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Table of Contents:
Keywords: common loons, seabird mortality, marine ecological health, lead, oil spills, beached bird surveys, wind farms, harmful algal blooms |
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At the Tufts Wildlife Clinic, calls are often received about large numbers of dead and dying birds on our coast, but there has not been any organized reporting of these events, as there is for marine mammals and sea turtles. Numerous threats contribute to these mortality events, such as diseases, fisheries operations, persistent organic pollutants and metals, and oil pollution. Without regular monitoring of beaches, it is nearly impossible to detect bird mortality levels from such threats. Over the past year, Tufts Center for Conservation Medicine / Wildlife Clinic launched the Seabird Ecological Assessment Network (SEANET) to monitor the northeastern coastal corridor of North America. SEANET is collecting the information necessary to predict where and what dangers exist to marine birds in the northeastern U.S. and Atlantic Canada, which seabird species are most vulnerable, and what resources are available to assess and counteract these risks. The goal is to involve citizen scientists and students in conducting regular beached bird surveys throughout the region in order to detect high-mortality events (such as disease outbreaks and oil spills) and to establish baseline data on marine bird mortality. Seabirds are particularly good indicators of marine environmental health, and also allow us to assess disease and contaminant threats to human health.
Background| Fig. 3. Causes of mortality in breeding and wintering common loons in New England, 1987-2000
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While the US Fish and Wildlife Service banned the use of lead shot for waterfowl hunting in 1991, there is no federal legislation banning the use of lead fishing gear. Because of the efforts of Dr. Pokras and his collaborators, several northeastern states and Canada have passed legislation limiting lead fishing gear. The success of these measures is hindered by the fact that legislation varies among states. For example, because it is illegal to buy lead sinkers in Maine and illegal to use lead sinkers in New Hampshire, it is perfectly legal to buy lead weights in New Hampshire and drive to Maine to use it. The ban on use is particularly difficult to enforce. In New Hampshire during 2002 there were no warnings and no fines issued to any anglers (Major et al. 2003). It is highly unlikely that this lack of penalties was due to lack of violations of the ban.
| Fig 2. Lead sinkers and other gear found in common loon carcasses.
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People tend to be fond of loons; they are a symbol of wild New England, and their calls echo the peacefulness of remote lakes. In a sense, loons are an ideal “sentinel” species for New England’s lacustrine ecosystem health. However, because loons migrate to marine habitats in the winter, their survival reflects not only the conditions of freshwater systems, but those of the marine environment as well. Most research has focused on the breeding biology of loons and mortality during the summer season, yet at least 25% of the dead loons recovered by Tufts come from the wintering grounds. In a report from beached bird surveys conducted in the Northeast from 1975-1983, loon mortality was reported on coastal beaches in every quarter (quarters ending the last day of February, May, August, and November), even though one might not expect to find the species in coastal waters during the summer (Simons 1985). What is killing loons when they are on the ocean?
This question, along with the arrival at the Tufts Wildlife Clinic of Dr. Flo Tseng, a veterinarian with seabird rehabilitation and oil spill response experience on the West Coast, led to the development of the Seabird Ecological Assessment Network (SEANET). If we are going to ask what is killing loons on the ocean, the natural extension of this question is: what is killing any bird that is living in the marine environment?
Recent events point to one obvious answer. The Bouchard Barge B120 spill of nearly 100,000 gallons of no. 6 fuel oil in Buzzards Bay on April 27, 2003 has killed more than 460 birds as of May 28th, 2003 (http://www.buzzardsbay.org/oilspill-4-28-03.htm). A drop of oil the size of a coin condemns a bird to a slow, painful death from hypothermia and starvation by compromising the insulating capacity of its feathers. Oil ingested during preening often results in delayed death. 
