The Unsuspected Decline of the Herring Gulls

Kent Island has the densest population of gulls that I have ever seen in one place, and when we first pulled in to the Island on the Susannah Kent, they welcomed me with their enormous racket. The large number of gulls in the sky and the abundance of their nests gave me the initial impression that the population was thriving. One night after dinner, during one of the conversations of days past that follow a good meal, Nat Wheelwright, a former BSS Director, revealed that the Herring Gull population on the Island is actually in decline. He recalled that one visitor who hadn’t been to the Island for forty years asked, “Where are all the gulls?” when he arrived. Nat pointed out the quietness of the evening, saying that the clamor that is now largely confined to the shore and to the South End used to be inescapable everywhere.

The scientific record of the gulls supports these more qualitative measures of abundance. Alfred Gross, a Bowdoin ornithology professor, conducted a census of the gulls in 1940 that found 11,000 pairs nesting on the South End, and estimated at least 25,000 gulls on the Island during peak breeding season. Gross postulated that the colony was the largest on the Atlantic seaboard. His son, Bill Gross, the first Director of the Bowdoin Scientific Station, remarked that the gulls were under government protection because they were on the verge of extinction, but now were over-populating Maine and the Maritimes. Fishermen resented the gulls for stealing bait from boats, and on Kent Island, half-starved gulls were preying upon savannah sparrows, petrels, and eider chicks. In response to the over-population problem, the United States Biological Survey began making annual cruises along the Maine coast to destroy gull eggs by piercing them with a needle, rendering them infertile without the gulls being the wiser.

In a stark contrast to the earlier abundance of gulls, a 1983 study estimated only 5,000 nesting pairs on Kent Island, and references Herring Gull declines in New England and the Maritimes. A later census of the colony in 1989 found 1,441 nesting pairs, and high egg and chick mortality. Possible causes of the gulls’ low reproductive success included bad weather and visitation by local “eggers” who took between 50 and 100 eggs on several weekends, in violation of the Migratory Birds Convention and Act. There is a long tradition of egging in the Bay of Fundy, and even Niko Tinbergen, champion of the Herring Gulls and author of The Herring Gull’s World, proclaims gull eggs “an excellent food.” This practice has consequences beyond the obvious reduction in the number of eggs, because the disturbance increases the gulls’ nest abandonment and cannibalism, furthering the decline of the colony. While egging is a dying pastime on Grand Manan, a few eggers occasionally come to Hay Island and take from nests with one or two eggs. Gulls typically lay three eggs in succession and do not begin to incubate them until the third “insurance egg” is laid. Despite the lack of egging on Kent Island and the relative stability of the gull habitat, the population has probably decreased by an order of magnitude in the past fifty years. Damon told me that the most likely causes of the decline are the closing of landfills, and the collapse of the groundfish fishery, which used to produce large amounts of bycatch that the gulls fed on. The Herring Gulls that return to Kent Island to breed every summer are dispersed all over North America the rest of the year, and changes in their other habitats may also play a role in the decline.

My first impression of the abundant Herring Gull population on the Island is a good example of how baselines skew our perception of the world. I had never seen so many gulls in one place, and therefore assumed that the population was thriving, while gull censuses from scientific studies showed a decline over time. Long-term data is an extremely important part of environmental science, because otherwise policies may be based on a baseline that makes false assumptions about a population’s health. These misguided policies can have drastic consequences, as evidenced by the collapse of the groundfish fisheries.

Sources:

Gross, A.O. 1940. The migration of Kent Island Herring Gulls. Bird-Banding 11: 129-155. (BSS Contribution no. 7)

Cannell, P.F. and Maddox, G.D. 1983. Population Change in Three Species of Seabirds at Kent Island, New Brunswick. Journal of Field Ornithology 54 (1): 29-35.

Hébert, P.N. 1989. Decline of the Kent Island, New Brunswick, Herring Gull, Larus argentatus, colony. Canadian Field-Naturalist 103: 394-396.

W.A.O. Gross. 1936. Kent’s Island, Outpost of Science. The American Museum of Natural History. Natural History 37 (4): 195-210.

The Tide Pool

On Tuesday I ventured out to the South end of the Island with Drew, who was checking on his settlement plates in the large tide pool that is a favorite spot for swimming as well as for scientific research. The pool is near the tip of the Island, where the currents and the tides converge and create huge waves that come crashing against the rocks. While every field project is affected by the weather, Drew’s is especially at the mercy of the elements because he is attempting to study the effects of currents on “fouling communities,” organisms that settle on hard surfaces in the intertidal zone. Drew has lost two racks of settlement plates to normal wave action, and lost three more in the storm that reached Kent Island during Hurricane Arthur, which brought 60 mph winds and turbulent seas. Drew has to check on the plates he has placed in high current areas frequently to do maintenance work, and has no idea what condition his plates will be in, or whether they will be there at all.

