Document RJEY9KJVRKdEyo6Zwy0E3QkMX

Tlhi [EairOy MsunraBirag if tiki Tinn) Thousands of terns have replaced the Army on an island fortress originally designed to detect an enemy invasion of New York. The enemy has now arrived, and a major ornithological disaster may bo upon us by Helen Hays and Robert W. Risebrough Great Cull Island is a small, un inhabited pile of rocks, clay, and shifting sands at the entrance of Long Island Sound between the eastern tip of Long Island and Con necticut. Because of its strategic lo cation, for half a century the island served as part of the defense system of the nation; today, the striking in crease of birth-deformed birds there may be a warning of a new and more insidious danger. 1*he island is an excellent habitat for terns, small member* of the gull family that nest on isolated coasts and barrier beaches throughout the world. To survive in these tem pestuous areas of winds, tides, and shifting sands, the terns have to be adaptive and sensitive to change: always shifting, colonizing newly formed habitats, or quickly desert ing old ones as they arc destroyed by the elements or by man. Nearly a century ago, when the rapacious millinery trade in its pur suit of feathers for fashion threat ened the survival of terns on the East Coast, conservationists pro vided a warden on Great Cull Is land to save the birds. The 14,000 terns on the island became the last nesting colony, the last hope for terns in the New York region, as other colonics on Long Island Sound were wiped out by plume hunters and eggera. Shortly after 1900, terns became a protected species when a pioneer ing piece of conservation legislation was passed in the United States. But, ironically, the legislation came too late for the terns on Great Gull Island, for in 1897, on the eve of the Spanish-Amcrican War, fearing attack by a Spanish armada, the United states government had be gun the construction of Fort Michie on the island. With the arrival of the military, the terns disappeared. On the following decades, the shadow of war rarely lifted from Great Gull Island. During World Wars I and II, the military used the island for its continental warning and defense system. From tall ob servation lowers, soldiers scanned the ocean, ulwuv* alert to the dan ger of attack. Over the years, the fort became a complex maze of gun emplacements, ammunition depots, barracks, and towers. Bv the end of World War II. the island was al most completely covered with con crete and asphalt. And the terns avoided this unnatural transforma tion of their former habitat. Then, in the late 1940's. Fori Michie lost its function in the warning and defense system for the continent. It became a symbol of obsolete military eq,,:pment and strategy, and in 1949 the Army abandoned the island, leaving be hind its concrete and asphalt, junkpilcs, man-made hills, and a necklace of traprock boulders placed around the island to stabilize its shores. Although man was gone, the habitat was too disturi>rd for the terns to return. Yet by the late 1940's, the terns of Long Island badly needed a new breeding area; the old protecti\e legislation was no longer adequate lo save them from new devel opments. The encroachment of fac tories and housing developments in coastal areas, along with the con version of beaches lo public parks, drastically reduced the number of undisturbed nesting areas for terns in the New York region. Aware of the island's history. The American Museum of Natural History and the Linriacan Society of New York worked to acquire Great Gull Island, hoping that it might again become t large colonv for nesting terns. In 1919. the Museum received title and assigned to the Linnacan Society the task of return ing it to a condition suitable for terns. In 1949 and 1950. several of the buildings were leveled, vegetation was burned, and sand was deposited in an effort to create artificial bearhes. Each voar the island *js visited by ornithologists from the Linnaenn Socictv and the Museum, but it was not until 1955, after ev eryone had given up hope that the < MGNS 062933 < 39 birds would ever breed there again, that twenty-five pain of common terns were found nesting. The birds . had not utilized any of the areas prepared for them, but had laid their eggs on the traprock at the eastern edge of the island. The numbers of terns increased each $V 'w , succeeding year and today, once , l again, .the island is the site of one of `>t uj. the largest colonies in Long Island (A ' Sound, comprising about 7,000 pit'* i 1 b|rd`- . ik`J W ' f hen people how land on the island in late spring or early sum mer, the terns swirl noisily from the mins of the fort, challenging the in truders and diving at them should they approach the nest sites. Re minders of the island's occupation by the military still remain every where. The ruins of the abandoned fort, overgrown with vegetation, stretch from one end of the island to the other, The battlements are manned, however, by new defend ers. On patches of