Acrocephalus nijoi (Aguiguan Reed-warbler)

[sebbe67]

Acrocephalus luscinia nijoi, this is a subspecies is sometimes only called Aguiguan Reed-warbler, it is from the Marianna island group and seems to have become extinct in the late 1980, habitat lost, huntign and introcued animals has in recent year been a huge problem on this island and it is therefore this bird are gone today. first reported in 1940 by a Japanese collector, and surveys conducted by the Commonwealth in 1983 and 1985 yielded a maximum count of six individuals. And in recent counts in 1999, 1996 and 2001 none bird has been found.

[Deleted]

Hi !

It seems that nijoi is now included in luscinius (or luscinia).

[sebbe67]

two siging males was reported 1996, after months of search, this seems to be the last reports of this subspecies.

[another specialist]

Past & Present:
Three subspecies of nightingale reed-warbler are currently recognized in the Mariana Islands: Acrocephalus luscinia luscinia (Guam, Saipan, Alamagan), Acrocephalus luscinia nijoi (Aguiguan) and Acrocephalus luscinia yamashinae (Pagan). The validity of these subspecies warrants further study, however.

Of the three recognized subspecies, Acrocephalus luscinia luscinia, originally found on Guam, Saipan, and Alamagan, has been extirpated on Guam since the late 1960s. Acrocephalus luscinia nijoi of the presently uninhabited island of Aguiguan was first reported in 1940 by a Japanese collector, and surveys conducted by the Commonwealth in 1983 and 1985 yielded a maximum count of six individuals. Acrocephalus luscinia yamashinae of uninhabited Pagan has been little studied, and is believed to have survived in small numbers until at least the 1960s. The population is now thought to be extirpated. The total number of nightingale reed-warblers is approximately 6,225-6,230 individuals distributed over three islands: Aguiguan (1-6), Saipan (4,225), and Alamagan (2,000).

Past and present threats to populations include habitat destruction, vulcanism, and introduced predators such as the brown tree snake, rat, and monitor lizard.

www.fws.gov/pacificislands/wesa/nightreedwarb.html

[Melanie]

Split from nominate race in 2012

now Acrocephalus nijoi

The extinct Aguiguan Reed-Warbler, Acrocephalus nijoi, has been split from the Nightingale Reed-Warbler, Acrocephalus luscinius, as recommended by Saitoh et al. (2012). They also suggest some changes to the English names that I'm not adopting at this time.
[Acrocephalidae, Sylvioidea I, 2.66]

www.jboyd.net/Taxo/changes.html

[Melanie]

The complex systematics of the Acrocephalus of the Mariana Islands, western Pacific

Takema Saitoh A, Alice Cibois B D, Sayaka Kobayashi A, Eric Pasquet C and Jean-Claude Thibault C

A Yamashina Institute for Ornithology, 115 Konoyama, Abiko, Chiba, 270-1145, Japan.
B Natural History Museum of Geneva, Department of Mammalogy and Ornithology, CP 6434, CH-1211 Geneva 6, Switzerland.
C Muséum National d’Histoire Naturelle, Département Systématique et Evolution, UMR7205 Origine, Structure et Evolution de la Biodiversité, 55 rue Buffon, and Service de Systématique Moléculaire, UMS2700-CNRS, 43 rue Cuvier, F-75005 Paris, France.
D Corresponding author. Email: [e-mail]

Emu - dx.doi.org/10.1071/MU12012
Submitted: 15 February 2012 Accepted: 25 June 2012 Published online: 19 September 2012

Abstract

The Nightingale Reed-Warbler (Acrocephalus luscinius) is known from six islands of the Mariana Archipelago in the Pacific Ocean. A recent phylogeny of the reed-warblers of the Pacific islands suggested however that the species was polyphyletic, the result of at least three independent colonisations. We present here a complete phylogeny of the Mariana reed-warblers that includes two populations, from Alamagan and Aguiguan, not yet studied using molecular techniques. Both of these populations belong to the Pacific Acrocephalus radiation, with birds from Alamagan closely related to the Saipan population, and those from Aguiguan having unresolved relationships within the Micronesian clade. These results suggest that the Mariana Islands experienced multiple colonisations by reed-warblers. We use a combination of molecular phylogeny and biometry of museum specimens to propose a new species-level taxonomy for Acrocephalus of the Marianas. These results have conservation implications for the two remaining populations, on Alamagan and Saipan, which probably belong to the same taxon, Acrocephalus hiwae (Nightingale Reed-Warbler).

www.publish.csiro.au/paper/MU12012

[Peter]

Oct 30, 2005 18:46:40 GMT another specialist said:

Past & Present:
Three subspecies of nightingale reed-warbler are currently recognized in the Mariana Islands: Acrocephalus luscinia luscinia (Guam, Saipan, Alamagan), Acrocephalus luscinia nijoi (Aguiguan) and Acrocephalus luscinia yamashinae (Pagan). The validity of these subspecies warrants further study, however.

