Brown Noddy Anous Stolidus Research Articles

FOUR CASES OF DIFFERENT PLUMAGE CHROMATIC ABERRATIONS IN GALAPAGOS BIRDS

Plumage chromatic aberrations usually represent a problem for field ornithologists. Chromatic aberrations are originated by genetic mutations that result in a pigment deficiency, drastically altering the typical colour of individuals, and can vary both within and between species. Here, we present four different colour aberrations in four bird species native and endemic to the Galapagos Islands: Lava Gull Leucophaeus fuliginosus, Brown Noddy Anous stolidus, Floreana Mockingbird Mimus trifasciatus, and Small Ground Finch Geospiza fuliginosa. These records expand taxonomically the occurrence of chromatic aberrations on Ecuadorian birds and in the Galapagos archipelago.

The marine avifauna of Matthew and Hunter Islands, two remote volcanoes of the New Hebrides chain

The marine avifauna of Matthew and Hunter Islands, two remote volcanoes of the New Hebrides chain Breeding birds recorded on Matthew and Hunter Islands in the tropical southwestern Pacific between 1973 and 2018 are summarised from a compilation of reports, for which various methods were used for counting seabirds. These methods included line transects, or direct observations using telescope or binoculars, or exhaustive counts, depending on the species observed and its nesting habitat. Population size estimates and reproductive periods are given. The total number of seabird species recorded breeding on the two islands was n = 14. This total includes seabird species breeding on both islands (n = 7): black-winged petrel Pterodroma nigripennis, wedge-tailed shearwater Ardenna pacifica, red-tailed tropicbird Phaethon rubricauda, masked booby Sula dactylatra, brown booby S. leucogaster, brown noddy Anous stolidus, and grey noddy A. albivitta. Hunter island also harbours a small colony of Herald petrel Pterodroma heraldica, and colonies of lesser and great frigatebirds (Fregata ariel and F. minor), red-footed booby S. sula and, black noddy A. minutus and white tern Gygis alba. Matthew Island harbours a large colony of sooty tern Onychoprion fuscatus; an undetermined storm petrel may also breed there. Differences between the two islands regarding community composition of seabirds are explained by the absence of trees on Matthew Island and the presence of the Polynesian rat Rattus exulans on Hunter Island. Brown noddies bred exclusively during the austral summer, as did black-winged petrels and wedge-tailed shearwaters, while the Herald petrel and the two frigatebirds seemed to preferentially breed in the winter. The red-tailed tropicbird, the three boobies, the grey noddy and the sooty tern appeared to reproduce year-round. Disturbance caused by human activities was irregular but devastating to seabird colonies. The diversity and abundance of seabird species breeding on these islands makes them regionally important sites for conservation. Key words: Seabird, Population, Reproduction, Threats, Polynesian rat; Helicopters

Avifauna of the Ninigo, Hermit, Sae and Kaniet Islands, and adjacent seas, Papua New Guinea

One of us (SMH) surveyed the Ninigo and Hermit Islands (27 January–13 February and 2–14 October 2019), providing the first observations of birds on these islands for c.50 years. KDB collated data from the unpublished diaries of W. F. Coultas, a member of the Whitney South Sea Expedition, including observations from the nearby Kaniet and Sae Islands. Four new landbirds, in addition to six new shorebirds and five new seabirds, were added to the list of birds for these poorly known islands, bringing the total list to 59 species. We also document significant extensions of the known breeding ranges of Brown Noddy Anous stolidus, Black Noddy A. minutus and Red-footed Booby Sula sula. The biological importance of the West Melanesian Trench is further emphasised by our seabird observations.

Using photographs to record plastic in seabird nests

The incidence of plastic in seabird nests can be used to track changes in the amounts of marine debris, but large sample sizes are needed for accurate estimates. Surveys of active nests cause disturbance to breeding birds, so we need an efficient way to sample nest plastics. Photographs of brown noddy Anous stolidus nests at Ducie Atoll, southeast Pacific Ocean, allowed rapid characterisation of plastic use with limited disturbance, and showed selection for blue-green items. Plastic was more prevalent in noddy nests at Ducie Atoll (97%) than at Inaccessible Island, South Atlantic Ocean (41%), despite lower debris densities at Ducie. Differences in nesting habitat and the resultant availability of natural nesting material drive this difference in plastic loads. Using photographs to record plastic in seabird nests reduces disturbance to breeding birds and might decrease the risk of missing cryptic debris items. Photographs also provide a permanent record of pollution levels.

