Passive acoustic monitoring captures spatiotemporal dynamics of urban zoo soundscapes

Urban zoos are important but complex artificial ecosystems that integrate wildlife conservation with public education. Their soundscapes, including anthrophony, biophony, and geophony, show significant spatiotemporal dynamics. Persistent fluctuations could contribute to chronic stress in captive animals and human visitors, impairing welfare and conservation outcomes. Existing research focuses on static noise levels, neglecting spatiotemporal dynamics in zoo soundscapes. To address this gap, we deployed passive acoustic monitoring (PAM) with 20 acoustic recorders at Zhengzhou Zoo across seven functional zones between weekdays and weekends during summer in 2024. We analyzed six acoustic indices: Acoustic Complexity Index (ACI), Acoustic Diversity Index (ADI), Acoustic Evenness Index (AEI), Bioacoustic Index (BIO), Normalized Difference Soundscape Index (NDSI) and A-weighted sound pressure level (SPL(dBA)). These were combined with non-metric multidimensional scaling, generalized additive models, and kernel principal component analysis. Quantitatively, we found that SPL (dBA) increased by up to 10 dB on weekends compared to weekdays, while ACI rose by approximately 20%. A very strong negative correlation was observed between ADI and AEI, indicating an inverse dynamic between acoustic diversity and evenness. Building on these results, the analysis revealed distinct diel patterns, with biophony dominating during dawn and dusk periods, while anthrophony peaked during day hours. The weekend effect was significantly identified with these elevated SPL (dBA) and ACI, alongside reduced acoustic stability. Significant acoustic divergence was observed among functional zones, with elevated SPL (dBA) and ACI in High-traffic Zone but with reduced BIO in others. The results indicate that biological rhythms, human activities, and environmental structures collectively shape zoo soundscapes, and PAM and acoustic indices can provide a robust scientific basis for acoustic-based animal welfare and visitor management in zoos.