Of the three recognized subspecies, Acrocephalus luscinia luscinia, originally found on Guam, Saipan, and Alamagan, has been extirpated on Guam since the late 1960s. Acrocephalus luscinia nijoi of the presently uninhabited island of Aguiguan was first reported in 1940 by a Japanese collector, and surveys conducted by the Commonwealth in 1983 and 1985 yielded a maximum count of six individuals. Acrocephalus luscinia yamashinae of uninhabited Pagan has been little studied, and is believed to have survived in small numbers until at least the 1960s. The population is now thought to be extirpated. The total number of nightingale reed-warblers is approximately 6,225-6,230 individuals distributed over three islands: Aguiguan (1-6), Saipan (4,225), and Alamagan (2,000).

Past and present threats to populations include habitat destruction, vulcanism, and introduced predators such as the brown tree snake, rat, and monitor lizard.

www.fws.gov/pacificislands/wesa/nightreedwarb.html

An 2012 update:
"Acrocephalus luscinia nijoi of the presently uninhabited island of Aguiguan was first reported in 1940 by a Japanese collector, and surveys conducted by the Commonwealth in 1983 and 1985 yielded a maximum count of six individuals. Nightengale reed-warblers have not been observed there since 1995 and may be extirpated."

USFWS (2012). Nightingale Reed-warbler / Acrocephalus luscinia / ga‘ga‘ karisu. Endangered Species in the Pacific Islands. U.S. Fish and Wildlife Service, Pacific Islands Fish and Wildlife Office. Downloaded from www.fws.gov/pacificislands/fauna/nightingalereedwarbler.html

[Sebbe]

It was apparently searched for in 2008.

Acrocephalus luscinia nijoi, the subspecies status of which USFWS (1998b) questions, has only been reported from Aguiguan and appears to have always been rare on that island (Reichel et al. 1992). After conducting surveys work in 1982, Enbring et al. (1986) reported a population of 4–15 birds on the island. Currently, Aguiguan’s population may be extirpated as no reed- warblers have been observed there since 1995 (USFWS 1998b), despite extensive surveys by CNMI DFW and USFWS in 2000 (Cruz et al. 2000b), 2002 (Esselstyn et al. 2002), and 2008 (USFWS unpublished data). The disappearance of reed-warblers from the island is probably due to a combination of feral goats, extensive clearing for agricultural development by the Japanese prior to World War Two, and the small size of the island (Enbring et al. 1986; Reichel et al. 1992).

www.pacificbirdconservation.org/nightingale-reed-warbler.html

[Sebbe]

Here is an interesting report about an expedition to Aguiguan in May 1992, during which small numbers of reed warblers were found. At that point there had been no records of this species from the island since 1985 and it was feared extinct.

www.birdconservationresearch.org/pdf/aguiguan%20expedition.pdf

[Sebbe]

A tiny population was reported to occur on uninhabited Aguijan (1-6 birds) but has not been observed on the island since the mid-1990s despite extensive surveys in 2000, 2001, 2008, and 2009 (USFWS 1998, Esselstyn et al. 2003, Camp et al. 2009b), and so is unlikely to number more a few individuals, if any (Marshall et al. 2008).

www.birdlife.org/datazone/speciesfactsheet.php?id=7611

On Aguiguan, Engbring et al. (1986) report 3 probable records of nightingale reed-warblers during their 1982 surveys, though none were recorded on the counts. Several incidental observations of nightingale reedwarblers
were also made during the survey team’s visit 1-4 June 1982; and therefore, based on this information, they made a liberal estimation of 15 birds on the Island (Engbring et al. 1986). Glass (1987) reported on 10 observations of nightingale reedwarblers, one made in 1984 and the other nine in February 1987. Following that report, the species was thought to be extirpated from Aguiguan (Reichel et al. 1992), but two singing males were observed in 1992 (Craig and Chandran 1992), and one was observed in 1993 (Lusk 1993). The last observation of nightingale reed-warblers on Aguiguan occurred in 1995 (USFWS 1998). Focused survey efforts in 2000 and 2002 failed to detect nightingale reed-warblers (Cruz et al. 2000, Esselstyn et al. 2003).

