Research and More on an Island in the Gulf of Maine
By Justin Stilwell
Pre-Veterinary Medicine '12
Before I tell you about the Shoals Marine Laboratory and my experiences there, I want to paint you a picture of the ecological marvel that is the Isles of Shoals. The Isles of Shoals, an archipelago in the Gulf of Maine, consists of 9 islands split between New Hampshire and Maine. In New Hampshire, White and Seavey Islands are home to a Common Tern breeding colony, the successful result of the Tern Restoration Project. If you’ve been to Portsmouth Harbor during the summer, you may have seen these beautiful birds clicking loudly and plunging into the water for small fish to bring back to their hungry chicks. Lunging Island is the site for a breeding colony of Double-Crested Cormorants, those excellent divers with their stunning blue eyes. In Maine, Smuttynose and Malaga Islands are home to a breeding colony of predominantly Great Black-backed Gulls, the ocean scavenger regularly found chasing lobster and commercial fishing boats miles offshore. Appledore Island, where the Shoals Marine Laboratory campus is located, is also the home for a mixed-species breeding colony of Herring Gulls and Great Black-backed Gulls with over 1,000 pairs of nesting Herring Gulls. Appledore and Smuttynose Islands are also the southern-most breeding site for the Black Guillemot, a small, black seabird with splendid red feet and red gape that is one of my research mentor’s favorites. Many other birds also breed at the islands including Common Eiders, Mallard Ducks, Barn Swallows, Tree Swallows, etc. Hundreds of songbirds pass through the islands as they migrate to and from their summer breeding grounds including various Warblers, Flycatchers, Sparrows, etc. There are several different species of Sandpipers and Plovers that can be found picking through the intertidal, searching for food. Going just offshore, you may see a variety of other seabirds like the Wilson’s Storm Petrels dancing on the water’s surface, the Greater and Sooty Shearwaters gliding in and out of the waves, or my personal favorite, the Northern Gannet flying high above the surface and plunge diving from 80 feet in the air to catch fish. Several different species of herons and egrets have also been seen frequenting the islands.
The isles are certainly a birder’s delight, but it’s not all the islands offer. Duck Island is the home for a colony of Gray and Harbor Seals. It is one thing to see them at the aquarium performing tricks, but to see them out in the wild, circling your boat, poking their heads out of the water, curiously investigating you before disappearing beneath the surface once more, that’s something stays with you. Although I will admit, getting a kiss from a seal at the aquarium is also very exciting!
The intertidal zone found on the islands is similar to that found along the coast with the rockweeds, barnacles, mussels, starfish, periwinkles, and dog whelks, but going beneath the surface is like entering a whole other world. The granite slab gives way to sandy bottom where lobsters abound. The remains of an old Navy pier provide a boon of life from lobsters, urchins, and crabs to cunner, pollock and flounder. It is truly one of my favorite places to dive. The various macroalgaes, tunicates, and anemones paint an artistic masterpiece unlike anything I had ever seen before. Words just cannot do the natural beauty of the Isles of Shoals justice so I encourage you to see them for yourself.
For me, my first experience with the Shoals came before I even reached the UNH campus. Coming into my first year, I took part in the Marine Immersion course held for incoming UNH freshmen. The course was taught by Dr. Jessica Bolker, Dr. Aaron Freeman, and Ph. D candidate Jason Goldstein and served as an introduction to college level biology. The one thing I will always remember was how I felt when I first stepped on the island, it completely blew me away; it had me at hello. It was everything I had imagined studying marine biology would be. While I’m a Pre-Veterinary Medicine major, I’ve always been fascinated by the ocean and trying to combine the two led me to UNH and Shoals in the first place. As part of the course, I not only established the work ethic and organization necessary to succeed in college, but I was able to meet other incoming freshmen and network with my professors and guest lecturers. It also served as an excellent introduction to field research as we were assigned different projects to study. My group and I surveyed crab species in the intertidal zone and looked for differences between sites exposed to and protected from wave action. It was a short, but invaluable week that got me hooked and wanting more.
My second Shoals experience came the very next summer and lasted from the end of May through to the middle of August. I took a total of 5 courses for 16 credits, which included Field Ornithology, Anatomy and Function of Marine Vertebrates, Forensic Science for Wildlife Biologists, Biology of the Lobster, and Underwater Research. Every course was absolutely spectacular with excellent faculty and hands on experiences unique to Shoals. To me, the best part about these courses was that you learned about something then you’d go out and see it for yourself. Whether it was banding a songbird or performing a necropsy on a cetacean, I felt immersed in whatever I was learning about. Whatever I was studying became my life for one or two weeks, going all day and into the night. It’s one thing to learn about something from a textbook in a classroom back on campus. It’s another to learn from professors who are passionate about what they study and then take that knowledge right out the door, out into the field and experience it for yourself.
