Tern Eggs Research Articles

Polychlorinated -dibenzo-p-dioxins/furans and -dioxin-like biphenyls in eggs of common terns from lime island, St. Mary's river, Michigan, USA

Population collapse of common tern (Sterna hirundo) from Lime Island in the St. Mary's River, Michigan, USA were related to the 2,3,7,8-chlorine substituted dioxins, furans, dioxin-like PCBs, and other possible factors using unhatch egg target contaminant analysis. The most toxic congeners, 2,3,7,8-TCDD/DF was found in all samples at noticeable concentrations. Magnitude of sum 2,3,7,8-PCDD/DFs were within the range of 39–93 pg/g wet wt. Dioxin-like PCBs were within the range of 360–1230 ng/g wet wt. Great Toxic Equivalent Quantity (TEQ) contributions by 2,3,7,8-TCDF, 2,3,4,7,8-PeCDF, 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, and dioxin-like PCBs such as CB-77, CB-126 and CB-105 are considered greatly due to their influence of poor embryo development and consequent damage of embryos of common terns in egg injection studies. However, other organochlorines, heavy metals, and/or synergistic effects also taken in to account. On the whole, TEQs in the tern eggs were greater than the Lowest-Observable-Adverse Effect Level (LOAEL) for bald eagle (Haliaeetus leucocephalus) embryos observed in British Columbia, Canada. Concentrations of dioxin-like PCBs, dioxins, furans in the St. Mary's River food chain are at levels for concern for nesting colonial waterbirds. Eventually, the possible movements of analyzed chemicals downstream from a man-made flood event are discussed.

Spatial and temporal patterns in metal levels in eggs of common terns ( Sterna hirundo) in New Jersey

Seabirds are excellent subjects for examination of metals because they feed at different trophic levels, including as top-level piscivores, they are long-lived, and many are abundant and widely distributed. In this paper we examine the levels of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in eggs from common terns ( Sterna hirundo) nesting on five saltmarsh islands in Barnegat Bay, New Jersey from 2000 to 2002. We test the null hypothesis that there were no locational or temporal differences from 2000 to 2002. There were significant locational differences in all metals in some years, although the differences were not large. The levels of most metals do not seem sufficiently high to cause adverse effects, although the levels of mercury in eggs of some common terns from the bay are within the range known to cause adverse effects. Mercury in common tern eggs may be a contributing cause to their local decline.

Mercury and selenium levels in eggs of common terns (Sterna hirundo) from two breeding colonies in the Ebro Delta, Spain.

Mercury and selenium levels in eggs of common terns (Sterna hirundo) from two breeding colonies in the Ebro Delta, Spain.

Maternal steroids and contaminants in common tern eggs: a mechanism of endocrine disruption?

We looked for evidence for the hypothesis that exposure of female birds to polychlorinated biphenyls (PCBs) results in alteration of blood steroid hormone concentrations and alters subsequent hormone transfer of steroids to eggs. Eggs of three-egg clutches were collected from a PCB-exposed common tern ( Sterna hirundo) colony (Ram Island, Buzzards Bay, MA, USA) and from a relatively clean colony (Bodkin Island, Chesapeake Bay, MD, USA), and were analyzed for concentrations of organochlorine contaminants and steroid hormones (17β-estradiol, 5α-dihydrotestosterone, testosterone and androstenedione). There was no relationship between total PCBs and steroid concentrations considering all eggs together, considering eggs of different laying order or considering differences between sequentially laid eggs in a clutch. Similarly, concentrations of di- and tri-chlorinated biphenyls and steroids in eggs were not related. The concentrations of PCBs, mercury and selenium were below estimated thresholds for toxicity to embryos. Maternal steroids, except estradiol, were present in yolk of all eggs, with increasing concentrations in the second and third eggs laid. Our data provided no evidence for a maternal toxicological event that might alter the amount of maternal steroid hormone transferred to eggs.

Contaminants in Eggs of Western Snowy Plovers and California Least Terns: Is There a Link to Population Decline?

Contaminants in Eggs of Western Snowy Plovers and California Least Terns: Is There a Link to Population Decline?