Flight‐initiation response reflects short‐ and long‐term human visits to remote islets

The increasing use of, and visits to, isolated territories by people (especially tourists) enables the investigation of how biodiversity reacts to evolutionarily novel pressures. We explored the behavioural reaction of a breeding seabird species, the Brown Noddy Anous stolidus, to our repeated visits at two study sites in the Chesterfield Islands, a newly classified reserve in the Coral Sea Natural Park. Repeated measures of flight‐initiation distances (FIDs) at three sites and over time suggest that human visitations induced both a spatial phenotypical sorting or learning of individuals and a temporal habituation. In light of the novel ‘Sit and Defend’ mode of avian nest defence, the study finally provides the first dataset of FIDs for this species, and highlights management opportunities that could arise from the replication of such an approach to other breeding seabirds and therefore the conservation of remote island ecosystems.

An updated assessment of the seabird populations breeding at Príncipe and Tinhosas

The Príncipe Autonomous Region is recognised as a marine biodiversity hotspot, although little is known about the status of its marine fauna. It holds most breeding seabirds of the tropical eastern Atlantic Ocean. Based on anecdotal accounts of increased fishing and seabird harvesting, regular monitoring of seabird populations is considered a priority. Therefore, a survey of Príncipe’s seabird colonies was conducted in 2017. The results revealed that the more accessible seabird colonies have disappeared. Around Príncipe, Boné de Joquei is the present main stronghold for Brown Boobies Sula leucogaster and White-tailed Tropicbirds Phaethon lepturus. The Tinhosas islands hold an estimated 300 000 seabirds, predominantly Sooty Terns Onychoprion fuscatus, but also Brown Boobies, Black Noddies Anous minutus and Brown Noddies Anous stolidus. Long-term multi-annual monitoring is needed to understand the breeding phenology of each species and to better assess population trends. Ensuring a protective status for both Tinhosas and the seabirds under national legislation is a key priority for future conservation policy in São Tomé and Príncipe.

Population estimates of the breeding birds of the Tinhosas islands (Gulf of Guinea), the only major seabird colony of the eastern tropical Atlantic

The Tinhosas islands, in São Tomé e Príncipe, host the most important seabird breeding colony in the Gulf of Guinea, but information on its conservation status was hitherto unpublished or anecdotal, the last assessment having been performed in 1997. A two-day expedition to the Tinhosas islands was undertaken to estimate the status of breeding seabirds in 2013. Four of the five seabird species known to breed in São Tomé e Príncipe, namely Brown Booby Sula leucogaster, Sooty Tern Onychoprion fuscatus, Brown Noddy Anous stolidus and Black Noddy Anous minutus, occur on the Tinhosas. A decrease of 80% in Brown Booby numbers, possibly due to occasional exploitation, and a 30% increase in Sooty Tern and Black Noddy numbers, were found compared to 1997 data although survey methods differed. Breeding of Brown Noddy and Madeiran Storm-petrel Hydrobates castro remains unconfirmed. Our estimates confirmed that BirdLife International Important Bird and Biodiversity Area criteria are met for at least one species, the Sooty Tern. The islands are not legally protected, nonetheless, apart from moderate levels of disturbance by fishermen who land on Tinhosa Grande, no alien species were seen, and no immediate threats to the Tinhosas colony were detected. Multiple visits within and between years are recommended, to census breeders, monitor threats and establish breeding phenologies.

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.

Role of body size in shaping the trophic structure of tropical seabird communities

Ecological segregation among coexisting seabird species can occur due to morpho- logical and behavioral differences. This segregation is especially important as it reduces competi- tion during the breeding season, when birds are central-place foragers. Furthermore, seasonal variation in oceanographic processes may change prey availability and shape seabird community trophic structure and species isotopic niche. We used stable isotope analyses of seabird whole blood and prey muscle in 5 tropical seabird communities representing 12 species (Charadri- iformes, Phaethontiformes, Procellariiformes and Suliformes) inhabiting 5 offshore islands off Brazil from 00°55' N to 20° 30' S and 65 to 1160 km from the coast. We evaluated how community trophic structure was correlated with morphology (body mass and bill length), and we verified seasonal variation in isotopic niche in 2 communities. Overall, seabird trophic position (TP) was positively correlated with body size, with frigatebirds and boobies occupying a higher TP than noddies and terns. Structuring of seabird communities according to body size probably occurred due to consumption of prey of different sizes and TP, which contributed to niche segregation by reducing interspecific competition during the breeding season. All species showed isotopic niche segregation at 2 islands, and ~60 to 70% of species segregated at the other islands, except at Atol das Rocas, where 43% of species segregated. Niche overlap occurred mainly among closely related species at Atol das Rocas, Fernando de Noronha and Trindade. The isotopic niche and TP changed across islands for all 3 boobies (red-footed Sula sula, brown S. leucogaster and masked S. dactylatra), brown noddy Anous stolidus and red-billed tropicbird Phaethon aethereus; these factors also changed seasonally in other species, such as in magnificent frigatebird Fregata mag- nificens, brown booby, both the red-billed P. aethereus and white-tailed P. lepturus tropicbirds and both the brown A. stolidus and black Anous minutus noddies. Such changes probably occurred due to differences in prey availability, opportunistic behavior (e.g. feeding on fishery dis- cards) and/or local foraging and diet specialization.

Breeding Biology of Brown NoddiesAnous stolidusat Their Southern-Most Breeding Site, Gough Island, in Comparison to Other Sites

We investigated the breeding biology of the Brown Noddy Anous stolidus at its southern-most breeding locality, cold-temperate Gough Island (40°S) in the South Atlantic Ocean. We monitored 19 nests over three seasons for breeding schedules, and measured the growth of eight chicks and six fledglings during the 2005/06 breeding season. Across all seasons, egg-laying occurred between 2–12 December, mean incubation was 37 days and median hatch date was 15 January. Three late hatch dates suggest that replacement clutches can be laid if failure occurs early in the season. Chicks fledged after a mean of 46 days, but remained in the vicinity of the nest and were provisioned by adults for up to 11 days. Hatching success was 88%, fledging success 92% and breeding success 81%, which is higher than at most other sites. The size, chick growth-rates and pre-fledging fast displayed by Gough's Brown Noddies are similar to that of Brown Noddies breeding at other mid-latitude Atlantic locations. These similarities of these migratory noddy populations, as well as mirrored breeding schedules suggest a single mid-latitude Atlantic meta-population.

Associations between seabirds and subsurface predators around Oahu, Hawaii

Many species of tropical seabirds rely on subsurface predators such as tuna and dol- phins to drive prey close to the ocean's surface. We observed seabird foraging events from fishing vessels around the island of Oahu, Hawaii, to determine the prevalence and relative importance of different subsurface predators to seabird foraging. Sixty-nine seabird foraging events were observed, in 62 of which the presence and/or identity of subsurface predators could be determined. Of those 62, all but two involved subsurface predators and accounted for 99.8% of all foraging birds. Skipjack tuna Katsuwonus pelamis were the predominant (81%) subsurface predator involved in seabird feed- ing events, with odontocetes Stenella attenuata and Pseudorca crassidens (8%), mahimahi Coryphaena hippurus (6%), and yellowfin tuna Thunnus albacares (2%) being less common. Wedge- tailed shearwaters Puffinus pacificus and brown noddies Anous stolidus foraged in association with tuna schools more often than would be expected by chance alone. Red-footed boobies Sula sula, in contrast, did not associate with any subsurface predator in greater proportion than what would be expected by chance. Nine additional seabird species were observed foraging in association with sub- surface predators, but not in numbers large enough for statistical analysis. This study highlights the value of regional investigations able to uncover the variable nature of seabird-subsurface-predator associations. The finding that, in Hawaii, at least 2 species of seabirds showed tight dependence on tuna underlines the need for tuna fishery management to address the potential indirect ecological effects of fishing.

Seabird populations of the Chagos Archipelago, Indian Ocean: an evaluation of IBA sites

Indian Ocean seabirds are subject to numerous threats, and populations are thought to be at a fraction of historical levels. We carried out a rapid assessment of the seabird breeding populations of the Chagos Archipelago, a UK Overseas Territory, during early March 2006. We surveyed 26 islands covering the four island groups of the Archipelago. A total of 17 species of breeding seabird were recorded. Since the last survey in 1996, nine species showed reductions in the number of breeding pairs, with brown noddy Anous stolidus and lesser noddy Anous tenuirostris showing reductions of c. 22,000 and c. 27,000 pairs, respectively. These reductions, coupled with apparent sooty tern Sterna fuscata colony relocations, are central to our suggested changes to the Important Bird Areas (IBAs) criteria in the Archipelago and we propose two new sites for IBA status. We discuss our findings within a regional conservation context and provide recommendations for the implementation of an annual monitoring scheme of Chagos seabird populations to allow appropriate conservation management.

