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- Steven, R., Pickering, C., and Castley, J.G. A review of the impacts of nature based recreation on birds. Journal of Environmental Management 92(10): 2287-2294, 2011.
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Nature based recreation such as wildlife viewing, hiking, running, cycling, canoeing, horse riding and dog walking can have negative environmental effects. A review of the recreation ecology literature published in English language academic journals identified 69 papers from 1978 to 2010 that examined the effect of these activities on birds. Sixty-one of the papers (88%) found negative impacts, including changes in bird physiology (all 11 papers), immediate behaviour (37 out of 41 papers), as well as changes in abundance (28 out of 33 papers) and reproductive success (28 out of 33 papers). Previous studies are concentrated in a few countries (United States, England, Argentina and New Zealand), mostly in cool temperate or temperate climatic zones, often in shoreline or wetland habitats, and mostly on insectivore, carnivore and crustaceovore/molluscivore foraging guilds. There is limited research in some regions with both high bird diversity and nature based recreation such as mainland Australia, Central America, Asia, and Africa, and for popular activities such as mountain bike riding and horse riding. It is clear, however, that non-motorised nature based recreation has negative impacts on a diversity of birds from a range of habitats in different climatic zones and regions of the world.
- Ibáñez-Álamo, J.D., Sanllorente, O., and Soler, M. The impact of researcher disturbance on nest predation rates: a meta-analysis. Ibis 154(1): 5-14, 2012.
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The effects of visits to nests by researchers interested in quantifying avian nesting success have received considerable attention, as researchers have long been concerned about the possible negative effects of their own activities on the resulting estimates. There is a widely held view that investigator disturbance has an overall negative effect on breeding success by increasing nest predation rates in the nests studied. However, to date no one has statistically assessed the empirical evidence for such a relationship. We undertook a meta-analysis of published results to assess whether researcher activities increase nest predation in birds. We also assessed the variability in this effect in relation to the traits of the study species and the methodology used. These analyses used data from 18 experimental studies involving 25 species from six avian orders. Our results suggest that, contrary to the traditional view, researcher activities do not generally affect the incidence of nest predation. Moreover, this relationship appears inconsistent among avian orders and, surprisingly, nest survival of passerines increased weakly with researcher activities. We also found significant positive effects of researcher activity on nest survival for species breeding on coastal areas and for species nesting on the ground. The possible explanation for these differences among orders and guilds could be due to different nest predator communities. This new perspective on the effect of investigators could have important implications for bird management and conservation, as well as for other fields of study such as ecology and evolution, in which nest survival rates measured in the field are widely used to test and support a range of hypotheses.
- Yang, H.-Y., Chen, B., Barter, M., Piersma, T., Zhou, C.-F., Li, F.-S., and Zhang, Z.-W. Impacts of tidal land reclamation in Bohai Bay, China: ongoing losses of critical Yellow Sea waterbird staging and wintering sites. Bird Conservation International 21(3): 241-259, 2011.
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The coast of Bohai Bay, north-western Yellow Sea, is critical for waterbirds migrating along the East Asia-Australasian Flyway. Between 1994 and 2010, a total of 450 km² of offshore area, including 218 km² of intertidal flats (one third of the original tidal area in the bay), has been reclaimed along the bay for two industrial projects. This has caused the northward migrants to become concentrated in an ever smaller remaining area, our core study site. The spring peak numbers of two Red Knot subspecies in the East Asia-Australasian Flyway, Calidris canutus piersmai and C. c. rogersi, in this so far little affected area increased from 13% in 2007 to 62% in 2010 of the global populations; the spring peak numbers of Curlew Sandpiper C. ferruginea increased from 3% in 2007 to 23% in 2010 of the flyway population. The decline in the extent of intertidal mudflats also affected Relict Gulls Larus relictus, listed by IUCN as 'Vulnerable'; during normal winters 56% of the global population moved from the wintering habitats that were removed in Tianjin to the relatively intact areas around Tangshan. Densities of wintering Eurasian Curlew Numenius arquata, and spring-staging Broad-billed Sandpiper Limicola falcinellus and Sanderling Calidris alba have also increased in the remaining areas. With the proposed continuation of land reclamation in Bohai Bay, we predict waterbird densities in the remaining areas to increase to a point of collapse. To evaluate the future of these fragile, shared international resources, it is vital to promote an immediate conservation action plan for the remaining coastal wetlands in this region, and continued population monitoring to determine the effects of this action.
- Watts, B.D. and Truitt, B.R. Decline of whimbrels within a mid-Atlantic staging area (1994-2009). Waterbirds 34(3): 347-351, 2011.
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Whimbrels (Numenius phaeopus) were monitored during spring migration across a network of ten aerial transects within the barrier island-lagoon system along the lower Delmarva Peninsula, Virginia, USA. Transects were surveyed weekly from the last week of April through the first week of June (1994-1996, 2008-2009). Whimbrel numbers increased to a peak during the first and second weeks of May then decreased sharply during the third and fourth weeks of May in all years. Between the 1990's and 2000's, peak numbers declined by 50%, corresponding to a 4.2% annual rate of decline. A similar decline was detected in accumulated, season-wide numbers. Though similar in pattern, migration phenology was significantly different between the decades. The phenology difference resulted from a greater reduction in numbers during the first half of the study period compared to the last. Habitats used by Whimbrels (N = 31,314) included mudflats (95%) and salt marshes (5%). Habitat-specific densities (birds/km2) were 443 ± 26.6 and 9 ± 1.6 (mean ± SE) for mudflat and marsh patches, respectively, during the 1990's and 222 ± 11.1 and 8 ± 4.6 during the 2000's. These results support suggestions that Whimbrels are declining on the Hudson Bay breeding grounds and perhaps at major Atlantic Coast wintering sites.
