New records of birds from Central Vietnam

Abstract Background There has been a series of bird surveys conducted in Vietnam over the last 20 years. However, most of these studies and surveys have focused on sites in Tonkin, the Red River Delta, Cochinchina (Mekong Delta), the Central Highlands and mountainous areas of Central Annam (Central region of Vietnam). The central coastal plain as well as the mountainous region of North Annam have rarely been comprehensively investigated. New information As a result of our field surveys in 2023 and 2024, a total of 15 species of birds are recorded for the first time from North, Central and South Annam, comprising one Frigate-Bird species (Fregatidae), one ibis (Threskiornithidae), one reed-warbler (Acrocephalidae), one Treecreeper (Certhiidae), two buntings (Emberizidae), one chat (Muscicapidae), one yuhina (Zosteropidae), two nuthatches (Sittidae), two members of the laughingthrush family (Leiothrichidae) and three bulbuls (Pycnonotidae). In addition to photographs confirming the new records, we provide information on the distribution and conservation status of these newly-recorded bird species from Central Vietnam.


Introduction
Vietnam is identified as one of the avifaunistically most diverse countries in Southeast Asia (Craik and Minh 2018).Vietnam falls within Indo-Burma, a globally important hotspot for biodiversity and hosts a large number of rare and endemic species (Sterling et al. 2006).To date, a total of 63 Important Bird Areas (IBA) (Tordoff et al. 2002) and 102 Key Biodiversity Areas (KBA) have been identified in Vietnam (Tordoff et al. 2012).Over the past 30 years, the number of Vietnamese bird species has risen significantly due to an increase in avifaunal surveys as well as the number of researchers, birdwatchers and wildlife photographers.The number of bird species recorded in Vietnam in 1995 amounted to 828 and rose to 918 species in 2021 (Quy and Cu 1995, Cu et al. 2000, Robson 2008, Hung 2012, Craik and Minh 2018, Hung et al. 2021b).Many species have undergone range extensions as our knowledge of their distribution has become better over the past ten years (Hung et al. 2014, Hung et al. 2016, Hung and Quyet 2017, Hung et al. 2017a, Hung et al. 2017b, Hung et al. 2017c, Hung et al. 2019, Hung et al. 2020, Hung et al. 2021).
As a result of our recent field surveys in the wetland areas along the central coastal plain (Thua Thien Hue, Da Nang, Quang Nam, Quang Ngai, Binh Dinh, Khanh Hoa Provinces) and Na Ngoi Commune, Ky Son District Nghe An Province, we herein report 15 new records from central Vietnam.
The typical habitat types along the central coastal plain include lagoons (Tam Giang -Cau Hai in Thua Thien Hue Province), coastal beaches (Da Nang and Quang Nam Provinces), freshwater lakes and swamps (Quang Ngai, Binh Dinh and Khanh Hoa Provinces).Surrounding the lagoons and lakes are paddyfields, reeds, grasses, gardens and plantations (Fig. 2).

Field surveys
In the central coastal plain areas, we conducted line transects and point counts: Every day (from 5:45 am to 10:00 am and from 2:30 pm to 6:00 pm), the observers walked slowly along the existing trails (around the lagoon, lakes and fishponds) with frequent Map showing the survey areas: Red star is Ky Son area, Nghe An Province, North Annam: A1 = Tam Giang -Cau Hai Lagoon (Thua Thien Hue Province), A2 = Son Tra Forest and My Khe Beach (Da Nang Province), A3 = An Khe Lake (Quang Ngai Province), A4 = Tra O Lake (Binh Dinh Province), A5 = Thuy Trieu Lake (Khanh Hoa Province).
stops to observe mixed feeding flocks or birds flying over.The observers predominantly focused on key habitats within the survey areas, using the point counts method (Bibby et al. 1998) to count and record all bird species.Boats were also used at some large lakes and lagoons.
For the Ky Son area, only line transect surveys were used.All the bird species and individuals were recorded by direct observation, acoustic recordings and photography.The following equipment was used during the surveys: Swarowski EL 8 x 32 and 10 x 42 binoculars, Swaroski 20 x 80 telescope and field guides for identification (Robson 2008, Hung et al. 2021b), as well as cameras including Canon 1D max III and Nikkon D6 bodies with 500 mm and 600 mm lenses.The conservation status of recorded species follows the IUCN Red List 2024 (IUCN 2024).The ornithological regions in Vietnam follow Robson (2008) and Hung et al. (2021b), which includes six different regions: West Tonkin, East Tonkin, North Annam, Central Annam, South Annam and Cochinchina.Taxonomy follow IOC World Bird List -Version 14.1 (Gill et al. 2024).The diagnoses of 15 species in this study follow Robson (2008).
The Ky Son area is close to the Laos -Vietnam border (Fig. 1).The typical habitat types in the area include scrub, secondary growth and broadleaved evergreen forest.This area covers an elevation range from 300 to 2,280 m a.s.l.While most of the forest areas from 300 to 1,600 m are highly degraded, the forest from 1,600 to 2,200 m was still fairly intact (Fig. 3).
These records all represent firsts for the region, with none appearing in the most recent reference works (Robson 2008, Hung 2012, Craik and Minh 2018, Hung et al. 2021b).Here, we document fifteen range extensions or regional firsts.

