Magnificent Frigatebird Fregata Magnificens Research Articles

Seabirds under environmental pressures: Food supplementation has a larger impact than selenium on chicks exposed to mercury and a viral disease

Although infectious disease outbreaks represent a serious threat for wildlife population viability, the environmental factors that underlie such outbreaks are poorly investigated. The French Guiana breeding population of Magnificent frigatebird Fregata magnificens is subjected to recurrent episodes of chicks’ mortality likely caused by a viral disease. We hypothesized that high mercury (Hg) concentrations may be responsible for the emergence of clinical signs. We therefore investigated whether healthy and sick chicks show different Hg concentrations in blood. Because the essential element selenium (Se) may be highly depleted during Hg poisoning, we further experimentally tested whether an increased intake of dietary Se has an effect on blood levels of Hg, increases circulating Se, and improves the oxidative status of chicks. Finally, we compared the results of this experiment with a previous food supplementation experiment. Our results show similar Hg concentrations between healthy and sick chicks with visible clinical signs of the disease. Se concentrations were significantly depleted in sick chicks. Se concentrations increased while Hg concentrations simultaneously decreased in chicks that naturally recovered from the disease. Both the Se and fish supplementation experiments significantly increased Se concentrations in blood, while Hg levels were only modestly affected. Providing food to chicks appeared to have greater benefits than only supplementing chicks with Se pills as, although food supplementation had an impact on blood Se similar to that of supplementation with Se pills, it also reduced the vulnerability of chicks to the viral disease, possibly by reducing nutritional stress and providing essential nutrients.

Distribution, abundance, and on-land threats to Cabo Verde seabirds

SummaryPelagic seabird populations have declined strongly worldwide. In the North Atlantic there was a huge reduction in seabird populations following the European colonization of the Azores, Madeira and Canary archipelagos but information on seabird status and distribution for the subtropical region of Cabo Verde is scarce, unavailable or dispersed in grey literature. We compiled and compared the historical and current distribution of all seabird species breeding in the Cabo Verde archipelago, updated their relative abundance, investigated their inland habitat preferences, and reviewed their threats. Currently, the breeding seabird community in Cabo Verde is composed of Bulwer’s Petrel Bulweria bulwerii, White-faced Storm-petrel Pelagodroma marina aedesorum, Cape Verde Shearwater Calonectris edwardsii, Cape Verde Storm-petrel Hydrobates jabejabe, Cape Verde Petrel Pterodroma feae, Boyd's Shearwater Puffinus lherminieri boydi, Brown Booby Sula leucogaster, and Red-billed Tropicbird Phaethon aethereus. One breeding species is currently extinct, the Magnificent Frigatebird Fregata magnificens. The relative abundance of Cape Verde Shearwater, Boyd’s Shearwater, Cape Verde Petrel, and Cape Verde Storm-petrel was determined from counts of their nocturnal calls in Santo Antão, São Vicente, Santa Luzia, Branco, Raso and São Nicolau. Cape Verde Petrel occurred only on mountainous islands (Santo Antão, São Nicolau, Santiago, and Fogo) from mid-to high elevations. Larger species such as the Cape Verde Shearwater and Boyd’s Shearwater exhibited a wider distribution in the archipelago, occurring close to the coastline but at lower densities on populated islands. Small procellariforms such as the Cape Verde Storm-petrel occurred at high densities only on rat-free islets and in steep areas of main islands where introduced cats and rats are unlikely to occur. The main threats to seabird populations in Cabo Verde range from predation by introduced predators, habitat alteration or destruction, and some residual human persecution.

Detection and Phylogenetic Characterization of a Novel Herpesvirus in Sooty Terns Onychoprion fuscatus.

