References of "Ramos, Ja"
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See detailAdult Survival Of Tropical Roseate Terns Breeding On Aride Island, Seychelles, Western Indian Ocean
Monticelli, D.; Ramos, Ja.; Guerreiro-Milheiras, Sa. et al

in Waterbirds (2008), 31(3), 330-337

Survival of tropical Roseate Terns (Sterna dougallii) from the western Indian Ocean was modeled using a capture-mark-recapture dataset of 102 breeding adults ringed and resighted on Aride Island ... [more ▼]

Survival of tropical Roseate Terns (Sterna dougallii) from the western Indian Ocean was modeled using a capture-mark-recapture dataset of 102 breeding adults ringed and resighted on Aride Island, Seychelles, from 2002 to 2007. The effect of covariates reflecting oceanographic conditions and resighting effort was also examined during the modeling. A time-invariant survival rate was best supported by our data, with annual adult survival estimated at 0.807 ± 0.033 (SE). Resighting probability was found to be influenced by sea-surface temperature (SST) anomalies, as expressed by the mean Indian Ocean Dipole mode index recorded during the nonbreeding period. Years of higher SST in the western part of the Indian Ocean in September-April (8 months) corresponded to a lower probability of resighting adults at the colony during the breeding season (May-August), which may be related to a tendency for some adults to refrain from breeding in less favorable years. Comparing our results with temperate studies, Roseate Terns breeding on Aride were found to exhibit similar survival estimates. Consequently, this study does not support the hypothesis that tropical Roseate Terns may counterbalance their lower fecundity (clutch size and breeding success) compared to their temperate and northern-hemisphere counterparts (Europe, North America, Caribbean) by relatively higher survival rates. [less ▲]

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See detailInfluence of woodland cover on habitat selection and reproductive parameters of tropical roseate terns: implications for colony management
Monticelli, D.; Ramos, J. A.; Doucet, Jean-Louis ULg

in Endangered Species Research (2008), 4

We examined the effect of vegetation structure, in particular canopy closure, on colony site occupancy, nesting densities, and reproductive parameters of roseate terns Sterna dougallii breeding in a ... [more ▼]

We examined the effect of vegetation structure, in particular canopy closure, on colony site occupancy, nesting densities, and reproductive parameters of roseate terns Sterna dougallii breeding in a Pisonia grandis dominated woodland on Aride Island, Seychelles, western Indian Ocean. Long-term observations (1995 to 2006) revealed that areas with high vegetation density and canopy cover (>50%) were abandoned, in favour of nearby more open forest areas, such as clearings. The attractiveness of a forest clearing (0 to 25% canopy cover) to breeding birds was also largely supported by experimental manipulation of vegetation density in 2004. Most birds moved from areas under canopy cover to experimentally cleared plots, where they nested at higher densities and had a higher probability of successfully fledging a chick. However, some individuals remained in their original areas, despite their greater canopy cover, and had a lower fledging success. This site tenacity is presumably explained by an imprinting process leading some birds to breed in successive years in the same, familiar locations, despite their nest-sites having become sub-optimal for fledging success. Roseate terns choosing a nest site in woodland on Aride must trade off the need for some cover, offering protection from the sun, against the need for easy access through gaps in the canopy to fly to and from their nests. A suitable nest-site should also minimize chick/parent infestation by ticks and mortality caused by contamination of feathers with the sticky fruits of Pisonia grandis. We suggest that, when they are not formed naturally, small artificial forest clearings within the usual breeding area are likely to be attractive for roseate terns and may result in enhanced colony productivity. These findings may be applicable to other seabird colonies (e.g. sooty terns) found under forest cover on oceanic islands throughout the Indo-Pacific region. [less ▲]

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See detailDiet and foraging ecology of Roseate terns and lesser noddies breeding sympatrically on Aride Island, Seychelles
Monticelli, David; Ramos, J. A.; Tavares, P. C. et al

in Waterbirds (2008), 31(239), 248

Inferences on seabird ecology from stable isotopes ratios (δ13C, δ15N) and mercury concentrations analysis of feathers have been made for temperate and polar species but are far more rare for tropical ... [more ▼]

Inferences on seabird ecology from stable isotopes ratios (δ13C, δ15N) and mercury concentrations analysis of feathers have been made for temperate and polar species but are far more rare for tropical species. In this paper, we used this approach combined with analysis of regurgitations and feeding observations at colonies to examine diet segregation between Roseate Terns (Sterna dougallii) and Lesser Noddies (Anous tenuirostris) breeding sympatrically on Aride Island (Seychelles), western Indian Ocean. Our results indicated extensive overlap between the two species in trophic level and foraging area during the breeding season. Goatfish predominated (93-97%) in all diet samples of adults and chicks collected in the colonies, except in prey fed to mates by Roseate Terns, of which scad and tuna comprised 20%. The isotopic analyses of feathers replaced by adults during molt (primary and body feathers) suggested, however, that the two species differ in foraging ecology during the nonbreeding period. Roseate Tern adults had consistently lower δ15N values than Lesser Noddies which, in turn, had δ15N values comparable to those of chick feathers grown on Aride. Moreover, low but similar mercury levels were found in body feathers of Lesser Noddy adults and Roseate Tern chicks, whereas Roseate Tern adults were significantly more contaminated. Overall, these results support the hypothesis that the Lesser Noddy is largely sedentary, being associated with the same food web in the vicinity of the colonies year-round. In contrast, Roseate Terns rely on distinct prey during the molting (nonbreeding) season which may be also consistent with a change in food web (i.e., a migratory regime) although the assignment of potential wintering areas remain difficult without isotopic basemaps currently available for the Indian Ocean. [less ▲]

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See detailQuantitative approach to the conservation of a tropical seabird population in the western Indian Ocean
Monticelli, David; Ramos, J. A.; Doucet, Jean-Louis ULg et al

Poster (2006)

The roseate tern (Sterna dougalli) is an oceanic seabird species showing mainly a tropical distribution, with a relatively fragile status worldwide. It was still recently considered as a "near-threatened ... [more ▼]

The roseate tern (Sterna dougalli) is an oceanic seabird species showing mainly a tropical distribution, with a relatively fragile status worldwide. It was still recently considered as a "near-threatened" (IUCN red list) due to the strong decline in population trends over the last decades. For instance, the annual breeding population found on Aride Island, western Indian Ocean, has fluctuated between a high of 4,000 in the 1970's to a low of 60-1200 pairs from 2000 onwards. As a result, an intensive monitoring program was conducted on Aride between 1998 and 2006 in order to understand how environmental factors may affects this breeding population. This included the estimation of annual productivity (no of chicks fledged per pair), demographic parameters such as survival rate and recruitment (age-specific breeding probabilities), and their affecting co-factors (e.g. food availability, tick parasitism,...). We suggest that these three parameters (productivity, survival, recruitment) constitute the necessary basis to model the life-cycle of this population, and, ultimately, to provide local managers with conservations measures. [less ▲]

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