The diversity of birds in a place is dynamic. Changing environmental conditions and the addition of new information mean that our understanding of bird diversity continues to evolve. In 2024, we will find that bird diversity in Indonesia will continue to change. Meanwhile, documenting these changes is important because it can be the main basis for determining conservation priorities.

Indonesian Birds again summarizes all the information that may be obtained from various sources about changes in bird diversity in Indonesia in the Status of Birds in Indonesia. Bird Status in Indonesia is a summary of the latest information on all bird species spread across various regions in Indonesia. The information contained in the Status of Birds in Indonesia is the result of searches from various sources, such as scientific publications, validated records of bird observers, the results of discussions with experts at research institutions and universities. The discussion activities carried out involved conservation, taxonomy and ecology experts. The main taxonomic basis used in the Status of Birds in Indonesia follows the Handbook of the Birds of the World (HBW) and BirdLife International (HBW & BirdLife International, 2023).

Every year since 2014, Burung Indonesia updates data regarding the status of birds in Indonesia which contains the number of species, taxonomic changes, endemicity and threat status. Apart from being a practical reference in carrying out work programs to conserve birds and their habitats, this data can also be accessed by the public at large to be referred to as a source of knowledge.

Searches throughout 2023 found that the richness of bird species in Indonesia in early 2024 reached 1836 species. This number means a difference of ten species more than at the beginning of the previous year (1826 species at the beginning of 2023). This change in species richness was caused by several factors, namely mainly by taxonomic splits and new records of bird species spread across Indonesia. In addition, there was also a taxonomic merger that had an impact on the reduction in the number of species.

No less than eight bird species have undergone taxonomic division. This division has resulted in nine new species and has increased the wealth of bird species in Indonesia. Meanwhile, five other species are only known to have been distributed for the first time in Indonesia.

Thus, there was an addition of 14 species to the list. The list of added species can be seen in Table 1 below.

From the table above, it is also known that there are five bird species that are new records for the Indonesian region, including the slender-billed gull (Larus genei), the Bornean uncal (Macropygia tenuirostris), the kermadec petrel (Pterodroma neglecta), the black shearwater (Ardenna grisea), and the Indian magpie (Terpsiphone paradisi). The encounter of the slender-billed gull was known from observations of bird watchers in Sumatra who monitored its presence while migrating in the South Sumatra Province (Iqbal et al., 2023). Meanwhile, records of the presence of the other four species in Indonesia were obtained from data mining of field observations collected by bird watchers in various regions into the eBird citizen science platform. The use of citizen science platforms such as eBird is increasingly in demand, because it offers convenience in the process of recording and documenting observation results, as well as facilitating the exchange of information between observers. On the other hand, citizen involvement in data collection allows the diversity of bird species in Indonesia to be monitored more inclusively and systematically. Therefore, citizen science platforms and citizen scientists are currently also playing an important role in providing data and information for the conservation and management of bird habitats in Indonesia.

However, the long list of bird species in Indonesia has also experienced a reduction due to taxonomic lump. A total of nine bird species in Indonesia have been merged into five species. Four bird taxa have been returned to subspecies or races of previously existing bird species, resulting in a reduction in the number of species by four from the previous list. The list of birds that have undergone taxonomic lump is as follows.

Bird Friendly City, Providing Habitat for Birds

Indonesian endemic birds are defined as bird species that are only distributed within the administrative boundaries of Indonesia. The taxonomic division that occurred also affected the number and composition of endemic bird species in Indonesia. Of the 15 species that were newly included in the list in this period, four of them are distributed only in Indonesia. Thus, the total wealth of endemic bird species in Indonesia in 2024 is 542 species. This number further confirms Indonesia as the country with the most endemic bird species in the world. The four species and their distribution are explained in the following table.