Taxon treatments
Fregata ariel (Gray, GR, 1845) Diagnosis: Size: 71-81 cm.: Overall blackish plumage with prominent whitish patches extending from side of body to inner underwing-coverts diagnostic.Red gular pouch.: Combination of black hood, belly and lower flanks, white remainder of underparts, extending in axillary spur on to inner underwing-coverts.: shows rufous to brownishwhite head, black breast-band, triangular white belly-patch.White axillary spur always present, originating from line of breast-band and angled outwards (towards wing-tip).Band across upperwing-coverts buffish, moderately prominent (Fig. 4)  Diagnosis: Size: 12-14 cm.Adult non-breeding: Small with finely dark-streaked breast and flanks and rather uniform base colour of upperside.Bold broad blackish (streaky) lateral crown-stripes, eye-stripe and border to rufous-chestnut ear-coverts.Median crown-stripes, supercillium, submoustachial stripe and spot on rear earcoverts contrastingly buffish, shows rufescent lores and forehead, whitish eye-ring (Fig. 5).Adult breeding: Attains diagnostic chestnut flush over most of head, lateral crown-stripes solid black.Juvenile: Similar to adult non-breeding.Initially shows much duller lateral crown-stripes, less neat breast and flanks streaking, brower-tinged underparts.

Conservation status: Least Concern
Distribution: Little Bunting has been recorded as a fairly common to common winter visitor in West and East Tonkin (Robson 2008, Craik and Minh 2018, Hung et al. 2021b).This is the first confirmed record for the species in North Annam.Elsewhere, this species has been recorded breeding in Norway, Russian and Sweden, resident in Bangladesh, Bhutan, China, Finland, Hong Kong, India, Japan, Kazakhstan, Kuwait, Laos, Malaysia, Mongolia, Myanmar, North Korea, Nepal, Pakistan, Philippines, Taiwan, Thailand, non-breeding in Iran, Saudi Arabia and vagrant in  Diagnosis: Size: 20 cm.Adult: Brown upperparts, black cap and cheeks, short crest, brown ear-coverts and breast-band, white throat, plain pale greyish underparts, deep yellow undertail-coverts, little or no white on tail-tip (Fig. 6).Juvenile: Breast-band less distinct, dark head markings browner, paler underparts.Diagnosis: Size: 23 cm.Adult: Combination of heavy yellowish-white streaking on head and body, prominent crest and yellow spectacles, mostly yellow throat and undertail-coverts (Fig. 7).Diagnosis: Size: 21.5 cm.Adult: Greenish to yellowish-green plumage, thick pale yellowish bill and erect pointed crest distinctive.Head mostly greyish with blacker lores, crest and throat, blackish tail-tip (Fig. 8).Juvenile: Crown and crest paler and mixed with green, yellowish-green forehead and throat, paler ear-coverts, dark tailband less distinct.

Conservation status: Least Concern
Distribution: Crested Finchbill has been recorded as a common resident in West Tonkin (Robson 2008, Craik and Minh 2018, Hung et al. 2021b).This is the first confirmed record of the species for North Annam, Central Vietnam.Elsewhere, this species has been recorded as a resident in Bangladesh, China, India, Laos, Myanmar and Thailand (IUCN 2024).

Conservation status: Least Concern
Plegadis falcinellus Linnaeus, 1766 Diagnosis: Size: 55-65 cm.Adult non-breeding: Mostly uniform dark brownish with white streaks on head and neck, green gloss on scapulars and upperwing-coverts.Pale brownish bill, dark brownish legs and feet, dark facial skin bordered above and below by distinctive narrow white line.Adult breeding: Head, neck and body mostly deep chestnut, forecrown glossed green, much of plumage with purplish tinge, no streaks on head and neck, but more pronounced white border to lores, bill mostly flesh-coloured (Fig. 13).

Conservation status: Least Concern
Distribution: Glossy Ibis has been recorded as a vagrant in East Tonkin and a fairly common resident in Cochinchina (Robson 2008, Craik and Minh 2018, Hung et al. 2021b).This is the first confirmed record for the species in Central Annam.Globally, this species is widespread from Africa to southern Europe.In Southeast Asia, Glossy Ibis is recorded as a resident in Cambodia, Myanmar, Philippines and Thailand (IUCN 2024).