Since 2005, we have recorded annual episodes of alphaherpesvirus outbreaks in chicks of magnificent frigatebird Fregata magnificens on the Ile du Grand Connétable Nature Reserve in French Guiana. In 2009, we found sooty terns, Onychoprion fuscatus, that live sympatrically with frigatebirds, with visible clinical signs of a potential viral infection. To determine if the symptoms observed in sooty terns could be associated with an alphaherpesvirus previously identified in frigatebirds, we carried out molecular screening of samples collected from seven individuals. We identified and characterized a novel viral sequence from five birds. BLAST searches, pairwise nucleotide, and amino acid sequence comparisons, as well as phylogenetic analyses confirmed that the sequence belonged to the Herpesviridae family, of the Alphaherpesvirinae subfamily. We observed that it clustered with strains isolated from Podargidae (Caprimulgiformes), Columbiformes, and Falconiformes, but was distinct from the frigatebird herpesvirus. We have tentatively named it Onychoprion fuscatus alphaherpesvirus 1, (OfusAHV1). These two sequences, although found syntopic on the Ile du Grand Connétable, belong to two distinct alphaherpesvirus strains. Thus, the clinical symptoms showed by sooty terns do not likely result from a cross-species transmission event. Future work is needed to better characterize the virus and to investigate herpesvirus prevalence in healthy, free-ranging sooty terns, and to assess the impact of the virus on population viability.

Florida's Strategic Position for Collaborative Automated Telemetry Tracking of Avian Movements Across the Americas

Florida's Strategic Position for Collaborative Automated Telemetry Tracking of Avian Movements Across the Americas

Osteology of the feeding apparatus of Magnificent Frigatebird Fregata magnificens and Brown Booby Sula leucogaster (Aves: Suliformes)

In this paper, we describe the skulls of Magnificent Frigatebird Fregata magnificens (Fregatidae) and Brown Booby (Sulidae) Sula leucogaster, with focus on the structures associated with the Musculi mandibulae. We discuss the results in the context of the feeding biology of the two species, which feed mainly on flying fish and squids. Frigatebirds capture prey from just above, or just below, the water surface in flight. The hook-shaped Apex maxillae in F. magnificens can be viewed as an adaptation for grasping prey from near the water surface. Boobies catch prey by plunging; thus, the dorsoventrally flattened skull and conical bill of S. leucogaster may reduce water resistance when it dives, or swims underwater. The bill is long in both species, such that it is on average 70% of the whole skull length in F. magnificens and 60% in S. leucogaster. Consequently, the Mm. mandibulae in the two species are more posteriorly positioned relative to the Apex rostri. This results in low mechanical advantage for the mandible opening-closing lever, indicating adaptations for a fast, rather than a strong, bite. Fast-moving mandibles would be advantageous for ‘mandibulating’ prey while swallowing. The Fossa musculorum temporalium and the Palatum osseum in both species provide a broad area for origins of the Musculus adductor mandibulae externus (all parts) and the Musculus pterygoideus. The Processus orbitalis quadrati is longer and thicker in F. magnificens than in S. leucogaster, and so is the Musculus pseudotemporalis profundus. We suggest that Mm. adductores mandibulae are relatively well developed in the two species; therefore, their mandibulae are still probably capable of a powerful adduction. In both species there is a mechanisms that contribute to protect the jaws from disarticulation and damage. Such mechanism involves the incorporation of a ‘flange-like’ Crista intercotylare on the Margo medialis cotylae medialis fossae articularis quadratica that grips the Condylus medialis quadrati. In S. leucogaster, the retractor-stop ‘notch’ formed by Ossa lacrimale et nasale also serves to protect the jaws against sudden external forces when birds are diving or swimming underwater for prey. A more detailed hypothesis for the jaw movements and strength in F. magnificens and in S. leucogaster and their relation with feeding habits should necessarily incorporate data on the jaw and anterior neck musculatures.

