出口 智広

Abstract Long-lived territorial bird populations often consist of a few territorial breeding adults and many nonbreeding individuals. Some populations are threatened by anthropogenic activities, because of human conflicts for high-quality breeding habitat. Therefore, habitat restoration projects have been widely implemented to improve avian population status. In conjunction with habitat restoration, conservation translocations have been increasingly implemented. Adequate nonbreeder survival can be a key factor in the success of these attempts because nonbreeding birds may represent reservoirs for the replacement of breeders. The maintenance of breeding pair numbers is also influenced by the transition rate of nonbreeders to breeders. The reintroduction of Oriental Stork (Ciconia boyciana), a long-lived, territorial, endangered species, was initiated in Japan in 2005 using captive birds in hopes of increasing the population’s use of restored habitat. Our objective of this study was to elucidate the factors determining reintroduced stork survival and recruitment to the breeding populations. We estimated the survival rate and breeding participation rate by sex, age, generation, wild-born or not, haplotypes, and breeding status in storks reintroduced during 2005–2022 using Bayesian hierarchical models. There was no significant difference in survival rate between nonbreeders and breeders. However, the survival rate was lower in wild-born birds than released birds, which may be related to the longer-distance natal dispersal of new generations. Accelerated habitat restoration around breeding areas and preventive measures for collision with human-built structures should be implemented for the sustained growth of reintroduced populations. A low survival rate was also detected for a specific mitochondrial DNA (mtDNA) haplotype that accounts for the majority of the reintroduced population. This phenomenon might be explained by mtDNA-encoded mutations. Moreover, captive breeding and release history might contribute to an increase in the proportion of this haplotype in the wild.

Marine protected areas (MPAs), particularly large MPAs, are increasing in number and size around the globe in part to facilitate the conservation of marine megafauna under the assumption that large-scale MPAs better align with vagile life histories; however, this alignment is not well established. Using a global tracking dataset from 36 species across five taxa, chosen to reflect the span of home range size in highly mobile marine megafauna, we show most MPAs are too small to encompass complete home ranges of most species. Based on size alone, 40% of existing MPAs could encompass the home ranges of the smallest ranged species, while only < 1% of existing MPAs could encompass those of the largest ranged species. Further, where home ranges and MPAs overlapped in real geographic space, MPAs encompassed < 5% of core areas used by all species. Despite most home ranges of mobile marine megafauna being much larger than existing MPAs, we demonstrate how benefits from MPAs are still likely to accrue by targeting seasonal aggregations and critical life history stages and through other management techniques.

Abstract Understanding encounters between marine predators and fisheries across national borders and outside national jurisdictions offers new perspectives on unwanted interactions to inform ocean management and predator conservation. Although seabird–fisheries overlap has been documented at many scales, remote identification of vessel encounters has lagged because vessel movement data often are lacking. Here, we reveal albatrosses–fisheries associations throughout the North Pacific Ocean. We identified commercial fishing operations using Global Fishing Watch data and algorithms to detect fishing vessels. We compiled GPS tracks of adult black‐footed Phoebastria nigripes and Laysan Phoebastriaimmutabilis albatrosses, and juvenile short‐tailed albatrosses Phoebastria albatrus. We quantified albatrosses‐vessel encounters based on the assumed distance that birds perceive a vessel (≤30 km), and associations when birds approached vessels (≤3 km). For each event we quantified bird behaviour, environmental conditions and vessel characteristics and then applied Boosted Regression Tree models to identify drivers and the duration of these associations. In regions of greater fishing effort short‐tailed and Laysan albatrosses associated with fishing vessels more frequently. However, fishing method (e.g. longline, trawl) and flag nation did not influence association prevalence nor the duration short‐tailed albatrosses attended fishing vessels. Laysan albatrosses were more likely to approach longer vessels. Black‐footed albatrosses were the most likely to approach vessels (61.9%), but limited vessel encounters (n = 21) prevented evaluation of meaningful explanatory models for this species of high bycatch concern. Temporal variables (time of day and month) and bird behavioural state helped explain when short‐tailed albatrosses were in close proximity to a vessel, but environmental conditions were more important for explaining interaction duration. Laysan albatrosses were more likely to associate with vessels while searching and during the last 60% (by time) of their trips. Our results provide specific species–fisheries insight regarding contributing factors of high‐risk associations that could lead to bycatch of albatrosses within national waters and on the high seas. Policy implications. Given the availability of Global Fishing Watch data, our analysis can be applied to other marine predators—if tracking data are available—to identify spatio‐temporal patterns, vessel specific attributes and predator behaviours associated with fishing vessel associations, thus enabling predictive modelling and targeted mitigation measures.

Abstract Restoration or establishment of colonies using translocation and hand‐rearing can be an effective tool for conserving birds. However, well‐designed post‐release evaluation studies for long‐lived species are rarely implemented. We investigated the attendance and breeding attempts of hand‐reared short‐tailed albatross (STAL) Phoebastria albatrus chicks (n = 69) translocated to a historic breeding island in the Ogasawara Islands, 350 km from the source colony, for 8 consecutive years after the first translocation. Thirty‐nine percent of hand‐reared birds (n = 27) returned to the translocation site at least once per breeding season, of which 67% (n = 18) also visited the natal island. The number of hand‐reared birds returning each year was lower at the translocation site (mean: 0.3–2.3 birds per day) versus the natal island (0.4–3.5 birds per day). The first breeding attempt occurred 5 years after the first translocation. Three pairs (producing three chicks) recruited to the translocation site or neighboring islands and five pairs (producing nine chicks) recruited to the natal island by 8 years after the first translocation. Every hand‐reared bird that raised a chick paired with a naturally reared bird. At the translocation site and neighboring islands, two hand‐reared birds paired with a mate from the natal island and a breeding colony 1850 km away, respectively, while the parents of the third chick were unknown. Their breeding at the translocation region was observed among conspecific social attractants (decoys, audio playback; one pair) or congeners (two pairs). Our preliminary results suggest that even though more translocated and hand‐reared albatrosses visited and recruited to their natal island compared to the translocation site, the early re‐establishment of breeding by short‐tailed albatrosses in the Ogasawara Islands 80 years after extirpation would not have occurred without the initial translocation effort. Further study is needed, however, to fully understand formation of breeding colonies beyond conspecific attraction and philopatry.

Capture and handling are essential methods for many studies of wild animals but can induce several harmful effects on individuals being studied. The relationship between physiological and behavioral responses in individuals exposed to these effects is not well known. We measured the blood level of muscle enzymes, aspartate aminotrasnsferase (AST) and creatine kinase (CK), indicating muscle damage in hand-reared short-tailed albatross (Phoebastoria albatrus) chicks before and after prolonged restraint for transmitter attachment beyond the usual feeding. We analyzed the relationships between enzyme levels and albatross pre- and post-fledging behaviors. Prolonged restraint for transmitter attachment elevated the blood levels of AST and CK in chicks. In chicks with higher levels of these enzymes, fledging date was earlier and the period to sustained flight after fledging was longer. These results indicated that prolonged handling for transmitter attachment on pre-fledging albatross chicks caused moderate muscle damage and behavioral changes before and after fledging. Although immediate post-fledging survival (the first 2 weeks at sea) did not appear to be affected, whether longer-term survival may be influenced is unknown. Reducing handling time for albatross chicks is important to reduce muscle damage and behavioral consequences. (c) 2014 The Wildlife Society.

The Black-Footed Albatross (Phoebastria nigripes) breeds in two remote regions, approximately 4,000 km apart, in the North Pacific. The population in the central North Pacific region (Northwestern Hawaiian Islands), which contains >95% of the total population, is currently stable, although concerns exist about future declines. In contrast, the population in the western North Pacific (Izu and Ogasawara Islands in Japan) is rapidly increasing, and the breeding areas are expanding. To estimate possible gene flow caused by dispersal between populations, we performed genetic analysis on six colonies of Black-Footed Albatross using 10 microsatellite markers. The central and western North Pacific populations were genetically differentiated. However, an estimation of migrants per generation indicated directional dispersal from the western to the central North Pacific. In particular, the population on Kure Atoll, the westernmost atoll in the Hawaiian Islands in the central North Pacific, exhibited weak genetic differentiation from the western North Pacific populations, suggesting frequent immigration from the western North Pacific. The recent expansion of the western North Pacific population may be due to an increase in returning individuals, which may be caused by increased breeding success rates and/or survival rates. Range-wide and long-term monitoring of the Black-Footed Albatross population using genetic markers may help to uncover dispersal dynamics of this highly mobile but philopatric albatross species and to make appropriate conservation decisions in light of environmental changes.