It has been suggested that the birds detected during the Craig and Chandran (1992) surveys were actually young birds colonizing from Saipan, and that the subspecies designation of nightingale reed-warblers
on Aguiguan is not valid (Craig and Chandran 1992, Esselstyn et al. 2003).

www.cnmijointmilitarytrainingeis.com/system/assets/31/original/usfws__2009__final_terrestrial_res_surveys_of_tinian___aguiguan.pdf?1367958992

[Sebbe]

Nightingale Reed-warbler (Acrocephalus luscinius) is being split: list A. nijoi as Critically Endangered (Possibly Extinct), A. hiwae as Critically Endangered, and A. astrolabii, A. yamashinae and A. luscinius as Extinct?

Following recognition as a species Aguijan Reed-warbler A. nijoi is of the utmost conservation concern, but is likely to already be extinct. Engbring et al. (1986) estimated 15 birds on the island in 1982, two singing males were observed in 1992 (Craig and Chandran 1992, cited in Marshall et al. 2009), one in 1993 (Lusk 1993, in Marshall et al. 2009) and a single male was observed in 1995 by Annie Marshall (USFWS 1998). Additional surveys in 2000 and 2002, and a focus study in 2008 failed to find any evidence of the species (Marshall et al. 2009). There is some indication that one or more of the recent observations may pertain to individuals of A. hiwae from Saipan (Marshall et al. 2009). However, there remains the vague possibility that the species is still extant, and for this reason A. nijoi is suggested to be listed as Critically Endangered (Possibly Extinct).

www.birdlife.org/globally-threatened-bird-forums/2016/10/nightingale-reed-warbler-acrocephalus-luscinius-is-being-split-list-a-nijoi-as-critically-endangered-possibly-extinct-a-hiwae-as-critically-endangered-and-a-astrolabii-a-yamashinae-and-a/

[Melanie]

Scientific Name: Acrocephalus nijoi
Species Authority: (Yamashina, 1940)
Common Name(s):
English – Aguijan Reed-warbler
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.
Identification information: 18 cm. Large, lanky, scruffy-looking warbler with long bill and often dishevelled feathers and erect head feathers when singing. Dingy olive-yellow above, with dull yellow eyebrow and underparts. Voice Call was a loud chuck or tchack. Males sang long, loud, varied and complex song.

Assessment Information [top]
Red List Category & Criteria: Extinct ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Camp, R., Dutson, G., Freifeld, H., Saunders, A., Radley, P., Mosher, S., Amidon, F. & Gourley, J.
Facilitator/Compiler(s): Benstead, P., Bird, J., Calvert, R., Khwaja, N., Mahood, S., O'Brien, A., Stattersfield, A., Derhé, M., Symes, A. & Wright, L
Justification:
There are no records of the species since 1995, despite extensive surveys in 2000, 2001, 2008 and 2009. Additionally it is possible that the last few records actually pertain to dispersing individuals of Acrocephalus hiwae (Marshall et al. 2009). It is therefore classified as Extinct.
Geographic Range [top]
Range Description: This species is historically known only from Aguijan in the Northern Mariana Islands (to USA).

Countries occurrence:
Regionally extinct:
Northern Mariana Islands
Additional data:
♦ Continuing decline in area of occupancy (AOO): Yes
♦ Extreme fluctuations in area of occupancy (AOO): No ♦ Estimated extent of occurrence (EOO) - km2: 140
♦ Continuing decline in extent of occurrence (EOO): Yes ♦ Extreme fluctuations in extent of occurrence (EOO): No
♦ Number of Locations: 2 ♦ Continuing decline in number of locations: Yes
♦ Extreme fluctuations in the number of locations: No
♦ Upper elevation limit (metres): 500
Range Map: Click here to open the map viewer and explore range.
Population [top]
Population: A tiny population was reported to remain on the uninhabited island but has not been observed on the island since the mid-1990s despite extensive surveys in 2000, 2001, 2008, and 2009 (USFWS 1998, Esselstyn et al. 2003, Camp et al. 2009b, Amidon et al. 2014), and the species is now considered to be Extinct.