The majority of the birds killed in the Bouchard B 120 spill were loons, as the timing of the spill hit the “change-over” period when most loons would be staging along the coast, preparing to migrate inland. Endangered piping plovers (Charadrius melodus) were also arriving on beaches just as the oil spill happened. Weeks after the spill, at least 80% of the piping plovers that had been prospecting in the Dartmouth area were moderately oiled (http://www.buzzardsbay.org/oilspill-4-28-03.htm). The timing also was bad for endangered roseate (Sterna dougallii) and threatened common terns (Sterna hirundo) returning from South America. The largest nesting colony of roseate terns in North America is in Buzzards Bay, with over 2,000 adult roseate terns (up to 30% of the entire North American population) usually nesting on Bird and Ram Islands (GOMSWG minutes 2002). [See Szcyzs article: Using Molecular Techniques in Roseate Tern Conservation] 
Less than a week after the spill, extensive areas of Ram Island’s beach were covered with oil, and within two weeks of the spill, Bird Island’s beaches were lightly oiled. Two roseate terns were found dead due to suspected oiling as of May 28th.
While crews attempted to clean up the beaches, the USFWS deployed non-lethal air horns, noise cannons, and strobe lights at night to prevent birds from landing on oil-covered beaches. At the time, no one knew what the birds, which have fairly high adult site fidelity, would do or where they would go to nest if the scare tactics worked. Imagine flying thousands of miles, navigating through storms and treacherous conditions to locate your tiny, temporary home, only to be scared off by deafening blasts and flashing lights. Do you fly on into the night on tired wings, searching blindly for the familiar cacophony of voices that draws you downward? 
Suitable nesting islands are scarce, and colonially nesting seabirds require visual and auditory social cues to entice them to land. Establishing a new colony from scratch is virtually impossible; it is the very nature of this social attraction that managers have been able to exploit. By broadcasting calls from a speaker and providing wooden decoys, we can manipulate birds into establishing colonies in locations that we deem suitable, but this process often takes years. Due to land-based predators, gull populations (associated with human garbage dumps and fishing practices), and human disturbance, very few islands actually qualify as quality habitat for nesting terns. If the displaced birds were successful in relocating, how did the influx of new birds affect the established populations on the handful of other islands in the Northeast?
All of these issues are fundamental to one of the tenets of colonial waterbird management and conservation: don’t have all of your eggs in one basket. Or in this case, don’t let the birds lay all of their eggs on one island. As a tragedy like this spill reminds us, if we continue putting habitats and species at risk -- by transporting oil in single-hulled ships in ecologically sensitive areas, for example -- we cannot afford to focus our efforts on protecting only a few potential nesting sites.
As it turned out, Ram and other islands were sufficiently cleaned in time for some roseate and common terns to nest there, although the start of the nesting season was somewhat delayed. Concerns now turn to whether sub-lethal effects of oil will impair breeding adults, eggs, and chicks. A network of researchers, interns, and volunteers with the US Fish and Wildlife Service, state wildlife agencies, and non-profit groups like National Audubon Society (http://www.projectpuffin.org/), Maine Audubon Society (www.maineaudubon.org), and Massachusetts Audubon Society (www.massaudubon.org) are spending their summers monitoring the populations of terns and other breeding seabirds up and down the coast. But who monitors mortality once the oil spill response crews have left the beaches and the oil spill is deemed “cleaned up”? This question brings us back to the issue of what is killing marine birds.
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As Mark Pokras has documented with loons, there are numerous threats to aquatic avian populations, and oil is only one of them. For marine birds, oil and chemical spills, harmful algal blooms, entanglement in fishing gear and other debris, disease, lead shot and fishing gear, illegal hunting, habitat loss and degradation, and persistent contaminants, plastics and other pollutants can all add up to have potentially significant impacts on populations. Because there is no centralized reporting system for seabird mortality in the northeastern U.S., mortality events often go unnoticed, unreported and/or unsolved. Some examples of mortality events that were probably large enough to impact marine bird populations include:
Not all mortality happens at such large scales. What about “normal” background mortality? Because no one is doing regular monitoring, it is hard to know what the background level of mortality is for certain avian species. This becomes even more pertinent when an oil spill or other large-scale mortality event occurs. For legal and management purposes, we want to know what the impact will be on populations and how much of the mortality can actually be attributed to the obvious threat.