Many endemic species, particularly those on remote islands, have been driven to extinction or near extinction by anthropogenic influences. The short-tailed albatross Phoebastria albatrus once numbered in the millions but was thought to be extinct by the mid 20th century. Albatrosses, of the family Diomedeidae, are among the most threatened birds globally as a result of commercial exploitation, introduced predators, and mortality in commercial fisheries. We applied an experimental approach over 5 years to evaluate the translocation and hand-rearing of albatross chicks by comparing growth, physiological health indices, post-fledging survival, and migration patterns with a control group of naturally reared chicks in the source population. Hand-reared chicks had comparable or superior health and similar rates of immediate post-fledging mortality (15%), with mortality strongly female-biased in both groups. Hand-reared birds had longer post-fledging drift periods before attaining sustained flight (also female-biased) but comparable, albeit somewhat wider ranging, migration patterns to naturally reared chicks during their first 6 months at sea. Recruitment to the translocation site of a breeding pair that included a hand-reared bird occurred within 5 years of the first translocation. Success will ultimately depend on continued recruitment and breeding over the coming decades, given delayed breeding in these long-lived species. The results to date, however, have exceeded initial expectations and can inform potential reintroductions of other long-lived, migratory avian species with strong natal philopatry, and reintroductions of native species to former breeding islands.

We used a combination of seabird data (both fishery-dependent and fishery-independent) and fishing-effort data to evaluate the relative fisheries risk of five west coast groundfish fisheries and one shrimp fishery to black-footed (Phoebastria nigripes), short-tailed (P. albatrus) and Laysan albatrosses (P. immutabilis). To assess risk, an overlap index was derived as the product of total fishing effort and at-sea survey density of black-footed albatross. This index was used as the primary tool to estimate overlap with the endangered, relatively rare short-tailed albatross, which show similar habitat utilization from satellite telemetry tracks. Telemetry data indicate Laysan albatross primarily occur offshore beyond observed fishing effort. Black-footed and short-tailed albatross-fishery overlap was highest at the shelf-break (201-1000 m) north of 36 degrees N. Overlap and reported albatross mortality indicate that the sablefish (Anoplopoma fimbria) longline and Pacific hake (Merluccius productus) catcher-processor fisheries pose the greatest risk to these species; the near-shore rockfish (Seabastes spp.) longline, pink shrimp (Pandalus jordani) trawl, California halibut (Paralichthys californicus) trawl, and non-hake groundfish trawl fisheries pose relatively little risk. Implementing proven seabird bycatch-reduction measures will likely minimize albatross mortality in the highest-risk fishery, sablefish longline. (C) 2013 Elsevier B.V. All rights reserved.

Many breeding colonies of Procellariiformes have been threatened with extinction. Chick translocation has been shown to be an effective method for establishing new "safer" colonies of burrow-nesting species, but techniques for surface-nesting species have not been fully developed. The entire breeding population of the threatened Short-tailed Albatross Phoebastoria albatrus is restricted to two sites, Torishima Island and the Senkaku Islands, and neither site is secure due to volcanic activity or political instability. The Short-tailed Albatross Recovery Team has recommended facilitating the recovery of this species by establishing at least one additional colony through the translocation and hand-rearing of chicks at a safe historical breeding site. To evaluate the feasibility of this approach, we hand-reared 10 post-guard phase chicks of two related species in 2006-2007: Laysan Albatross P. immutabilis translocated from Midway Atoll to Kaua'i Island, Hawai'i and Black-footed Albatross P. nigripes translocated from a nearby islet in the Ogasawara (Bonin) Islands to Mukojima Island, Japan. In these pilot studies, 40% of Laysan Albatross chicks and 90% of Black-footed Albatross chicks fledged successfully. Following this groundwork, 40 post-guard phase Short-tailed Albatross chicks were translocated from Torishima Island to Mukojima Island in February 2008-2010 and hand-reared to fledging. Their fledging success has been 100% in all three years. Fledging body sizes were similar or greater in hand-reared chicks at the release site than parent-reared chicks on Torishima Island. There were significant differences in levels of some blood chemistry parameters between pre-fledging hand-reared and parent-reared chicks. The techniques developed in our studies have broad-reaching implications for the future conservation of threatened populations of other surface-nesting seabirds.