Organochlorine and mercury contamination of little terns ( Sterna albifrons) breeding at the western Baltic Sea, 1978–96

Between 1978 and 1996, egg and chick samples of little terns ( Sterna albifrons) breeding at different colony sites along the eastern coast of Schleswig-Holstein, Germany, were annually gathered by chance in the framework of a long-term ringing programme. Analyses of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), hexachlorobenzene (HCB), hexachlorocyclohexane (HCHs), and mercury were carried out on eggs, chicks, and down (only mercury). In all matrices, pollutant concentrations decreased over the 19-year period. The mixture compositions of ΣPCB, ΣDDT, and ΣHCH changed during the previous decades indicating decreasing releases of PCB mixtures, DDT, and technical HCH mixtures. The pollutant concentrations currently found in the tern eggs are compared with those of other bird species from other Baltic Sea subregions, suggesting a relatively low pollution of the Belt Sea. The temporal trends in contamination are related to international measurements and conventions on bans of pollutants. Since individually known females were recaptured up to three times, inter-individual variation in pollutant burdens could be studied. Remarkable variation among individuals as well as between breeding seasons were found that were not explainable by general temporal trends. Influences of individually and seasonally varying feeding habits on this phenomenon are discussed. Compositions of individual PCB mixtures varied in relation to total PCB concentrations found in eggs suggesting a concentration-dependent metabolization of PCBs as with other species. Amounts of particular organochlorines varied between matrices possibly indicating metabolization of low chlorinated PCBs, β-HCH, and HCB during embryogenesis. In mercury, body detoxification via down is assumed. As indicated by eggshell parameters (thickness and index) being not related to organochlorine concentrations and being similar to that found in historical studies, respectively, effects of recent organochlorine contamination on eggshell thickness seem to be improbable. In conclusion, influences of contamination on declining little tern stocks observed in Germany are discussed. Negative influences of contamination in the 1960s and 1970s are assumed to be probable.

Contaminants in Eggs of Western Snowy Plovers and California Least Terns: Is There a Link to Population Decline?

Environmental contaminants may have adverse effects on avian reproduction and may be contributing to declines of avian species nesting along the southern California Coast. Examples of impaired reproduction caused by organochlorine pesticides, PCBs, and elements such as mercury (Hg) and selenium (Se) include delayed ovulation, reduced egg production, defective eggshells, decreased hatchability, embryotoxicosis, aberrant incubation behavior, and mortality of chicks and adults (Heinz 1976; Blus 1982; Ohlendorf et al. 1986).

Predation and breeding success in roseate terns (Sterna dougallii)

Predation limits the breeding success of many colonial seabirds and is a major factor in the decline of a number of marine bird species. The goal of our study was to determine how predation affects the breeding success of threatened roseate terns (Sterna dougallii) nesting on Country Island, Nova Scotia, Canada. This site is one of only three Canadian breeding colonies and the first to be systematically studied. Forty-five pairs of roseate terns, 330 pairs of arctic terns (Sterna paradisaea), and 130 pairs of common terns (Sterna hirundo) nested at this colony in 1996. Predation was the most important source of egg and chick mortality for roseate terns on Country Island. Twenty-four percent (18/75 eggs) of roseate tern eggs were depredated, presumably by corvids, while 77% (24/31 chicks) of roseate tern chicks were depredated by gulls. Overall, roseate terns at this site produced a maximum of 0.11 fledglings per nest. Roseate terns abandoned Country Island in 1997, presumably because of predation in 1996. We discuss the implications of our results for the long-term survival and management of the Canadian roseate tern population.

Predation and breeding success in roseate terns (<i>Sterna dougallii</i>)

Predation limits the breeding success of many colonial seabirds and is a major factor in the decline of a number of marine bird species. The goal of our study was to determine how predation affects the breeding success of threatened roseate terns (Sterna dougallii) nesting on Country Island, Nova Scotia, Canada. This site is one of only three Canadian breeding colonies and the first to be systematically studied. Forty-five pairs of roseate terns, 330 pairs of arctic terns (Sterna paradisaea), and 130 pairs of common terns (Sterna hirundo) nested at this colony in 1996. Predation was the most important source of egg and chick mortality for roseate terns on Country Island. Twenty-four percent (18/75 eggs) of roseate tern eggs were depredated, presumably by corvids, while 77% (24/31 chicks) of roseate tern chicks were depredated by gulls. Overall, roseate terns at this site produced a maximum of 0.11 fledglings per nest. Roseate terns abandoned Country Island in 1997, presumably because of predation in 1996....

Contaminants in eggs of colonial waterbirds and hepatic cytochrome P450 enzyme levels in pipped tern embryos, Washington State.