- Wilson, H.B., Kendall, B.E., Fuller, R.A., Milton, D.A., and Possingham, H.P. Analyzing variability and the rate of decline of migratory shorebirds in Moreton Bay, Australia. Conservation Biology 25(4): 758-766, 2011.
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Estimating the abundance of migratory species is difficult because sources of variability differ substantially among species and populations. Recently developed state-space models address this variability issue by directly modeling both environmental and measurement error, although their efficacy in detecting declines is relatively untested for empirical data. We applied state-space modeling, generalized least squares (with autoregression error structure), and standard linear regression to data on abundance of wetland birds (shorebirds and terns) at Moreton Bay in southeast Queensland, Australia. There are internationally significant numbers of 8 species of waterbirds in the bay, and it is a major terminus of the large East Asian-Australasian Flyway. In our analyses, we considered 22 migrant and 8 resident species. State-space models identified abundances of 7 species of migrants as significantly declining and abundance of one species as significantly increasing. Declines in migrant abundance over 15 years were 43-79%. Generalized least squares with an autoregressive error structure showed abundance changes in 11 species, and standard linear regression showed abundance changes in 15 species. The higher power of the regression models meant they detected more declines, but they also were associated with a higher rate of false detections. If the declines in Moreton Bay are consistent with trends from other sites across the flyway as a whole, then a large number of species are in significant decline.
- Smith, D.R., Jackson, N.L., Nordstrom, K.F., and Weber, R.G. Beach characteristics mitigate effects of onshore wind on horseshoe crab spawning: implications for matching with shorebird migration in Delaware Bay. Animal Conservation 14(5): 575-584, 2011.
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Disruption of food availability by unfavorable physical processes at energetically demanding times can limit recruitment of migratory species as predicted by the match-mismatch hypothesis. Identification and protection of disruption-resistant habitat could contribute to system resilience. For example, horseshoe crab Limulus polyphemus spawning and shorebird stopover must match temporally in Delaware Bay for eggs to be available to shorebirds. Onshore winds that generate waves can create a mismatch by delaying horseshoe crab spawning. We examined effects of beach characteristics and onshore winds on spawning activity at five beaches when water temperatures were otherwise consistent with early spawning activity. Onshore winds resulted in reduced spawning activity during the shorebird stopover, when spawning typically peaks in late May. During the period with high onshore wind, egg density was highest on the foreshore exposed to the lowest wave heights. Onshore wind was low in early June, and spawning and egg densities were high at all sites, but shorebirds had departed. Beaches that can serve as a refuge from wind and waves can be identified by physical characteristics and orientation to prevailing winds and should receive special conservation status, especially in light of predicted increases in climate change-induced storm frequency. These results point to a potential conservation strategy that includes coastal management for adapting to climate change-induced mismatch of migrations.
- Chowdhury, S.U. Survey and conservation of the critically endangered Spoon-billed Sandpiper in Bangladesh. Ibis 154(1): 210-211, 2012.
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- Catry, T. et al. Long-term declines of wader populations at the Tagus estuary, Portugal: a response to global or local factors? Bird Conservation International 21(4): 438-453, 2011.
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Migratory wader populations face global threats, mainly related to increasing rates of habitat loss and disturbance driven by human activities. To a large extent, the long-term survival of these populations requires the conservation of networks of sites along their migratory flyways. The Tagus estuary, Portugal, is among the most important wetlands for waders in the East Atlantic Flyway. Annual winter wader counts have been carried in this wetland since 1975 and a monthly roost-monitoring programme was implemented in 2007. Wintering populations of three out of the five most abundant species, Dunlin Calidris alpina, Grey Plover Pluvialis squatarola and Redshank Tringa totanus, showed significant population declines over the past three decades, which are most likely due to the loss and degradation of roost sites as a result of increasing human activity. The situation is unlikely to improve, as a high proportion of the wintering waders use roost sites that are situated in highly urbanised areas with no legal protection. The use of different roost sites by waders is highly variable both temporally and spatially, thus emphasizing the need for a network of good quality roost sites. Additionally, during migration, 60-80% of all the waders of the Tagus estuary concentrate at a single refuge, thus increasing the risk for wader populations during these periods.
- Skov, H. et al. Waterbird Populations and Pressures in the Baltic Sea. TemaNord 2011:550: 201pp., 2011.
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This report outlines the results of the internationally coordinated census of wintering waterbirds in the Baltic Sea 2007-2009 undertaken under the SOWBAS project (Status of wintering Waterbird populations in the Baltic Sea). The estimated total number of wintering waterbirds was 4.41 million compared to 7.44 million during the last co-ordinated census 1992-1993. Despite the general declines stable or increasing populations of herbivorous species were recorded. While benthic carnivores with a coastal distribution have either shown moderate declines, stable or increasing populations seaducks with an offshore distribution have declined seriously. Based on analyses of trends in wintering waterbirds and pressures indicators are suggested as performance indicators in relation to the international and national actions taken to reduce the anthropogenic pressures in the Baltic Sea.
- Lopez-Darias, M., Luzardo, J., Martínez, R., González, D., García, E.A., and Cabrera, J. Poaching vs. patrolling: effects on conservation of Cory's Shearwater Calonectris diomedea borealis colonies. Bird Conservation International 21(3): 342-352, 2011.
