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The Isles Dernieres Barrier Island Refuge in Louisiana, USA, constitutes a major colonial waterbird breeding site, and several restoration projects have been undertaken to sustain waterbird populations on the refuge. However, very little is known about food resources that colonial waterbirds depend on in the Gulf of Mexico. Royal (Thalasseus maximus) and Sandwich (T. sandvicensis) tern diet composition was investigated to determine important food resources during the breeding period. Regurgitated prey items in the 2013 and 2014 breeding seasons were used to compare diet composition, prey item frequency, and prey item mass among four groups: Royal Tern adults, Royal Tern chicks, Sandwich Tern adults, and Sandwich Tern chicks. The two most frequent prey items were Atlantic croaker (Micropogonias undulatus) and bay anchovy (Anchoa mitchilli). Royal Tern adults consumed significantly more Sciaenids than any other tern group, and Sandwich Tern adults consumed more Engraulids than any other tern group. Royal and Sandwich tern adults partitioned food resources by prey species and prey size, while chick diet showed more overlap in prey species composition. Royal and Sandwich tern diet closely reflected the species composition of trawls from nearby waters, suggesting opportunistic prey selection. The diets of both tern species contained a variety of demersal prey items indicating use of discards from local fisheries activities. Interactions between breeding waterbirds and fisheries in coastal Louisiana may be an important conservation consideration with profound implications on breeding abundance and breeding success of waterbirds.

A frequently used method to estimate diet composition is based on the identification of fish otoliths present in pellets and feces. However, whether pellets and feces provide similar unbiased estimates of the diet remains poorly understood. The diet of African Royal Terns (Thalasseus maximus albididorsalis) breeding in the Parc National du Delta du Saloum, Senegal, was studied. Prey species composition based on otoliths in freshly regurgitated pellets and a mixture of pellets and feces (excrement) accumulated near nests during the incubation period were compared. Altogether, 59 fish species were identified. Pellets contained far less prey species than excrement. Maximum diet overlap between excrement and pellets varied between 0.34 and 0.43 (mean = 0.36). Differences between minimum and maximum overlap between both sample types were small in all years. Pellets contained almost exclusively large otoliths (widths 3.0–8.5 mm), whereas excrement contained two fractions: large sized ones, identical to those present in the pellets and smaller-sized ones (0.5–3.0 mm) originating from feces. It is hypothesized that large otoliths cannot pass the intestinal tracts of the birds and are therefore regurgitated. Differences in prey species composition in pellets and excrement could potentially be explained by a combination of seasonal changes in availability of prey species and size of otoliths. Neither pellets nor feces alone give an unbiased picture of the diet of African Royal Terns.

In South America, Royal Terns (Thalasseus maximus maximus) and Cayenne Terns (Thalasseus sandvicensis eurygnathus) breed mostly in Argentina and Brazil. Royal Terns have been recorded in at least 22 locations (six in Brazil and 14 in Argentina). Cayenne Terns have been recorded in at least 38 locations (15 in Brazil and 23 in Argentina). At 15 locations, mostly located in Argentina, Royal and Cayenne terns breed in association, often with their nests intermingled. Total population size for Royal Terns was estimated in at least 750 pairs in Brazil and less than 5000 in Argentina, while that of Cayenne Tern was estimated in at least 8000 pairs in Brazil and less than 10000 in Argentina. However, lack of counts at some coastal sectors and changes among breeding sites between seasons preclude an accurate estimation of total population size for both species and make spatial management challenging. Main threats faced by their populations in both countries are human disturbance, fisheries, egging, and expanding Kelp Gull (Larus dominicanus) populations. Priority research and conservation actions are presented.

We analyzed temporal and spatial trends in annual nest counts of Brown Pelicans (Pelecanus occidentalis), Royal Terns (Sterna maxima), and Sandwich Terns (Sterna sandvicensis) throughout South Carolina from 1969 through 2005. There was an increase in the number of active pelican nests from 1969 through the mid 1980s, although this was followed by a steady decline that continued through 2005. Numbers of Royal Tern nests have declined during the study period, especially since 1990. In contrast, annual counts of active Sandwich Tern nests remained relatively stable through the mid 1980s, then increased substantially and have since remained stable. During the early years of the study, a greater proportion of nests from each species occurred on colonies within the Cape Romain region, although this distribution appears to have shifted with a greater proportion of nests now occurring along the southern coast. At the statewide level and at each of the primary colonies, we observed a positive correlation in counts of Brown Pelican and Royal Tern nests. Mechanisms underlying the observed trends are unclear. We suggest that priorities for research include (1) determination of diet and foraging locales for all three species, (2) impacts of ectoparasites on condition and survival of pelican chicks, and (3) metapopulation structure of all three species. Management activities should focus primarily on protection of colony sites.

Once the most abundant large tern in California, populations of Royal Terns (Thalasseus maximus) are now greatly reduced statewide. However, these terns are still common in southern California where the population appears to be increasing. We estimated survival of this species, for which no robust estimate of survival is available, using mark-resighting data. Apparent survival of birds >3 yr of age was estimated to be ~0.95; first-year survival was lower at 0.86. The lower survival estimate for first-year birds probably reflects increased mortality, but could also be a function of permanent emigration by individuals in this age class. The adult survival probability is the highest reported among terns and suggests that survival is playing an important role in the recovery of this tern population and that the current population growth is not solely due to immigration. Improvements in resighting protocols, marking technology, and mark-recapture methods are recommended to better use live resighting, dead recovery, and multistate data. /// Thalasseus maximus, entre las gaviotas grandes, fue la más abundante en California. Sin embargo, en la actualidad sus poblaciones se han reducido sustancialmente en todo el estado, aunque todavía son comunes en el sur de California, en donde la población parece estar incrementando. Utilizando datos de reobservar aves marcadas, estimamos una sobrevivencia de 0.95 en gaviotas>3 años y de 0.86 en aves de un año. Este estimado probablemente refleje un incremento en la mortalidad de aves jovenes, pero también pudiera ser función de la emigración permanente de este grupo de aves. La sobreviviencia de los adultos es la más alta informada entre gaviotas y sigiere que la sobrevivencia tiene un rol muy importante en el recobro de las poblaciones de esta especie y que los aumentos locales no se deben únicamente a la inmigración. Se recomienda el mejorar los protocolos para detectar animales marcados, la tecnología para marcar aves, al igual que métodos de captura y recaptura para poder utilizar de forma más eficiente las reobservaciones, recobro de aves muertas y los datos tomados en diferentes estados.

