Woodpeckers, as keystone species, are critical indicators of forest ecosystem health due to their cavity excavation and sensitivity to habitat changes. Woodpecker diversity is hypothesized to correlate with that of other bird groups due to their role as indicators of habitat quality, resource availability, and ecological integrity. This study evaluates the potential of woodpeckers as indicators of non-picid bird diversity across seasons in the non-protected forests of Darjeeling, Eastern Himalaya. Bird community and forest attribute data were collected from 24 transects across elevations of 200–2300 m over four seasons. Results revealed seasonal associations of woodpeckers with various feeding guilds, emphasizing their importance as indicators of forest health. Although woodpecker abundance was positively correlated with non-picid bird abundance, the relationship was inconsistent, with a non-significant effect during the monsoon season. Woodpecker richness, however, was not a reliable indicator of non-picid richness. Seasonal variations in the influence of forest attributes on diversity of picid and non-picid birds highlighted contrasting ecological niches between woodpeckers and other birds. Certain forest characteristics, such as snag density and tree diameter diversity, positively influenced woodpecker richness and abundance, underscoring their reliance on mature forests. In contrast, non-picid birds were influenced more by basal area and tree height. Indicator Species Analysis identified the Darjeeling Woodpecker as a strong indicator of high bird diversity sites, while the Grey-capped Pygmy Woodpecker and Greater Flameback were associated with low bird diversity habitats. These findings suggest that woodpecker monitoring can inform conservation strategies aimed at maintaining ecosystem integrity and managing bird diversity, particularly by prioritizing the conservation of mature forest structures and resources critical to both woodpeckers and other bird groups.