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Negative effects of poaching on seabird populations are not usually evaluated quantitatively when assessing seabird colony conservation status, nor are they generally considered a major concern. We demonstrate that poaching is still intense in the Canary Islands, and has negative consequences for the conservation of seabird colonies. We quantified the effects of poaching of Cory's Shearwater fledglings on breeding success on different islands in the Canaries, comparing colonies that suffer from intense, medium, or no poaching. Poaching reduced the breeding success of affected colonies to almost a third, potentially causing the future extinction of the colony. Only colonies with intense wardening campaigns reached high values of reproductive success, showing that government surveillance in conjunction with volunteers from different NGOs is a very effective approach in reducing poaching. A population sensitivity analysis was also conducted to provide data on the factors that most affect the performance of the model. Although population growth and mean final population size varied with increases and decreases in mortality and carrying capacity, only harvesting resulted in a probability of 100% of extinction in 20-40 years. To promote seabird conservation in regions such as the Canary Islands, a core archipelago for seabird species in the Atlantic, poaching control should be elevated by society to a level of urgency, requiring dedicated funding and mobilisation of experts and volunteers to adequately address it through education, prevention and enforcement.
- Brodier, S., Pisanu, B., Villers, A., Pettex, E., Lioret, M., Chapuis, J.L., and Bretagnolle, V. Responses of seabirds to the rabbit eradication on Ile Verte, sub-Antarctic Kerguelen Archipelago. Animal Conservation 14(5): 459-465, 2011.
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Studies on the role of introduced rabbits, Oryctolagus cuniculus, on islands have mainly focused on their negative impacts on vegetation. However, little attention has been paid to their influence on vertebrate communities. On Ile Verte (148 ha) in the sub-Antarctic Kerguelen Archipelago, rabbits are the only mammal that have been introduced. The long-term consequences of their eradication in 1992 on both native, burrowing seabird prey populations and their predator, the brown skua Catharacta skua, were investigated between 1991 and 2005. Densities of breeding petrels were followed on site with three plant communities differing in their soil depth. In addition, the diet and breeding activities of skuas were evaluated on the entire island area. The density of breeding pairs of the most abundant petrel species, the blue petrel Halobaena caerulea, which only nested at the site with deep-soil, increased by approximately eightfold during the 6 years following the rabbit eradication. Of the other species nesting in deep soil, there was an approximately fourfold reduction in the Antarctic prion, Pachyptila desolata, but such a decrease in breeding pair densities was not observed in areas with shallow soils. The South-Georgian diving petrels, Pelecanoides georgicus, was the rarest species, nesting only on mineral soils, and for which breeding pairs did not vary through time. The total numbers of fledged chicks of skua on the island significantly increased during the study period, but not the total number of breeding pairs. Thus, brown skuas were not affected by the disappearance of rabbits and rather benefited from an increase of their preferred prey. Blue petrels recovered quickly to sites with deep-soil, benefiting from the rabbit eradication and the cessation of burrow disturbance. The decrease of Antarctic prions could have been the result of an exclusion process from nesting areas on the deep soil site by blue petrels.
- Huang, H.W. and Yeh, Y.M. Impact of Taiwanese distant water longline fisheries on the Pacific seabirds: finding hotspots on the high seas. Animal Conservation 14(5): 562-574, 2011.
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Seabird bycatch by the longline fisheries of the Pacific Ocean is a major conservation concern. However, relatively few studies have examined the impacts of distant water longline fishing on the high seas due to the difficulty associated with deploying observers. Our study addresses this data gap by analyzing data from 2666 Taiwanese scientific observation data sets from 2002 to 2007 to calculate the seabird bycatch rate and to estimate the mortality of seabirds as a result of fishing activities by the entire fleet. A total of 379 seabirds were caught and 88% were albatross. A negative binomial distribution was used to represent the observed data based on spatial and temporal stratification, which yielded bycatch rates that ranged from 0.0003 to 0.2213 birds per 1000 hooks. The bycatch rates were highest in the areas between 25–45°N and 165°E–160°W between October and March and the areas between 25–35°S and 170°E–165°W between April and September. Using the observed data for bycatch rates and total fishing effort, the estimated number of seabird deaths caused by the Taiwanese fleet ranged from 1120 to 4290 birds annually. Increasing the observer coverage of specific fleets and areas, prioritizing observer programs and combined with international cooperation in research, would improve bycatch calculations. Seabird conservation efforts can be improved by monitoring fishing effort and the mandatory implementation of multiple mitigation measures.
- Kissling, M.L. et al. Distribution and abundance of the Kittlitz's Murrelet in selected areas of southeastern Alaska. Marine Ornithology 39(1): 3-11, 2011.
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We conducted boat-based surveys for the Kittlitz's Murrelet Brachyramphus brevirostris during the breeding season in southeastern Alaska from 2002 to 2009. We completed a single survey in seven areas and multiple annual surveys in three areas. Although surveys spanned a broad geographic area, from LeConte Bay in the south to the Lost Coast in the north (~655 km linear distance), roughly 79% of the regional population of Kittlitz's Murrelet was found in and between Icy and Yakutat bays (~95 km linear distance). The congeneric Marbled Murrelet B. marmoratus outnumbered the Kittlitz's Murrelet in all areas surveyed except Icy Bay; in fact, Kittlitz's Murrelet abundance constituted a relatively small proportion (7%) of the total Brachyramphus murrelet abundance in our survey areas. In areas for which there are multiple years of survey data, Kittlitz's Murrelet abundance varied considerably, whereas Marbled Murrelet abundance was comparatively stable during the same time period. Since the southern distribution of this species has likely narrowed over the last 50 years, and the distribution of the Kittlitz's Murrelet appears to be restricted to glacially influenced marine waters in southeastern Alaska, we expect that any future changes in glacial extent will likely affect this species and its long-term persistence in the region.
- Birt, T.P., MacKinnon, D., Piatt, J.F., and Friesen, V.L. Genetic differentiation of the Kittlitz's Murrelet Brachyramphus brevirostris in the Aleutian Islands and Gulf of Alaska. Marine Ornithology 39(1): 45-51, 2011.
