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Foraging Areas of Nesting Ainley\u27s Storm Petrel \u3ci\u3eHydrobates cheimomnestes\u3c/i\u3e
No full textAcquiring basic knowledge such as at-sea distribution is often difficult for cryptic seabird species. Northern storm petrels (Hydrobatidae) are one family of seabirds that includes several cryptic species, including Ainley’s Storm Petrel Hydrobates cheimomnestes, which appears quite similar to southern Leach’s H. leucorhous and Townsend’s H. socorroensis Storm Petrels when at sea. For the first time, we describe the at-sea distribution of breeding Ainley’s Storm Petrels obtained using GPS tracking. We found that these birds visit waters of the eastern North Pacific between central Baja California, Mexico and southern Alta California, USA. These findings expand existing knowledge of the range of this species, which had previously been based on a few at-sea sightings and specimens
Atlantic Yellow-nosed Albatross \u3ci\u3eThalassarche chlororhynchos\u3c/i\u3e Feeding on a Dead Sea Turtle
No full textAlbatrosses mostly forage for fish, squid, and crustaceans (including discards from fishing vessels), but they also scavenge animal carcasses, a behavior still poorly characterized for some albatross species. In July 2021 during a pelagic birding trip off the coast of São Paulo State, Southeast Brazil, three Atlantic Yellow-nosed Albatross Thalassarche chlororhynchos were spotted feeding on the floating carcass of a Loggerhead Sea Turtle Caretta caretta. This behavior had not been previously documented in the literature, on-line citizen science platforms, or by personal observations. We believe this to be an uncommon feeding strategy for this albatross species
Digging In! Burrowing Penguins and Surface Predators
No full textA native Australian corvid, Little Raven Corvus mellori, has emerged as a dominant and problematic predator of an ecologically and economically important seabird, the Little Penguin Eudyptula minor. In 2013, ravens successfully preyed upon clutches/broods of the burrow-nesting penguin, especially those in shallower, more accessible burrows. Individual raven size might mediate which ravens attack penguins; smaller ravens may be able to enter burrows more easily; alternatively, larger ravens may be more capable of overcoming penguin parental defence. Here, we consider the predator-prey interactions to assess whether associations with burrow characteristics persisted and examine whether raven size mediated propensity to prey upon penguin eggs. We compared data from the 2013 and 2015 penguin breeding seasons at Phillip Island (Victoria, Australia) for differences in clutch survival and burrow characteristics. We also examined raven morphometrics to determine if any physical differences existed between known burrow-predators (“culprits”) and other birds. During the 2013 breeding season, penguins suffered clutch losses of 61.1% compared with 33.9% in 2015. Burrow characteristics changed between seasons—most noticeably, burrows were deeper in 2015 and ravens no longer discriminated between burrow characteristics. Culprits were heavier and larger. While we could not eliminate inter-annual variability as a possible contributing factor, our results were consistent with rapid adaptation of prey and predator to intense emergent depredation. Penguins may now construct deeper burrows, and ravens evidently no longer select more vulnerable burrows. Larger ravens may be more capable of approaching and attacking penguin burrows
In Memoriam: William (Bill) R.P. Bourne, 1930-2021
No full textThis tribute is a compilation of obituaries by Michael Harris and Mark Tasker, Craig Harrison\u27s speech at the ceremony for Bill\u27s Pacific Seabird Group (PSG) Lifetime Achievement Award in 1997, Michael Harris\u27s eulogy at Bill\u27s memorial service in Scotland, and emails I have received from PSG members, as well as from my memories of a very long friendship with Bill and his wife Sheila spanning over 30 years
Laying Sequence and Oceanographic Factors Affect Egg Size in Scripps\u27s Murrelets \u3ci\u3eSynthliboramphus scrippsi\u3c/i\u3e at Santa Barbara Island
No full textEgg size is an important avian life history parameter, with larger eggs indicating greater investment of resources in the chick. Prey availability can affect such investment. We investigated the effects of oceanographic conditions and laying sequence on Scripps’s Murrelet Synthliboramphus scrippsi egg size at Santa Barbara Island, California during 2009–2017. We evaluated oceanographic covariates characterizing marine productivity for their effect on egg size, including large-scale oceanographic indices such as the Pacific Decadal Oscillation (PDO) index, Oceanic Niño Index (ONI), and North Pacific Gyre Oscillation (NPGO) index. We also evaluated a larval anchovy catch-per-unit-effort (ANCHL) index and the Biologically Effective Upwelling Transport Index (BEUTI) as region-wide indices, and sea surface temperature (SST) as a local index. We evaluated oceanographic conditions over the entire year and during the breeding season only. We also considered the contribution of lagged effects to oceanographic conditions. Our results generally ran counter to our hypothesis that increased ocean productivity should increase egg size. Based on Akaike’s Information Criterion, the four top-ranked models provided support for an association between larger eggs and conditions indicative of lower oceanographic productivity, including lower values of BEUTI and NPGO, and higher values of ONI, PDO, and SST. The only result that supported our hypothesis was a positive relationship between ANCHL and egg size, although the 95% confidence interval for the effect included 0. The strongest relationship detected was between laying sequence and egg size, as second eggs were considerably larger than first eggs. Our results indicate substantial complexity in the relationship between ocean productivity and seabird demography. A better understanding of how ocean productivity affects seabird breeding outcomes through multiple mechanisms will help improve predictions of how seabirds will respond to changing ocean conditions