Indonesia is known to have seven avifauna regions, each of which has its own unique bird species diversity (Sukmantoro et al., 2007). Endemic species are also relatively unevenly distributed among these avifauna regions. Most (169 species, 31%) of Indonesia’s endemic species are spread across Sulawesi, followed by Maluku (23%), and Nusa Tenggara (20%). This also makes the Wallacea region, which encompasses these three regions, a hotspot for Indonesia’s endemic bird species. Kalimantan is the region with the fewest endemic species (6 species, 1%) because most of the island’s endemic bird species are also spread across Malaysia.

Bird Threat Status in Indonesia

There were quite a lot of changes in the threat status of bird species during this period. The annual evaluation of the IUCN Red List by BirdLife International showed that there were changes in the threat status of 62 bird species in Indonesia (Figure 3). These changes included the increase in the status of eight species from the low threat category to a category with a higher threat risk. Conversely, 40 other species were placed in a lower threat category than before. In addition, 14 other species were newly evaluated and assigned a threat category, including nine new species from taxonomic breakdown.

Of the eight species that experienced an increase in threat status, four species were evaluated as globally endangered. Three species are in the Vulnerable (VU) category, namely the Greater Frog-billed (Batrachostomus auritus), the Brown-rumped Loach (Harpactes orrhophaeus), and the Javan Coffee-bird (Pomatorhinus montanus), and one species is in the Endangered (EN) category, namely the Mongolian Sandpiper (Charadrius mongolus). According to the IUCN (2023), the threat of forest damage and degradation has caused the population of the Greater Frog-billed and the Brown-rumped Loach to decline significantly. Meanwhile, the population of the Javan Coffee-bird is significantly affected by the threat of capture for trade and keeping. Meanwhile, the Mongolian Sandpiper faces quite diverse threats throughout its migration process, such as the threat of predation and reclamation in its breeding grounds and habitat degradation in its migration locations.

Meanwhile, 40 species were downgraded to lower threat categories, generally to Near Threatened (NT) and Low Risk (LC) categories (Figure 3). From the IUCN evaluation (2023), in general the downgrade of the species status was caused by the addition of new information and understanding about the population and its threat level. Several species are known to have larger population size estimates than previously thought so that they do not reach the threshold of a higher threat category.

A further 14 species were newly evaluated this year. The snow robin (Petroica archboldi), white-fronted plover (Charadrius dealbatus), star-billed atoku (Aegotheles tatei), and bird-headed atoku (Aegotheles affinis) were previously categorized as data deficient (DD). However, with the addition of new information on their distribution and population, these four species are now evaluated in the NT, LC, LC, and NT categories respectively. The white-eye (Zosterops beak besar) is a bird whose threat status was only evaluated this year, although it has been known to the scientific world since its description in 2022. The relatively small population size and only spread on Wangi-Wangi Island, as well as the high threat from habitat loss and hunting, made this species immediately assigned to the Endangered (EN) category (IUCN, 2023).

Closing

Bird diversity in Indonesia changes very dynamically from year to year. Taxonomic revisions have contributed greatly to the addition of bird species diversity in Indonesia by revealing bird taxa that were previously ‘hidden’ in more complex species classifications. The contribution of citizen scientists through various citizen science platforms has also become increasingly important. Data collected voluntarily by citizen scientists can be a valid reference in monitoring bird diversity in Indonesia. This is also what prompted Burung Indonesia to develop the AMATISEKITAR citizen science platform to open up opportunities as widely as possible for the community who want to contribute to updating data and information on bird diversity.

Compilation of data in recent years shows that the increase in bird diversity also has implications for the increase in the number of endemic bird species in Indonesia. These results also show Wallacea as the main distribution area for endemic species. This has been indirectly predicted before, considering the biogeographic history of the islands in Wallacea which are so unique that they have a much higher speciation rate than other regions.

Despite the increasingly advanced knowledge of Indonesia’s bird diversity, there are still many mysteries about the biology and life history of bird species that are still unknown. The lack of information also makes it increasingly difficult to assess the threat status. More research, observations, and expeditions are needed in the future to fill this knowledge gap. Updating this information ultimately also aims to support more effective bird conservation efforts in order to achieve the sustainability of bird diversity in Indonesia.

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