Getting to the tide pool is an adventure in itself, because it involves crossing deep into gull territory, and then clambering over the forest of slippery rockweed that is exposed on the bedrock at low tide. Drew managed the journey with all of his equipment in tow, while I, struggling to keep up, followed behind him almost all the way to the edge of the sea. In the early morning, these rocks are a prime spot for watching migrating Minky Whales and harbor porpoise when there is less glare off of the water. I have also seen puffins and razorbills in the distance, birds that are in the same auk family as the Black Guillemots that Ben studies, and share the Guillemots’ black and white coloring and red feet.

The fauna in the tide pool are less obvious, but equally fascinating. The water is dark turquoise with a cobbled bottom, and the walls are wreathed in Laminaria digitata kelp around the edges. Digitata are so named because their brown, palm-shaped fronds look like fingers, which, like rockweed, provides habitat for a variety of organisms, including the fouling communities that Drew is studying. In the shallows of the pool I saw pink and yellow sponges, delicate anemones, large and small periwinkles, a swirling neudobronch, and a tiny sea star. Deeper in the pool, benthic fish swim silently, grazing the ocean floor.

Drew’s settlement plates float in the center of the pool, and the device is anchored to submerged aquaculture cage on one end and the huge iron wreck of a salmon weir that is moored on the rocks. He created a clothesline system that allows him to pull on the rope to check the plates for growth and to photograph them without having to enter the pool every time. One of the ropes had snapped in the storm, so Drew donned his snorkeling mask and wetsuit, complete with a hood, booties, flippers, and a knife strapped to his calf. He is an experienced scuba diver, and expertly entered the water and dove down into the dark center of the pool. He asked me to stand by the edge and watch the tide, which was outgoing, but the powerful surf crashed against the nearby rocks. Hannah Baggs, another Bowdoin student, filmed the process for an educational video about Kent Island ecosystems that she is making for Maine biology classrooms.

Drew diving to fix his plates in the tide pool

Drew diving to fix his plates in the tide pool

“Wow, it’s a mess,” was the first thing that Drew said when he surfaced. His plates were thankfully still in the pool, but the snapped line had tangled on itself in the turbulent water. For half an hour he unsnarled the lines with his knife, and Hannah and I helped him to retie the clothesline system while he was in the water. While the tide pool may look like a swimming pool, its temperature is in the high 40s. On a day off I had jumped off the rocks into the water in my bathing suit, and was completely numb after a few minutes. When I asked Drew whether he was cold, he said “It’s pretty comfortable with my wetsuit, and I can probably swim for an hour or so without getting cold.” A wetsuit is another item of clothing that I wish I had packed, because it would be great to explore the intertidal ecosystem more thoroughly.

drew_scuba

After re-attaching and photographing his plates, which were vacant of fouling communities, Drew conducted some plot surveys of the smaller tide pools in the area. He used Christine’s quadrant, a square wooden frame, and surveyed the organisms floating underneath it and those attached to rocks and algae. Unlike Christine, who counts all of the organisms that she is looking for, Drew’s quick and dirty method records the presence or absence of the fouling community organisms that he is studying. The plot surveys will give him an idea of the biodiversity of fouling communities that are present on the Island, and will serve as a point of comparison for those that may grow on his plates. If nothing grows on his plates by some function of his experimental design, the surveys can serve as a backup plan that will give him positive results. He hasn’t given up hope yet that fouling communities will grow on his plates, however, and is lucky enough to be able to return to Kent Island in September to check for bryozoans, sea squirts, tunicates, and other organisms on his list.

Life in the Herring Gulls’ World

The Herring Gulls’ World, a small, turquoise volume in the Kent Island library, is popular reading among scientists and artists alike. It is a record of thorough, observational fieldwork that provides insights into an organism that is a defining element of the Kent Island experience. Herring Gulls are by far the most visible birds on Kent Island. The Jacks-of-all-trades of sea birds, they can walk, fly and swim equally well, and are scavengers as well as hunters. The large Herring Gull colony on Kent Island, which returns every summer to breed, is an obvious study subject. The Herring Gull’s World references early BSS scientist Alfred Gross’s work with the birds several times. Gross and his team banded an impressive 1,030 Herring Gulls on Kent Island from 1937-1939, and he terms the process “the sport of bird banding” in one of his Station Reports. Niko Tinbergen, the author of The Herring Gull’s World who later won the Nobel Prize in physiology,  began studying the gulls in the Netherlands around the same time as Gross. He observed and experimented on them for twenty years, to discover what he terms the “mysteries of gull sociality.” He approaches understanding gull behavior by pursuing two questions: what are the causes of the behavior, and how does the behavior help the animal maintain itself or its offspring. His style, however, is more entertaining than this formulaic approach would suggest, and his commentary on the gulls’ behavior is often hilarious.