Underwater Kleptoparasitism on a Human Diver by a Galapagos Flightless Cormorant \u3ci\u3eNannopterum harrisi\u3c/i\u3e
No full textWe describe underwater kleptoparasitism on a human diver by a Galapagos Flightless Cormorant Nannopterum harrisi, a behavior that has not been previously described for this species
Characterizing the Diet of a Threatened Seabird, the Marbled Murrelet \u3ci\u3eBrachyramphus marmoratus\u3c/i\u3e, Using High-throughput Sequencing
No full textUnderstanding prey consumption patterns is critical to understanding the ways in which seabirds cope with a changing ocean. However, characterizing the dietary habitats of seabirds can be challenging. In this study, we investigated the diet of the Marbled Murrelet Brachyramphus marmoratus population that lives in waters off California, Oregon, and Washington, USA, using fecal DNA, custom metabarcoding, and high-throughput sequencing. Murrelets were captured at sea by dip-netting at night. Across this region, murrelets consumed highly diverse prey types including 17 fish species and 10 invertebrate species, in accord with previous work indicating the species’ forage on a wide range of prey. Pacific Herring Clupea pallasii was the most common prey in Washington and Oregon (frequency of occurrence = 0.84 and 0.69, respectively), replaced by Northern Anchovy Engraulis mordax in California (frequency of occurrence = 0.77). In Oregon, where our sample size was sufficient, diet composition differed between the 2017 and 2018 breeding seasons, with an apparent decline in the proportional consumption of energy-dense prey. Common and energy-dense prey were consumed in equal proportions by males and females, perhaps because of foraging in the same habitat. Diet did not vary between breeders and non-breeders. Our study offers the first detailed report on the diet of adult Marbled Murrelets in waters where they are listed as Threatened by the US federal government. This indicates that managing fisheries and conserving spawning habitat for high-occurrence prey species could benefit murrelet populations
Lesser Noddy \u3ci\u3eAnous tenuirostris\u3c/i\u3e Migration from a Non-breeding Area in the Northern Maldives to a Breeding Site in the Seychelles
No full textThe Lesser Noddy Anous tenuirostris occurs in large numbers in the northern Maldives during the northeast monsoon season (December to April). These birds do not breed in the Maldives, but their breeding site(s) are unknown. We attached GPS Argos satellite transmitters to seven Lesser Noddies roosting on Gallandhoo Island (Haa Alifu Atoll, northern Maldives) on 25 March 2022. Only one transmitter provided data, but it tracked the migration of one Lesser Noddy to the Seychelles, where the bird first roosted on the island of Poivre before moving to the large nesting colony on Cousine. The tracked bird departed the Maldives on 02 April and arrived in the Seychelles on 10 April, covering approximately 2400 km in eight days. Our results highlight the potential benefit of enhanced cooperation and knowledge exchange between the Seychelles and Maldives for improving conservation of Lesser Noddies in the Indian Ocean
Oiling Threats to Marine Birds on Southern Vancouver Island, British Columbia, Canada
No full textInformation on the distribution and abundance of marine birds is needed to evaluate current status in relation to threats from potential increases in vessel traffic off southern Vancouver Island, British Columbia (BC), Canada, in the Salish Sea. We conducted year-round boat based surveys in waters between Sidney, BC and Victoria, BC from November 2015 to August 2019 and examined seasonal variation in bird distribution and abundance. Our study area included parts of the Sidney Channel Important Bird Area, the Shoal Harbour and Victoria Harbour Migratory Bird Sanctuaries, and the Chain Islets Ecological Reserve, adjacent to major shipping lanes, as well as ports and marinas. With the approval for the proposed expansion of the Trans Mountain pipeline to Burnaby, BC, tanker traffic is expected to increase in our study area. Increases in several categories of marine vessel traffic have occurred recently in the Salish Sea and are expected to increase further with the development of Liquefied Natural Gas projects and the Delta Port expansion on Roberts Bank. Within that context, we counted all marine birds but focused primarily on alcids: Rhinoceros Auklet Cerorhinca monocerata, Common Murre Uria aalge, Pigeon Guillemot Cepphus columba, Marbled Murrelet Brachyramphus marmoratus, and Ancient Murrelet Synthliboramphus antiquus. Alcids were present year-round but showed species-specific seasonal spatial patterns. These patterns are likely related to seabird annual cycles as well as fluctuations in forage fish prey populations, their habitats, and variation in seasonal availability to birds. Increasingly busy shipping lanes for tanker, cargo, and passenger vessels pass nearby and through our study area. These shipping lanes, together with traffic from tugs, fishing vessels, and recreational motor and sailing vessels, plus the many marinas and terminals in the area, pose significant risks to marine birds