Search

Remote sensing has long been used to study wildlife; however, manual methods of detecting wildlife in aerial imagery are often time-consuming and prone to human error, and newer computer vision techniques have not yet been extensively applied to wildlife surveys. We used the object-based image analysis (OBIA) software eCognition to detect laughing gull (Leucophaeus atricilla) nests in Jamaica Bay as part of an ongoing monitoring effort at the John F. Kennedy International Airport. Our technique uses a combination of high resolution 4-band aerial imagery captured via manned aircraft with a multispectral UltraCam Falcon M2 camera, LiDAR point cloud data, and land cover data derived from a bathymetric LiDAR point cloud to classify and extract laughing gull nests. Our ruleset uses the site (topographic position of nest objects), tone (spectral characteristic of nest objects), shape, size, and association (nearby objects commonly found with the objects of interest that help identify them) elements of image interpretation, as well as NDVI and a sublevel object examination to classify and extract nests. The ruleset achieves a producer’s accuracy of 98% as well as a user’s accuracy of 65% and a kappa of 0.696, indicating that it extracts a majority of the nests in the imagery while reducing errors of commission to only 35% of the final results. The remaining errors of commission are difficult for the software to differentiate without also impacting the number of nests successfully extracted and are best addressed by a manual verification of output results as part of a semi-automated workflow in which the OBIA is used to complete the initial search of the imagery and the results are then systematically verified by the user to remove errors. This eliminates the need to manually search entire sets of imagery for nests, resulting in a much more efficient and less error prone methodology than previous unassisted image interpretation techniques. Because of the extensibility of OBIA software and the increasing availability of imagery due to small unmanned aircraft systems (sUAS), our methodology and its benefits have great potential for adaptation to other species surveyed using aerial imagery to enhance wildlife population monitoring.

Plastic pollution is increasingly recognised as a global problem. In particular. plastic pieces <5 min in si, e emicroplastics') are of interest due to their prevalence and association with hannful. persistent organic pollutants (POPs). Very little is known about the pirvalence of microplasties in coastal birds. Yet. these water-associated birds are at a high risk of ingesting microplastics that accumulate near the water's surface. This study describes the niicroplastics found in the proventriculus and sentriculus of four species of coastal birds regarding quantity, size. type (fiber or fragment). and color (light. mid. or dark). A total of 643 microplastic particles were identified. with 43 of the 44 study specimens containing inicroplastics (97.7% frequency). The 'fiber' type and the inid' color were the' most common microplastics. There were no significant differences between species for particle sizes. but Brown Pelicans contained significantly more particles than the other three species. These results highlight the prevalence of plastic pollution in medium-sized seabirds. bul more work is needed to determine microplastic patterns between laxa and RN·aging environments. [ABSTRACT FROM AUTHOR]

In many seabird and waterbird species, salinity can impose physiological stress on recently hatched chicks because they have a limited capacity to excrete salt loads. In response, parents can select low‐salt food for their nestlings in the first stage of their growth. We determined the growth‐related variation in the diet of laughing gull Leucophaeus atricilla nestlings by using stable isotope analysis of feathers. Isotopic measurement of hatchling down reflects the mother's diet before laying eggs. At the same time, the primary feather tip indicates the food intake during the initiation of feather growth (one week of age), and the primary feather base indicates the food provided by parents during the period immediately before fledging. δ15N and δ13C values among the feather types showed a spatiotemporal shift in the nestlings' diet. Younger chicks consumed more terrestrial prey sources (weevil beetles Sphenophorus sp.; ~51%) than chicks at fledging (~2%). However, fledging chicks and females before egg‐laying consumed mostly marine prey sources (Pacific white shrimp Litopenaeus vannamei and anchovy Anchoa sp.; > 90%). The base and primary tip portions had similar δ15N values, but both sections were less enriched than the hatchling down. This change was diet‐related, as the nestlings showed a lower percentage of anchovy consumption (13.3–14.7%) compared to females before egg‐laying (30.4%). Younger chicks had a different spatial niche than fledglings and females before egg‐laying, indicating a diet shift through the chick growth period. Assuming that the availability of food in the terrestrial or marine foraging areas did not vary through the nestlings' growth period (five weeks), our findings support food resource selectivity by parents for their offspring during the first days of life, to reduce the physiological stress caused by high salt loads. [ABSTRACT FROM AUTHOR]

