2004 study mapped 46 Komodo dragon nesting sites on Komodo Island

Labuan Bajo — A 2004 peer‑reviewed study on Komodo Island documented 46 Komodo dragon nesting sites, of which 26 were assessed as active during the 2002/2003 nesting season, in coastal valleys and adjacent habitats within Komodo National Park, according to research by Tim S. Jessop and colleagues published in Biological Conservation.

The study, titled “Distribution, use and selection of nest type by Komodo Dragons,” surveyed major coastal valleys and nearby flats on Komodo Island to map nesting sites and examine how female Komodo dragons select nests. It focused on female nesting ecology as a practical tool for long‑term monitoring rather than on producing a full population census of the species.

Jessop and co‑authors reported that they systematically surveyed coastal valleys on Komodo Island during the 2002/2003 nesting season, cataloguing 46 distinct nesting locations and classifying 26 as active based on signs of recent excavation consistent with egg‑laying females. Subsequent summaries of the work by conservation groups and research platforms repeat these figures, citing Komodo Island as the study location and the 2002–2003 nesting season as the survey period.

What the survey found

The nesting sites recorded by the researchers were concentrated in large coastal valleys in northern Komodo Island. The paper noted that breeding females showed a strong preference for mound nests associated with megapode birds, which accounted for 61% of the nests identified. Open hillside burrows and ground burrows each represented 19.5% of the total recorded nest sites.

In the study, mound nests were typically modified from the nesting mounds of the orange‑footed scrubfowl (Megapodius reinwardt

The authors described the recorded nesting sites as locations that could be reused in successive years, and noted that some nesting sites were already well known to park rangers before the systematic survey. They suggested that combining mapped nest locations with observations of individually marked females could allow managers to track breeding intervals and female survival over time, providing a cost‑effective way to build demographic data.

Key numerical findings from the Komodo Island survey include:

• Total nesting sites identified: 46
• Sites assessed as active in the 2002/2003 nesting season: 26
• Proportion of nest types: 61% mound nests, 19.5% open hillside burrows, 19.5% ground burrows

Subsequent conservation summaries describe the nest density revealed by the study as relatively low across Komodo Island and reiterate that female Komodo dragons show a marked preference for abandoned megapode mound nests.

What the study did and did not establish

Jessop and colleagues framed annual counts of active nests as a practical indicator of the number of breeding females and, indirectly, of future hatchling recruitment, arguing that repeated nest surveys could yield long‑term demographic information at lower cost than many other reproductive monitoring techniques. However, they did not present the 46 nesting sites as a complete inventory of all nests on Komodo Island, and emphasised that some suitable habitats remained difficult to access.

The study did not attempt to generate a definitive total population estimate for Komodo dragons on Komodo Island. Instead, it was conceived as a baseline for understanding the distribution and characteristics of nesting habitat and for developing a monitoring protocol based on nest activity.

Later park and program documents that reference Jessop’s work likewise treat nest counts as one tool among several for tracking the status of the species, noting that additional surveys in Komodo National Park continue to find new nesting sites and report that some areas remain unsurveyed.

Context for conservation

Komodo dragons are naturally restricted to a handful of island populations in eastern Indonesia, with Komodo Island and several neighbouring islands forming the core of the species’ range. Conservation analyses cite habitat alteration, human‑caused fires and competition with people for prey species such as Timor deer as ongoing pressures on the species within and around Komodo National Park.

The Jessop study was received by Biological Conservation in June 2003, revised in August 2003 and published in volume 117 of the journal in 2004, on pages 463–470. By documenting the number, distribution and physical characteristics of Komodo dragon nesting sites on Komodo Island, the authors provided a detailed starting point for future surveys that use comparable coverage and methods, and for management strategies that prioritise the protection of coastal valleys and mound‑nest habitats essential to successful breeding.

Sources

• Jessop TS et al., Distribution, use and selection of nest type by Komodo Dragons, Biological Conservation 117:463–470 (PDF via seaturtle.org)
• Komodo Guide – Sarang Naga Komodo (Jessop dkk., 2007)
• Herpetological Journal – Distribution and conservation of the Komodo monitor (Varanus komodoensis)
• International Varanid Interest Group – Varanus komodoensis report (PDF)
• Komodo Survival Program – Publications
• US Fish and Wildlife Service – Komodo dragon nesting survey report (attachment in regulatory docket)
• Journal of Tropical Biodiversity and Biotechnology – Sutomo (2020)