地球規模の気候変動が鳥類の渡り・繁殖に及ぼす影響の有無は，ヨーロッパや北米に生息する種について数多く報告されているが，アジアにおける報告は著しく乏しい．本研究では，大規模な気候変動が生じたこの50年の間に，日本に訪れるツバメの渡り時期，繁殖時期，繁殖成績が変化したかどうかを検討するため，1961～1971年の11年間（以下，1960年代）と，2000～2010年の11年間（以下，2000年代）の標識調査データを比較解析した．日別放鳥数の頻度分布において，成鳥の急増時期は2000年代の方が半月ほど早まったが，急減時期は変わっていなかった．幼鳥については，2000年代と1960年代の頻度分布はほぼ一致した．巣内雛については，急増時期が2000年代の方が半月ほど早まっていた．成鳥に対する幼鳥の放鳥数の比率は2000年代の方がやや減少していた．これらの結果は，ツバメの飛来時期・繁殖開始時期は2000年代の方が早まったが，渡去時期は両期間で変わっておらず，また繁殖成績は2000年代の方が低下したことを示唆している．飛来時期と繁殖開始時期については，調査環境や調査時期の影響も考えられるが，多くの既有の知見と一致することから，比較結果にはある程度の妥当性が判断された．一方，渡去時期や繁殖成績については，国土スケールの長期変動解析に有効な情報が他に乏しく，標識調査情報が重要なデータになると言える．

In alcids, growth rate and hatching date of chicks appear to affect fledging age and mass. Underlying mechanisms are hypothesized to be (1) critical wing length at fledging for postfledging survival, (2) synchronization of fledging to dilute predation risk, and (3) variable parental provisioning according to timing of breeding. To elucidate the effects of growth rate and hatching date on fledging age and mass, and to test those mechanistic hypotheses, we measured chick growth and fledging periods in Rhinoceros Auklets (Cerorhinca monocerata) at Teuri Island from 1995 to 2000. The multiple-linear regression analysis showed that intrayear variations of fledging age and mass were explained by growth rate or hatching date in five out of six years. Faster-growing chicks fledged younger and heavier, and earlier-hatched chicks fledged older and heavier. Consequently, no apparent correlation between fledging age and mass was observed in five out of six years. Analysis of interyear variation showed a negative correlation between fledging age and mass, which indicates that growth rates rather than hatching dates had a major effect. Wing length at fledging was independent of growth in mass. More than 80% of chicks fledged when they attained a narrow range of wing length (130-150 mm), presumably because they remained in their nests until they attained the critical wing length. In five out of six years, the chicks did not synchronize timing of fledging relative to timing of hatching. Later-hatched chicks attained lighter peak masses and at younger ages, which may indicate that their parents decreased provisioning rates when the chicks were still young. We suggest that (1) critical wing length at fledging and (2) variable parental provisioning according to timing of breeding could be underlying mechanisms determining these relationships between fledging age and mass.

Many ribbon seals (Phoca fasciata) appear in winter in Nemuro Strait, eastern Hokkaido. We propose that their presence is partly related to an exploitation of the large numbers of spawning walleye pollock (Theragra chalcogramma). To investigate feeding habits of ribbon seals in winter, we sampled stomachs from seals for prey composition and size taken in the strait from February–April 1996–1998. Nine fish and five squid species were identified from sixty-four seal stomachs. Walleye pollock and magistrate armhook squid (Berryteuthis magister) were predominant in the diet of seals each year. The index of relative importance of prey showed that walleye pollock was the most dominant prey item. Most pollock eaten by seals had reached maturity. Prey distribution suggested that ribbon seals foraged in the intermediate-bottom layer of the continental slope water. No differences were found between prey composition and size of male and female ribbon seals. Subadult and adult ribbon seals consumed more pollock and less squid than young seals, which also tended to consume smaller pollock. Pinpoint lanternfish (Lampanyctus regalis) and saffron cod (Eleginus gracilis) occurred only in stomachs of adults and young, respectively. Foraging technique and diving ability may explain the differences in prey composition and size among seal age classes.<br>

Daily measurement of chick mass could be a useful method to estimate daily food intake under the assumption that the effects of the body mass on daily mass increment do not differ between chicks receiving different amount of food. To evaluate this assumption, 40g and 60g anchovy per day were fed to Rhinoceros Auklets chicks in semi-captivity. Negative relationships between chick mass and daily mass increment were found in 40g-and 60g-fed chicks. There was no significant difference in the slope of regression equation between 40g-fed chicks (-0.037±0.018) and 60g-fed chicks (-0.041±0.016). The intercept in 60g fed chicks (17.578±3.491g) was larger than that in 40g fed chicks (10.950±3.491g). Therefore, the daily amounts of food intake in Rhinoceros Auklet chicks can be estimated from body mass and daily mass increment.