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Information about the distribution of genetic variation within and among local populations of the Kittlitz's Murrelet Brachyramphus brevirostris is needed for effective conservation of this rare and declining species. We compared variation in a 429 base pair fragment of the mitochondrial control region and 11 microsatellite loci among 53 Kittlitz's Murrelets from three sites in the western Aleutian Islands (AttuIsland) and Gulf of Alaska (Glacier Bay and Kachemak Bay). We found that birds in these two regions differ genetically in three assessments: (1) global and pairwise indices of genetic differentiation were significantly greater than zero, (2) mitochondrial haplotypes differed by a minimum of nine substitutions, and (3) molecular assignments indicated little gene flow between regions. The data suggest that birds in these regions have been genetically isolated for an extended period. We conclude that Kittlitz's Murrelets from Attu Island and from the Gulf of Alaska represent separate evolutionarily significant units, and should be treated as such for conservation. Genetic data for Kittlitz's Murrelets from the remainder of the breeding range are urgently needed.
- Piatt, J.F., Arimitsu, M., Drew, G., Madison, E.N., Bodkin, J., and Romano, M.D. Status and trend of the Kittlitz's Murrelet Brachyramphus brevirostris in Glacier Bay, Alaska. Marine Ornithology 39(1): 65-75, 2011.
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We conducted standardized surveys for marine birds in Glacier Bay in seven years between 1991 and 2008. From our most recent survey, a combination of line- and strip-transect methods completed in 2008, we estimated that 4981 (95% CI 1293–8670) Kittlitz's Murrelets Brachyramphus brevirostris resided in Glacier Bay during the month of June, together with 12 195 (5607–18 783) Marbled Murrelets B. marmoratus. When counts were prorated to assign unidentified Brachyramphus murrelets to species, population estimates increased to 5641 Kittlitz's Murrelets and 13 810 Marbled Murrelets. Our surveys of bird numbers in Glacier Bay between 1991 and 2008 revealed that Kittlitz's Murrelet declined by =85% during this period. Trend analysis suggested a rate of decline between -10.7% and -14.4% per year. No direct human impacts (e.g., bycatch, oil pollution, vessel disturbance) in our study area could fully account for a decline of this magnitude. Widespread declines of Brachyramphus murrelets and Harbor Seals Phoca vitulina in the Gulf of Alaska during the 1980s–1990s suggest large-scale influences on these marine predators, perhaps related to climate-mediated cycles in food supply. Other natural factors that may impact Glacier Bay populations include predation by avian and terrestrial predators, widespread glacial retreat and its effect on nesting and foraging habitats, and competition for food with marine predators whose abundance in Glacier Bay has increased markedly in recent years (Humpback Whales Megaptera novaeangliae and Steller Sea Lions Eumetopias jubatus).
- Kuletz, K.J., Speckman, S.G., Piatt, J.F., and Labunski, E.A. Distribution, population status and trends of Kittlitz's Murrelet Brachyramphus brevirostris in Lower Cook Inlet and Kachemak Bay, Alaska. Marine Ornithology 39(1): 85-95, 2011.
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Lower Cook Inlet (LCI) in south-central Alaska is unusual among the breeding areas of Kittlitz's Murrelet Brachyramphus brevirostris because of human impacts on the marine and terrestrial environments and because of the lack of tidewater glaciers. In LCI the Kittlitz's Murrelet co-exists with the more abundant Marbled Murrelet, which complicates abundance estimates because of the difficulty of species identification. We compared survey data for an area with overlapping coverage in LCI (Core area) in 1993 (June) and from 1996 to 1999 (July-early August). Within this LCI Core area, the surveys in 1996–1999 estimated ~1600 Kittlitz's Murrelets and ~17 000 Marbled Murrelets, including prorated unidentified murrelets. The Kittlitz's Murrelet population declined between 1993 and 1999 at 26% per annum (84% overall). Simultaneously, Marbled Murrelets declined by 12% per annum (56% overall), though the decline was not statistically significant. Declines were estimated conservatively because the 1993 survey was conducted in June, when both murrelet species are less abundant on the water. We also surveyed Kachemak Bay, a large embayment of LCI, during mid-summer (July) of 2005–2007 and estimated a population of 2047 Kittlitz's Murrelets (SD 1120, n = 3 years) residing primarily in the inner bay. Marbled Murrelets numbered 11 040 (SD 1306) and were found throughout the bay. On one transect set in inner Kachemak Bay, Kittlitz's Murrelet density in late summer (1–16 August) declined 7.5% per annum between 1988 and 2007 (n = 6 years), and Marbled Murrelet density increased 4.9% per annum. On two other transect sets in the inner bay, however, neither murrelet species showed a change in density between 1996 and 2007. Inner Kachemak Bay is a persistent hotspot for Kittlitz's Murrelet and may attract murrelets from LCI and beyond. We recommend monitoring murrelet populations in Kachemak Bay, although Kittlitz's Murrelets likely move between the main body of Cook Inlet and Kachemak Bay, and a complete LCI survey is needed to gauge regional population trends.
- Kuletz, K.J., Nations, C.S., Manly, B., Allyn, A., Irons, D.B., and McKnight, A. Distribution, abundance, and population trends of the Kittlitz's Murrelet Brachyramphus brevirostris in Prince William Sound, Alaska. Marine Ornithology 39(1): 97-109, 2011.