Granted, combing the beaches for dead birds is much less glamorous than holding a fluffy tern chick in your hand and feeling the pulse of a tiny new life. But some would argue that keeping track of death is almost as important as keeping track of life. For marine mammals, stranding networks have existed for years on many miles of New England beach, but no such infrastructure exists for birds.
In Atlantic Canada, volunteer-based, beached bird surveys have been ongoing in Newfoundland since 1984, and in Nova Scotia since 2001. These monitoring projects, as well as long-term efforts on the west coast of the U.S., have yielded some striking results. In Atlantic Canada, it is not just the attention-grabbing disastrous oil spills that are killing large numbers of seabirds. The much more pernicious and, perhaps, even more devastating threat is chronic oil pollution. Continual oil pollution, mainly from illegal discharge of oily bilge wastes, has a dramatic effect on seabird populations, with estimates of at least 600,000 birds dying from oil in Atlantic Canada each year (Wiese 2002). Auks -- including puffins, murres, and razorbills -- and sea ducks have some of the highest rates of oiling; up to 72% of individuals found dead on beaches in Newfoundland likely succumbed to oil exposure (Wiese 2002). In many cases, the oil recovered from a dead bird can be “fingerprinted” and its source can be pinpointed to some degree of certainty, so beached bird surveys have the potential to become a useful enforcement tool (Vanvleet 1984).
Fortunately, due to a stricter system of fines, illegal dumping of chemicals and discharge of oil wastes appears to be less prevalent in the United States than in Canada. However, illegal dumping and small-scale spills occur, and the problem defies international boundaries. Most importantly, because regular beached bird monitoring efforts have taken place in the northeastern U.S. recently (but see Simons 1985) the actual mortality rates of marine birds in this region are unknown.
The main goal of the Seabird Ecological Assessment Network (SEANET) is to fill the apparent void in seabird mortality monitoring in the northeastern U.S. We are taking a lesson from our Canadian collaborators, who are far ahead of us in terms of monitoring, to extend beached bird surveys throughout the Gulf of Maine and south to Delaware Bay.
Ironically, our efforts started in the very area where the Bouchard tanker spill made headlines. In collaboration with the Lloyd Center for Environmental Studies in South Dartmouth, MA (http://www.thelloydcenter.org), we held a training in October 2002 for more than 26 volunteers who have since been regularly monitoring approximately 36 miles of beach in southeastern Massachusetts. [Click here to see the beaches covered by Lloyd Center volunteers.] Students from Tabor Academy and Rochester High School have been involved in conducting surveys, giving teachers the chance to incorporate numerous topics including seabird biology, conservation, GIS, and applied field work into the curriculum. Several volunteers and students from science classes at Triton High School are also regularly walking beaches on Plum Island on the north shore of Massachusetts.
In March 2003 we began a collaboration with the Massachusetts Audubon Society Wellfleet Bay Wildlife Sanctuary (http://www.wellfleetbay.org/), where approximately 30 more volunteers walk beaches on Cape Cod. From the Wellfleet Bay sanctuary, we draw on an established volunteer base that is already active in beached sea turtle and marine mammal surveys, as well as attractfurther participation from local birdwatchers, school science classes, and other interested citizens. (If you are interested in volunteering, visit the website www.tufts.edu/vet/seanet or contact becky.harris@tufts.edu. For a sample SEANET datasheet click here; for the volunteer handout click here.
In the coming months, we hope to expand volunteer-based beached bird surveys in New Hampshire with the NH Coastal Program (http://www.state.nh.us/coastal/), in Maine with Maine Audubon Society (http://www.maineaudubon.org/), and to the tri-state area in collaboration with Wildlife Trust (http://www.wildlifetrust.org/). Managers on many of the seabird breeding islands have agreed to monitor their colonies for mortality as well (National Audubon Society’s Seabird Restoration Project, http://www.projectpuffin.org and US Fish & Wildlife Service, Petit Manan National Wildlife Refuge, http://petitmanan.fws.gov/).