exfoliating con crete in the gun emplacements and in the open areas that were once building foundations, common terns incubate their eggs and feed and brood their young. The roseate terns, less aggressive than the com mons, deposit their eggs in the grassy edges of the open areas or under boulders on the outer beaches. Their utilization of the ruins of the old fort on Great Gull Island demonstrates the tern's remarkable adaptability and use ol habitat, a previously unknown characteristic of the species. A number of other species also occupy parts of the ruins. Barn swallows dart in and out of the weathered buildings, patching them with mud for their nests. Baybcrry and wild rose, as well as several species of grasses, have invaded the ruins, making them habitable for nesting red winged blackbirds, song sparrows, and spotted sandpipers. Starlings also nest in the eaves of buildings. By 1966. the colony appeared suffici^il^JacgcJuid-Stablc to per mit ornithologists from the Museum to undertake studies of the breeding biology of both species of terns, as well as of several of the other spe cies nesting on the island. During the summers of 1967 and 1968, however, there was a great deal of rain and a scarcTtyTof fish. .^Chemical pollutants, such v m PCB's, are highly suspect,^ Su the cause ofagJalaryfVing ^ mereaiTngross birth deformities among the terns on Great Gull Island. This four-legged common tern chick died three days after hatching. 40 Still straining to fly after fourteen week*, the abnormal common tern, right, can only manage to rise a few feet. It had the double misfortune of being born without secondary flight feathers In a nest built within the insurmountable rim of a huge gun emplacement. It is doomed in this concrete enclosure. The fate of the five-weekold chick, far right, is similarly 6calcd: it was born without tail feathers, primary, and secondary flight feathers. Fort Michic's ruins, below, still dominate the landscape. j. * X T-' i, HONS 062936 41 Many young terns died from ex* posurc, starvation, or both. A major rohlcm in the Reid of population iology is determining the produc tivity of a species under a variety of environmental conditions, favorable and unfavorable. The colony on Great Gull Island appeared to dc an appropriate site to study this prob lem in relation to terns because the island's size, seventeen acres, was mall enough to permit a daily checking of all nesting areas. Daily coverage of the nesting grounds permitted large numbers of young terns to be marked at hatch ing, then followed with relative ease up to the time of fledging and de parture from the colony, studies of survival and mortality of both spe cies of terns were begun in 1969. "Hie number of field workers in creased each weekend with the arri val of volunteers from the Museum. To avoid exposing the eggs and the young terns to the midday sun. all work in the colony was carried out whenever temperatures were favor able, usually in the early morning or late afternoon. The terns in variably put up a vigorous defense. Working in a tern colonv is strictly a "hard hat" job, since the terns do not hesitate to strike unsuspecting heads with formidable force ana very sharp beaks. Usually several workers would traverse an area to gether, looking for new nests and young birds. At hatching in 1969, more than 2,000 young tern* were examined and marked with temporary plastic hands. Of these, one voung com mon tern was found with an abnor mal bill and an upper mandible crossed over its lower. Then, two young roseate terns were found, which appeared normal, but which were missing flight feathers in both wings. We noted these deformities, but the flight feathers of the rose ttes appeared to be growing again. In a sample as large as 2,000 indi viduals, a few abnormalities are to be expected, and we did not attach special significance to these. fl N H_ 1970. however, when the studv was repealed, we noted a sharp in crease, .in the. number of abnor malities. Four young roseate terns and thirtv-threc voung common terns were found with visible de fects. Some of these appeared nor mal at the time of hatching, but later, when they were between two and four weeks old, lost (heir pri mary and secondary flight feathers. Feather loss is a new phenome non' that has not been previously described, although in the past many thousands of terns have been banded in Masaachusetts, the Carib- M0NS 06293? 