Another great aspect of the courses was that many of them included some form of a research project. For Field Ornithology, I looked at the predation of gulls on intertidal crabs. Although it is known that gulls play an integral role as a top predator in the intertidal, the gulls seemed to prefer the lobster boats and did very little foraging in the intertidal. Even though it didn’t turn out as I would’ve liked, the project served as a good learning experience for the realities and limits of field research. For Anatomy & Function of Marine Vertebrates, I did a research project on the strength of bones in the wing bones of Great Black-backed Gulls. I found that the carpometacarpus, the bone that supports the primary feathers, was the strongest bone in the wing, significantly stronger than both the Ulna and Humerus. For both projects, I gave an oral presentation at symposiums for each class. In Forensics for Wildlife Biologists, I led a team responding to a mock crime scene involving two seals. We would later testify in a mock trial as to our findings from processing and investigating the scene. For Biology of the Lobster, we conducted an experiment on feeding by free-floating larval lobsters. For Underwater Research, I collected preliminary data for a project looking at the spatial distribution of sand dollars and their relation to lobster burrows and wrote a grant proposal for it. I’d have the say between the learning experiences I had and the faculty, staff, and fellow students I met, it was one of the most incredible summers of my life.
The classes themselves were nothing short of amazing, but you might be wondering why I took so many different courses. One of the reasons why I took so many classes was the advanced level background knowledge it gave me. I believe that knowledge has given me an edge when applying for internships and made me a more desirable candidate. I’m currently interning at the New England Aquarium’s Medical Center in Boston. Another reason was the people I met and the networking I did opened so many doors for me. For example, while taking the Forensics class, I met Dr. Inga Sidor, a veterinary pathologist at the New Hampshire Veterinary Diagnostic Lab here on campus. Since then, she has written several letters of recommendation for me and last spring, I did an Investigations (ANSC 795) class with her on Marine Mammal Strandings where I trimmed tissue samples from marine mammals for histopathology and participated in discussions on marine mammal disease. One of the main reasons why I returned to conduct research at the Shoals was to work with one of my professors from that summer.
The Gulls of Appledore
I would like to give you some background on the life cycle of my study subject before I go into talking about my research. Herring Gulls are one of the largest species of gull in the world. They come to Appledore every year in late April or early May to establish nesting territories in dense breeding colonies. They nest primarily out on the rocky shore above the tide. They have a normal clutch size of 3 eggs and incubate them for 4 weeks until the eggs hatch. For the first few days after hatching, the chicks stay in the nest, but begin to wander by Day 5. Considerable inter and intraspecific predation occurs during this stage of development as chicks sometimes wander into the territory of a neighboring gull and may be attacked and killed if the parent doesn’t intervene. The chicks grow over the course of about 7-8 weeks to adult size, losing their downy feathers in place of their juvenile flight feathers. After learning how to fly, the juvenile gulls begin taking day trips away from the nest in a process known as fledging. After 1-2 weeks of these trips, the juvenile gulls fledge and don’t return to the nest for the rest of the season. They spend the next 3-5 years learning effective foraging techniques and other skills necessary to be reproductively successful. As a result, the gulls experience delayed breeding and typically don’t return to the island to breed until their 5th summer. They do sometimes return to the island to prospect for potential breeding territories the summer before their first attempt to breed.
This past summer I returned to the island to conduct research with one of my professors from the previous summer. The Shoals Marine Lab funds a 7 week program called RIFS (Research Internships in Field Sciences) that allows undergraduates to conduct field research under the supervision of a research mentor. My research mentors were Dr. David Bonter from the Lab of Ornithology at Cornell University, who also teaches the Field Ornithology course, and Dr. Julie Ellis of the Cummings School of Veterinary Medicine at Tuft’s University. My study looked at the reproductive success of Herring Gulls in terms of age of parents, nesting habitat, chick survival and growth rates.
I headed out to the island the day after finals ended to begin helping on another RIFS study looking at extra-pair-paternity, what we would consider cheating on your mate, in Great Black-Backed Gulls. For the first week, we captured breeding pairs of adult gulls, took size measurements, banded them, and took blood samples for DNA. The intern would collect blood samples from each of the chicks as they hatched throughout the season, monitor their reproductive success, and is currently back at Cornell working in the lab to analyze the samples.
For my study, I worked with Christine Wilkinson, a senior Natural Resources major from Cornell University. Together, we monitored 118 nests daily over the course of the summer. Initially, we took certain measurements on each nest, on the eggs, and determined whether either parent was a Sub-Adult bird (i.e. a first time breeder). Sub-Adults were identified by signs of juvenile plumage (feathers) on the tail, wings, beak, breast, or head and are considered first time breeders. I was responsible for monitoring 59 Sub-Adult nests while she monitored 59 Adult nests. Each day, I would walk around the island and record the contents of each nest. As the chicks hatched, we would measure them on Days 1, 3, 5, 7, and 9 to look at differences in growth rates. After Day 9, I would continue to monitor the nest until it had either failed or fledged its chicks. We also developed a protocol for assessing habitat and its potential role in nest site selection.