Bird Studies Canada (http://www.bsc-eoc.org/bscmain.html), a co-partner of BirdLife International and the Canadian Wildlife Service, has agreed to share data collected from its beached bird surveys, which will expand throughout Nova Scotia this year. Ultimately, SEANET and the Canadian efforts will merge geographically, encompassing the entire Gulf of Maine, a marine ecosystem where threats to a wide variety of avian, aquatic and terrestrial species extend beyond political boundaries.
With our collaborators at Wildlife Trust (http://www.wildlifetrust.org/), part of the Consortium for Conservation Medicine (http://www.conservationmedicine.org/) of which we are founding members, we will be expanding beached bird surveys southward, all the way to Delaware Bay. There are many important nesting grounds for seabirds such as the endangered roseate tern throughout the New York and New Jersey region, where sandy beaches are an even more prevalent coastal habitat type than in the Gulf of Maine. The expansion southward will also encompass coastal areas in Connecticut and Rhode Island, particularly in collaboration with organizations that are monitoring coastal waterbird breeding areas such the US Fish & Wildlife Service (Stewart B. McKinney National Wildlife Refuge, for example).
Within the next 2 months, a web-based strandings reporting system will be available to volunteers to directly enter their beached bird data. It will be housed at the Wildlife Disease Information Node of the National Biological Information Infrastructure at the USGS, and will allow for storage of large amounts of data and quick compilation of results. Because of the accessibility of the web-based information, volunteers will be able to see the fruits of their labors. This system is currently being developed by our collaborators at USGS; a rough demo stage of this reporting system is accessible at http://wildlifedisease.nbii.gov/wdin/. One can zoom down to street level and click on the ‘Place Point’ button in order to mark the location of the beached bird. Clicking on the location on the map will drop a dot, and return the coordinates. The form then pops up at the bottom to record the event information, which will be expanded to reflect the SEANET datasheet that volunteers are currently using.
Analyses from this project will be significant in detecting causes of mortality and in developing vulnerability indices of various seabirds to hazardous marine events such as oil spills. The baseline data that we compile is being used to produce GIS maps and conduct spatial correlation analyses on population distribution, mortality, contaminant patterns, oil spill and transport locations. These databases and associated GIS maps will be linked and readily available to the public, in collaboration with the USGS and the US EPA.
In addition to monitoring for oiled birds, beached bird surveys have the potential to ascertain the extent of other threats to marine birds. Harmful algal blooms (HABs), commonly known as red tides, historically have impacted marine bird populations (see Other Threats to Marine Birds, above), but are relatively understudied. Usually coastal shellfish are used to monitor harmful algal blooms, but there is evidence that these populations are not always reliable indicators of what is happening offshore (Shumway et al. 2003). Filter feeders, such as mollusks, can concentrate biotoxins in their tissues at high levels; but filter-feeding fish, such as sand lance and herring, also have shown very high levels of marine biotoxins. Diving ducks that eat mollusks and terns and gulls that eat small fish may then concentrate these toxins at even higher levels. It is difficult to determine the total mortality of birds and which species are affected, because only a small proportion of birds tend to wash ashore. With regular monitoring, however, at least a small proportion of the birds might be recovered, indicative of offshore events. Because of the low reproductive rate of seabirds, significant mortality events can have major impacts on populations. The deaths of up to 20% of populations have been attributed to harmful algal blooms; losses in adult populations at this level would be likely to have long-term effects on population persistence (Shumway et al. 2003).
Although algal blooms can be natural phenomena, the frequency and extent of toxic blooms have increased in recent years. The increase of HABs in both space and time has raised concerns that accelerated eutrophication of coastal waters due to human activities (Anderson et al. 2002) and global climate change (Hayes et al. 2001) may be contributing to this expansion. Drifting plastic debris has also been cited in the expansion of algal blooms; potentially harmful organisms have been found to adhere to plastic debris, and as it drifts on ocean currents, the debris serves as an effective vector for these microalgae. For seabirds, plastic ingestion and entanglement is a serious threat, but more subtle impacts also might result from this anthropogenic blight on the marine and coastal ecosystems.
