We report a massive mortality of 5,224 sea lions (Otaria flavescens) in Peru that seemed to be associated with highly pathogenic avian influenza A(H5N1) virus infection. The transmission pathway may ...have been through the close contact of sea lions with infected wild birds. We recommend evaluating potential virus transmission among sea lions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The great cormorant (Phalacrocorax carbo) has been a persistent source of human–wildlife conflicts in the Baltic Sea area. Fishers have perceived cormorants as competitors for fish resources, while ...conservationists have resisted mass hunting of the birds. In this paper, we analyse the cormorant conflict in Finland, with a special focus on its factual dimensions and the previous attempts to address the conflict at the national and regional levels. We also present the results from a knowledge co-production process, structured as a joint fact-finding process to address the contested knowledge claims concerning cormorant-fishing interactions. The results suggest that the factual controversy about the cormorant effect on fishing livelihood is essentially a frame conflict resulting from different scales of analysis. Our findings support the assumption that knowledge co-production processes have the potential to address science-intensive environmental conflicts and create practically useful and contextually appropriate knowledge, which integrate scientific knowledge with place- and practice-based knowledge. The process developed a shared understanding of the fishers’ practical wildlife-induced problems and several other questions, including cormorant impacts on migratory fish in Finland. A key to generating shared information was that the participants had control over information used in the process. Furthermore, third-party facilitation was important to ensure effective dialogue. While interpersonal conflicts have not been the original source of the impasse, they have become an important part of it and prevented efforts to constructively address the conflict.
•An important element of the cormorant-fishing conflict is disagreement over factual claims•Knowledge-co production generated shared information among scientists and stakeholders•Shifting the focus from fish stocks onto wildlife-induced damage to fishing would be helpful•The conflict is sustained by ineffectual communication and interpersonal relationships•Joint monitoring of cormorants could build trust and rapport among the local actors
Double-crested cormorants (Nannopterum auritum) have been implicated as causes of fish population declines in many locations across their breeding range. Two challenges facing managers are ...identifying fisheries population metrics indicative of cormorant impacts and determining when this evidence becomes actionable. Building upon existing studies, we conducted a meta-analysis of eight data-rich systems across the Laurentian Great Lakes region of the United States for common fish population responses to changes in cormorant abundance. Specifically, we examined trends in mean total female length at age-3 (TL3), female mean length and age at 50 % maturity, and mean age evenness as indicated by Shannon’s Equitability Index. Annual observations for these metrics were independently regressed linearly against cormorant density by system for walleye (Sander vitreus), yellow perch (Perca flavescens), smallmouth bass (Micropterus dolomieu), and northern pike (Esox lucius) populations. TL3 was the most sensitive with 9 of the 14 datasets statistically significant (r2 range 0.29 to 0.86). Maturity metrics were moderately sensitive to trends in cormorant predation with mean total length at 50 % maturity significant in 4 out of 11 datasets (r2 range 0.27–0.41) and mean age at 50 % maturity significant in 3 out of 11 datasets (r2 range 0.12 – 0.51). Least sensitive was age evenness with the Shannon Index significant in 3 out of 12 datasets (r2 typically < 0.25). Of metrics tested, TL3 was the most reliable indicator of changes in cormorant effects despite varying system changes and management responses among locations.
Anthropogenic debris, namely plastic, is a concern across aquatic ecosystems worldwide, with freshwater systems being understudied relative to marine systems. In this study, we quantified and ...characterized debris in the diet of double-crested cormorant chicks (Phalacrocorax auritus) from three sites in two of the Laurentian Great Lakes to (i) determine whether or not the diet of double-crested cormorants in the Laurentian Great Lakes includes anthropogenic debris, (ii) characterize the size, shape, and type of debris incorporated, and (iii) examine relationships between the amount of debris ingested and their proximity to industrial–urban centres. Overall, >86% of cormorants in our study had anthropogenic debris (mostly fibers) in their digestive tracts with no correlation between site and the amount of debris ingested. The ingested debris includes microplastics, natural fibres from textiles, and other anthropogenic materials (e.g., glass). To the best of our knowledge, this is one of the first studies to examine anthropogenic debris in a diving bird in the Laurentian Great Lakes and one of few studies investigating this in freshwater birds.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The current information about the diet composition of the rock shag (
Phalacrocorax magellanicus
) in the SW Atlantic coast comes mainly from conventional pellet or stomach content analysis from a ...few locations situated in northern Patagonia (Chubut Province, Argentina). In this work, we studied the diet of breeding rock shags over several years at a colony from southern Patagonia (Ría Deseado, Santa Cruz Province, Argentina) using a combined technique of conventional diet assessment (pellet analysis) and stable isotope analysis of carbon and nitrogen. Our results confirm the importance of benthic prey and the low inter-annual variability in the diet of the rock shag. These results coincide with previous research in relation to the exploitation of slow moving, predictable, but low-energy density prey. The stable isotope mixing models, which was informed with prior data obtained from pellet analysis, allowed for the detection of subtle differences between the diet of adults and chicks, consisting in the incorporation of higher proportions of cephalopods, an energy-rich prey, in the diet of chicks. By comparing our results with the diet of the red-legged cormorant, which breeds in sympatry in the Ría Deseado Estuary and whose diet composition is strongly pelagic, we suspect a certain level of trophic resource partitioning between these rock shag and red-legged cormorant.
