- Great news! The latest survey has shown an increase in the population of the Javan hawk-eagle, an iconic bird of prey endemic to Indonesia, from the previous survey carried out in 2009.
- However, the research also found that habitat isolation is a growing concern, linked to the small size of forest patches as the primary forest is lost due to human activity.
- Did you know that the Javan hawk-eagle heavily relies on primary forests for breeding, particularly for the tall trees in which it builds its nests?
- The hawk-eagle is Indonesia’s national bird, and conservation efforts were meant to boost its population by 10% from a 2019 baseline; this hasn’t happened, according to the recent survey.
JAKARTA — Most of the habitat of the Javan hawk-eagle is protected, but threats of forest degradation and isolation loom over the surviving population of Indonesia’s national bird, a new study shows.
The latest population estimate for the Javan hawk-eagle (Nisaetus bartelsi) is 511 breeding pairs, an increase from 325 pairs in 2009, according to the research. It added that 70% of the species’ habitat lies within protected areas across the islands of Java and Bali, while the remainder is in farmland.
“Improved habitat distribution data are needed to better estimate the current population size and to facilitate development of new strategies and action plans,” says the study published Nov. 21 in the Journal of Raptor Research.
A juvenile Javan hawk-eagle in Bromo Tengger Semeru National Park. Image courtesy of Heru Cahyono.
Researchers observe a Javan hawk-eagle nest in Bromo Tengger Semeru National Park. Image courtesy of Rofifah Aulia Suyitno.
The researchers conducted field surveys between 2008 and 2019 by observing the nests of eagle couples and revisiting them during the breeding season, and also collected information through interviews with local communities, key informants from local nongovernmental organizations, government officials, and site managers. To analyze the data, they included improved study methods, such as higher-resolution satellite imagery, which helped in identifying the important habitats.
The scientists credited these improved methods with helping them come up with a population estimate that was higher than previously calculated. They also found that while the species prefers big forest areas for breeding, they can adapt to smaller patches when necessary and available, especially in areas where much of the land is used by humans for farming.
But the researchers also noted a slight decrease in suitable habitat for the hawk-eagles during the study period due to significant degradation of primary forest, and also a strong indication of habitat isolation associated with the small size of forest patches.
“The Javan hawk-eagle is very dependent on primary forests because of the availability of emergent trees which are its preference for making nests,” study lead author Syartinilia, a professor in landscape management at the Bogor Institute of Agriculture (IPB),