During the fall of 2002 there were large, unexplained die-offs of loons and gannets up and down the Atlantic coast of the U.S., and similar bird deaths were reported in Europe. It is possible that these large mortality events were the result of pan-Atlantic toxic blooms or some unknown pathogen. The wide-ranging, migratory nature of seabirds has the potential to make them particularly effective at spreading disease. Disease also can devastate a breeding population, as occurred on Stratton Island, in Saco Bay, Maine last year. At least 20-30% of the common and roseate tern chicks in the colony died after suffering numerous symptoms including lethargy, shaking, enlarged kidneys, puffy skin, and bloody nasal cavity and legs. At present, the cause of the chick mortality is unknown, but is suggestive of some kind of pathogen or toxic agent (GOMSWG Minutes 2002). Coincident with this threat, 2002 was a year of heavy chick and egg predation by a black-crowned night heron (Nycticorax nycticorax) and great horned owl (Bubo virginianus). Particularly for endangered and threatened species, additive threats can have devastating impacts.
Wind turbines present several risks to flying birds: lighting at night can attract and disorient migrating songbirds, moving blades can appear invisible even to species with high visual acuity such as raptors, and wires (if present) can be an obstacle, particularly for birds like waterfowl and shorebirds that fly in tight flocks. Most studies of offshore wind farm impacts are inconclusive, particularly in terms of impacts on seabirds (Kingsley and Whittam 2001).
Monitoring beaches for bird mortality has the potential to be particularly relevant to the current controversy surrounding the proposals for offshore wind farms. Until recently, most concern about bird strike mortality at wind farms has been about raptors and songbirds; with increasing interest in building offshore facilities, questions are emerging about risks to waterbirds, shorebirds, sea ducks, and seabirds. Cape Wind Associates, LLC has proposed a wind farm of 130 417-foot-high turbines over a 24 square mile area on Horseshoe Shoals in Nantucket Sound. Another company, Winergy, LLC has proposed 21 different sites for wind farms up and down the Atlantic coast.
While it is unlikely that all of the proposed construction will occur, wind is likely to increase in importance as a source of renewable energy. There is clearly a need to determine where the most appropriate sites for wind farms are, particularly with the goal of minimizing impacts on birds. If we have a profile of ‘baseline’ bird mortality before construction, we have the potential to determine levels of mortality associated with turbines after they are built as well as which particular species affected by wind turbines.
A few findings so farMark Pokras and Flo Tseng are using their expertise to venture where most ecologists dare not go. Drs. Pokras and Tseng and numerous veterinary students have done nearly 200 necropsies on marine birds this year (the animal equivalent of an autopsy is called a necropsy). Among the birds examined starvation, ingestion of fishing line and hooks, and gunshot wounds have been among the causes of death. Several specimens have been necropsied from mid-Atlantic states, particularly loons and gannets, the result of what appeared to be a major die-off in the mid-Atlantic region. Most of these birds showed signs of emaciation and starvation, but other factors such as pathogens, contaminants, and other toxins have yet to be analyzed.
Among the interesting findings was a northern gannet that had ingested marine fishing gear. The hook had not perforated any internal organs, but the bird appeared to have died from lead poisoning; the gear was held together with lead solder. [Lelia – insert fig.14] Much to Mark Pokras’ dismay, he cannot seem to escape the hazard of lead; animals in both freshwater and marine environments face a bevy of threats, and lead emerges as one of the most pervasive.
Anderson, D.M., P.M. Gilbert, and J.M. Burkholder. 2002. Harmful algal blooms and eutrophication: nutrient sources, composition, and consequences. Estuaries 25: 704-726.
Daoust, P.Y., G. Conboy, S. McBurney, and N. Burgess. 1998. Interactive mortality factors in common loons from Maritime Canada. Journal of Wildlife Diseases 34: 524-531.
Forsell, D.J. 1999. Mortality of migratory waterbirds in Mid-Atlantic coastal anchored gillnets during March and April, 1998. U.S. Fish and Wildlife Service, Chesapeake Bay Field Office.
