Kalimantan island, known as Borneo, has a high biodiversity that remains one of the most forested provinces in Indonesia ¹ . Kalimantan, especially east Kalimantan, also has a close relationship with Mahakam river. In the lower part of the Mahakam river, there are several large seasonal lakes and hundreds of small lakes that form wetland area ² . In addition, the lakes have several small rivers, both inflows and backflows, which flow from both the Kelinjau and Kedang Kepala Rivers ³ . One of these small rivers is called the Suwi River, located in Muara ancalong district, Kutai Timur regency, East Kalimantan Province, Indonesia.

Recently, the wetland area in Suwi river and Mesangat lake have been proposed as an essential ecosystem (13.964,13 hectare) to support in the protection of both Crocodylus siamensis and Tomistoma schlegii, to prevent them from becoming extinct ( see merdeka.com article). In addition, populations of fish can be also found in the Suwi River, which is surrounded by a large area of forest with populations of birds.

Though some studies have been done in the Suwi River ^{1, 4} , there is no information regarding the bird diversity in this area. Therefore, the aim of the current study was to inventory the bird diversity in this essential ecosystem of the Suwi River to support the conservation actions of Mesangat and Suwi wetland essential ecosystem, Muara Ancalong, Kutai Timur, Indonesia.

This study was performed in the Suwi River, Muara Ancalong, Kutai Timur, Indonesia ( Figure 1) from April 2017 to March 2018. The observation locations were

a. Upper stream (latitude: 0,42469; longitude 116,61273)

b. Middle stream (latitude: 0,40816; longitude: 116,61749)

c. Downstream (latitude: 0,38983; longitude: 116,60514)

d. Ketiaw (latitude: 0,40638; longitude: 116,60346)

e. Loa Bekara (latitude: 0,41527; longitude: 116,63173)

Direct observation by researchers in the field at two different time points, 06.00–09.00 AM and 15.00–18.00 PM (Indonesia Central Standard Time-eight hours ahead or UTC+8 of GMT) was performed to collect the numbers of the individual birds and to identify species in each location. The equipment used included Binocular celestron, upclose G2 10-30×50 zoom porro (Torrance, California, United States) and Global Positioning System (GPSMAP) Garmin 78s. Images of found-birds were taken using a digital camera (Canon PowerShot SX520 HS PC2152 16.0MP Digital Camera, Canon, Inc., USA), To identify the species of the birds found, the guidelines book of Mackinnon et al. ⁵ was used.

The diversity index was performed following Shannon Index of Diversity, with the equation of Ludwig and Reynolds ⁶ using Microsoft Excel 2013:

H’ = Σ (ni/N) log (ni/N)

where :

H’ = Shannon-Weiner index diversity

ni = the number of individuals found for a species

N = the number of individuals from all species

63 bird species from 27 family were found during the study ( Table 1). The full data of all birds found in the Suwi River wetland, Muara Ancalong, Kutai Timur, Kalimantan Timur, Indonesia can be seen in Dataset 1 ⁷ .

Bird species that frequently were found in each observation location were Pelargopsis capensis (n = 35), followed by Ardeola speciosa (n = 31), Treron vernans (n = 29), Anhinga melanogaster (n = 25) and Clamator coromandus (n = 20).

The presence of Pelargopsis capensis, Anhinga melanogaster and Ardeola speciosa is likely due to the abundance of fish in the observation locations. Meanwhile, Treron vernans is a seed and fruit-eating bird species that can be observed in the Suwi river wetland area where local tree species such as Ficus sp. and Malotus sumatranus can be widely found. Further, Coromandus Clamator is a small insectivorous bird species and lives among trees, mangroves, farmland and bushes. Some of the birds that were observed during the study are categorized in the threatened-list of International Union for Conservation of Nature (IUCN), Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), or Indonesia government regulation document (PP) number 7 year 1999 about the preservation of plants and animals ⁸ ( Table 2).

In the present study 63 species were identified, of which 15 species have protected status according to the Indonesia Government regulation document (PP) number 7 year 1999 on the preservation of plants and animals. Moreover, 6 species are categorized in appendix II of CITES indicating that the species are not necessarily threatened with extinction, but the trade of these animals must be controlled and regulated in order to avoid utilization incompatible with their survival. Furthermore, only one species is classified in appendix I of CITES, meaning the species is threatened with extinction. Trade in specimens of this species is only permitted under special circumstances. 4 species were found to be vulnerable according to the IUCN.

The diversity index of birds of the Suwi River, Muara Ancalong, Kutai Timur, Kalimantan Timur, Indonesia was found to be 3.56. According to Shannon-Wiener index, the diversity of birds of the Suwi river, Muara ancalong was H > 3, a high diversity index. However, illegal hunting for commercial use and land-use change for palm oil plantations might threaten the habitat of the birds. Thus, conservation actions and further regulation should be considered.

The first report of bird diversity an essential ecological area of the Suwi River wetland, Muara Ancalong, Kutai Timur, Kalimantan Timur, Indonesia has found it contains a number of birds that are protected according to the IUCN, CITES and Indonesia government document. Though the diversity index of bird is classified as high, conservation action should be taken into consideration in order to protect the birds as well as their natural habitat.

The data referenced by this article are under copyright with the following copyright statement: Copyright: � 2018 Isa NL et al.

Data associated with the article are available under the terms of the Creative Commons Zero "No rights reserved" data waiver (CC0 1.0 Public domain dedication).

Dataset 1: List of found-birds during observation between April 2017 and March 2018 in the Suwi River wetland, Muara Ancalong, Kutai Timur, Kalimantan Timur, Indonesia. 10.5256/f1000research.16251.d219571 ⁷

Dataset 2: Pictures of found-birds during observation between April 2017 and March 2018 in the Suwi River wetland, Muara Ancalong, Kutai Timur, Kalimantan Timur, Indonesia. 10.5256/f1000research.16251.d219586 ⁹