of a mid-season break provided for us by the refuge staff. Now that we’re back and catching up on our work, here’s the second part of  “Citizens of Ship Island”, as promised.

In my last post, I wrote about the songbirds that call Ship Island home during the summer. This time, it’s all about water birds of all kinds. While we have songbirds breeding right on the island, most of our seabirds and shorebirds are found on the three islands surround Ship: East Barge, West Barge, and Trumpet.

Take for example the Great Black-backed and Herring Gulls. Because both of these species of gulls will eat tern eggs and chicks, they aren’t permitted to breed on Ship itself. Both species, however, make (usually unwelcome) appearances on Ship and have nests on both the Barges and Trumpet. Great Black-backed Gulls are one of the biggest North American gulls, with a wing span of over 6 feet while Herring Gulls are a bit smaller. Check out the photo below for a comparison.

Great Black-backed Gull on the left, Herring Gull on the right

Also nesting on Trumpet are North America’s largest sea duck: the Common Eider. While the females may look like a standard brown duck, the males have flashy black and white plumage.

A handsome Common Eider male with two Common Terns on the beach of Ship Island

Most often we see these large ducks paddling around with their heads under the water before they dive down for mollusks and other invertebrates. As you can see, they are quite a bit bigger than a tern!

A male Common Eider on the left, a female on the right, and a Common Tern in the middle

Eiders are best known for the incredibly warm down they produce – the females actually line their nests with these soft feathers. Eider ducklings take to the water the same day they hatch. Females with ducklings will gather together to form crèches, made up of several females and their young, to help protect the ducklings from predators like gulls. Although eiders pose no threat to our terns, they find people a bit intimidating and so prefer to nest on Trumpet.

A female Common Eider and her ducklings

Out on West Barge, in addition to lots of Great Black-backed Gulls, we have a colony of Double-crested Cormorants. Like the eiders, the cormorants prefer to nest on human-free islands, but we see them every day in the waters around Ship.

West Barge’s Double-crested Cormorant colony

They also sometimes come to shore to gather seaweed for nesting materials, like the one flying off in the picture below. The colony on West Barge seems to be doing well – we’ve counted about 50 cormorants on the south side of the island.

A Double-crested Cormorant flies off with some nesting material.

Not all of the water birds find us so intimidating. We have several Mallards on and around Ship, including a female with her ducklings. We usually see this fluffy gang paddling around in a swampy depression in the middle of the island.

Female Mallard paddling with her ducklings. Photo taken by Jill


Finally, we have our beloved Spotted Sandpipers. The only shorebirds that nest on Ship Island, Spotted Sandpipers are easily identified by their “teetering” behavior: as they walk (or even when they stand), they bob their rumps up and down. The purpose of this behavior is still unknown, but it makes them easy to pick out of a crowd.

An adult Spotted Sandpiper on the shores of Ship Island

We have several pairs of these nesting on the island, and we recently spied our first chick running around on the beach. Compared to other young birds, Spotted Sandpiper chicks are quick and agile. This one was already practicing its teetering! Jill snagged a photo of him bobbing his way down the beach.

A Spotted Sandpiper chick out for a run on the beach

Next time, the terns will be back in the spotlight with fuzzy chicks galore!

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