# Nest Box Condition and Maintenance of Barn Owls (Tyto alba) in Tropical Oil Palm Plantations

## TL;DR

This study found that maintaining barn owl nest boxes in good condition is crucial for effective rodent control in oil palm plantations, especially in tropical regions.

## Contribution

The study provides empirical evidence on the impact of nest box maintenance on barn owl presence and pest control effectiveness in tropical oil palm systems.

## Key findings

- Plantations with regular nest box maintenance had significantly lower damage rates and better owl presence.
- The rainy season increased deterioration of wooden nest boxes, highlighting the need for weather-resistant materials.
- Proper nest box maintenance reduces reliance on chemical rodenticides in oil palm plantations.

## Abstract

This study examined the condition of barn owl nest boxes in five oil palm plantations in Southern Thailand between January 2022 and May 2023. Barn owls are commonly used to control rodent pests in oil palm systems, but the effectiveness of this approach depends on maintaining the nest boxes in good condition. The results showed clear differences among plantations. CPI1 had the largest number of nest boxes and the lowest damage rate, with repairs carried out regularly. In contrast, CPI4 had the highest proportion of damaged boxes and no evidence of repair activity. Statistical tests confirmed that damage rates differed significantly among plantations, although monthly variation was not significant. Field observations suggested that box deterioration increased during the rainy season, likely due to weather exposure affecting wooden structures. Overall, the findings highlight that regular maintenance of nest boxes is essential to support long-term predator-based rodent control and to reduce dependence on chemical rodenticides in tropical oil palm systems.

Barn owls (Tyto alba) are widely used as biological control agents in Southeast Asian agroecosystems, especially in oil palm plantations where rodent pests cause major yield losses. The success of such programs relies not only on nest box installation but also on maintaining the structural condition of these boxes. We analyzed monthly nest box monitoring data from January 2022 to May 2023 across five oil palm plantations (CPI1–CPI5) in Southern Thailand, including numbers of total, damaged, repaired, and unrepaired boxes. Substantial spatial variation was observed: CPI1 maintained the highest number of boxes (289) with a very low damage rate (~1.2%) and consistent repairs, whereas CPI4 showed the highest proportion of damaged boxes (~11%) and no repair activity. Chi-square and Kruskal–Wallis tests confirmed significant differences in damage rates among plantations (p < 0.001), although monthly variation was not statistically significant (p = 0.42). Visual inspection indicated increased deterioration during the wet season, suggesting weather-related stress on wooden structures. These results highlight the importance of maintaining nest box infrastructure as part of plantation management practices that support barn owl presence in oil palm agroecosystems. Keeping boxes functional throughout the year helps sustain a nature-based pest control service, reducing reliance on rodenticides and enhancing agroecosystem sustainability under humid tropical conditions.