Delaware Bay, US is the only documented location where influenza A virus (IAV) is consistently detected in a shorebird species, the Ruddy Turnstone (RUTU; Arenaria interpres morinella). Although IAV in shorebirds has been well studied at this site for decades, the importance of other species in the avian community as potential sources for the IAVs that infect RUTUs each spring remains unclear. We determined the susceptibility of Mallards (Anas platyrhynchos) and Laughing Gulls (Leucophaeus atricilla), to IAVs isolated from RUTUs in order to gain insight into the potential host range of these viruses. Captive-reared gulls were challenged with RUTU-origin H6N1, H10N7, H11N9, H12N4, and H13N6 IAV, as well as Mallard-origin H6N1 and H11N9. We challenged captive-reared Mallards with the same viruses, except for H13N6. At a biologically plausible challenge dose (104 50% embryo infective doses/0.1 mL), one of five gulls challenged with both H6N1 IAVs shed virus. The remaining gulls were resistant to infection with all viruses. In contrast, all Mallards were infected and shed virus. The H12N4 Mallard challenge group was an exception with no birds infected. These results indicated that Mallards are permissive to infection with viruses originating from a shorebird host and that interspecies transmission could occur. In contrast, host adaptation of IAVs to RUTUs may compromise their ability to be transmitted back to gulls. [ABSTRACT FROM AUTHOR]

We evaluated bird and small mammal use of two mowed (15 to 25 cm height) and two unmowed vegetation plots (40 to 88 ha) at John F. Kennedy International Airport (JFKIA), New York, in 1998 to 1999 to determine which management strategy would best reduce wildlife use of the airport. We counted more birds per 5- minute observation period in unmowed plots than mowed plots in both 1998 (9.0 versus 7.9) and 1999 (11.7 versus 8.6). Maximum vegetation height was greater (P

Scoping studies were designed to determine if double-crested cormorants ( Phalacocorax auritus ), laughing gulls ( Leucophaues atricilla ), homing pigeons ( Columba livia ) and western sandpipers ( Calidris mauri ) that were gavaged with a mixture of artificially weathered MC252 oil and food for either a single day or 4–5 consecutive days showed signs of oil toxicity. Where volume allowed, samples were collected for hematology, plasma protein electrophoresis, clinical chemistry and electrolytes, oxidative stress and organ weigh changes. Double-crested cormorants, laughing gulls and western sandpipers all excreted oil within 30 min of dose, while pigeons regurgitated within less than one hour of dosing. There were species differences in the effectiveness of the dosing technique, with double-crested cormorants having the greatest number of responsive endpoints at the completion of the trial. Statistically significant changes in packed cell volume, white cell counts, alkaline phosphatase, alanine aminotransferase, creatine phosphokinase, gamma glutamyl transferase, uric acid, chloride, sodium, potassium, calcium, total glutathione, glutathione disulfide, reduced glutathione, spleen and liver weights were measured in double-crested cormorants. Homing pigeons had statistically significant changes in creatine phosphokinase, total glutathione, glutathione disulfide, reduced glutathione and Trolox equivalents. Laughing gulls exhibited statistically significant decreases in spleen and kidney weight, and no changes were observed in any measurement endpoints tested in western sandpipers. [ABSTRACT FROM AUTHOR]

During the Deepwater Horizon Natural Resource Damage Assessment, gross morphologic cardiac abnormalities, including softer, more distensible musculature, were noted upon gross necropsy in hearts from laughing gulls and double-crested cormorants exposed to weathered MC252 crude oil. A species specific, echocardiographic technique was developed for antemortem evaluation of function that was used to evaluate and better characterize cardiac dysfunction. Control (n=12) and treated (n=13) cormorant groups of similar sex-ratio and ages were dermally treated with approximately 13 ml of water or weathered MC252 crude oil, respectively, every 3 days for 6 dosages. This resulted in a low to moderate external exposure. Upon visualization and clinical assessment of the hearts of all test subjects, comprehensive diagnostic cardiographic measurements were taken twice, prior to oil application and after a 21 day dermal oil exposure. Oil-treated birds showed a decrease in cardiac systolic function, as characterized by an increased left ventricular internal dimension-systole and left ventricular stroke volume as well as concurrent decreased left ventricular ejection fraction and left ventricular fractional shortening when compared to both control birds’ and the treated birds’ time zero values. These changes are indicative of a possible dilative cardiomyopathy induced by oil exposure, although further elucidation of possible collagen damage is recommended. Arrhythmias including tachycardia in two treated birds and bradycardia in all treated birds were documented, indicating further clinically significant abnormalities induced by MC252 oil that warrant further investigation. A statistically significant increase in free calcium concentration, important to muscular and neurologic function in treated birds was also noted. This study documents that weathered MC252 oil caused clinically significant cardiac dysfunction that could result in mortality and decrease recruitment. [ABSTRACT FROM AUTHOR]