Nest and chick census data gathered from 1975–2005 at all known breeding colonies of Royal (Sterna maxima) and Sandwich (S. sandivicensis) Terns in three mid-Atlantic States are reported. Nest census data were gathered sporadically in North Carolina, Virginia, and Maryland throughout this period. Royal Tern chick counts based on annual banding efforts were obtained in Maryland since 1975 and North Carolina and Virginia since 1977, while Sandwich Tern chick counts date from 1977 in North Carolina and 1980 in Virginia. Royal Tern chick counts show significant annual variation by state, and are positively correlated between North Carolina and Virginia, but negatively correlated between Maryland and both North Carolina and Virginia. Sandwich Tern nest counts showed significant annual variation in North Carolina, as did chick counts in North Carolina and Virginia. These results suggest regional, rather than local, trends in Royal Tern numbers over time. While Royal Tern numbers indicate a gradual decline in nests and chick production since the 1980s, followed by an increase in recent years, Sandwich Tern numbers have remained consistently lower than Royal Terns but stable over the entire study period. Causes for the decline in Royal Tern numbers are attributed primarily to loss of open sandy habitat from vegetational succession at breeding sites on dredged material islands and to invasive species at nesting sites, including quadraped predators. Increased habitat management and regular censusing with consistent methodology are recommended to help maintain these species at sustainable levels.

Royal Tern (Sterna maxima) chick diet at Fisherman Island National Wildlife Refuge, Virginia, was investigated in 2003 and 2004. Primary objectives were to document common prey species, annual and seasonal variation in prey selection, and seasonal variation in prey size based on average bill length in this species. Over 2200 Royal Terns bred on this island each year of the study. Single items of prey species carried in the bill by adult terns feeding their chicks were identified using 8 × 42 binoculars. A total of 11,566 and 33,646 prey items were identified during 44 and 87.5 h of systematic observations in 2003 and 2004, respectively. Terns foraged largely on anchovy (Anchoa spp.) early in the season, then switched to herrings (Clupeidae); average prey size also increased seasonally each year. Prey switching was similar to that of Royal Terns in North Carolina (but with drum as well as herring), indicating regional adaptations to forage fish availability by this species along the mid-Atlantic seaboard.

We studied the foraging ecology of Royal Terns (Sterna maxima) and Sandwich Terns (S. sandvicensis) in North Carolina during the breeding seasons in 1999 and 2000. Foraging habitats were surveyed using 95 fixed-point observations (30-45 min each) and over 100 h of inshore and offshore transects. Stable isotopes (13C:12C,15N:14N, and18O:16O) in eggshells were analyzed for evidence of differences in foraging habitats. Water masses were delineated using satellite imagery of sea surface temperatures. We determined diet for each species with observations of chick provisioning and fecal analyses. Although Royal and Sandwich Terns nested together in the same colonies, their prey and foraging habitats differed. Sandwich Terns fed their chicks 48% anchovies (Anchoa sp.), 39% herring (Clupeidae)/jacks (Carangidae)/mackerels (Scombridae), and 9% drums (Sciaenidae)/porgies (Sparidae)/mullets (Mugil sp.), and foraged primarily in the marine coastal environment. Conversely, Royal Terns provided their chicks with 9% anchovies, 30% herring/jacks/mackerels, and 41% drums/porgies/mullets, and fed more frequently in the estuary. The species' foraging ranges overlapped at inlets and the river mouth. Stable isotope ratios also suggested that foraging differences occurred between colonies. The results of this investigation indicate that Royal and Sandwich Terns in North Carolina partition food resources by habitat and prey choice.

On 22 March 2007, I observed Royal Terns (Sterna maxima) flushing and capturing flying fish off the northern tip of the Yucatan Peninsula. Individual terns struck the water which flushed flying fish out of the water and allowed other terns to capture them in midair. This observation is an example of opportunistic foraging by conspecifics.

We studied possible genotoxic exposure in Royal Terns (Sterna maxima) by collecting blood from adults and juveniles at five breeding colonies in coastal North Carolina in 1999. These colonies are located in three estuarine systems (Core Sound, Pamlico Sound, and Cape Fear River), each subjected to different contaminant loads. DNA in red blood cells was analyzed using the comet assay to determine levels of DNA strand breaks, a technique previously not applied to birds. In addition, we weighed each bird and estimated its fat reserves as an indication of nutritional health. Gross health assessments showed no significant differences between study sites, both for adult and juvenile terns. The comet assay indicated that blood cells from the adult and juvenile terns from two Core Sound colonies, Wainwright and Sand Bag Islands, had significantly higher levels of apparent DNA damage than the remaining study sites. Based on previously published studies of sediment contaminants, the Core Sound colonies have relatively low overall pollutant loads, a finding contrary to the expected result based on the DNA damage. Plausible explanations for these finding are that birds from the Core Sound are exposed to an undetected genotoxic contaminant(s) or that birds from the more polluted sites have had an adaptive response to the contaminant exposure.