Pages from "The Herring Gull's  World" (image:https://seanetters.wordpress.com/page/9/)

Pages from “The Herring Gull’s World”
(image:https://seanetters.wordpress.com/page/9/)

An illustrative example that proves that the book is very much a product of the 1960s:

“the initiative in-love-making is usually taken by the female, not the male, a very shocking fact to most of my friends when I mention it to them—as I like to do in order to watch their reaction.”

I was initially skeptical of Tinbergen’s more qualitative observations of the gulls when I came across the statement, “the voice of the Herring Gull is wonderfully melodious.” Anyone who has heard the screeching, squawking, and barking noises that the gulls make can attest that their calls are distinctive, but certainly nowhere near “melodious.” The sounds that Herring Gulls make are also extremely difficult to translate phonetically: “Kew” does not capture their piercing cry, and “hahaha,” Tinbergen’s word for their alarm call, is in reality somewhere between a chuckle and a honk. Tinbergen’s descriptions of the characteristics of different calls and their contexts were useful, however, because they helped me to put my piecemeal observation in context.

For example, when an intruder enters an incubating gull’s territory, the gull will either let out a low, barely audible alarm (hehehe) or a louder one (hahaha), depending on how close the threat is to the nest. The alarmed gull readies its wings for flight, and will abandon its nest and leave the camouflaged eggs unguarded if the threat is too powerful. At the sound of the alarm, chicks will instinctively crouch and run away to hiding places. The gulls will sometimes “charge,” circling overhead and diving right above the threat. While their charge is mostly a bluff, they will occasionally make contact with an extended foot, or will drop a warm, smelly bomb from above.

Though I am still agitated when the gulls attack, my understanding of the reasons for their behavior makes my anger less personal. Their territorial behavior, which translates into aggression towards trespassers, is warranted because a high rate of chick mortality that accompanies their drive for reproductive success. The chicks do have some natural defenses, such as their “disruption coloration,” grey with black speckles that is lighter underneath to counter the effects of shadow, that camouflages them. They are helpless and mostly immobile when they are first hatched, however, and when they hide in the underbrush, it puts them in danger of being stepped on. Several times a gull chick has run directly onto the path in front of me when it saw me approaching, squawking and stumbling like a drunk.

Herring Gulls lay three eggs, the third a smaller "insurance egg" that will not hatch unless the first two fail. Both the chicks and the eggs are gray and speckled, a "cryptic coloration" that helps them to blend into the nest and the rocks.

Herring Gulls lay three eggs, the third a smaller “insurance egg” that will not hatch unless the first two fail. Both the chicks and the eggs are gray and speckled, a “cryptic coloration” that helps them to blend into the nest and the rocks.

I have had ample opportunity to compare my own experience with the gulls to Tinbergen’s descriptions, because the birds have agency over the entire Southern end of the Island. When we first arrived, Damon and Janet warned us that the Herring Gulls would become increasingly aggressive as they filled they laid eggs and once the chicks had hatched, pointing out a set of construction helmets for protective purposes. While the Gulls were wary of our presence from the start, I was dismissive of their attacking abilities until sure enough, a few weeks later, the first eggs hatched. Suddenly the South End became a place mired with the dangers of gull droppings, screeching, dive-bombing, and sometimes a painful thwack on the head with a surprisingly solid wing or foot. I have nothing but sympathy for Ben and Drew, who frequently venture out into this war zone to do fieldwork. It is an increasingly rare experience to feel threatened by another animal. The combination of the gulls’ large numbers, their piercing cries, and their targeted attacks make entering gull territory alone an intimidating experience.

Besides their aggressiveness and noisiness, another cause of my general distaste for the Gulls is their predation upon their own kind. Herring Gulls will eat the eggs and chicks of other bird species, including those of Tree Swallows and Eiders that leave their nests unguarded. They will also prey upon the young of other Herring Gulls, and once they begin to recognize their own young after five days or so, will peck a strange chick to death if it enters their territory. Jackson has seen a Herring Gull chick attempting to swallow an adult gull’s leg, no doubt copying the cannibalistic behavior of its parents.

