In this study, we carried out two surveys of avifauna in Truong Sa Island, Truong Sa Archipelago, Vietnam. The duration time of first survey from October 21-25, 2020 and the second survey from May 22-27, 2021. The results at the surveys showed that there were 82 bird species belonging to 29 families and 10 orders recorded. Among them, Passeriformes has the most abundant with 35 species (42.7% of the total), Charadriiformes has 18 species with a rate of 22%, Ciconiiformes has 11 species with a rate of 13.4%, Cuculiformes has 5 species with a rate of 6.1%, Accipitriformes has 4 species with a rate of 4.9%, and other orders have from 1 to 3 species with a rate of 10.9% of the total. We also observed the Chestnut cheeked starling - Agropsar philippensis (Forster, 1781) in Truong Sa (Truong Sa Archipelago), this species was first recorded for the Avifauna of Vietnam and need to be added to the bird checklist of Vietnam.

No abstract

The study describes some migration charateristics of Clupeiformes ichthyoplanton in downstream of the Red river at the end of the dry season. At that time the migratory phenomenon takes place at all sampling points along 200 km downstream of the river. It is found that among the ichthyoplanton collected the Clupeifomes account for the highest percentage (62,7%) and of which 93% is eggs. The migration of Clupeiformes ichthyoplanton occurs mostly near the estuary. Its density and distribution depend on the location and time of sampling, and closely relate to the flow and tide at the downstream.

Two bird surveys were conducted in Truong Sa Islands (Spratly Islands), Khanh Hoa province, Viet Nam (from October 13 to November 21, 2020 and May 16 to June 21, 2021). A total of 110 bird species belonging to 34 families and 13 orders had been recorded. One of them is listed in the IUCN Red List as Near-threatened as: Grey-tailed Tattle. One of them is listed in the Vietnam Red Data Book as Endangered as Great cormorant. Among recorded species, the most abundant are Passeriformes (45 species accounting for 40.9%), next are Charadriiformes (25 species - 22.7%), Pelecaniformes (12 species - 10.9%), Cuculiformes and the Accipitriformes (6 species - 5.5%). The surveys were also recorded the first time Chestnut cheeked starling - Agropsar philippensis (Forster, 1781) in Vietnam.

A total of 125 bird species belonging to 39 families and 10 orders have been recorded, of which Passeriformes was the most abundant with 88 species accounting for 70.4%, Piciformes 11 species - 8.8%, Columbiformes 6 species - 4.8%, Accipitriformes and Cuculiformes 5 species - 4%, others order 1 to 3 species, accounting for 11.8%. We confirmed the first record of Collared Treepie for the North Central of Vietnam and adding one more species for the birdlist of Pu Hoat Nature Reserve (Rufous-cheeked Laughingthrush).