Trend Justification: Considerable survey effort appears to have adequately documented the disappearance of a species of Acrocephalus from the island of Aguijan between 1982 and 1995 (Engbring et al. 1986, USFWS 21998, Marshall et al. 2009).

Additional data:
♦ Continuing decline of mature individuals: Unknown
♦ Extreme fluctuations: No ♦ Population severely fragmented: No
♦ Continuing decline in subpopulations: Yes
♦ Extreme fluctuations in subpopulations: No ♦ All individuals in one subpopulation: No
Habitat and Ecology [top]
Habitat and Ecology: It inhabited formerly disturbed areas vegetated by groves of trees and thickets. (Engbring et al. 1982, Reichel et al. 1992, USFWS 1998).

Systems: Terrestrial; Freshwater
Continuing decline in area, extent and/or quality of habitat: Yes
Generation Length (years): 5.7
Movement patterns: Not a Migrant
Threats [top]
Major Threat(s): Introduced predators, including feral cats (Felis catus) and rats (Rattus spp.), and possibly monitor lizard (Varanus indicus), may have been a large factor in the declines, or possibly the impact of Ivy Gourd Coccinia grandis (USFWS 1998, Mosher 2006).

Conservation Actions [top]
Conservation Actions: Conservation and Research Actions Underway
A recovery plan exists for the pre-split taxon (U.S. Fish and Wildlife Service 1998) but there has been little or no active management for the species to date and the milestones in the plan are now out of date. However, provisions to protect habitat and mitigate loss have generally been included in major land development projects. In 1989, a goat removal programme was begun on Aguijan but, by 1995, goat populations had begun to rebound with reduced hunting pressure. Trap lines for snakes are maintained at ports, night searches are conducted and a sniffer dog programme has recently been established. Publicity campaigns were conducted to raise the general awareness of island residents, including port workers, about the dangers of snake colonisation (USFWS 1998). Repeat surveys have been conducted in 2000, 2001, 2008, and 2009 (USFWS 1998, Esselstyn et al. 2003, Camp et al. 2009b, Amidon et al. 2014).

Conservation and Research Actions Proposed
Repeat surveys of the avifauna of Aguijan: should any Acrocephalus be discovered, enact measures from the Species Recovery Plan and additionally genetically sample the individuals to establish that they are A. nijoi and not a secondary arrival of A. hiwae. If the latter, enact measures from the Species Recovery Plan for that species.

www.iucnredlist.org/details/103780109/0

[Melanie]

Engbring, J., Ramsey, F. L., Wildman, V. J. 1982. Micronesian forest bird survey, 1982: Saipan, Tinian, Agiguan, and Rota. U.S. Fish and Wildlife Service, Honolulu.

Free available here:

www.fwspubs.org/doi/suppl/10.3996/112014-JFWM-085/suppl_file/112014-jfwm-085.s17.pdf?code=ufws-site

Notes on the Aguiguan reed warbler are on pages 65-67

[Sebbe]

Status of endemic reed-warblers of the Mariana Islands, with emphasis on conservation strategies for the endangered Nightingale Reed-warbler.

Insular species, particularly birds, experience high levels of speciation and endemism. Similarly, island birds experience extreme levels of extinction. Based on a 2012 taxonomic assessment, historically there were four reed-warbler species in the Mariana Islands, the Guam Reed-warbler Acrocephalus luscinia (Guam), the Nightingale Reed-warbler Acrocephalus hiwae (Saipan and Alamagan), the Aguijuan Reed-warbler A. nijoi (Aguiguan or Aguijuan), and the Pagan Reed-warbler A. yamashinae (Pagan). Between 2008 and 2010 we surveyed for three of these species on Alamagan, Aguiguan, and Pagan. Our results indicate that reed-warblers are extinct on Aguiguan, likely extinct on Pagan, and only the Nightingale Reed-warbler on Alamagan and Saipan remains. We estimated the global population at between 1,019 and 6,356 birds (95% CI; mean estimate 3,688), which has declined by more than 1,000 birds since the first quantitative surveys were conducted in 1982, i.e. a 24% decline in 28 years. Camp et al. (2009) describe the status of the Nightingale Reed-warbler on Saipan, which has also declined. We estimated the Alamagan population to be between 428 and 1,762 birds in 2010 (mean estimate 946). Thus, the Alamagan population is ~25 % of the global population, and it has declined slightly since 2000. This decline was not significant but is concerning, especially given a similar decline on Saipan. Restoration and protection of tall-stature native and secondary forest could benefit the Alamagan population, as would similar conservation on Saipan that includes wetland habitat. After suitable restoration of forest and wetland habitats on Aguiguan, Guam and Pagan, individuals from Alamagan and Saipan could serve as founder populations. Careful consideration of the extent and habitat preference of individuals translocated to Tinian, where an unknown reed-warbler species previously occurred, is warranted.