Acrocephalus tangorum La Touche, 1912
• GBIF https://www.gbif.org/species/5789158 Nomenclature: Diagnosis: Size: 13-14.5 cm.Adult: Crown and upperparts warm olive-brown with slighly more rufescent rump and uppertail-coverts, underparts whitish with warm buff breast-sides and flanks, whitish supercilium, narrow blackish line on crown-sides, long bill with pale lower mandible, white throat (Fig. 14).Diagnosis: Size: 15-16 cm.Adult: Brown upperparts with buff and white streaks, spots and mottling and an orange-brown rump, brown tail.Combination of drab greyish throat and underparts, buffy vent and indistinct supercilium diagnostic (Fig. 15).Juvenile: Shows faint darker scaling on throat and breast.Distribution: Hume's Treecreeper has been recorded as an uncommon to locally common resident in West Tonkin and South Annam (Robson 2008, Craik and Minh 2018, Hung et al. 2021b).This is the first confirmed record of the species for North Annam, Central Vietnam.Elsewhere, this species has been recorded as resident in India (Manipur), Laos, Myanmar and Thailand (IUCN 2024).Diagnosis: Size: 12 cm.Male: Grey upperparts with two black lines from eyes to lower nape, buff underside, white on the uppertail coverts, small bill and rufous-orange underparts with unmarked bright rufous undertail-coverts, whitish throat (Fig. 16).

Conservation status: Least Concern
Distribution: White-tailed Nuthatch has been recorded as an uncommon resident in West Tonkin (Robson 2008, Craik and Minh 2018, Hung et al. 2021b).This is the first confirmed record of the species for North Annam, Central Vietnam.Elsewhere, this species has been recorded as a resident in Bhutan, China, India, Laos, Myanmar and Nepal (IUCN 2024).

Sitta formosa Blyth, 1843
• GBIF https://www.gbif.org/species/2484903Diagnosis: Size: 16.5 cm.Adult: Large, upperparts black, streaked brilliant blue to white on crown, nape and mantle, broad blue band along scapulars to back and rump, black wings with two narrow white wing-bars, dull rufous-buff underparts with paler throat and head-sides (Fig. 17).Juvenile: Very similar to adult, but white streaks on upperparts may be bluer, whiter and paler underparts, particularly on breast.

Conservation status: Vulnerable
Distribution: Beautiful Nuthatch has been recorded as a scarce to uncommon resident in West Tonkin and East Tonkin (Robson 2008, Craik and Minh 2018, Hung et al. 2021b).This is the first confirmed record of the species for North Annam, Central Vietnam.Beautiful Nuthatch was recently listed as Vulnerable in the IUCN Red List 2024.Elsewhere, this species has been recorded as a resident in Bhutan, China, India, Laos, Myanmar and Thailand (IUCN 2024).Diagnosis: Size: 17-19.5 cm.Male: Bluish-slate crown, black head-sides, rufouschestnut rest of upperparts, whitish underparts with bold black bars on breast-sides and flanks, wings black with tertials and flight-feathers fringed bluish-grey, flanks and vent washed buff (Fig. 18).Female: Like male, but mantle, back and scapulars more olive-brown with broad blackish streaks, dark brown head-sides.Juvenile: Duller than respective adults with browner crown and fainter dark bars on underparts.

Discussion
The documentation of new distribution data for 15 bird species in Central Vietnam has shown that the region still holds a high potential to discover additional species diversity.
The central coastal region of Vietnam is located along the East Asia -Australia Flyway.
Collecting information related to migratory and wintering bird species is necessary and urgent to provide comprehensive information on the status of migratory species as well as migratory routes, which would help decision-makers with wildlife conservation planning for a better conservation of existing sensitive habitats (mudflats, marshes, reedbeds).
Many of the bird species recorded in the Ky Son area of Nghe An Province have the centre of their distribution in the Himalayan range (Robson 2008, Craik and Minh 2018, Hung et al. 2021b).In Vietnam, the easternmost extensions of the Himalayan range end at the Hoang Lien Mountain of Lao Cai Province (about 500 km away from the Ky Son area).This shows that the area forms an important transition between the Himalayan and Annam mountain ranges.
Our surveys also brought to light many impacts on bird species including habitat destruction and development projects in a number of wetland areas (Suppl.material 1), particularly at the Tra O and Thuy Trieu Lakes (Binh Dinh and Khanh Hoa Provinces).Hunting, trapping and bird trade still occur regularly (Suppl.material 2), especially impacting waterfowl during migration seasons and targeting songbirds for the pet trade.

New records of birds from Central Vietnam
This raises an alarming situation and requires immediate treatment and management measures to preserve wild birds and their habitats in Vietnam.

Figure 7 .
Figure 7.The adult of Alcurus striatus (IEBR B.569) was photographed in Ky Son area, Nghe An Province.