43 Crossed mandibles were in the held, complex research in the discovered in the colony in 1969, the first full year of the research project. This roseate tern chick, from the 1970 breeding season, was chemistry laltoratory is also neces. sary. The studies during the present I year, therefore, were carried out I with the realisation that we were dealing with a new kind of enemy foren, far different from the ravages collected when three weeks old for chemical analysis of its tissues. // of the plume hunters or the destruc tion of breeding sites. This enemy 1 foreshadowed grave consequences for the future of the terns and quite possibly for man himself. There was no doubt that we were looking at , the tip of s potentially disastrous I iceberg. , Tfria year's incidence of cross de fects among newly, hatched chirks was approximately comparable to that fit IV/0. the Ural to tic found had arT abnormal foot and leg. The second had s rudimentary upper bean, and on islands in the Pacific. mandible, which had grown out Although these birds appeared to be healthy and vigorous, they could from above its eyes. The third ap peared as if injected with air or wa not fly. Two lived as long as six ter; its skin was swollen about the weeks. Many disappeared, however, head, neck, and abdomen. The so complete observations of their fourth had no left eye and a slightly mortality rate were not possible. crossed bill. Three others had bald Thcjfeathcr loss did not seem to be spots on their bodies where feathers nrrAmnly permanent, as one "of had not developed. The loss of the young common terns found with no primary and secondary flight feathers was again observed in many of the chicks. These are flight feathers was seen flying a the kinds of effects thatrmlghl~bc month later at Milford, Com expected from a chcmicar'capanie nccticut, about 80 miles away. of Iffrcling gene reproducliondur- Other abnormalities were com* parable to those observed in human ing embryonic cell division. ' 'Added to this, in 1971 a new ab 'thalidomide babies." One chicle normality was observed in the col had underdeveloped legs and feet with almost no down, and another ony for the first time: thin-shcllcd eggs not sufficiently strong to sup had four legs. Several showed ab* port the weight of the incubating normalities m the development of the bill. One chick had extremely parent. This phenomenon is now fa* miliar to pollution biologists, ftav- mil) eyes. ing been first reported in British It was at this time that the au* peregrine falcons in the 1950s. thors combined forces and ex* nte Drown pelicans in California pcricnce in an attempt to determine have not bred successfully for a the causes of the abnormalities. Our suspicions centered on envtronmcn7 number of years because of this problem, and some of the birds of tal pollutants in Lone Island Sound, IhefltTah (ar much of the effluvia of prey in this country are suffering serious population declines for the New York and Connecticut. An invesiigailon of this type, however, same reason. Researchers in this area believe encompasses many different dis that in causedjyrimar- ciplines, and only detailed studies, over a period of time, will tell us ily hy thj DDT compound, ^DETim pollutant, a derivative of the what is actually happening to the insecticide, is only slightly poi population structure and reproduc sonous to most individual organ* tive capacity of the species affected by pollutants. In order to identify isms, but it may produce such ef fects aa shell-thinning, which lowers the pollutants that might be respon the reproductive capacity of the sible for the abnormalities observed species. DDE has been shown to produce shell-thinning under ex- perimcnlal conditions in mallard ducks, American kestrels, quails and doves. Wild species that are suffering from the thin eggshell svndromc nave also been found to He contaminated with DDE. The DDT levels wc measured in I the abnormal young terns on (7?eal Gull Island an3~Tnthe fish brought to tHjLfcbtony ay the aduitaan>1970. however, were no higher than in man?' other bird populations. Tn fact, they were lower than some. Wmlc we have no basislwr bcli^' ing that any of the DDT compounds arc responsible for the observed de formities in the young terns, we cannot rule it out as a possible cause of shell-thinning. This was not observed until 197], and we hnve not yet measured DDT levels in the 1971 specimens. < Levels of other heavy metals. 9 such as lead and cadmium, are dUff renttv being measurwl murh more data from other popu lations are accumulated, we shalT Hnot know what the expected natural levels of these elements in tern eggs Shoufp hi*, or hw la jh concentrations found. V W hat we did find were rclalively high level, of polychlorinated biphenyls, PCB'a, in the tern tissues end in Ore fait upon which the bird, feed. These compounds have a number of chemical properties similiar to DDT. Like DDT and its de rivatives, they become concentrated in the fatty tissues of animals when present in a food chain, but thev re even more stable. Used exten sively as heat-cxchange and in sulating fluids in high-voltage elec trical equipment, l'CB's are also added to paints, plastics, and rub ber to make these materials more resistant to breakdown. This prop erty of resistance to most kinds of biological and chemical degrada tion, which has mode them so use- MGNS 062936 45 ful to industry, are what make PCB'a such persistent pollutants (when released in the environment. in whkhTc!B*s werTMtoTbhds'in order to determine toxic effects, the Birds Tost feathers. The PCBTmay