Breeding seabird populations in Brazilian oceanic islands: historical review, update and a call for census standardization

In recent decades, several seabird populations have declined globally due to anthropogenic activities. In Brazil, 14 seabird species breed at four oceanic islands and one atoll: the Abrolhos, Fernando de Noronha, and Sao Pedro and Sao Paulo (SPSPA) archipelagos; the Trindade/Martin Vaz Islands; and the Atol das Rocas. Seven species are listed as nationally threatened by extinction. This study aimed to present new information on breeding seabird populations in Brazilian oceanic islands, compile all available data previously published and, when possible, to provide updated information on population estimates from censuses carried out sporadically at different islands between 2006 and 2013. Based on new data and the thorough review provided here, of the 35 seabird breeding populations analysed, 14% were increasing (as Red-billed Tropicbird Phaethon aethereus , Magnificent Frigatebird Fregata magnificens and Brown Noddy Anous stolidus in Abrolhos), 11% were decreasing (as Brown Booby Sula leucogaster in Atol das Rocas and Great Frigatebird Fregata minor in Trindade Island), 23% were stable (as White-tailed Tropicbird Phaethon lepturus in Fernando de Noronha and Brown Noddy and Black Noddy Anous minutus in Sao Pedro and Sao Paulo Archipelago), and the remaining 49% were unknown or not possible to evaluate. The Red-footed Booby ( Sula sula ) is locally extinct in Trindade Island, however there are colonies of only a few individuals of other species, such as the Audubon's Shearwater Puffinus lherminieri and Red- billed Tropicbird in Noronha, Black Noddy in Martin Vaz, and Great ( Fregata ariel trinitatis ) and Lesser ( F. m. nicoll i) Frigatebirds in Trindade, that may become extinct soon. Censuses at distinct periods of the breeding cycles and protocols were highly variable, making temporal comparisons difficult. These results indicate an urgent need for long-term studies to improve the scenario to assess seabird population trends based on comparable methodologies, in order to determine trends in the future.

Important foraging areas of seabirds from Anguilla, Caribbean: Implications for marine spatial planning

Marine spatial planning (MSP) has become an important tool to balance the needs of commercial, economical and recreational users of the marine environment with the protection of marine biodiversity. BirdLife International advocate the designation of marine Important Bird Areas (IBAs) as a key tool to improve the protection and sustainable management of the oceans, including the designation of Marine Protected Areas, which can feed into MSP processes. This study presents the results of three years of seabird tracking from the UK Overseas Territory of Anguilla, where marine resources are currently relatively unexploited and MSP is in its infancy. The core foraging areas of 1326 foraging trips from 238 individuals, representing five species (brown booby Sula leucogaster, masked booby Sula dactylatra, sooty tern Onychoprion fuscatus, magnificent frigatebird Fregata magnificens and red-billed tropicbird Phaethon aethereus) breeding on three of Anguilla's offshore cays were used to calculate the hotspot foraging areas for each study species. These high activity areas were then compared with fishing activity within Anguilla's Exclusive Economic zone and to proposed coastal developments. Two marine IBAs were identified within Anguilla's waters: the first to be defined, using seabird tracking data, in the Caribbean region. Whilst the level of fishing activity and associated seabird by-catch is hard to quantify, the core foraging areas of seabirds breeding in Anguilla were observed to overlap with areas known for high fishing activity. These findings highlight the need to work both nationally and across territorial boundaries to implement appropriate marine spatial planning.

Population Genetic Structure of the Magnificent Frigatebird Fregata magnificens (Aves, Suliformes) Breeding Colonies in the Western Atlantic Ocean.

The Magnificent Frigatebird Fregata magnificens has a pantropical distribution, nesting on islands along the Atlantic and Pacific coasts. In the Caribbean, there is little genetic structure among colonies; however, the genetic structure among the colonies off Brazil and its relationship with those in the Caribbean are unknown. In this study, we used mtDNA and microsatellite markers to infer population structure and evolutionary history in a sample of F. magnificens individuals collected in Brazil, Grand Connétable (French Guyana), and Barbuda. Virtually all Brazilian individuals had the same mtDNA haplotype. There was no haplotype sharing between Brazil and the Caribbean, though Grand Connétable shared haplotypes with both regions. A Bayesian clustering analysis using microsatellite data found two genetic clusters: one associated with Barbuda and the other with the Brazilian populations. Grand Connétable was more similar to Barbuda but had ancestry from both clusters, corroborating its “intermediate” position. The Caribbean and Grand Connétable populations showed higher genetic diversity and effective population size compared to the Brazilian population. Overall, our results are in good agreement with an effect of marine winds in isolating the Brazilian meta-population.