While the birds have many unpleasant qualities, the aesthetic beauty of a Herring Gull in flight is difficult to deny. Sometimes two birds will suddenly fly in tandem, swooping and banking together until they abruptly go their separate ways. The young chicks are also undeniably adorable, and I have, I admit, occasionally cuddled one. Learning about the gulls, both from my own experience and from other scientists, has extended my awareness beyond their surface behavior, lending support to Tinbergen’s style of observational research. He claims that scientists should start with observation and work their way down to specific questions from there to understand the behavior as a whole, an approach that all of the scientists I have followed here have taken, both to their and to my benefit. Tinbergen laments, “So few people ever pause to look at what happens, and to investigate why it happens,” a statement that is certainly true of most of the world, but not of Kent Islanders.

*Read more about gull chicks from biologist Janet Gannon’s blog here

Sources:

Tinbergen, Niko. The New Naturalist, The Herring Gull’s World: A Study of the Social Behavior of Birds. New York: Anchor Books, 1960.

Gross, A.O. 1940. The migration of Kent Island Herring Gulls. Bird-Banding 11: 129-155. (BSS Contribution no. 7)

Views of Grand Manan

While the times are changing on Grand Manan, a fishing community in the Bay of Fundy, its isolation and the traditions carried on by the small population that lives there have slowed the process. Reminders of the past are everywhere, from the smokehouses on the wharves and weirs off the coast that were part of a booming herring industry to the lighthouses once operated by lighthouse keepers who lived there with their families. Grand Manan Lobstermen were still bending saplings into wooden traps as late as the 1970s, when wire traps had long been standard along the Maine coast.

When I visited the Swallowtail Lighthouse on the north end of the island, it was undergoing repair and looked closed from the outside. I was fortunate enough to catch a tour with Ken, the friendly lighthouse warden, who took us up three floors to the very top. He told us that Swallowtail began operating in 1860, after the famous wreck of the Lord Ashburton in 1857 (one of the 300 recorded wrecks in the area since 1720) created demand for more lighthouses for navigation around ports. The Bay of Fundy is notoriously treacherous, due to the combination of large tides, strong currents, and cliff-ringed islands, and it also has one of the highest densities of lighthouses in the world.

The lighthouse was de-staffed in 1985 and was de-commissioned by the Coast Guard, falling quickly into disrepair, the unfortunate fate of many historic lighthouses in the Maritimes. The Village of Grand Manan took ownership of Swallowtail, and the Coast Guard re-commissioned it, installing an automatic light, after the community decided it was an important part of their history and formed the Swallowtail Keepers Society to preserve it. Swallowtail is named after its unique construction: it is eight-sided and tapers towards the top, designed to break the heavy winds that blow through the cliffs. Lighthouses require constant maintenance because of their exposure to the corrosive ocean and to powerful gales, and the current restoration project has involved installing a fiberglass platform on the top, which also happens to have the best panoramic view of the island.

P1000180

Panorama of the Northern coast of Grand Manan from the top of Swallowtail Lighthouse

Grand Manan is extremely geologically interesting, because its formation is split down the middle. The East side of the island is composed of old sedimentary and metamorphic rock interspersed with treacherously jagged outcroppings of volcanic rock. The West side, by contrast, is composed of relatively young volcanic formations, including spectacular columns of basalt.  Most of the villages of Grand Manan are concentrated on the East side, which has many natural harbors and beaches, while the West side, with its 300 foot cliffs,  is much less accessible and is reserved mostly for nature trails and campgrounds.

P1000171

Swallowtail

P1000182

View of Whale Cove and North Head from the top of Swallowtail

P1000163

View looking South towards Stanley Beach and Castalia

Kent Island, Hay Island, and Sheep Island, which make up the “Three Islands” of the Bay of Fundy, are about five miles South of Grand Manan. The journey to Kent Island from the U.S. involves crossing the border, taking the ferry from Blacks Harbour in mainland Canada to Seal Cove on Grand Manan, then taking a boat to the skiff moored off of Kent Island, and sometimes walking from there through the Basin, depending on the tide. Besides weekly trips to Grand Manan for groceries, we have also had the opportunity to explore the Island’s immense natural beauty and to enjoy the hospitality of the islanders, many of whom are descendants of the Loyalists who moved here during the American Revolution.

Sources:

Swallow Tail Keepers Society: http://swallowtailkeepers.blogspot.ca

Marshall, Joan. Tides of Change on Grand Manan Island: Culture and Belonging in a Fishing Community. McGill-Queen’s Press-MQUP, 2008.