wrll. thrn`fnrt> h* r^jwT*iKi<. (nr the feather loss observed in the young terns on~Great Gull Island. Recent research conducted in the |PCB preparations often contain Small concentrations of compounds thfiyfe cftemlcaillv similiar to the exrrcnVelv toxic dioxins. These are (He chlorinated dibcnzolurans, and the relationship is significant be cause these dioxins have produced a high incidence of birth defects in recent experiments. Small amounts of the chemicals were injected into fertile citicken eggs, producing grossly deformed chicks of the same type wc have observed in the young turns. Obviously, much further re f search is""^>^7 before we can definitely pinpoint just what pollu tants arc responsible for what defor mities, anil wlmt the causeand-effecT relationships are. Bl important to point out that al though all the evidence ie not yet in and weighed, what is happening to the terns on Great Gull Island is of critical significance--not only to the local survival of the species, but quite possibly to humans os well. We might hypothesise that the effects of environmental pollutants, such as those mentioned, would be detected first in the tern colony. Long Island Sound is one of the more polluted areas of the world's oceans, a distinction it shares with the Baltic, the .Mediterranean, and the southern California coastal wa ters. And the effects of chemical pollutants could he expected to ap[M'ur first in u .Hprciir* that is rela tively high on the food clwin, esjw-f chilly one that preys upon fish. 46 Not all the pregnant women who ingested thaliaomide gave birth to defective children. Rather, the in cidence of defects was significantly increased. We could assume that environmental chemicals producing compurable effects would behave similarly and that their presence would not mean that all individuals would be equally affected. A nor mal-looking individual might have a higher concentration of certain pol lutants than one with four legs. Consequently, many thousands of young must be examined to detect the first effects of pollutants build ing up in a population of any spe cies. It is probable that as the levels of harmful pollutants increase in a population, more individuals will show adverse effects. But only con tinued work will verify this. In addition, high priority should be given to a detailed study of the pollutants now present in the wa ters of Long Island Sound. AU of these, we must emphasize, are waste products. Normally, the waste prod ucts within an ecosystem are re cycled, used again and again. Thus the tissues of a dead bird gradually re converted into elementary mate rial. Carbon dioxide re-enters the atmosphere to participate once again in photosynthesis. Phosphates re-enter the water To be in corporated once again into phyto plankton, from which they pass into sooplankton, then up the food chain through fish to terns, and ao on. Technological man has made two fundamental changes in this natural process. Dy mining vast amounts of certain heavy metals and salts, such as phosphates, (he mobilization has been greatly increased. When these become waste products in excessive amounts, the threshold of harm to certain species is passed. Alggsome of the new synthetic chemicals are rcUTWcly resistant to breakdown. ami so more readily build up to concentrations harmful to a great many more species. If our priorities are rearranged to meet the mounting environmental and biological crises caused by the exploitation of natural systems, suf ficient warning will be needed to provide lime to eliange our tech nological direction and com mitment of natural resources. We MCNS 062939 Bouldersdumped by the Army to prevent erosion cover the island's shoreline. It was thought that this ruination of habitat would prevent the terns from reclaiming their lost colony, but they have adapted and now nett in the network of rocks. have had such warning! about air pollution, sewage in our waterways and lead poisoning, for example, and some measures are being taken to correct these threats to human health and well-being. Now the terns on Great Gull Island are is suing a warning through their piti ful deformities and threatened sur vival. Thai seventeen-acre island that ia home to the colonv occupies a strategic position analogous to when it served as a military outpost. The terns occupying the approaches to New York City are now inadvert ently detecting a newer, more in sidious enemy to man: con taminants. Presently disturbing the reproduction of the terns, these contaminants may, somednv soon, result in an increase in the numbers of human birth defects as thev work up through the food chain to the ul timate consumer. Fort Midiie. now in ruins, may yet provide us with an early warning against encroaching danger. As we go to press, verified re ports of significant feather toss among chicks in tern colonies in Massachusetts; Jones Reach. Nett' York; and the Drv Torlogos. off Florida, hate been received. The scope of the disaster is broadening. IqUJs' \3ul/ li-