Summary The globally Endangered Giant Nuthatch Sitta magna remains poorly studied, with key factors affecting its reproductive success remaining largely unknown. With forest loss as the primary threat to Giant Nuthatch, urgent action is needed to find possible avenues for habitat restoration. Here we investigated nesting survival and nest-site and nest-cavity characteristics at a site supporting the largest known global subpopulation in a 62 km 2 landscape dominated by mature Pinus kesiya restoration plantings, a potential additional habitat for Giant Nuthatch in northern Thailand. Over three breeding seasons (2022–2024), we monitored 31 nests with 16 nests in plantation interiors and 15 nests in plantations close to villages and agricultural lands. The nesting period lasted about 43 days, with 11–15 days of incubation and 25–28 days with nestlings. We found that Giant Nuthatch primarily relied on available natural cavities, with an overall nesting success of ~25% (0.9686 ± 0.0079 SE daily survival rate). Daily survival rates were negatively affected by rainfall during cooler periods, while nests located in larger trees with a higher percentage of crown connectedness were associated with higher daily survival, likely due to better protection from severe weather conditions, such as rain combined with cooler temperatures. No significant differences were detected in daily survival between interior and edge nests, possibly reflecting lower abundance and diversity of nest predators in the more disturbed edge habitat. Although no strong preferences for specific cavity or nest-site characteristics were observed, nests tended to occur in cavities with greater horizontal depth and in flatter areas with a more open canopy. Our study represents the most comprehensive assessment of Giant Nuthatch nesting ecology, highlighting mature pine plantations as potential nesting habitat. These findings suggest that incorporating such plantations into conservation strategies may help sustain population viability, though further research is required on their long-term effectiveness.
Khamcha et al. (Thu,) studied this question.