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Monitoring population trends of rare species can be difficult if they cannot be readily separated from closely related, abundant species. Such species identification problems affect monitoring in Prince William Sound (PWS), Alaska, where Kittlitz's Murrelets Brachyramphus brevirostris co-exist with Marbled Murrelets B. marmoratus. We examined murrelet trends using data from PWS-wide surveys conducted in 11 years between 1972 and 2007, and models that incorporated murrelets not identified to species in population estimates. We examined modeled trends with and without unusually high (1972, 1993) or low (1998) population estimates. In 2001 and 2009, we also conducted intensive surveys for Kittlitz's Murrelets. Based on field estimates, identified Kittlitz's Murrelets declined by 63% (5% per annum) between 1989 and 2004 but appeared stable thereafter. Model estimates that incorporated unidentified birds suggested a steeper decline of 13% per annum between 1989 and 2007, and negative trends were obtained regardless of which years were included. Marbled Murrelets showed a lower rate of decline in modeled estimates, but field estimates for identified Marbled Murrelets continued to decline after 2004. Intensive surveys for Kittlitz's Murrelets produced a higher population estimate in 2009 than in 2001. Recent estimates for Kittlitz's Murrelet were 2346 birds (95% CI 514–4178) from the PWS-wide surveys in 2007, and 2080 birds (1409–2990) from the intensive surveys in 2009. We conclude that both murrelet species have declined since 1972, with the lower population size and restricted distribution of the Kittlitz's Murrelet putting it at greater risk of extirpation in PWS. Kittlitz's Murrelet may have stabilized after the mid-2000s, but our sample size was insufficient to make a determination. Our results emphasize that future conservation efforts will depend on frequent, long-term monitoring of species-specific trends.
- Madison, E.N. et al. Status and distribution of the Kittlitz's Murrelet Brachyramphus brevirostris along the Alaska Peninsula and Kodiak and Aleutian islands, Alaska. Marine Ornithology 39(1): 111-122, 2011.
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The Kittlitz's Murrelet Brachyramphus brevirostris is adapted for life in glacial-marine ecosystems, being concentrated in the belt of glaciated fjords in the northern Gulf of Alaska from Glacier Bay to Cook Inlet. Most of the remaining birds are scattered along coasts of the Alaska Peninsula and Aleutian Islands, where they reside in protected bays and inlets, often in proximity to remnant glaciers or recently deglaciated landscapes. We summarize existing information on Kittlitz's Murrelet in this mainly unglaciated region, extending from Kodiak Island in the east to the Near Islands in the west. From recent surveys, we estimated that ~2400 Kittlitz's Murrelets were found in several large embayments along the Alaska Peninsula, where adjacent ice fields feed silt-laden water into the bays. On Kodiak Island, where only remnants of ice remain today, observations of Kittlitz's Murrelets at sea were uncommon. The species has been observed historically around the entire Kodiak Archipelago, however, and dozens of nest sites were found in recent years. We found Kittlitz's Murrelets at only a few islands in the Aleutian chain, notably those with long complex shorelines, high mountains and remnant glaciers. The largest population (~1600 birds) of Kittlitz's Murrelet outside the Gulf of Alaska was found at Unalaska Island, which also supports the greatest concentration of glacial ice in the Aleutian Islands. Significant populations were found at Atka (~1100 birds), Attu (~800) and Adak (~200) islands. Smaller numbers have been reported from Unimak, Umnak, Amlia, Kanaga, Tanaga, Kiska islands, and Agattu Island, where dozens of nest sites have been located in recent years. Most of those islands have not been thoroughly surveyed, and significant pockets of Kittlitz's Murrelets may yet be discovered. Our estimate of ~6000 Kittlitz's Murrelets along the Alaska Peninsula and Aleutian Islands is also likely to be conservative because of the survey protocols we employed (i.e. early seasonal timing of surveys, strip transects).
- Luczak, C., Beaugrand, G., Jaffré, M., and Lenoir, S. Climate change impact on Balearic shearwater through a trophic cascade. Biology Letters 7(5): 702-705, 2011.
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A recent study showed that a critically endangered migratory predator species, the Balearic shearwater Puffinus mauretanicus, rapidly expanded northwards in northeast Atlantic waters after the mid-1990s. As a significant positive correlation was found between the long-term changes in the abundance of this seabird and sea temperature around the British Isles, it was hypothesized that the link between the biogeographic shift and temperature occurred through the food web. Here, we test this conjecture and reveal concomitant changes in a regional index of sea temperature, plankton (total calanoid copepod), fish prey (anchovy and sardine) and the Balearic shearwater for the period 1980-2003. All three trophic levels exhibit a significant shift detected between 1994 and 1996. Our findings therefore support the assertion of both a direct and an indirect effect of climate change on the spatial distribution of post-breeding Balearic shearwater through a trophic cascade.
- Tuck, G.N. Are bycatch rates sufficient as the principal fishery performance measure and method of assessment for seabirds? Aquatic Conservation: Marine and Freshwater Ecosystems 21(5): 412-422, 2011.
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1. Seabird bycatch in oceanic and coastal fisheries is believed to be the principal cause of the population declines that have been observed for many seabird populations. Pelagic and demersal longline and trawl operations have been implicated in these declines. 2. Many government and national fishery bodies have environmental and fishery legislation that requires fisheries to be managed in a manner that is not harmful to non-target species, including seabirds. A common tool for measuring the impact of a fishery on incidentally caught seabirds is an estimate of the bycatch rate. Unfortunately, the estimation and interpretation of bycatch rates is not trivial and is complicated by poor observer coverage, under-reporting of bycatch and data lacking species specificity. 3. In this paper, a stochastic simulation model of two seabird populations affected by a single fishing fleet is presented. The model is used to explore the consequences of applying a bycatch rate management control rule to assess and manage the fishery's incidental mortality of seabirds. Comparisons are also made with values derived from Potential Biological Removal (PBR) theory. 4. Results conclude that using bycatch rates as a measure to assess performance of the fishery and to reduce bycatch is, under many circumstances, not sufficient to achieve conservation goals. Bycatch rates can be within the limit recommended by management, giving the impression that the fishery has reduced bycatch to sustainable levels, when in fact the low rates are due to the populations having collapsed. 5. The interpretation of bycatch rates, and any subsequent bycatch rate management rules, needs to be considered with respect to changes in fishing effort, to population-specific impacts, to levels of compliance, and to the robustness of the bycatch rate estimate. Simply applying a bycatch rate control rule without caution can lead to catastrophic results for incidentally caught populations of seabirds.