Yellow Warbler Nestlings & Jackson’s New Project

Eight day old Yellow Warbler nestlings, begging for food  photo by Jackson Bloch

Eight day old Yellow Warbler nestlings, begging for food
photo by Jackson Bloch

Every Sunday after dinner, the Bird List of every bird ever seen on Kent Island is read with the solemnity of ritual. Whoever has seen the bird that was called from the list shouts out, and the bird is checked off, or, very rarely, added to the list. While I am unlikely to recognize a Hooded Merganser or a Black-crowned Night Heron, I have made it my goal to see the nestlings of every Bowdoin Scientific Station study species. So far I have seen (and held) the nestlings of Herring Gulls, Tree Swallows, and as of yesterday, Yellow Warblers, with Savannah Sparrows, Petrels, and Guillemot nestlings still to go. Many bird species have breeding grounds on Kent Island, but they are invisible to the untrained eye, with one exception. Herring Gull nests are everywhere, from the shoreline to the fields on the interior, and now that they have hatched, the chicks are everywhere underfoot, stumbling like drunks in the undergrowth. I never would have been able to glimpse the well-hidden nestlings of smaller bird species, however, without going into the field with scientists.

On Thursday Jackson invited me to watch him band the four Yellow Warblers from the nest that he found in the woods right behind the shower. He reached into the bushes and emerged with two of the smallest, most delicate birds that I have ever seen. Jackson explained that they were six days old, though they looked much younger than the week-old Tree Swallow nestlings I had examined a few days before. The Warbler nestlings were bald except for two little tufts of fuzz that drew attention to their wizened, pinkish faces. They barely had feathers, and the underlying architecture of their wings was exposed, as were their tendons, their fat, and the contents of their almost transparent bellies. Like the Tree Swallows, their faces were dominated by wide beaks, the receptacles for the insects that their parents spend most of the day hunting and feeding to their young. Jackson had remarked on the short tarsus of the Tree Swallow, which made them more difficult to band, but these nestlings had almost comically long legs. Tree Swallows spend most of their day in the air, hence their huge wingspan, while the long legs of the Yellow Warbler are adapted to perching.

Yellow Warbler fledgling photo by Jackson Bloch

Yellow Warbler fledgling
photo by Jackson Bloch

Yellow warblers fledge and leave their small nests at about ten days old, much sooner than tree swallows, which are in no hurry to leave their spacious bird boxes. Jackson explained that leaving the nest so soon is a survival strategy, because the offspring are dispersed and less likely to be killed all at once by a predator. Once they leave the nest, the fledglings, which are gray except for the yellow that edges their wing feathers, stay close to the nest, and their parents continue to feed them. Jackson has watched them foraging in a huge gooseberry bush for butterflies, mosquitos, and other insects in the North Field.

Besides banding nestlings and observing fledglings, Jackson is also putting recorders in the nests to capture the nestlings’ begging calls. Like Ben, Drew, and Liam, Jackson has had to adapt his project to field conditions, though luckily his previous research has not been wasted. His original goal was to record the incubation calls of females to see if they were encoding a “password” that their young repeated in the nest as a way of identifying intruders. When he wasn’t hearing the females’ incubation calls, he decided to shift his project’s focus on the development of the nestlings’ begging calls, and the structural differences between calls in different ambient noise conditions. “It was actually a seamless transition,” Jackson remarked, saying that his methods of close observation and recording in the nest are the same as for his previous project. He has already noticed that the nestlings’ calls increase in frequency as they get older, and hypothesizes that the calls differ in frequency range based on the ambient noise around the nest, such as the (always grating) sounds of Herring Gulls. Thanks to Jackson, I can now recognize the chipping of fledgling Yellow Warblers as well as the distinctive calls of their parents. The heightened satisfaction that I get from knowing exactly where the bird calls I hear all on Kent Island come from instead of dismissing them under the umbrella of birdsong as I would have in the past is remarkable.

The Controversy Over Rockweed Harvest

Unharvested rockweed beds on Kent Island

Unharvested rockweed beds on Kent Island

The extensive rockweed beds that I have explored on Kent Island with Christine Walder, who is studying intertidal biodiversity, are also an economic resource that has caused controversy in the coastal communities where it proliferates. Harvesting rockweed is fundamentally different from the harvest of other marine species, because not only is it an important primary producer in the food web, but it also provides habitat for hundreds of species. By reducing the biomass of rockweed through harvest, countless other species are also reduced. Despite these ecological concerns, wild seaweed harvesting is a global industry that is growing every year, with millions of tons harvested for such varied uses as fertilizers, food additives, and cosmetics. Rockweed harvesting is a growing industry in Maine and in the Maritimes, which landed 88.1 million tons in 2010 (reviewed by Seeley and Schlesinger, 2012).