As it turns out, pairs with a younger parent aren’t as experienced or as reproductively successful as mature pairs. Adults laid more eggs, were more likely to have their eggs hatch and hatch earlier, and were more likely to have their chicks survive than those from Sub-Adult nests. The chicks had several sources of mortality including interspecific predation, weather, starvation, and, oddly enough, possibly ants. Nests in areas with shrubs sometimes became overrun with ants as they were seen swarming both adults and chicks. The chicks appeared immobilized by the ants and likely starved as a result.
At the end of the 7 weeks, we presented on our research to the island populace and several other guests. Instead of leaving though, I stayed on to help with several other projects.
RIFS 2010: On the Side
Throughout my internship, I worked on several other projects while out on the island. One of my favorite parts of this experience was all of the hands on work I got with the gulls and other birds, particularly when it came to banding, or “gull wrangling” as its been called. I helped capture incubating adult gulls and chicks getting ready to fledge, collected blood samples for a DNA archive, and banded them. Banding birds is important for a multitude of long-term studies. By banding a bird as a chick, one could look at migratory patterns, identify individual birds in the population of a known age, track lifetime reproductive success and many other things over the lifetime of the bird.
Barn Swallows, beautiful passerines with a distinctive forked tail, nest under the buildings on Appledore and Star Islands. They lay a maximum clutch size of 6 eggs and typically nest twice a summer. I was responsible for monitoring their reproductive success on both islands and banding those we captured in mist nets on Appledore. I banded over 50 Barn Swallow chicks and several adults during the summer and all the chicks fledged so hopefully some will be recaptured next year.
To determine what species of fish the gulls were eating, I collected fish otoliths from prey remains around Great-Black-backed Gull nests. Otoliths are structures of the inner ear in fish that are species specific for the fish. I was able to collect and identify about 200 samples collected from Appledore and Smuttynose islands down to at least their family. What I found was that a majority of the otoliths had come from two families of fish, which are found at over 200 meters deep; the diving capacity of a gull is less than one meter. The most likely scenario is that these gulls could be getting bycatch from commercial fisheries or used bait from lobster boats. I will be heading to Woods Hole in the near future to have an expert confirm the IDs of the otoliths.
I collected and processed fecal samples from Herring Gulls as part of Dr. Ellis’s ongoing research looking at the transmission of antibiotic resistant bacteria between birds in the breeding colonies. The Herring Gulls are commonly found at landfills and wastewater treatment plants, where they may pick up and transport human bacteria. This work has potential public health implications as they may be introducing these bacteria to the marine environment, an invaluable recreational and commercial resource.
To track prospecting behaviors, I conducted surveys of all the rooftops around the island every evening. Prospecting happens when the gulls return to search for potential nesting territories for the next year. Gulls that are prospecting are quickly attacked when trying to enter the breeding colony. Therefore, they require neutral ground to watch from such as the intertidal zone and the roofs of the buildings. For each roof, I would spend 5 minutes noting the number of gulls in terms of species and age and the numbers of any banded gulls. The number of potentially prospecting birds seemed to peak just after the peak hatching time for chicks. Gulls may use the presence of chicks as an indicator for a potential nesting site for the next year if they try to breed.
After the first 7 weeks ended I stayed on to continue to track prospecting behaviors, collect otoliths, collect habitat data on our nests, and help out Joe Simonis, a graduate student from Cornell, who’s research looks at the mechanisms for transport of organisms between the tidal pools of the supratidal zone and their affects on the pools’ food webs. The gulls frequently visit these pools because they are utilized as a source of drinking and bathing water. He wanted to know if the gulls could transport organisms between pools by seeing if they carried any organisms on their legs after visiting a pool. We captured gulls that had recently been in pools, “dunked” them in a tub of water for a set amount of time, and filtered out the water to collect the sample. In the end, he was able to identify every taxa from the tide pools in his samples from the gulls.
As you can see, the Shoals Marine Lab has given me the opportunity to do so many great things from classes to research. As for what comes next, I will be wrapping up research I did this summer and presenting on it in November at Cornell University. In the future, I hope to come back to the island to help Dr. Ellis continue banding gulls and possibly conduct more research.
As I recall the memories I have of the Shoals, I realize that words really can’t describe how much my time there has meant to me. The Shoals Marine Lab has truly given me the experience of a lifetime, learning so many new things and making many spectacular friends. I remember long nights working on presentations and papers, exploring the island with friends, visiting the Shoe Tree and the Cave, playing volleyball or soccer and jumping off the dock after. I remember my professors, my mentors, the staff and the students and how wonderful they all were. I worked very hard during my time there, but I remember stopping to watch the magnificent sunsets. They were an artist’s delight, each one more beautiful than the last; the best I’ve ever seen.
Lastly, I encourage you to go and experience it for yourself. The Shoals are truly an ecological wonder and magnificent place to study everything, not just marine biology. The Shoals Marine Lab has something for everyone from archeologists and engineers to artists and writers. It has courses for people of all ages from high school and college students to adult and family education. For me, it was worth every penny, I cherished every second of it, and I can’t wait to get back out there. I think Jacques Cousteau said it best when he said, “The sea, once it casts its spell, holds one in its net of wonder forever.”