- Pascoe, S., Wilcox, C., and Donlan, C.J. Biodiversity offsets: A cost-effective interim solution to seabird bycatch in fisheries? PLoS ONE 6(10): art. e25762, 2011.
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The concept of biodiversity offsets is well established as an approach to environmental management. The concept has been suggested for environmental management in fisheries, particularly in relation to the substantial numbers of non-target species-seabirds in particular-caught and killed as incidental bycatch during fishing activities. Substantial areas of fisheries are being closed to protect these species at great cost to the fishing industry. However, other actions may be taken to offset the impact of fishing on these populations at lower cost to the fishing industry. This idea, however, has attracted severe criticism largely as it does not address the underlying externality problems created by the fishing sector, namely seabird fishing mortality. In this paper, we re-examine the potential role of compensatory mitigation as a fisheries management tool, although from the perspective of being an interim management measure while more long-lasting solutions to the problem are found. We re-model an example previously examined by both proponents and opponents of the approach, namely the cost effectiveness of rodent control relative to fishery area closures for the conservation of a seabird population adversely affected by an Australian tuna fishery. We find that, in the example being examined, invasive rodent eradication is at least 10 times more cost effective than area closures. We conclude that, while this does not solve the actual bycatch problem, it may provide breathing space for both the seabird species and the industry to find longer term means of reducing bycatch.
- Marinao, C.J. and Yorio, P. Fishery discards and incidental mortality of seabirds attending coastal shrimp trawlers at Isla Escondida, Patagonia, Argentina. Wilson Journal of Ornithology 123(4): 709-719, 2011.
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We evaluated seabird attendance and incidental mortality at coastal trawl vessels targeting Argentine red shrimp (Pleoticus muelleri) in the Isla Escondida fishing area, Argentina, during 2006-2007 and 2007-2008. Eight seabird species attended vessels, and the most frequent and abundant seabird (percent occurrence, mean number per haul) in the two seasons was the Kelp Gull (Larus dominicanus) (100%, 112.3 and 100%, 263.4, respectively), followed by the Black-browed Albatross (Thalassarche melanophris) (85%, 17.6, and 90%, 32.4, respectively). Eleven Magellanic Penguins (Spheniscus magellanicus) and one Imperial Shag (Leucocarbo atriceps) were killed in nets with a mean capture rate of 0.003 and 0.0003 birds per haul, respectively. The estimated total number of birds killed was 53 penguins and five shags considering the total number of hauls made by the fishery in the two seasons. No contacts between seabirds and warp cables were recorded. Coastal shrimp vessels generally operated between 15 and 20 km offshore, at a mean distance from the main Kelp Gull colony (Punta Tombo) of 43.9 km. At least 100 fish and invertebrate species were discarded, mostly Argentine hake (Merluccius hubbsi). Total amount discarded per season by this coastal fishery in the two seasons was estimated at 3,284 and 6,590 tonnes, respectively. The coastal shrimp fishery in the Isla Escondida area appears to have a small impact on seabirds in terms of incidental mortality but provides significant amounts of supplementary food during the breeding season of the Kelp Gull.
- Saraux, C., Le Bohec, C., Durant, J.M., Viblanc, V.A., Gauthier-Clerc, M., Beaune, D., Park, Y.H., Yoccoz, N.G., Stenseth, N.C., and Le Maho, Y. Reliability of flipper-banded penguins as indicators of climate change. Nature 469(7329): 203-206, 2011.
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In 2007, the Intergovernmental Panel on Climate Change highlighted an urgent need to assess the responses of marine ecosystems to climate change. Because they lie in a high-latitude region, the Southern Ocean ecosystems are expected to be strongly affected by global warming. Using top predators of this highly productive ocean (such as penguins) as integrative indicators may help us assess the impacts of climate change on marine ecosystems. Yet most available information on penguin population dynamics is based on the controversial use of flipper banding. Although some reports have found the effects of flipper bands to be deleterious, some short-term (one-year) studies have concluded otherwise, resulting in the continuation of extensive banding schemes and the use of data sets thus collected to predict climate impact on natural populations. Here we show that banding of free-ranging king penguins (Aptenodytes patagonicus) impairs both survival and reproduction, ultimately affecting population growth rate. Over the course of a 10-year longitudinal study, banded birds produced 39% fewer chicks and had a survival rate 16% lower than non-banded birds, demonstrating a massive long-term impact of banding and thus refuting the assumption that birds will ultimately adapt to being banded. Indeed, banded birds still arrived later for breeding at the study site and had longer foraging trips even after 10 years. One of our major findings is that responses of flipper-banded penguins to climate variability (that is, changes in sea surface temperature and in the Southern Oscillation index) differ from those of non-banded birds. We show that only long-term investigations may allow an evaluation of the impact of flipper bands and that every major life-history trait can be affected, calling into question the banding schemes still going on. In addition, our understanding of the effects of climate change on marine ecosystems based on flipper-band data should be reconsidered.
- Barbraud, C., Gavrilo, M., Mizin, Y., and Weimerskirch, H. Comparison of emperor penguin declines between Pointe Géologie and Haswell Island over the past 50 years. Antarctic Science 23(5): 461-468, 2011.