Regulations on rockweed harvest are different in Maine and Canada, and vary locally. In New Brunswick, Canada, private property rights only extend to the top of the intertidal zone, below which is open to public access. In Maine, however, waterfront property owners own everything down to the low tide mark. But Maine law provides public access to privately owned intertidal lands for the purposes of “fishing, fouling, and navigating.” The question is whether rockweed harvesting should be considered “fishing,” which is how the state currently defines harvesting.

In Canada, the federal government is responsible for managing rockweed resources through the Department of Fisheries and Oceans (DFO). However, DFO has signed a Memorandum of Understanding with the provinces of New Brunswick and Nova Scotia that delegates management authority to the provinces. These provincial governments have granted long-term harvesting leases to large companies that own the harvesting boats and equipment (Vandermeulen, 2013). In the United States, by contrast, the federal government is not involved in regulation, and until now, harvest has been largely owner operated. Maine is currently in the process of developing a management plan that resembles New Brunswick’s operation model, which favors vertically integrated harvesting companies. There are also different methods of rockweed harvest: hand-harvesting from boats is the typical method used in New Brunswick, while mechanical harvesting is used more widely in Maine (reviewed by Seeley and Schlesinger, 2012). Mechanical harvesting ensures a more uniform cutting height, but may cause more long-term damage to the rockweed holdfasts than hand harvesting (Seeley and Schlesinger, 2012). In both countries, there is no closed season for Rockweed harvest, but it is mostly cut in the early summer when the weather is better. Unfortunately, the Rockweed is at its reproductive peak in the summer, making the timing of the harvest a short-sighted management practice (Vandermeulen, 2013).

Uncut Rockweed on Kent Island, which can grow to 3m in length

Uncut Rockweed on Kent Island, which can grow to 3m in length

Rockweed cut to the 16'' harvest limit from one of Christine's experimental areas

Rockweed cut to the 16” harvest limit from one of Christine’s experimental areas

In New Brunswick, harvest is capped at 26 million pounds per year, and the regulatory guideline theoretically limits the industry to removing 17% of available rockweed biomass, which is based on the assumption that there is 50% regrowth in three years (reviewed by Seeley and Schlesinger, 2012). This harvest rate may not be sustainable in all areas, however, because rates of regrowth are dependent on many factors, and biomass can take anywhere from 3 to 11 years to recover. Furthermore, local patches of Rockweed are harvested at up to 50% of biomass (Ugarte et al, 2006), and a report from the Canadian Science Advisory Secretariat concluded that the present hand harvest rate is often between 20 and 30% in Nova Scotia, far above the 17% guideline (Vandermeulen, 2013).

Harvesting rockweed on a large scale would not only change the landscape of the intertidal, but it would also have ecological effects that could reverberate through the food web. As I have mentioned in previous posts, rockweed is the “old growth forest” of the intertidal, and provides vital habitat for hundreds of species. The rockweed industry claims that their harvesting operation is sustainable because the strands grow back, and are therefore a renewable resource that can be managed. This definition of sustainability is not what most ecologists would consider sustainability, because when rockweed is cut it no longer provides the same habitat for the species that depend on it. While rockweed may grow back at a faster rate after it is harvested, the regrowth is shorter and bushier than the uncut strands (reviewed by Seeley and Schlesinger, 2012). This fundamental alteration of the rockweed habitat structure will inevitably have ecological consequences, because of the high degree of interdependence of organisms in a food web.

Of particular concern is the impact of the rockweed harvest on Common Eiders. The Common Eider population has declined in the Bay of Fundy in recent years, (Ronconi and Wong 2003). The reason for this decline is not completely understood, but rockweed harvesting may play some role. Eiders feed in the Rockweed canopy, and the long Rockweed strands protect foraging Eider ducklings from predators. One study found that Rockweed clumps over 130 cm that are harvested are reduced up to 55% of their length and 78% of their biomass (Ugarte et al, 2006). The Rockweed strands on Kent Island can reach to three meters in length, and removing 78% of their biomass would make much less food available for Eiders. Reducing rockweed biomass and length that much would decrease cover for the eider ducklings, and would make much less food available. Shortening the rockweed will also force the eiders to dive more often and to greater depths for their food. Adult eiders are capable of diving, but it is energetically demanding, while young ducklings are incapable of diving for their food. Existing studies have found that rockweed harvested sites with a steep slope supported fewer Eider ducklings on Grand Manan, and harvested sites had fewer ducklings on mainland New Brunswick than did unharvested control sites (Blinn et al, 2008).