Eggs of Forster's terns (Sterna forsteri) collected in 1991 from nesting colonies on Crescent Island (Columbia River) and the Potholes Reservoir in south central Washington generally contained low residues of organochlorine pesticides and metabolites, 2,3,7, 8-tetrachlorodibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzofuran, and polychlorinated biphenyls (PCBs). Hepatic cytochrome P450 enzyme activity in pipped embryos of Forster's terns from the two colonies seemed unaffected by contaminants. At Crescent Island, examination of 23 Forster's tern eggs with large embryos (19 viable [10 pipped] and four dead [two pipped]) revealed developmental abnormalities in two viable pipped embryos (missing maxilla and deformed pelvic girdle) and a viable prepipping embryo (shortened beak). Our limited sample sizes and number of compounds analyzed preclude us from determining whether or not the abnormalities are related to contaminants. No abnormalities were noted in 10 pipped eggs (nine viable and one dead at collection) of Forster's terns collected from the Potholes Reservoir colony. Eggs of Caspian terns (Sterna caspia) collected from Crescent Island in 1991 also contained generally low residues of contaminants, only one developmental abnormality was noted, and limited data indicated that cytochrome P450 enzyme activity apparently was unaffected by contaminants. Organochlorine contaminants were generally low in addled eggs of American white pelicans (Pelecanus erythrorhynchos) collected from Crescent Island in 1994.

Sonic boom environmental impact prediction methods and issues

Concerns over the environmental impact of sonic booms include their effect on humans, other animals, and fabricated structures. Over the past few years, CAA has been involved in a number of projects focusing on the latter two concerns. Specifically, working with Hubbs Sea World to supplement previous empirical studies, an analytical model was developed for estimating the sonic boom induced response of fertilized tern eggs and evaluated the potential for damage. Working with Wyle Laboratories, Inc., both direct and reciprocal structural-acoustic testing techniques were developed for simulating structural responses in order to assess damage. These methods were validated by comparison with data from actual flyovers. Curently, with Marine Acoustics, Inc., the authors are involved in a project to assess testing and other issues associated with predicting the subsea penetration of sonic booms for assessing marine mammal impacts. Here at issue are those physical processes that may transform from second to first order in light of the evanescent attenuation of the typically subsonic, ‘‘primary’’ acoustic wave that penetrates to depth. These three projects are reviewed in this talk. Particular attention is given to idealizations in the prediction process, the associated uncertainties, and their effects on the overall impact evaluation process. [Work supported by The Armstrong Laboratory of The U.S. Air Force.]

Temporal Trends in Metal Levels in Eggs of the Endangered Roseate Tern (Sterna dougallii) in New York

Female birds sequester certain organic and inorganic compounds in their eggs which have been widely used as a bioindicator for examining the body burdens of contaminants and therefore the temporal and spatial trends of the contaminants in the environment. The same analyses can also reflect the status or vulnerability of the indicator species. Extensive bridge de-leading activities in the New York Bight (Cape May to Montauk) in the early 1990s coincided with a long-term study of the endangered roseate tern (Sterna dougallii) on Long Island, New York, affording the opportunity to test the utility of such fish-eating species as bioindicators of lead contamination, as well as the potential impact on the bird population itself. In this paper we test the null hypothesis that there were no temporal trends between 1989 and 1994 in metal levels in eggs of roseate terns nesting at Cedar Beach, Long Island, where the birds have been declining since the late 1980s. We report levels and trends for cadmium, chromium, manganese, mercury, and selenium as well as lead in abandoned eggs collected each year. There were significant interyear differences for all metals, with 1990 to 1992 generally having higher levels than 1989 and 1994. The yearly differences were particularly prominent for lead, where the 10-fold increase may have been partially due to the increased removal of leaded paint from bridges in the early 1990s, leading to increased lead in the aquatic environment. Cadmium and chromium are also released during de-leading. The causes for the higher levels in the other metals in the early 1990s are unclear. Metal levels in roseate tern eggs are several times higher than the median reported for most birds, and the possible impact on the population requires study.