The explosion of the Deepwater Horizon oil rig released, millions of gallons of oil into the environment, subsequently exposing wildlife, including numerous bird species. To determine the effects of MC252 oil to species relevant to the Gulf of Mexico, studies were done examining multiple exposure scenarios and doses. In this study, laughing gulls ( Leucophaeus atricilla , LAGU) were offered fish injected with MC252 oil at target doses of 5 or 10 mL/kg bw per day. Dosing continued for 27 days. Of the adult, mixed-sex LAGUs used in the present study, ten of 20 oil exposed LAGUs survived to the end of the study; a total of 10 of the oil exposed LAGUs died or were euthanized within 20 days of initiation of the study. Endpoints associated with oxidative stress, hepatic total glutathione (tGSH), oxidized glutathione (GSSG) and reduced glutathione (rGSH) significantly increased as mean dose of oil increased, while the rGSH:GSSG ratio showed a non-significant negative trend with oil dose. A significant increase in 3-methyl histidine was found in oil exposed birds when compared to controls indicative of muscle wastage and may have been associated with the gross observation of diminished structural integrity in cardiac tissue. Consistent with previous oil dosing studies in birds, significant changes in liver, spleen, and kidney weight when normalized to body weight were observed. These studies indicate that mortality in response to oil dosing is relatively common and the mortality exhibited by the gulls is consistent with previous studies examining oil toxicity. Whether survival effects in the gull study were associated with weight loss, physiologic effects of oil toxicity, or a behavioral response that led the birds to reject the dosed fish is unknown. [ABSTRACT FROM AUTHOR]

Copyright of Avian Diseases is the property of American Association of Avian Pathologists, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article reports on rare birds sighted across Colorado between June and July 2014. Topics include rare species reported nesting in unusual places including Red-necked Grebe, Acorn Woodpecker, and Pacific Wren, the sighting of adult and young Cattle Egrets at Walden Reserve, and an adult Laughing Gull seen at Ball Reserve.

The article discusses a survey of the seabird colonies in the small islands of Bahía Santa Marí-La Reforma, Sinaloa, Mexico during the breeding seasons from 2010 to 2012. The survey showed that Bahia Santa María had the largest breeding colonies for Laughing Gull, Royal Tern and Black Skimmer while colonies on El Rancho increased due to increased habitat availability. For reasons unknown, decrease was noted on Brown Pelican population breeding in mangrove islands.

From March 29 to July 8, 2012, in Ensenada de La Paz, southern Baja California Peninsula, we observed at least six individuals of the Roseate Spoonbill (Platalea ajaja), three adults and three subadults (maximum counts), and from April 29 to July 28, we observed two adults of the Wood Stork (Mycteria americana, seen at the same time). These records represent the longest period of stay in the area for both species. Additionally, in June 16, we found 30 adults and 13 chicks of the Laughing Gull (Leucophaeus atricilla), 70 adults and 15 chicks of the Caspian Tern (Hydroprogne caspia), and 120 adults and one chick of the Black Skimmer (Rynchops niger) in artificial islands in the water inlet. In San Gabriel bay of the Espíritu Santo Island, located in La Paz Bay, we found 700 adults and 600 chicks of the Magnificent Frigatebird (Fregata magnificens). These observations are new to the area and expand the nesting range of the last four species mentioned above. The results described show the need for continuous monitoring of the bird community structure of La Paz Bay. [ABSTRACT FROM AUTHOR]

The Deepwater Horizon oil spill was an ecologically devastating event in the Gulf of Mexico, which saw the estimated release of over 4 million barrels of oil after flowing for three months in 2010. The US Fish and Wildlife Service provided a data set of 7,229 bird records. We aimed to illustrate the important features of the data set utilizing a blend of analytics and graphics executed through traditional and cloud-based software. It is concluded from the graphs that the areas containing the greatest concentration of birds were nearest to the coasts adjacent to New Orleans and the Deepwater platform. Moreover, the result of the logistic regression confirmed what is seen in bar charts, that the Laughing Gull and Brown Pelican, among many others, were most mortally impacted by the oil spill. Furthermore, additional investigation into the morbidity impact on birds over time indicates a lagging effect. A similar lag is present in the oiling of the birds where a separate time series shows the oiled/not visibly oiled birds alternating in frequency over the collection period. [ABSTRACT FROM AUTHOR]

The article focuses on the highlights of the 68th report of the Colorado Bird Records Committee (CBRC) which covers the period July 2005 to June 2013. Topics discussed include state records of Sandwich Tern and Hoary Redpoll, the San Luis Valley record of Laughing Gull and the first county records for Neotropic Cormorant, Band-tailed Pigeon and Carolina Wren. Members of the CBRC who voted on the reports include John Drummond, Doug Faulkner and Bill Maynard.

The article presents a study on the foraging habitat of four gull species, including laughing gulls, herring gulls, and ring-billed gulls, at the coastal-urban boundaries in New York City area. It mentions that dietary analysis was done through autopsy of the stomach contents of the four gull species. The study found that laughing and herring gulls mainly foraged from marine foods while ring-billed gulls were generalists.

The article discusses bird sightings for summer 2012, June-July, in Colorado. One defining characteristic of the summer was a mass movement of Dickcissels west to the edge of the mountains. There were also many rarities enjoyed during the period, including a Black-chinned Sparrow at Devil's Kitchen in Colorado National Monument, a Royal Tern at Barr Lake, two Reddish Egrets and two Laughing Gulls in southeastern Colorado, and a family of Acorn Woodpeckers in Pueblo County.

Despite extensive studies of methylmercury (MeHg) toxicity in birds, molecular effects on birds are poorly characterized. To improve our understanding of toxicity pathways and identify novel indicators of avian exposure to Hg, the authors investigated genomic changes, glutathione status, and oxidative status indicators in liver from laughing gull ( Larus atricilla) hatchlings that were exposed in ovo to MeHg (0.05-1.6 µg/g). Genes involved in the transsulfuration pathway, iron transport and storage, thyroid-hormone related processes, and cellular respiration were identified by suppression subtractive hybridization as differentially expressed. Quantitative polymerase chain reaction (qPCR) identified statistically significant effects of Hg on cytochrome C oxidase subunits I and II, transferrin, and methionine adenosyltransferase RNA expression. Glutathione- S-transferase activity and protein-bound sulfhydryl levels decreased, whereas glucose-6-phosphate dehydrogenase activity increased dose-dependently. Total sulfhydryl concentrations were significantly lower at 0.4 µg/g Hg than in controls. Together, these endpoints provided some evidence of compensatory effects, but little indication of oxidative damage at the tested doses, and suggest that sequestration of Hg through various pathways may be important for minimizing toxicity in laughing gulls. This is the first study to describe the genomic response of an avian species to Hg. Laughing gulls are among the less sensitive avian species with regard to Hg toxicity, and their ability to prevent hepatic oxidative stress may be important for surviving levels of MeHg exposures at which other species succumb. Environ. Toxicol. Chem. 2012; 31: 2588-2596. © 2012 SETAC [ABSTRACT FROM AUTHOR]

The Laughing Gull (Leucophaeus atricilla) was extripated as a breeding bird from New York State by 1900. Recolonization of coastal New York by this colonial waterbird occurred in 1979 with discovery of 15 breeding pairs in Jamaica Bay (Queens County) New York, New York. We conducted a survey of Long Island salt marsh habitats in 2008 to document if other breeding colonies of Laughing Gulls existed. We identified 66 individual possible breeding areas and field surveys were conducted in each area during June 2008. Many areas appeared to provide suitable nesting habitat (i.e., large areas of salt marsh dominated by Spartina), but no evidence of Laughing Gull nesting was found. A better understanding of Laughing Gull populations within the northeast coastal region and the effects of ongoing gull control near New York airports is needed for their conservation. [ABSTRACT FROM AUTHOR]

