Monitoring of Avifauna to Estimate the Effect of Ecological Restoration in Mukojima, Bonin Islands

Emura, Naoko; Furuya, Wataru; Ando, Haruko; Deguchi, Tomohiro

doi:10.3312/jyio.46.89

Cited by 4 publications

(1 citation statement)

References 18 publications

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“…Second, natural and/or anthropogenic drivers of common seabird declines must be identified. Although an array of factors have been suggested as potential threats, such environmental data are not available for most seabird colonies (Jones et al 2016; but see Emura et al 2015). For example, seabird bycatch from commercial fisheries is believed to have substantial negative impacts on populations in many seabird species such as albatrosses and petrels (Croxall et al 2012).…”

Section: Future Research Directions and Implications For Conserving Jmentioning

confidence: 99%

Long-term declines in common breeding seabirds in Japan

Senzaki

Terui

Tomita

et al. 2019

Bird Conservation International

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SummaryGlobal seabird populations are in decline, with nearly half of all seabird species currently in an extinction crisis. Understanding long-term seabird population trends is an essential first step to inform conservation actions. In this study, we assembled historical breeding records of seabirds throughout the Japanese archipelago and quantified the long-term population trends of 10 major breeding seabird species using a hierarchical Bayesian state-space model. The model revealed that six species had increasing or no detectable trends (Short-tailed Albatross Phoebastria albatrus, Leach’s Storm Petrel Oceanodroma leucorhoa, Pelagic Cormorant Phalacrocorax pelagicus, Japanese Cormorant Phalacrocorax capillatus, Spectacled Guillemot Cepphus carbo, and Rhinoceros Auklet Cerorhinca monocerata). However, decreasing trends were found not only in nationally threatened species (Common Murre Uria aalge, and Tufted Puffin Fratercula cirrhata) but also common species that are often described as abundant (Black-tailed Gull Larus crassirostris and Slaty-backed Gull Larus schistisagus). These declining species have declined to 3–35% of baseline levels over the past 30 years. This study provides the first evidence of long-term declines in common and widespread seabirds in Japan.

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Section: Future Research Directions and Implications For Conserving Jmentioning

confidence: 99%

Long-term declines in common breeding seabirds in Japan

Senzaki

Terui

Tomita

et al. 2019

Bird Conservation International

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The history of anthropogenic disturbance and invasive alien species impact on the indigenous avifauna of the Ogasawara Islands, southern Japan

Kawakami

2019

Jpn. J. Ornithol.

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The Ogasawara Islands are subtropical oceanic islands in the Northwestern Pacific. Since their unique ecosystem is recognized to have outstanding universal value, they are registered as a UNESCO World Natural Heritage site. However, human settlement since 1830 has seriously impacted the biota. So far, the breeding of 20 land birds and 21 seabirds, including three introduced species, has been recorded on the islands. Seven endemic species/subspecies have become extinct, and breeding populations of five species have disappeared completely. Such extinctions have been caused by habitat loss, overhunting, and alien species invasion. Specifically, alien mammals are thought to have had devastating effects on avian populations. At least ten mammal species have been introduced, five of which (goats, cats, black rats, Norway rats, and house mice) still occur there today. Owing to their serious ecological impacts, eradication programs have been implemented. Feral goats had spread to 20 islands, but have been completely eradicated from all except Chichijima. Feral cats currently exist on only four islands and are being removed from natural areas on Chichijima. Non-native rodents have invaded almost all of the islands. Eradication programs using rodenticide are ongoing on some of the islands and have succeeded on four of them. After successful eradication, some land birds and seabirds have increased in numbers and expanded their distribution. However, undesired results also have been confirmed. For example, invasive plants have increased following goat eradication due to the elimination of grazing, and increasing seabirds have become dispersers of alien plants with adhesive seeds. Rat populations have likely increased after cat eradication due to their release from predation. These accumulated experiences should inform future adaptive management of the islands based on scientific evidence of specific species interactions.

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Rapid increase in seabird breeding population after feral goat eradication on Mukojima, Ogasawara Islands, Japan

Suzuki¹,

Horikoshi²,

Sasaki³

et al. 2019

Jpn. J. Ornithol.

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During inhabitation from 1881 to 1994 grazing and agricultural lands were widely established on the Mukojima Group of islands. Although Mukojima, Nakoudojima and Yomejima, the main islands of the group, were widely covered by forest before human settlement, damage caused by feral goats, such as grazing and trampling, caused deforestation and soil erosion. Feral goats were eradicated from the islands during the period from 1999 to 2003. Alien Black Rats were also eradicated from Mukojima in 2010, although they still survive on Nakoudojima and Yomejima. In order to evaluate changes in seabird breeding status after goat removal, the numbers and distribution of nests of each species were recorded at three to four year intervals. After goat eradication, large-size ground nesters such as Brown Booby Sula leucogaster and Black-footed Albatross Phoebastria nigripes, have increased remarkably on islands where moderate populations had survived, whereas only limited increase has occurred on islands where initial populations were small. The Wedge-tailed Shearwater Puffinus pacificus, a mid-sized burrow nester, has shown outstanding increases regardless of the initial population sizes. Bulwer s Petrel Bulweria bulwerii, a small-sized burrow nester, which did not initially occur on all islands, has colonized two islands. The populations were, however, relatively small, and the limited increase may have been limited by rat predation. Because these population increases and range expansions have occurred over a relatively short time span, direct disturbance by feral goats, such as trampling, seems to have affected seabird breeding, rather than their indirect effects through environmental alteration. Responses to goat eradication varied among species. The three species that showed greatest recoveries each preferred open habitats such as grass and rocky areas. Before human settlement, forest breeding seabirds would have been common in natural forest environments. Thus the current avifauna is biased towards those species that breed in open habitats. To recover the original avifauna, it is necessary to promote forest restoration and rat eradication.

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Monitoring of Avifauna to Estimate the Effect of Ecological Restoration in Mukojima, Bonin Islands

Cited by 4 publications

References 18 publications

Long-term declines in common breeding seabirds in Japan

Long-term declines in common breeding seabirds in Japan

The history of anthropogenic disturbance and invasive alien species impact on the indigenous avifauna of the Ogasawara Islands, southern Japan

Rapid increase in seabird breeding population after feral goat eradication on Mukojima, Ogasawara Islands, Japan

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