There is a need for baseline information about how much plastics are ingested by wildlife and potential negative consequences thereof. We analysed the frequency of occurrence (FO) of plastics >1 mm ...in the stomachs of five pursuit-diving seabird species collected opportunistically.
Atlantic puffins (Fratercula arctica) found emaciated on beaches in SW Norway had the highest FO of plastics (58.8 %), followed by emaciated common guillemots (Uria aalge; 9.1 %) also found beached in either SW or SE Norway. No plastics were detected in razorbills (Alca torda), great cormorants (Phalacrocorax carbo), and European shags (Gulosus aristotelis) taken as bycatch in northern Norway. This is the first study to report on plastic ingestion of these five species in northern Europe, and it highlights both the usefulness and limitations of opportunistic sampling. Small sample sizes, as well as an unbalanced sample design, complicated the interpretation of the results.
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•Stomach plastic occurrence was reported in five seabird species in northern Europe.•Pursuit-diving seabirds from bycatch in northern Norway contained no plastics.•Beached, emaciated diving seabirds from southern Norway contained plastics.•Results may reflect spatio-temporal distribution of plastics and birds.•The biases in sampling design due to opportunistic sampling need careful attention.
After initial colonization of the Strait of Georgia in the late 19th and early 20th centuries, nesting populations and number of colonies of Pelagic Cormorant (Phalacrocorax pelagicus) and ...Double-crested Cormorant (P. auritus) increased in abundance until 1987, but subsequently both species declined by 2000. To update population status, we conducted surveys of 45 Pelagic Cormorant and 24 Double-crested Cormorant nesting colonies in 2014, and supplemented this survey with recent and historic counts conducted from 1955 to 2015. We modeled changes in population size over 6 decades to measure long-term population changes, and found strong non-linear trends that varied widely among colonies. Using years when all known colonies in the Strait of Georgia were surveyed, we documented that the Pelagic Cormorant population increased from 961 to 2234 nests in 1959–1974, remained fairly stable (approximately 2250–2450 nests) from 1974 to 1987, decreased after 1987 to approximately 1100 nests in 2000, and then rose slightly to approximately 1400 nests in 2014. The Double-crested Cormorant population increased from approximately 250 nests from 1959–1960, to approximately 1900 nests in 1987, before decreasing to approximately 600 nests in 2000, and remaining at this level through 2014. Many smaller colonies of both cormorant species no longer exist, and the majority of Pelagic and Double-crested Cormorants currently nest on Mandarte Island, Mitlenatch Island, and 3 bridge locations (Second Narrows, and Burrard & Granville) in Vancouver. The main factors apparently causing decline after 1987 are increased predation and disturbance by Bald Eagles (Haliaeetus leucocephalus), a potential reduction in availability of forage-fish prey, and human disturbance. Remaining large colonies offer some protection from eagle impacts (cliff habitats or man-made structures) or alternate avian prey for Bald Eagles, such as Glaucous-winged Gulls (Larus glaucescens) at Mandarte and Mitlenatch islands. In 2013–2015, small numbers of Brandt's Cormorants (P. penicillatus) nested at Mandarte Island. Continued monitoring is needed to track changes in populations and nesting locations and to inform management of cormorants in the Strait of Georgia.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Monitored seabird populations-useful sentinels of marine ecosystem health-have been declining worldwide at a rapid pace. Yet, lack of reliable long-term monitoring data constrains assessment of the ...conservation status of many seabird populations. Unmanned aerial vehicles (UAVs) have the potential to increase survey efficiency and count precision of seabird populations, especially where time constraints or inaccessible terrain, such as sea stacks, limit meaningful ground-based surveys. Furthermore, tremendous potential exists to combine fine-scale spatially integrated habitat mapping obtained from UAV images with occupancy to unravel how abiotic factors such as topography affect animal populations. In late December 2018, we used an UAV to create a georeferenced orthomosaic image and digital elevation model (DEM) from which we determined the size of the Antarctic shag (Leucocarbo bransfieldensis) breeding colony at Harmony Point, Nelson Island, South Shetland Islands. Our population estimate of 69 breeding pairs is approximately double that reported for the early 2000s and the highest count since the late 1980s. Most nests were located 10 to 20 m above sea level, on relatively shallow gradients that predominantly faced southeast. While it is difficult to compare historical ground-based counts with the UAV-derived estimates presented here, our new data provide robust baseline information for future monitoring of the colony population size using comparable survey methods. Our basic mapping of the topography of the breeding colony also highlights how UAV-derived habitat information can facilitate our understanding of the influence of landscape structure on animal population dynamics.
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