GOMSWG minutes. 2002. Gulf of Maine Seabird Working Group, 12 August 2002, Hog Island, Bremen, Maine, U.S.A. Maine Department of Inland Fisheries & Wildlife.
Haebler, M., A. Kuhn, J. Copeland, M. Pokras, and M. Nicholson. 2003. Use of wildlife mortality data to quantify risks to populations across space and time. Poster, US EPA, Narragansett Bay, Rhode Island, U.S.A.
Hayes, M.L., J. Bonaventura, T.P. Mitchell, J.M. Prospero, E.A. Sinn, F. Van Dolah, and R.T. Barber. 2001. How are climate and marine biological outbreaks functionally linked? Hydrobiologia 460: 213-220.
Kingsley, A. and B. Whittam. 2001. Potential impacts of wind turbines on birds at North Cape, Prince Edward Island: A report for the Prince Edward Island Energy Corporation, Bird Studies Canada, Sackville, New Brunswick, Canada.
Kushlan, J.A. 1993. Colonial waterbirds as bioindicators of environmental change. Colonial Waterbirds 16: 223-251.
Major, D., K. Munney, K. Taylor, and M. Pokras. 2003. New Hampshire’s lead fishing tackle ban – is it working? 59th Annual Northeast Fish & Wildlife Conference, April 13-16th, Newport, RI.
Podolsky, R. 1989. Entrapment of sea-deposited plastic on the shore of a gulf of Maine Island. Marine Environmental Research 27: 67-72.
Shumway, S. E., S.M. Allen, and P.D. Boersma. 2003. Marine birds and harmful algal blooms: sporadic victims of under-reported events? Harmful Algae 2: 1-17.
Sidor, I., M.A. Pokras, A.R. Major, K.M. Taylor, and R.M. Miconi. 2003. Mortality of the common loon in New England, 1987-2000. Journal of Wildlife Diseases 39: 306-315.
Simons, M.M. 1985. Beached bird survey project on the Atlantic and Gulf coasts. American Birds 39: 358-362.
Pokras, M.A. and R. Chafel. 1992. Lead toxicosis from ingested fishing sinkers in adult common loons (Gavia immer) in New England. Journal of Wildlife Medicine 23: 92-97.
Vanvleet, E.S. 1984. Fingerprinting oil spills in the marine environment. Marine Technology Society Journal 18: 11-23.
Wiese, F. 2002. Seabirds and Atlantic Canada’s ship-source oil pollution: Impacts, trends, and solutions. World Wildlife Fund Canada. available on the web at http://www.wwfcanada.org/en/news_room/pdf/02_09_24_SeaBirdsReport.pdf
1. Common loon (Gavia immer), photo credit: Mark Pokras
2. Graph: Causes of common loon mortality in New England, 1987-2000, adapted from Sidor et al. 2003
3. Lead sinkers and other gear found in common loon carcasses, photo credit: Mark Pokras
4. Oil sheen in Buzzards Bay, MA, May 4, 2003, photo credit: US Coast Guard
5. Double-crested cormorant (Phalacrocorax auritus) oiled in Bouchard spill, April 29, 2003, photo credit: Buzzards Bay Project
6. Oil on Barney’s Joy Beach, Dartmouth, MA, April 29, 2003, photo credit: Aria Brisette, Buzzards Bay Project
7. Roseate tern (Sterna dougallii), photo credit: Pat Lynch
8. Common loon (Gavia immer) tangled in net, photo credit: Mark Pokras
9. X-ray of common loon (Gavia immer) with ingested fish hook, photo credit: Mark Pokras
10. Gull entangled in plastic debris, photo credit: Mark Pokras
11. Map of beaches walked monthly by SEANET volunteers conducting in beached bird surveys, in association with the Lloyd Center for Environmental Studies
12. X-ray of northern gannet (Morus bassanus) with ingested fish hook with lead solder, photo credit: Mark Pokras
The views and opinions expressed in all articles that appear in "Conservation Perspectives" are those of the authors and do not necessarily reflect those of NESCB.