Comparative Ectoparasite Loads of Five Seabird Species in the Galapagos Islands

In this paper we describe the ectoparasitic lice (Insecta: Phthiraptera) found on 5 species of seabirds (magnificent frigatebird Fregata magnificens; great frigatebird Fregata minor ; Nazca booby Sula granti ; blue-footed booby Sula nebouxii ; and red-footed booby Sula sula ) on the Galapagos Archipelago. We found 9 species of ectoparasitic lice: 5 species of Pectinopygus ischnocerans, 1 infesting each host; 2 species of Colpocephalum amblyceran lice, 1 on each frigatebird species; and 2 shared amblycerans, Eidmanniella albescens (Piaget, 1880) found on Nazca and blue-footed boobies and Fregatiella aurifasciata (Kellogg, 1899) found on the 2 frigatebirds. We tested the relative importance and interactions of host sex, body size, host, island, host family, and breeding status and found that inter-island differences were the main predictors of prevalence and infestation intensity. These differences could be related to host density or weather, but further evidence is needed.

Utilisation of discards from small-scale fisheries by seabirds in coastal waters of Paraná State, Brazil

Fishery discards support scavenging seabird populations in many parts of the world, but little is known of this relationship in Brazil. The present study of the coast of Paraná, southern Brazil conducted monthly surveys over twelve months. We observed nine species of scavenging seabirds taking discards, Magnificent Frigatebird Fregata magnificens and Brown Booby Sula leucogaster being the most abundant and frequent. The highest numbers of scavenging seabirds were observed during trawling activities, which provided far more discards at sea than driftnet fishing. During a fishing moratorium, when no use of trawl nets was permitted, numbers of scavenging seabirds at boats were lower. It seems likely that scavenging seabird populations of the Paraná coast benefit from this supplementary food supply, but the extent to which their numbers are affected is unknown.

Breeding seabirds in the British Virgin Islands

Caribbean seabirds are subject to numerous threats, and population levels are thought to be at a fraction of historical levels. Despite being a well-known taxonomic group there is still a paucity of data for most seabird species on many of the Caribbean islands. We carried out detailed surveys of the seabird breeding populations in the British Virgin Islands (BVI) during the breeding seasons of 2004 and 2005. We surveyed 42 different islands and cays over the 2 yr with 60 and 63% of these having at least one breeding seabird species in 2004 and 2005, respectively. A total of 15 spe- cies of breeding seabird was recorded, one of which, the gull-billed tern Sterna nilotica, was pre- viously thought to have been extirpated. Two species, roseate tern Sterna dougallii and magnificent frigatebird Fregata magnificens, had globally significant colonies in the BVI and a further 8 species had a regionally significant population in the BVI. We discuss our findings within a global and regional conservation context and provide recommendations for ensuring the continued existence of BVI seabird populations.

The Diet of the Magnificent Frigatebird During Chick Rearing

Abstract We describe the diet of the Magnificent Frigatebird Fregata magnificens at Isla Isabel off the Pacific coast of Mexico based on 158 regurgitates (555 prey items) from males, females, chicks, and juveniles. The diet included 50 species of fishes (21 identified to genus only), 1 species of squid, and 2 species of crustaceans. Diplectum pacificum and Anchoa lucida were the most frequent species of fish in the frigatebird's diet. No differences in prey composition or prey size were found between males and females, but females disgorged 62% more food. This difference mirrors the bigger size (15% larger than males) and larger contribution of females to chick feeding. Flying juveniles consumed prey in different proportions than the adults and disgorged marginally more food. Juveniles may obtain food in different patches than adults and complement this source with maternal feedings, or they may be more likely to regurgitate. Diet composition of males, females, and flying juveniles changed during the 4-month period of this study, but the mass of regurgitates did not change as the breeding season progressed, suggesting that availability of prey species changes over time. Most of the diet of this population probably comes from opportunistic feeding on fisheries, because the variety of fishes disgorged is remarkably similar to the published list of fishes discarded by prawn-fishing boats in the area. If our assumption is true, kleptoparasitism and direct fishing are only marginally represented in the diet of this population.