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The emperor penguin (Aptenodytes forsteri) is highly dependent on sea ice conditions, and future climate change may affect its distribution and numbers. Most studies on the demography and population dynamics of emperor penguins in relation to sea ice characteristics were conducted at a single colony (Pointe Géologie). Several non-exclusive hypotheses have been proposed to explain the dramatic decline of this colony, including changes in sea ice conditions, predation, flipper banding and human disturbance. Here, we report and analyse updated long-term trends in numbers of breeding pairs made at two colonies (Pointe Géologie and Haswell Island) where counts are comparable. Similar changes were observed for both colonies and paralleled changes in sea ice extent. At Pointe Géologie and Haswell Island, populations declined similarly and later growth rates were also similar since the early 1990s for Haswell and early 1980s for Pointe Géologie. The magnitude of the decline was similar between both colonies when numbers of breeding pairs were assessed. This study suggests that a common large-scale environmental factor has probably negatively affected both colonies.
- Browne, T., Lalas, C., Mattern, T., and van Heezik, Y. Chick starvation in yellow-eyed penguins: Evidence for poor diet quality and selective provisioning of chicks from conventional diet analysis and stable isotopes. Austral Ecology 36(1): 99-108, 2011.
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The link between poor reproductive success and diet was investigated in yellow-eyed penguins Megadyptes antipodes, by assessing diet at two localities separated by about 30 km: the north coast of Stewart Island where breeding success is low (0.38–0.67 chicks per pair in recent years), and Codfish Island where breeding success is higher (0.96–1.51 chicks per pair), and relating this to published data from South Island localities, where average breeding success was 1.1 chicks per pair. Diet composition, meal sizes and energetic content of meals and prey were determined from stomach contents, and stable isotope analyses of chick down, fledgling feathers and adult blood provided information on diet throughout the fledging period. The high proportion of stomachs that were empty or lacked diagnostic remains reduced sample size considerably, and variability between samples reduced the power to detect significant differences in meal size, proportions of empty stomachs and prey diversity of meals. Energetic content of Stewart Island meals was less than Codfish Island meals, and there was a non-significant trend for smaller meal sizes and reduced prey diversity among Stewart Island samples. Both localities had lower prey diversity and smaller meals than South Island penguins. Blue cod Parapercis colias accounted for 99% of prey biomass in Stewart Island and 70% in Codfish Island stomach samples, where 27% of prey biomass was opalfish Hemerocoetes monopterygius. Isotopic mixing models carried out on larger sample sizes indicated that opalfish comprised a large proportion of the diet at both locations, with adults selectively provisioning chicks with opalfish while feeding mainly on blue cod themselves. We suggest the large blue cod consumed by Codfish Island and Stewart Island penguins, larger than those consumed by South Island penguins, is difficult to transfer to chicks by regurgitation. Oyster dredging around Stewart Island may have reduced the availability and abundance of alternative prey to Stewart Island penguins.
- Robson, B. et al. Revised population estimate and trends for the endangered Northern Rockhopper Penguin Eudyptes moseleyi at Tristan da Cunha. Bird Conservation International 21(4): 454-459, 2011.
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Around 80% of the world population of Northern Rockhopper Penguin Eudyptes moseleyi is found at Tristan da Cunha and Gough Island in the South Atlantic Ocean, where populations appear to be declining. However, numbers of birds at Middle Island, a small satellite island of Nightingale Island at Tristan da Cunha, have not been counted since 1973 when an estimated 100,000 pairs were recorded. Updated population counts were obtained for all four islands at Tristan da Cunha (Tristan, Inaccessible, Nightingale and Middle islands) in 2009 providing a census of the whole island group and the first repeat count of Middle Island. Estimated breeding numbers at these four islands were Tristan 6,700 pairs, Inaccessible 54,000 pairs, Nightingale 25,000 pairs and 83,000 pairs at Middle Island. These counts confirm that Tristan da Cunha is a vitally important site for this 'Endangered' species holding over 65% of the global population and that breeding number have been relatively stable over the last 30 years.
- Leat, E.H.K., Bourgeon, S., Borgå, K., Strøm, H., Hanssen, S.A., Gabrielsen, G.W., Petersen, Æ., Olafsdottir, K., Magnusdottir, E., Fisk, A.T., Ellis, S., Bustnes, J.O., and Furness, R.W. Effects of environmental exposure and diet on levels of persistent organic pollutants (POPs) in eggs of a top predator in the North Atlantic in 1980 and 2008. Environmental Pollution 159(5): 1222-1228, 2011.
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Concentrations of POPs in great skua eggs from Shetland are among the highest in North Atlantic seabirds, with up to 11,600 μg/kg (ww) DDE and up to 17,900 μg/kg ww SPCB. Concentrations of legacy POPs were significantly lower in 2008 than 1980. Decreases were greatest for least persistent compounds. Median ƩPBDEs increased from 99 μg/kg ww in 1980 to 173 μg/kg ww in 2008. There were changes in great skua breeding season diet, with more adult herring and mackerel and less sandeel. These changes increase exposure to POPs, since herring and mackerel accumulate more POPs than sandeels. In both years, eggs with higher δ15N had higher POP concentrations. In 1980, birds feeding more on demersal discard fish from trawl fisheries and less on sandeels, had higher POP levels in eggs. In 2008, individuals feeding more on herring and mackerel, and less on discards, had higher POP levels in eggs.
- Braune, B.M., Trudeau, S., Jeffrey, D.A., and Mallory, M.L. Biomarker responses associated with halogenated organic contaminants in northern fulmars (Fulmarus glacialis) breeding in the Canadian Arctic. Environmental Pollution 159(10): 2891-2898, 2011.