Figure 8 .
Figure 8.The adult of Spizixos canifrons (IEBR B.579) was photographed in the Ky Son area, Nghe An Province.

Figure 9 .
Figure 9.The male Saxicola jerdoni (IEBR B.582) was photographed in the Ky Son area, Nghe An Province.

Figure 10 .
Figure 10.The female of Saxicola jerdoni (IEBR B.583) was photographed in the Ky Son area, Nghe An Province.
Stripe-throated Yuhina has been recorded as a common resident in West Tonkin and the southern part of Central Annam(Robson 2008, Craik and Minh 2018, Hung et al. 2021b).This is the first confirmed record of the species for North Annam, Central Vietnam.Elsewhere, this species has been recorded as a resident in Bhutan, China, India, Laos, Myanmar and Nepal (IUCN 2024).

Distribution:
Manchurian Reed Warbler has been recorded as a scarce passage migrant in West Tonkin, East Tonkin and Cochinchina(Robson 2008, Craik and Minh 2018, Hung et al. 2021b).This is the first record of the species in South Annam.Manchurian Reed Warbler has recently been listed as Vulnerable by the IUCN Red List 2024.Elsewhere, this species has been recorded breeding in China, Myanmar and Russia and wintering in Cambodia, Laos, Malaysia, Peninsular and Thailand, with vagrant records in Korea (IUCN 2024).

Figure 15 .
Figure 15.The adult of Certhia manipurensis (IEBR B.675) was photographed in the Ky Son area, Nghe An Province.

Conservation status: Least Concern Distribution: Lesser
Frigate-Bird is a scarce non-breeding offshore visitor species in Vietnam, with the only previous records from Cochinchina(Robson 2008,

Craik and Minh 2018, Hung et al. 2021b). This is the first confirmed record for the species in Central Annam. Elsewhere, this species has been recorded resident in Australia, Brazil, British Indian Ocean Territory, Brunei Darussalam, China, Christmas Island, Comoros, Fiji, French Polynesia, India, Indonesia, Japan, Kiribati, North Korea, Madagascar, Malaysia, Mauritius, Mayotte, New Caledonia, Philippines, Singapore
, Solomon Islands, Sri Lanka, Taiwan, Tanzania, Thailand, Tonga, United States, Vanuatu, breeding in Cocos (Keeling) Islands, Maldives, Marshall Islands, Réunion, Seychelles and non-breeding in Micronesia, northern Mariana Islands, Palau, Timor-Leste, United States Minor Outlying Islands, Djibouti, Eritrea, Israel, Jordan, Kenya, Mozambique, New Zealand, Oman and Somalia (IUCN 2024).The juvenile individuals of Fregata ariel (IEBR B.501) were photographed in My Khe Beach, Da Nang City.
New records of birds from Central Vietnam Conservation status: Least Concern Distribution: kingdom: Animalia; phylum: Chordata; class: Aves; order: Passeriformes; family: Pycnonotidae; genus: Spizixos ; country: Vietnam; stateProvince: Nghe An; locality: Ky Son; verbatimElevation: 1,923 m; verbatimLatitude: 19°13.476'N;verbatimLongitude: 104°06.109'E;occurrenceID: DC8BCA75-3684-55D4-B7A6-74D2E3414F55 Himalayan Cu, Craik and Minh 2018 as a scarce to fairly common resident in West Tonkin(Robson 2008, Craik and Minh 2018, Hung et al. 2021b).This is the first confirmed record of the species for North Annam, Central Vietnam.Elsewhere, this has been recorded as a resident in Bhutan, China, India, Malaysia, Myanmar, Nepal and Thailand (IUCN 2024).Like female, but slightly darker with shorter crest, underparts buffier with more extensive, but fainter breast streaking.Male develops black blotching on body plumage.Crested Bunting has been recorded as an uncommon to locally common resident in West Tonkin and East Tonkin(Robson 2008, Craik and Minh 2018, Hung et al. 2021b).This is the first confirmed record of the species for North Annam, Central Vietnam.Elsewhere, this species has been recorded breeding in Bhutan, Bangladesh, China, India, Laos, Myanmar, Nepal, Pakistan and Thailand (IUCN 2024).
Diagnosis: Size: 16.5-17 cm.Male breeding : Blackish head and body, chestnut wings and tail, long erect crest (Fig.19).Male non-breeding: Blackish body feathers edged buffish-grey.Female breeding: Much paler and browner with less chestnut wings and tail, shorter crest.Upperpart olive-brown, streaked darker, underparts paler with faint dark breast streaking.Largely chestnut wings and tail; short crest and lack of white on tail rules out other buntings.Female non-breeding: A little darker than breeding, mantle sandy-brown and more diffusely streaked.Juvenile: