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Movements and Asynchronous Nesting of the Peruvian Tern \u3ci\u3eSternula lorata\u3c/i\u3e in Chile and Peru
No full textThe Peruvian Tern Sternula lorata is an endangered seabird that nests asynchronously in different parts of its nesting range from northern Chile to Ecuador. Asynchronous nesting raises the possibility of counting individuals more than once during annual population censuses. We deployed 10 light-level archival tags (geolocators) to terns at the nesting ground in Mejillones, Chile, at the southern end of this species’ range during 06–11 September 2015, and we retrieved three the following year at the same location. Results showed that the tagged birds remained at the nesting grounds in Mejillones from July to December then migrated north, some in stages, to non-breeding areas along the coast of Peru and possibly Ecuador. Here they remained until early to mid-July 2016, although some movement among specific sites occurred between December 2015 and July 2016. They returned to their nesting areas more rapidly in early to mid-July. We detected no indications of additional nesting by these individuals away from Mejillones, Chile. Though sample size is small, these observations indicate at least that terns that breed in northern Chile likely do not nest again in Peru/Ecuador, though they may stay for extended periods. Therefore, we recommend that population estimates sum the counts of all nests and/or nesting pairs at all sites throughout the range each calendar year and count large roosting flocks separately. In addition, we suggest further studies to examine the possibility of geographically and temporally separated breeding populations
Composition of the Seabird Community Off French Guiana
No full textWe provide information on the seabirds occurring year-round in waters of the French Guiana Exclusive Economic Zone, based on data obtained from three boat-based campaigns: a campaign by the Groupe d’Étude et de Protection des Oiseaux de Guyane was conducted for four days every two months from July 2011 to June 2012; a campaign by Cohabys was performed for five days per month from January to May 2018; and a campaign by Ocean Science & Logistic consisted of four 10-day surveys conducted in June, July, September, and October 2018. Overall, 30 seabird species within 1110 groups of birds were sighted along 6686 km of surveys conducted during favorable weather conditions (Beaufort \u3c 5). Seabirds of the family Laridae were the most frequently observed, followed by those of the family Procellariidae. In waters over the continental slope, the most frequently observed species were Sooty Tern Onychoprion fuscatus; Brown Noddy Anous stolidus; Wilson’s Oceanites oceanicus and Leach’s Hydrobates leucorhous Storm Petrels; Great Ardenna gravis, Manx Puffinus puffinus, and Audubon’s Puffinus lherminieri Shearwaters; and Masked Booby Sula dactylatra. In waters over the shelf, the most common species were Common Tern Sterna hirundo, Laughing Gull Leucophaeus atricilla, and Royal Tern Thalasseus maximus. In the coastal area, the most common species were Laughing Gull, Royal Tern, and Cayenne Tern T. acuflavidus eurygnathus. The Magnificent Frigatebird Fregata magnificens was sighted in all habitats. Monthly presence/absence and associations of species were also analyzed. Our results underline the high species diversity of seabirds within the waters of French Guiana as well as the diverse uses of available habitats. Indeed, the region is not only a major nesting area, but also a major foraging area for wintering, summering, and migrating species. We recommend strengthening seabird conservation measures and, in particular, increasing the extent of Marine Protected Areas
Upwelling Links Reproductive Success and Phenology in Tropical Brown Boobies \u3ci\u3eSula leucogaster\u3c/i\u3e
No full textFor organisms living in seasonal environments, timing of breeding is key to ensuring reproductive success. Accordingly, temperate and polar seabird species follow seasonal pulses, matching their breeding events with peaks in ocean productivity. However, the seasonality of breeding has been much less explored in tropical seabirds. Here, we report seasonal variation in oceanography that affects reproductive success of the Brown Booby Sula leucogaster, a species widely distributed in the tropics. We monitored 61 nests during the 2019 breeding season at Bona Island, Gulf of Panama, and collected remote-sensing information for upwelling, sea-surface temperature, rainfall, chlorophyll-α concentration, wind speed, and wind direction. We used egg/chick survival probability and a sliding-window statistical approach to assess temporal changes in reproductive success. Maximum chlorophyll-α concentrations (linear and quadratic expressions) had the strongest influence over survival probability in the two to three weeks prior to the death of the egg/chick. After model averaging, we found that survival probability was positively correlated with maximum chlorophyll-α (confidence interval CI(β) = 0.19 to 2.54 mg/m3) and negatively correlated with (maximum chlorophyll-α)2 (CI(β) = −4.19 to −0.31 mg/m3). In addition, survival probability decreased with later laying dates (CI(β) = 0.43 to 1.74 days), indicating that chicks born earlier in the breeding season had higher chances of survival. Given the correlation between chlorophyll-α and upwelling, we concluded that Brown Booby reproductive success in the Gulf of Panama is influenced by upwelling and that breeding in this tropical species follows seasonal pulses like those observed in polar and temperate species
Parental Infanticide by Egg Destruction in Red-billed Tropicbirds \u3ci\u3ePhaethon aethereus\u3c/i\u3e on the Caribbean Island of Sint Eustatius
No full textAvian reproduction is a process that requires extensive energetic input by parents, particularly in pelagic seabirds. Parental infanticide has rarely been reported in pelagic seabirds, and its frequency among taxa is therefore difficult to determine. Using data from remote cameras, two cases of probable parental infanticide in Red-billed Tropicbirds Phaethon aethereus were captured on Sint Eustatius in the 2021–2022 breeding season. Both cases are presented with images collected from remote cameras as evidence. While appearing counterproductive, parental infanticide may provide an alternative reproduction strategy that favors lifetime reproductive success over short term success
Reviews: Chasing The Sun (Musso, T.); New(Ish) And Noteworthy: Ocean Bestiary: Meeting Marine Life From Abalone To Orca To Zooplankton (King, R.J.); Flight Paths: How A Passionate And Quirky Group Of Pioneering Scientists Solved The Mystery Of Bird Migration (Heisman, R.); Nonviolent Communication: A Language Of Life, 3rd Edition (Rosenberg, M. B.); The Home Place: Memoirs Of A Colored Man\u27s Love Affair With Nature (Lanham, J.D.)
No full textEcological Experiences and Perceptions of Small-Scale Gillnet and Purse Seine Fishers on Seabirds and other Non-target Taxa in the Humboldt Current System, Chile
No full textStrategies to reduce the negative impacts of fisheries on ecosystems often come into conflict with fishers who have different experiences with, and perceptions of, biodiversity compared to policy makers and fisheries managers. We interviewed 800 fishers along 2400 kilometers of the Humboldt Current System (HCS) coast, assessing fishers’ perceptions of the impacts of marine predators on fishing and their proposals to reduce conflicts with small-scale net fisheries. Vessel captains saw seabirds as positive indicators of fish presence along the HCS (mean probability 62.7%). In contrast, sea lions were perceived negatively, affecting catches for all fishers and causing fishing gear damage among gillnet fishers (97.1%). Among different measures suggested by fishers to reduce conflicts with non-target taxa, night fishing and marine protected areas (MPAs) were viewed as least likely to be implemented because these affect fishing performance (6% and 13.1%) through changes to at-sea safety and fishing effort displacement, respectively. In contrast, economic compensation and culling of currently protected sea lions were the most popular but also the most sensitive measures (31% and 33%, respectively). Different dimensions of experiences and perceptions of fishers are key to the bottom-up understanding of interactions in small-scale fisheries. This is especially true when measures to mitigate their impacts do not have any consolidated installation/monitoring, which is a continuing challenge for these types of fisheries globally. This study emphasizes the role of small-scale fishers as a source of diverse ecological experiences and perceptions to complement knowledge on sensitive conservation issues
Melanistic Razorbill \u3ci\u3eAlca torda\u3c/i\u3e at Machias Seal Island, New Brunswick, Canada
No full textAberrant colouration in birds is relatively common but melanism occurs infrequently. We report an observation of a melanistic Razorbill Alca torda attending the nesting colony at Machias Seal Island, Bay of Fundy in 2022 and 2023. This is the third reported occurrence of a melanistic Razorbill and the first in over 100 years
Hybridization in Terns: A Review
No full textHybridization—the interbreeding of different species—is a relatively common phenomenon in birds, but its study is biased towards certain taxa. In this review, we focus on a bird group that has received less attention: terns (Laridae, Sterninae). Based on an extensive literature search, we found records for 16 hybrids between tern species, with varying levels of supporting evidence: ten cases had strong support, one had medium support, one had low support, and four cases were deemed unreliable (two were refuted and two could not be evaluated). The strongly supported hybrid records involved 14 different tern species (out of 41 species, 34%). The underlying mechanisms of tern hybridization remain to be studied in more detail. The most likely processes that can result in the breakdown of reproductive isolation are (1) a scarcity of conspecifics, (2) interspecific extra-pair copulations, and (3) mis-imprinting after brood parasitism. Based on the available evidence, a scarcity of conspecifics appears to be the mechanism that most frequently results in the formation of mixed pairs and the production of hybrid offspring in terns. Our literature search revealed that population-level genetic analyses of tern hybridization are currently lacking. Given the occurrence of multispecies hybridization, it is possible that some tern species act as “genetic bridges” within a network of tern hybrids. All in all, the interbreeding of tern species provides exciting opportunities for further research that may generate novel insights into avian hybridization and speciation
First Aberrant Coloured \u3ci\u3eCalonectris\u3c/i\u3e Shearwater recorded in Madeira, Portugal
No full textHerein, we report a Calonectris sp. shearwater with aberrant plumage, observed southwest off Madeira Island. The bird had an unusual amount of white feathering, more than has been reported so far for the genus. Both upperparts and underparts were predominantly white. Initially, we thought the bird was a leucistic Cory’s Shearwater C. borealis, but some characteristics could not be ascertained. Records of such aberrations should be published to provide a more comprehensive understanding of the subject
The Owl Gull: Exclusively Nocturnal Foraging by the Swallow-tailed Gull \u3ci\u3eCreagrus furcatus\u3c/i\u3e in Galápagos
No full textColony-based observations indicate that Swallow-tailed Gulls Creagrus furcatus go to sea only at night. Here, we use GPS tracking technology to reveal the species’ exclusively nocturnal foraging behavior at four colonies in the Galápagos Islands. All nocturnal trips proved to be foraging effort in pelagic waters 19–103 km from nests during breeding. While at sea, individuals spent approximately one-quarter of their time commuting, with half of the time dedicated to area-restricted search behavior. Three years of data from one colony indicate spatial fidelity to a general foraging area. Our research directly confirms that Swallow-tailed Gulls are the only obligate nocturnal foragers among Laridae and contributes to our understanding of nocturnal foraging strategies in tropical seabirds