Studies have also shown indirect impacts of Rockweed harvesting on fish biomass and biodiversity, both of which are important to the health of the coastal ecosystem (Seeley and Schlesinger, 2012). Furthermore, rockweed is an important primary producer in intertidal ecosystems, therefore removing it could have a large long-term impact on commercial fisheries (Vandermeulen, 2013). Rockweed harvest is, in fact, highly contentious among lobstermen and fishermen because the algae provides habitat for juvenile lobster and herring.

rockweed_fleet1

Rockweed harvesting boats in Seal Cove, Grand Manan, an Island in the Canadian province of New Brunswick

The designs of many of the existing studies of these impacts of rockweed harvesting, including Christine’s, are based on the assumption that the rockweed cutting height is restricted to 16 inches, a limit that is in reality often surpassed (Seeley and Schlesinger, 2012). The danger of overharvest is a very real one, especially because the industry must remove large volumes of seaweed to make a profit, as rockweed is only valued at two cents a pound (Seeley and Schlesinger, 2012). There is already a history of rockweed overharvest, and areas were closed in Nova Scotia beginning in 1988 (Seeley and Schlesinger, 2012). Studies have shown that if beds are completely denuded, they are replaced by other seaweeds such as Chondrus and Fucus (Jenkins et al 2004), which don’t provide the habitat structure offered by rockweed, and overharvested areas may take years to recover back to an ecologically and commercially viable standing stock (Vandermeulen, 2013).

It is a common theme in environmental policy that science and management efforts lag behind natural resource exploitation, and Ecosystem-based Management (EBM) is rarely used or enforced until a collapse occurs. EBM is very difficult to implement because it requires a large amount of scientific data to support it, and often faces the additional hurdle of political opposition from resource user groups. As of now, government standards for Rockweed are not based on cumulative impact assessments that study the long-term effects of repeated cutting on a large scale (Maine Department of Marine Resources, 2011). The comprehensive stock assessments that inform regulations in Nova Scotia are at least twenty years old (Vandermeulen, 2013) and mostly small-scale experiments have been conducted to determine the ecological effects of harvesting.

Continued research on rockweed will help to fill in the gap in the scientific understanding of the relationship between rockweed structure and the productivity of intertidal ecosystems. The recent report from the Canadian Science Advisory Secretariat on assessment and management of marine “plants” in Nova Scotia (Vandermeulen 2013) recommended establishing areas that are closed to harvesting to be able to distinguish between the long-term ecological effects of harvesting and those of climate change. Without areas closed to harvesting for study, ecological change in the rockweed community may go entirely unnoticed. Rockweed is an integral part of a delicate ecosystem, and a fuller understanding of its function will inform policy that integrates ecology, which in the long run will benefit commercial as well as conservation endeavors.

Another perspective on the Rockweed controversy: http://fishermensvoice.com/201402RockweedBoomsWhoBenefits.html

Sources:

Blinn, B. M., V.Violette and A. W. Diamond. 2006. Osprey, Pandion haliaetus, depredates Common Eider, Somateria mollissima, duckling. Canadian Field-Natu- ralist 120(2): 236-237.

Jenkins, S., Norton, T., and Hawkins, S. 2004. Long term effects of Ascophyllum nodosum canopy removal on mid shore community structure. Journal of the Marine Biological Association of the United Kingdom, 84: 327-329.

Maine Department of Marine Resources. 2011. Rockweed: ecology, industry, management. Re- trieved February 1, 2012, from http://www.maine.gov/dmr/ rm/rockweed/2011facts.pdf.

Ronconi, R. A. and S. N. P. Wong. 2003. Estimates of changes in seabird numbers in the Grand Manan archipelago, New Brunswick, Canada. Waterbirds 26(4): 462-472.

Seeley, R., and Schlesinger, W. 2012. Sustainable seaweed cutting? The rockweed (Ascophyllum nodosum) industry of Maine and the Maritime Provinces. Annals of the New York Academy of Sciences, 1249: 84-103.

Ugarte, R., Sharp, G., and Moore, B. 2006. Changes in the brown seaweed Ascophyllum nodosum (L.) Le Jol. Plant morphology and biomass produced by cutter rake harvests in southern New Brunswick, Canada. Journal of Applied Phycology, 18: 351-359.

Ugarte, R. & G.J. Sharp. 2011. Management and production of the brown algae Ascophyllum nodosum in the Canadian maritimes. J. Appl. Phycol. doi: 10.1007/s10811-011-9753- 5.