www.cambridge.org/core/journals/bird-conservation-international/article/abs/status-of-endemic-reedwarblers-of-the-mariana-islands-with-emphasis-on-conservation-strategies-for-the-endangered-nightingale-reedwarbler/CA910BD726F4F426944C3694F474A899

[Sebbe]

Conservation genomics and systematics of a near-extinct island radiation.

Conservation benefits from incorporating genomics to explore the impacts of population declines, inbreeding, loss of genetic variation and hybridization. Here we use the near-extinct Mariana Islands reedwarbler radiation to showcase how ancient DNA approaches can allow insights into the population dynamics of extinct species and threatened populations for which historical museum specimens or material with low DNA yield (e.g., scats, feathers) are the only sources for DNA. Despite their having paraphyletic mtDNA, nuclear SNPs support the distinctiveness of critically endangered Acrocephalus hiwae and the other three species in the radiation that went extinct between the 1960s and 1990s. Two extinct species, A. yamashinae and A. luscinius, were deeply divergent from each other and from a third less differentiated lineage containing A. hiwae and extinct A. nijoi. Both mtDNA and SNPs suggest that the two isolated populations of A. hiwae from Saipan and Alamagan Islands are sufficiently distinct to warrant subspecies recognition and separate conservation management. We detected no significant differences in genetic diversity or inbreeding between Saipan and Alamagan, nor strong signatures of geographic structuring within either island. However, the implications of possible signatures of inbreeding in both Saipan and Alamagan, and long-term population declines in A. hiwae that predate modern anthropogenic threats require further study with denser population sampling. Our study highlights the value conservation genomics studies of island radiations have as windows onto the possible future for the world’s biota as climate change and habitat destruction increasingly fragments their ranges and contributes to rapid declines in population abundances.

onlinelibrary.wiley.com/doi/10.1111/mec.16382

[Sebbe]

Untangling the colonization history of the Australo-Pacific reed warblers, one of the world’s great island radiations.

Island radiations, such as those of the Australo-Pacific, offer unique insight into diversification, extinction, and early speciation processes. Yet, their speciation and colonization histories are often obscured by conflicting genomic signals from incomplete lineage sorting or hybridization. Here, we integrated mitogenomes and genome-wide SNPs to unravel the evolutionary history of one of the world’s most geographically widespread island radiations. The Australo-Pacific reed warblers (Acrocephalus luscinius complex) are a speciose lineage including five species that have become extinct since the 19th century and ten additional species of conservation concern. The radiation spans over 10,000 km across Australo-Papua, Micronesia and Polynesia, including the Mariana, Hawaii and Pitcairn Island archipelagos. Earlier mtDNA studies suggested a stepping-stone colonization process, resulting in archipelago-level secondary sympatry of divergent mtDNA lineages in the Mariana Islands and Marquesas. These studies hypothesised that morphologically similar species on neighbouring islands arose from ecological convergence. Using hDNA from historical museum specimens and modern genetic samples, we show that incomplete lineage sorting and/or gene flow have shaped the radiation of Australo-Pacific reed warblers rather than secondary sympatry. The nuclear genome reconstructs a simpler biogeographic history than mtDNA, showing close relationships between species in the Mariana Islands and Marquesas despite their paraphyletic mtDNA lineages. Gene flow likely involved early and late colonizing waves of the radiation before the loss of ancestral dispersive ability. Our results highlight how collection genomics can elucidate evolutionary history and inform conservation efforts for threatened species.

academic.oup.com/evolut/advance-article/doi/10.1093/evolut/qpae136/7759539?login=false