Comparative developmental toxicity of planar polychlorinated biphenyl congeners in chickens, American kestrels, and common terns

AbstractThe effects of polychlorinated biphenyl (PCB) congeners, PCB 126 (3,3′,4,4′,5‐pentaCB) and PCB 77 (3,3′4,4′‐tetraCB), were examined in chicken (Gallus gallus), American kestrel (Falco sparverius), and common tern (Sterna hirundo) embryos through hatching, following air cell injections on day 4. PCB 126 caused malformations and edema in chickens starting at 0.3 ppb, in kestrels at 2.3 to 23 ppb, but in terns only at levels affecting hatching success (44 ppb). Extent of edema was most severe in chickens and least in terns. Defects of the beak were common in all species but with crossed beak most prevalent in terns. Effects on embryo growth were most apparent for PCB 126 in chickens and kestrels. The approximate 50% lethal dose (LD50) for PCB 126 in chickens was 0.4 ppb, in kestrels was 65 ppb, and in terns was 104 ppb. The approximate LD50 for PCB 77 in chickens was 2.6 ppb and in kestrels was 316 ppb. Induction of cytochrome P450 associated monooxygenase activity (ethoxyresorufin‐O‐dealkylase activity) by PCB 126 in chick embryo liver was about 800 times more responsive than in tern and at least 1,000 times more responsive than in kestrel. High concentrations of PCB 126 found in bald eagle eggs are nearly 20‐fold higher than the lowest toxic concentration tested in kestrels. Concentrations of PCB 126 causing low‐level toxic effects in common tern eggs are comparable to highest levels in common terns and Forster's terns in the field, suggesting additional involvement of other compounds in the Great Lakes.

Predation by Kelp Gulls Larus dominicanus at a mixed‐species colony of Royal Terns Sterna maxima and Cayenne Terns Sterna eurygnatha in Patagonia

We studied the predator‐prey interaction between Kelp Gulls Larus dominicanus and Royal Terns Sterna maxima and Cayenne Terns Sterna eurygnatha at Punta León, Argentina, from 1990 to 1992. Kelp Gulls were the main predator of tern eggs in all 3 years, accounting for 99% of observed predations (n = 454). A total of 99% of predations occurred on peripheral tern nests. Total predation rate on both tern species was highest in 1990 and varied significantly between years, with between 0.01 and 0.03 cases of predation per hour. Predation rates in all years were significantly higher on Cayenne than on Royal Terns probably because the latter were significantly more aggressive towards gulls than were Cayenne Terns. Royal and Cayenne Terns displayed aggressively towards gulls at least once in 64% and 10% of the observation periods, respectively. Defence behaviour, such as attacking and chasing the predator, was used more frequently by Royal than Cayenne Terns (13.2% v 3.6%). Predation on tern eggs was restricted to only a few Kelp Gulls which nested close to the tern colony periphery, and 50% of the eggs that were stolen were taken by only two pairs during 1991 and 47% by three pairs in 1992. This suggests that the current expansion of the Kelp Gull numbers at Punta León might not necessarily result in a proportional increase in predation rate on both tern species. Stealing eggs from the ground was more successful than from the air (77% v 17%). The nesting strategy shown by Royal and Cayenne Terns at Punta León appears to be an important factor which reduced the impact on their breeding success of high potential predation pressure by gulls.

Sensitivity of common tern (Sterna hirundo) embryo HepatocyteCultures to CYP1A induction and porphyrin accumulation by halogenated aromatic hydrocarbons and common tern egg extracts.

Experiments were conducted to compare the sensitivity ofprimary cultures of common tern (Sterna hirundo) and chicken(Gallus domesticus) embryo hepatocytes to cytochrome P4501A (CYP1A)induction and porphyrin accumulation after exposure to halogenated aromatichydrocarbons (HAHs) or tern egg extracts. The HAHs tested were2,3,7,8-tetrachlorodibenzo-p -dioxin (TCDD),2,3,7, 8-tetrachlorodibenzofuran (TCDF) 3,3',4,4'-tetrachlorobiphenyl (PCB 77;IUPAC nomenclature), 3,3',4,4',5-pentachlorobiphenyl (PCB 126),3, 3',4,4',5,5'-hexachlorobiphenyl (PCB 169) and Aroclor(R) 1254 (a commercialmixture of PCBs). Extracts were prepared from common tern eggs collected fromthree sites in the Great Lakes basin and one reference site on the east coastof Canada. CYP1A induction was assayed asethoxyresorufin-O-deethylase (EROD) activity and/or immunodetectableCYP1A protein, and total intracellular porphyrin accumulation was measuredfluorometrically. Unlike chicken embryo hepatocyte (CEH) cultures, nointracellular porphyrin accumulation was observed after treatment of ternembryo hepatocyte (TEH) cultures with HAHs or egg extracts. TEH cultures were approximately 50 to >1600 times less sensitive than CEH cultures to HAH-mediated CYP1Ainduction. In contrast, TEH cultures were either approximately equallysensitive or only 3.5-15 times less sensitive than CEH cultures to CYP1Ainduction mediated by tern egg extracts. These data suggest that common ternembryos may be more susceptible to the CYP1A inducing effects mediated bycomplex mixtures of environmental contaminants than indicated by theirresponse to individual HAHs.