THE DIET OF THE MAGNIFICENT FRIGATEBIRD DURING CHICK REARING

Abstract We describe the diet of the Magnificent Frigatebird Fregata magnificens at Isla Isabel off the Pacific coast of Mexico based on 158 regurgitates (555 prey items) from males, females, chicks, and juveniles. The diet included 50 species of fishes (21 identified to genus only), 1 species of squid, and 2 species of crustaceans. Diplectum pacificum and Anchoa lucida were the most frequent species of fish in the frigatebird's diet. No differences in prey composition or prey size were found between males and females, but females disgorged 62% more food. This difference mirrors the bigger size (15% larger than males) and larger contribution of females to chick feeding. Flying juveniles consumed prey in different proportions than the adults and disgorged marginally more food. Juveniles may obtain food in different patches than adults and complement this source with maternal feedings, or they may be more likely to regurgitate. Diet composition of males, females, and flying juveniles changed during the 4-mo...

Offspring Desertion in the Magnificent Frigatebird: Are Males Facing a Trade-Off between Current and Future Reproduction?

Timing of offspring desertion is expected to be the outcome of the trade-off between current and future reproductive benefits for deserters. I investigated this idea by analysing the timing of male desertion in the Magnificent Frigatebird Fregata magnificens. I recorded parental attendance, male desertion and chick survival from an average of 39 days old (+ 2.7 S.E. days) to fledging (181.2 + 3.4 days old, n = 24) at 42 nests, and checked the presence and breeding state of marked males (red gular pouch) at the colony the following breeding season. All male parents deserted their nest when their only chick was between 19 and 160 days old (77.1 + 5.0 days). Male desertion was influenced by settling and deserting dates: settling date correlated negatively with the age of the chick at the time of male desertion. Late-settling males deserted later during the year than males settling early, the condition of their chick (at the time of male desertion) was lower and their chick fledged late during the year. In spite of the obligate and apparently date-constrained desertion, chicks deserted when very young died more frequently than those deserted when older, and successful males deserting late during the year (after the average desertion date) were marginally less likely to be seen in reproductive state the following breeding season than those deserting early. The inter-individual variation is consistent with the idea that male frigatebirds may face a trade-off between current and future reproductive expectations: early-settled individuals began breeding before 16 October, deserted before the average deserting date, stayed with the chick for 92 days, their chicks survived well (84%) and 75% of these males were seen in reproductive state the following breeding season. Late-settled individuals began to breed around 19 December, deserted when their chick was 55 days old, chicks survived well (64%) but still only 50% of males were seen in breeding state the following breeding season. Some early-settled individuals who remained longer attending the chick (120 days) and whose chick survived, deserted after the average desertion date (20 April), but only 50% of them were seen in breeding state the following season.

Notes on the behavioural ecology of the Magnificent Frigatebird Fregata magnificens

The Magnificent Frigatebird population breeding on Man‐o‐War Cay, Belize in 1980 laid their single eggs between mid‐December and early April, and had a mean hatching date of mid‐ to late April. There were no differences between the sexes in the percent of time spent incubating eggs or brooding small chicks (males 48%, females 52%). However, males were not observed to feed larger (75–100 d) chicks. All 81 feedings of juvenile (approximately 1 year old) frigatebirds observed during 126 hr of observations were by females, and the majority of these feedings occurred at midday (46%) when approximately equal numbers of females and juveniles frequented the study area. Our data confirm Diamond's (1972, 1973) reports of unequal roles in chick rearing and post‐fledging care between male and female F. magnificens, and support the hypothesis that males and successful females may breed at one‐ and two‐year intervals, respectively.