Laughing gulls (Larus atricilla) are commonly found in many areas of North America and little is known about their diet, particularly in coastal-urban interfaces where gull-aircraft collisions can be a serious concern. The objective of this study was to describe and quantify the consumption of terrestrial invertebrates by laughing gulls at a coastal-urban interface in the northeastern United States. We examined the stomach contents of laughing gulls (n = 1053) collected during wildlife damage management operations at John F. Kennedy International Airport during the summers of 2003 and 2004. Terrestrial invertebrates consumed by laughing gulls represented 2 taxonomic phyla, 4 classes, 15 orders and 40 families. Beetles (Coleoptera) and ants (Hymenoptera) were the most common terrestrial invertebrates consumed by laughing gulls. We found evidence of temporal (i.e., monthly) variation in the frequency of occurrence of terrestrial insects in laughing gull diets. Laughing gull gender and age did not influence the frequency of occurrence of terrestrial insects in gull diets. Terrestrial environments (e.g., areas of turfgrass) appear to provide important foraging locations and food resources for laughing gulls in coastal-urban areas. This information is important for developing effective management approaches to reduce human-gull conflicts, such as gull-aircraft collisions at coastal airports. [ABSTRACT FROM AUTHOR]

The article discusses a study that was conducted in South Carolina between 2006 and 2007 concerning seabird attendance at shrimp trawlers in nearshore waters. The study procedure included seabird surveys that were conducted at several fishing vessels including Cape Romain, Miss Georgia, and Winds of Fortune. Analyses were focused on several types of birds including Sandwich terns, Laughing Gulls, and Brown Pelicans. The relationship between the abundance of species and variables was evaluated using a model selection approach and generalized linear models.

Methylmercury is the predominant chemical form of mercury reported in the eggs of wild birds, and the embryo is the most sensitive life stage to methylmercury toxicity. Protective guidelines have been based mainly on captive-breeding studies with chickens (Gallus gallus), mallards (Anas platyrhynchos), and ring-necked pheasants (Phasianus colchicus) or on field studies where whole eggs were collected and analyzed and the effects of the mercury were measured based on the reproductive success of the remaining eggs. However, both of these methods have limitations. As an alternative, we developed a technique that involves extracting a small sample of albumen from a live egg, sealing the egg, returning the egg to its nest to be naturally incubated by the parents, and then relating the hatching success of this microsampled egg to its mercury concentration. After first developing this technique in the laboratory using chicken and mallard eggs, we selected the laughing gull (Larus atricilla) and black-necked stilt (Himantopus mexicanus) as test subjects in the field. We found that 92% of the microsampled laughing gull eggs met our reproductive endpoint of survival to the beginning of hatching compared to 100% for the paired control eggs within the same nests. Microsampled black-necked stilt eggs exhibited 100% hatching success compared to 93% for the paired control eggs. Our results indicate that microsampling is an effective tool for nonlethally sampling mercury concentrations in eggs and, as such, can be used for monitoring sensitive species, as well as for improving studies that examine the effects of mercury on avian reproduction. [ABSTRACT FROM AUTHOR]

The article explains the differences between the bird species, Laughing and Franklin's Gulls. Laughing Gulls do not breed in the state of Connecticut, but in late summer and early fall birds from nearby breeding colonies. Franklin Gulls, meanwhile, are an abundant breeding gull of the midwestern prairies. In flight, Laughing Gulls have black primaries that blend right into the gray wings and small white primary mirrors while Franklin's have black-wingtips that are isolated from the gray wings by a white band and have large white mirrors.