Contaminant Concentrations in Eggs of Black Terns (Chlidonias niger) from Southern Ontario and Southern Quebec, 1989-1996

Contaminant Concentrations in Eggs of Black Terns (Chlidonias niger) from Southern Ontario and Southern Quebec, 1989-1996

An analysis of the response of Sooty Tern eggs to sonic boom overpressures

It has been hypothesized that sonic booms caused a mass hatching failure of Sooty Terns on the Dry Tortugas, FL by causing eggs to crack. In this paper the problem is analyzed using two levels of idealization. The first model represents the egg shell as a spherical elastic shell, the embryo as an inertial concentric sphere, and the albumen as an acoustic fluid that completely fills the intervening volume. The substrate is taken to provide a point support for the egg and to double the incident pressure. The second higher fidelity, numerical model accounts for the ‘‘egg shape’’ geometry and allows for an air sac. Here the substrate is modeled as a rigid boundary of infinite extent. In both cases the boom is modeled as an incident, planar N wave. Predictions are compared to each other and with the results of empirical studies previously performed by other investigators. Data from these earlier investigations were obtained with boom-like impulsive noise sources and indicate that the hypothesis that sonic booms crack eggs unlikely. [Work sponsored by Armstrong Lab., WPAFB, U.S. Air Force.]

An analysis of the response of Sooty Tern eggs to sonic boom overpressures.

It has been proposed that sonic booms caused a mass hatching failure of Sooty Terns in the Dry Tortugas in Florida by cracking the eggshells. This paper investigates this possibility analytically, complementing previous empirical studies. The sonic boom is represented as a plane-wave excitation with an N-wave time signature. Two models for the egg are employed. The first model, intended to provide insight, consists of a spherical shell, with the embryo represented as a rigid, concentric sphere and the albumen as an acoustic fluid filling the intervening volume. The substrate is modeled as a doubling of the incident pressure. The second, numerical model includes the egg-shape geometry and air sac. More importantly, the substrate is modeled as a rigid boundary of infinite extent with acoustic diffraction included. The peak shell stress, embryo acceleration, and reactive force are predicted as a function of the peak sonic boom overpressure and compared with damage criteria from the literature. The predicted peak sonic boom overpressure necessary for egg damage is much higher than documented sonic boom overpressures, even for extraordinary operational conditions. Therefore, as with previous empirical studies, it is concluded that it is unlikely that sonic boom overpressures damage avian eggs.

Aversive Conditioning to Reduce Raven Predation on California Least Tern Eggs

Aversive Conditioning to Reduce Raven Predation on California Least Tern Eggs

Organochlorine Contaminant Levels in Waterbird Species from Hamilton Harbour, Lake Ontario: an IJC Area of Concern

The levels of organochlorine (OC) contaminants in eggs and tissues of waterbird species nesting in Hamilton Harbour, Ontario, an International Joint Commission Area of Concern, were monitored between 1981 and 1992. PCBs, DDE, and mirex were present at the highest concentrations of the 29 organochlorines and one trace metal measured. Most contaminants in the various species tested showed a declining temporal pattern during that period. Double-crested cormorant eggs generally had higher concentrations of contaminants than those in herring gull eggs which in turn were higher than those in eggs of black-crowned night-herons, Caspian terns and common terns. The levels of contaminants in the eggs reflect the dietary preferences of the species with the fish-eating birds containing consistently higher accumulations of contaminants when compared to the herbivorous Canada goose for which the levels were consistently much lower for all compounds. The concentrations of contaminants detected are among some of the highest in the Great Lakes but when compared to other sites on Lake Ontario, the levels in Hamilton Harbour are generally equal or lower. Elevated levels of contaminants such as PCBs, mirex, and DDE were also detected in liver and muscle tissues of migrant waterfowl species from the harbor. Despite habitat degradation and continued presence of contaminants, the harbor supports a large number and wide variety of waterbird species. Except for black-crowned night-herons, the nesting populations of colonial waterbirds have increased between 21 and 1061 % since the last survey in 1987.