Vandermeulen, H. Information to Support Assessment of Stock Status of Commercially Harvested Species of Marine Plants in Nova Scotia: Irish Moss, Rockweed and Kelp. Canadian Science Advisory Secretariat (CSAS), Department of Fisheries and Oceans, Maritimes Region. 2013.

Tree Swallows Part III: Banding the Nestlings

Raquel and Tracey remove the nestlings to be banded and measured

Raquel and Tracey remove the nestlings to be banded and measured

Today Tracey, Hannah and I continued our project to monitor and band the two Tree Swallow families on Kent Island this summer, the last of what used to be a large population. We had to time our expedition carefully, to catch the hatchlings when they were big enough to band, but before they fledged and no longer returned to the nest. We checked the nests every other day to see if the eggs had hatched, because checking daily might put too much stress on the parents and cause them to abandon the nest. Nat told us to band the chicks thirteen days after our estimated hatch date, because the nestlings fledge twenty or so days after they hatch. While Nat had helped us to band the females earlier in the summer, he departed for Brunswick, leaving us with what he had taught us of bird fieldwork. We also had the help of Jackson, who studies Yellow Warblers, and Raquel, from the University of Guelph in Ontario, who is working with Savannah Sparrows. We approached the first box and were immediately warned off by a Herring Gull, who swooped threateningly and landed directly on top of the tree-swallow box. We soon realized the reason for its aggression when two Herring Gull chicks emerged from the high grass onto the path, squawking and scurrying on their awkward legs. After shooing the chicks away from our makeshift banding station of an overturned crate and warding off the parent gull with a stick, we approached the tree swallow box for a second time.

P1000193

Tree swallow nestling. Its yellow beak is partially visible.

The first thing Raquel said when she opened the box and removed the female from the nest was, “Are you sure these aren’t adults?” A huge transformation had occurred in the two weeks since we had last checked the chicks. What had been five flesh-colored blobs that Nat described as “tangled spaghetti” was now a mass of grey and white feathers and wide, yellow mouths. These nestlings were much larger than the Yellow Warbler and Savannah Sparrow nestlings that Jackson and Raquel had banded before. It was hard to tell which appendage belonged to which nestling, but we eventually figured out that there were five, as well as an egg that is unlikely to hatch at this point. Extracting the nestlings was difficult because their tiny hooked claws gripped the nest with surprising strength, but Raquel gently removed two and put them in a bird bag. We went through a similar process of banding, measuring, and weighing the birds as we had done before to the female swallows, except that the nestlings were much more difficult to hold. The “photographer’s grip” of necks between peace-fingers was less possible because the nestlings tucked their heads in and barely had necks to begin with, so we ended up cupping them in our hands. Jackson showed me how to hold a tree swallow with one hand while stretching out its leg between two fingers and using my other hand to close the metal band around its tarsus, the area between the bend in its leg and its foot. Banding is an extremely delicate process, because a band that is too tight can damage the leg and cause infections, severely reducing the bird’s chances of survival. The birds wiggled when we held them and even managed once to escape, but did not make it very far without the ability to fly. After processing the birds as quickly as possible, we returned the birds to their nests as quickly to placate their anxious parents, who swooped near the box helpless to prevent us from taking their babies.

A two week old Tree Swallow nestling

A two week old Tree Swallow nestling

The nestlings in the second nest were about a week younger than those in the first, and the difference in their appearance made the rapid growth that tree swallows undergo in their first few weeks very visible. They only had the beginnings of feathers, and Jackson pointed out the yellow fat deposits on their bellies and tarsus that were visible beneath their thin skin. When I held a nestling, it lay in my palm and wiggled its miniature wings helplessly.We banded two before deciding to wait another few days to band the remaining three, because the fat on their tarsi made it difficult.

Week-old nestlings

Week-old nestlings

P1000199

 

It was incredible to not only see all of the stages of the tree swallow’s growth, but also to be able hold the bird and feel its life in my fingers. While I was glad to have that experience, I also felt guilty for disturbing the tree swallows during a delicate developmental period, and for causing them stress that might damage their chances of success. Many scientific experiments, even if they mainly involve observation like our project, involve disturbing the study subject. Scientists take measures to minimize interference, but some damage is often inevitable. I was comforted by the thought that our project is for the larger purpose of conservation, and that our future efforts to fix tree swallow boxes will provide habitat for next year’s birds. I am hopeful that some of the nestlings that we banded will return to their birthplace, though only 20% of tree swallows survive their first year. Despite these odds, all but one egg hatched, and the birds survived what can be fatal stormy weather. I was heartened by their fierce will to survive that I sensed even as they lay prone in our hands.