Seasonal and inter-island variation in the foraging strategy of the critically endangered Red-headed Wood Pigeon<i>Columba janthina nitens</i>in disturbed island habitats derived from high-throughput sequencing

We studied the feeding ecology of the critically endangered Red-headed Wood Pigeon Columba janthina nitens, a subspecies endemic to a very remote and highly disturbed oceanic island chain, the Ogasawara Islands. An analysis based on high-throughput sequencing (HTS) was undertaken on 627 faecal samples collected over 2 years from two island habitats, and food availability and the nutrient composition of the major fruits were also estimated. The HTS diet analysis detected 122 food plant taxa and showed clear seasonal and inter-island variation in the diet of the Pigeons. The results indicated a preference for lipid-rich fruits, but the diet changed according to the availability of food resources, perhaps reflecting the foraging strategy of the Pigeons in isolated island habitats with poor food resources. Pigeons also frequently consumed introduced plants at certain times of year, perhaps compensating for the lack of preferred native food resources. However, the degree of dependence on introduced plants appeared to differ between the two island habitats, so the different impacts of introduced plant eradication on the foraging conditions for the Pigeons on each island should be considered. HTS diet analysis combined with field data may be useful for monitoring the foraging conditions of endangered species and may also inform an appropriate conservation strategy in oceanic island ecosystems with complicated food webs that include both native and introduced species.