First record of Brown Noddy Anous stolidus for Guinea-Bissau

First record of Brown Noddy Anous stolidus for Guinea-Bissau

The Establishment of a New Brown Noddy Anous stolidus Breeding Colony off South-Western Australia

SummaryA new breeding colony of the Brown Noddy, which started on Lancelin Island in south-western Australia around 1991, expanded exponentially between 1994–95 and 1996–97. This growth in the number of breeding pairs resulted from the immigration of noddies from another breeding area, probably the Houtman Abrolhos 275 km to the north. In the 1996–97 breeding season there were two distinct waves of laying. The initial laying period, which had occurred in the previous two seasons, peaked in early November and was more synchronous than the second one. The second wave peaked in early December and resulted from laying by new arrivals with probably some re-laying from earlier losses. There was a significant reduction in clutch volume after the first 15 days of laying. Factors which may have produced a decline in egg size later in the season are discussed.

Aspects of seabird biology at Atol das Rocas Biological Reserve, Rio Grande do Norte, Brazil

Reserva Biológica do Atol das Rocas is a marine biological reserve located about 250 Km west of Natal - Rio Grande do Norte, Brazil. It has an abundant fauna of visiting or nestíng seabirds. Its 2 islets, around 3 ha each, shelter the largest breeding colonies of Masked Booby Sula dactylatra and Brown Noddy Anous stolidus in Brazil and of Sooty Tern Sterna fuscata for the South Atlantic. Data on biological aspects of the bird species were collected in 1991, 1993 and 1994. Field work included population censuses; mapping of nesting areas, nest building; eggs, chicks and adults biometry and characterization; bird banding and recoveries, and general observations. The results indicate a breeding period seasonality, possible Iinked with climate. Climate also influences the local vegetation. The drier part of the year expanded the nesting habitat of Sterna fuscata and Anous stolidus (namely at Cemitério islet). The abundance and occurrence of fish species (preys) that are important on seabirds' diet.

The breeding biology and aspects of the feeding ecology of brown noddies Anous stolidus nesting near Culebra, Puerto Rico, 1985–1989

We have studied brown noddies Anous stolidus breeding on Cayo Noroeste in the Culebra National Wildlife Refuge for the past five years (1985–1989). Daily visits during our residence there each year permitted collection of precise data on arrival chronology, egg‐laying and incubation patterns, egg morphometries, chick growth rates, food delivered to chicks and breeding success. Over 150 adults are now individually colour‐banded, and each annual chick cohort has been uniquely marked. Some features of the breeding biology of Culebran brown noddies were similar to those reported for pairs at Atlantic and Pacific Ocean colonies; these included duration of egg development, mass of newly hatched chicks, chick growth rates and fledging periods. Other features appear unique to Culebra. These include a tightly synchronous arrival (range of first egg dates: 29 April‐4 May) and short egg‐laying period (about six weeks), a consistently high breeding success each year (average 84% hatching success, 88% chicks fledged from eggs hatched, 0.79 chicks fledged per pair), and an unusually narrow range of food items (two fish species) taken by adults for their own needs and those of chicks. Observations of the direction taken by adults departing the colony suggest a predictable and productive foraging area along a prominent east‐west shelf‐break located c. 20 km to the north. We conclude that during these five years, brown noddies on Cayo Noroeste were not limited by food during the breeding season.

Human exploitation of seabirds in Jamaica

All nesting species of seabirds in Jamaica are exploited or seriously disturbed by people. The species which are most affected are sooty terns Sterna fuscata and brown noddies Anous stolidus. Collection of eggs for the local luxury market is the most detrimental form of exploitation. The evidence of a decline in the Jamaican populations and the possible causes of this decline are reviewed. Past and present management strategies are critically evaluated and recommendations made for future policy and research.

The biology of terns nesting at Aldabra Atoll, Indian Ocean, with particular reference to breeding seasonality

Five species of tern breed on Aldabra Atoll (09° 24′ S; 46° 20′ E). The Caspian tern Sterna caspia and Crested tern S. bergii feed exclusively in very shallow reef/lagoon water, the Fairy tern Gygis alba and Brown noddy Anous stolidus feed out at sea, and the Black‐naped tern Sterna sumatrana is intermediate in its foraging. Both of the shallow‐water species lay during the south‐east monsoon season, the Caspian tern from April to August and the Crested tern from June to August, but the Crested tern also lays in December and January. The remaining three species have extended laying periods largely circumscribed by the north‐west monsoon season from November to March. Breeding population size of the Caspian tern is in the low tens and of the Brown noddy in the low thousands, with the other species each numbering in the hundreds. The distribution and abundance of the nine species of tern breeding within the Seychelles (sensu lato) vary on the different island groups in a manner interpretable in terms of depth of the surrounding waters. Systematic differences between the central Seychelles and Aldabra groups in timing of breeding by terns which feed out at sea may be associated with seasonal latitudinal movement of the divergence zone between the South Equatorial Current and the Equatorial Counter‐current, acting via correlated latitudinal shifts of prey species and game‐fish abundance.