During the 1980s, the exponential growth of laughing gull (Larus atricilla) colonies, from 15 to about 7600 nests in 1990, in the Jamaica Bay Wildlife Refuge and a correlated increase in the bird-strike rate at nearby John F. Kennedy International Airport (New York City) led to a controversy between wildlife and airport managers over the elimination of the colonies. In this paper, we review data to evaluate if: (1) the colonies have increased the level of risk to the flying public; (2) on-colony population control would reduce the presence of gulls, and subsequently bird strikes, at the airport; and (3) all on-airport management alternatives have been adequately implemented. Since 1979, most (2987, 87%) of the 3444 bird strikes (number of aircraft struck) were actually bird carcasses found near runways (cause of death unknown but assumed to be bird strikes by definition). Of the 457 pilot-reported strikes (mean = 23 ± 6 aircraft/yr, N= 20 years), 78 (17%) involved laughing gulls. Since a gull-shooting program was initiated on airport property in 1991, over 50,000 adult laughing gulls have been killed and the number of reported bird strikes involving laughing gulls has declined from 6.9 ± 2.9 (1983–1990) to 2.6 ± 1.3 (1991–1998) aircraft/yr; nongull reported bird strikes, however, have more than doubled (6.4 ± 2.6, 1983–1990; 14.9 ± 5.1, 1991–1998). We found no evidence to indicate that on-colony management would yield a reduction of bird strikes at Kennedy Airport. Dietary and mark–recapture studies suggest that 60%–90% of the laughing gulls collected on-airport were either failed breeders and/or nonbreeding birds. We argue that the Jamaica Bay laughing gull colonies, the only ones in New York State, should not be managed at least until all on-airport management alternatives have been properly implemented and demonstrated to be ineffective at reducing bird strikes, including habitat alterations and increasing the capability of the bird control unit to eliminate bird flocks on-airport using nonlethal bird dispersal techniques. Because the gull-shooting program may be resulting in a nonsustainable regional population of laughing gulls (>30% decline), we also recommend that attempts be made to initiate an experimental colony elsewhere on Long Island to determine if colony relocation is a feasible management option. [ABSTRACT FROM AUTHOR]

Presents the results of a study on intraspecific learning by laughing gull chicks. Role of visual identification in intraspecific recognition; Acoustic recognition; Innate and maturational preferences; Visual learning.

The presence of seabirds was related to offshore surface eddies and the freshwater plume of the Mississippi River in the northern Gulf of Mexico during autumn, winter, spring, and summer 1992–1993. Skuas (Stercorarius spp.) were the most common bird seen in autumn, whereas skuas and gulls (Larus spp.) were the most common in winter. Few birds were seen in the spring, and terns (Sterna spp.) were the most common birds seen in late summer. During summer, terns were associated with the freshwater plume of the Mississippi River. In the winter, herring (Larus argentatus) and laughing gulls (L. artricilla) were associated with areas with steep thermoclines, while pomarine skuas (Stercorarius pomarinus) were found in areas of low productivity. Herring and laughing gulls in the winter, all birds in the spring, and terns in the summer were more common outside eddies. Only pomarine skuas in the winter were seen more commonly inside warm-core eddies. [ABSTRACT FROM PUBLISHER]

1. The nesting strategy as determined by nonrandom variation in environmental features at laughing gull (Larus atricilla) nests in a salt marsh was studied (Fig. 3). Gulls tended to nest on mats in tall grass that grows on low ground (just above high tides) near water (Figs. 4-7). Grass height was inversely related to ground elevation and distance to water (Fig. 8). Throughout the season, gulls selected nest sites in grass about 35 cm in height; due to continued grass growth, early breeders had taller grass around nests (Fig. 9). Pairs in the colony center nested earlier and in taller grass than pairs in a peripheral area. 2. Mats apparently stabilize nests during flooding, and by settling on mats gulls may conserve energy in the collection of nest material. Tall grass around nests afforded chicks protection from predators and weather, and held floating nests in place during flooding. 3. Gulls spend about 4 weeks (two spring tidal cycles) on the nesting grounds before egg laying. During this time they perform virtually no nest building and probably gain important information about nest site suitability. 4. Tidal flooding, the greatest threat to reproductive success destroying 70-100% of the nests in the colony occurred on average once every 2 years over 10 years. Floods occurred during spring tides accompanied by sustained NE winds. 5. Following a flood that destroyed 70% of the nests in the colony, it was shown that a significantly greater proportion of successful pairs nested on mats and in significantly taller grass than unsuccessful pairs. Grass height, especially that on the SW side of the nest, was the most important predictor of success during flooding. 6. More pairs in the central area were successful than those in the peripheral one: the result of nesting in taller grass and the greater protection of the central area from tides and winds. Though not differing among successful and unsuccessful nesters, females in the peripheral area laid smaller eggs and clutches, and laid later than females in the central area (over 3 years), suggesting that females in the peripheral area were on average younger than females in the central area. It was speculated that, on average, younger pairs will experience during flooding lower reproductive success as a result of nesting inexperience and nesting in suboptimal habitat. The smaller reproductive investments of younger pairs in eggs and clutches can be interpreted as an adaptation to conserve energy during a period of the life cycle when new behavioral adjustments and nesting areas are being explored. [ABSTRACT FROM AUTHOR]