<b>Urban tree pruning as an ecological trap for breeding birds</b>

Average relative humidity is 70.3%, annual precipitation is 1,454 mm, and annual sunshine duration is 1,765 h (Chen et al. 2024).</p><p dir="ltr"><a href="" target="_blank">Vegetation pruning in urban landscaping is a frequent anthropogenic disturbance in urban ecosystems that can drastically alter avian nesting microhabitats. To investigate how this dynamic disturbance drives nest-site selection and reproductive consequences in urban breeding birds, we monitored the breeding of light-vented bulbuls (<i>Pycnonotus sinensis</i>) in Hangzhou, Zhejiang Province, eastern China, from May to August 2025.

Based on disturbance type and breeding sequence, nests were categorized into four groups: unpruned shrubs-first breeding (USF), unpruned shrubs-second breeding (USS), pruned shrubs-first breeding (PSF), and small trees-second breeding (STS). Results indicated that light-vented bulbuls exhibited significant behavioral plasticity: following pruning-induced first breeding failure, their second breeding attempts (STS group) occurred at significantly higher nest heights than those in the other three groups.

However, this spatial shift to higher locations was maladaptive, as nest concealment in the STS group (~56%) was significantly lower than that in the unpruned controls (~84%), remaining at levels comparable to those of the PSF group. Survival analysis demonstrated that PSF and STS groups exhibited extremely low reproductive success with no significant difference between them, while USF and USS groups maintained high success rates, effectively ruling out seasonal resource limitation as a factor in second breeding.

Cox proportional hazards regression confirmed that pruning-induced loss of nest concealment was the primary limiting factor determining reproductive failure, whereas nest height, distance to roads, and distance to buildings had no significant effects. This study demonstrates that landscape pruning not only directly causes reproductive failure through physical destruction but also compels light-vented bulbuls to occupy small tree habitats lacking effective cover, creating a dynamic ecological trap driven by decoupling between habitat cues and quality.

We recommend implementing pruning moratoriums based on avian breeding phenology and adopting mosaic habitat maintenance approaches to protect urban avian diversity.</a></p>