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We examined relationships between hepatic concentrations of halogenated organic contaminants and ethoxyresorufin O-deethylase (EROD) activity and retinoid (vitamin A) concentrations in livers, as well as retinol and thyroid hormone (TT3, TT4) levels in blood plasma, of northern fulmars at two breeding colonies in the Canadian High Arctic. Biomarker levels or responses did not differ significantly between males and females at either colony, nor was there any significant difference between colonies. No significant relationships were found between thyroid hormone or hepatic retinoid concentrations and any of the dioxin-like compounds or their Toxic Equivalents (TEQs) although significant positive correlations were found with plasma retinol (p < 0.03). EROD activity was significantly correlated with hepatic dioxin-like compounds and their TEQs (p < 0.001) as well as total PCBs (p < 0.01), which suggests that EROD induction occurs in northern fulmars at environmentally-relevant concentrations.
- Yamashita, R., Takada, H., Fukuwaka, M., and Watanuki, Y. Physical and chemical effects of ingested plastic debris on short-tailed shearwaters, Puffinus tenuirostris, in the North Pacific Ocean. Marine Pollution Bulletin 62(12): 2845-2849, 2011.
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We investigated the plastics ingested by short-tailed shearwaters, Puffinus tenuirostris, that were accidentally caught during experimental fishing in the North Pacific Ocean in 2003 and 2005. The mean mass of plastics found in the stomach was 0.23 g per bird (n = 99). Plastic mass did not correlate with body weight. Total PCB (sum of 24 congeners) concentrations in the abdominal adipose tissue of 12 birds ranged from 45 to 529 ng/g-lipid. Although total PCBs or higher-chlorinated congeners, the mass of ingested plastic correlated positively with concentrations of lower-chlorinated congeners. The effects of toxic chemicals present in plastic debris on bird physiology should be investigated.
- Nøst, T.H., Helgason, L.B., Harju, M., Heimstad, E.S., Gabrielsen, G.W., and Jenssen, B.M. Halogenated organic contaminants and their correlations with circulating thyroid hormones in developing Arctic seabirds. The Science of the Total Environment 414: 248-256, 2012.
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Thyroid hormones are essential for normal growth and development and disruption of thyroid homeostasis can be critical to young developing individuals. The aim of the present study was to assess plasma concentrations of halogenated organic contaminants (HOCs) in chicks of two seabird species and to investigate possible correlations of HOCs with circulating thyroid hormone (TH) concentrations. Plasma from black-legged kittiwake (Rissa tridactyla) and northern fulmar (Fulmarus glacialis) chicks were sampled in Kongsfjorden, Svalbard in 2006. The samples were analyzed for thyroid hormones and a wide range of HOCs (polychlorinated biphenyls (PCBs), hydroxylated (OH –) and methylsulphoned (MeSO –) PCB metabolites, organochlorine pesticides (OCPs), brominated flame retardants (BFRs), and perfluorinated compounds (PFCs)). Concentrations of HOCs were generally low in kittiwake and fulmar chicks compared to previous reports. HOC concentrations were five times higher in fulmar chicks compared to in kittiwake chicks. PFCs dominated the summed HOCs concentrations in both species (77% in kittiwakes and 69% in fulmars). Positive associations between total thyroxin (TT4) and PFCs (PFHpS, PFOS, PFNA) were found in both species. Although correlations do not implicate causal relationships per se, the correlations are of concern as disruption of TH homeostasis may cause developmental effects in young birds.
- Velarde, E., Navarro, C.J., Ruiz, E.A., and Aguilar, A. Status of the Craveri's Murrelet Synthliboramphus craveri and reoccupation of a former nesting area. Marine Ornithology 39(2): 269-273, 2011.
Open Access >>
- Baylis, A.M.M., Zuur, A.F., Brickle, P., and Pistorius, P.A. Climate as a driver of population variability in breeding Gentoo Penguins Pygoscelis papua at the Falkland Islands. Ibis 154(1): 30-41, 2012.
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Detecting and predicting how populations respond to environmental variability are eminent challenges in conservation research and management. This is particularly true for wildlife populations at high latitudes, many of which demonstrate changes in population dynamics associated with global warming. The Falkland Islands (Southwest Atlantic) hold one of the largest Gentoo Penguin Pygoscelis papua populations in the world, representing c. 34% of the global population. The numbers of breeding Gentoo Penguins at the Falkland Islands have shown a high degree of inter-annual variability since monitoring commenced in 1990. However, proximate causes of annual variability in breeding numbers have not been explored. Here we examine 21 years of Gentoo Penguin breeding surveys from the Falkland Islands and assess whether inter-annual variability in the number of breeding pairs were correlated with proxies of environmental variability. There was a positive correlation between the number of breeding pairs and a broad-scale climatic variation index, the Southern Oscillation Index (SOI). In turn, the SOI was significantly correlated with spring sea surface temperature anomalies, indicating a more immediate atmospherically forced response to El Niño Southern Oscillation variability in the Southwest Atlantic than previously reported. However, we also describe a non-linear response to environmental variability that may highlight foraging plasticity and/or the complexity of regional ecosystem interactions that operate across a range of different scales.
- Rodríguez, A., Rodríguez, B., and Lucas, M.P. Trends in numbers of petrels attracted to artificial lights suggest population declines in Tenerife, Canary Islands. Ibis 154(1): 167-172, 2012.
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The secretive breeding behaviour of petrels makes monitoring their breeding populations challenging. To assess population trends of Cory's Shearwater Calonectris diomedea, Bulwer's Petrel Bulweria bulwerii and Macaronesian Shearwater Puffinus baroli in Tenerife from 1990 to 2010, we used data from rescue campaigns that aim to reduce the mortality of fledgling petrels attracted to artificial lights as proxies for trends in breeding population size. Despite increases in human population size and light pollution, the number of rescued fledglings of Cory's Shearwater and Bulwer's Petrel increased and remained stable, respectively, whereas numbers of rescued Macaronesian Shearwaters sharply declined. In the absence of more accurate population estimates, these results suggest a worrying decline in the Macaronesian Shearwater's breeding population.
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