Data from: Reproductive plasticity and landscape heterogeneity benefit a ground-nesting bird in a fire-prone ecosystem

Disturbance is critical for the conservation of rangeland ecosystems worldwide and many of these systems are fire dependent. Although it is well established that restoring fire as an ecological process can lead to increased biodiversity in grasslands and shrublands, the underlying mechanisms driving community patterns are poorly understood for fauna in fire-prone landscapes. Much of this uncertainty stems from the paucity of studies that examine the effects of fire at scales relevant to organism life histories. We assessed the response of a non-migratory ground-dwelling bird to disturbance (i.e., prescribed fire) and environmental stochasticity over the course of a 4 year period, which spanned years of historic drought and record rainfall. Specifically, we investigated the nesting ecology of northern bobwhite (Colinus virginianus; hereafter bobwhite) to illuminate possible avenues by which individuals respond to dynamic landscape patterns during a critical reproductive stage (i.e., nesting) in a mixed-grass shrubland in western Oklahoma, USA. We found that bobwhites exhibited extreme plasticity in nest substrate use among time since fire categories (TSF) and subsequently maintained high nest survival (e.g., 57 – 70%). Bobwhites were opportunistic in nest substrate use among TSF categories (i.e., 72% of nest sites in shrubs in 0-12 months post fire compared to 71% in herbaceous vegetation in >36 months post fire), yet nesting decisions were first filtered by similar structural components (i.e., vertical and horizontal cover) within the vicinity of nest sites regardless of TSF category. Despite being a non-migratory and comparatively less mobile ground-nesting bird species, bobwhites adjusted to dynamic vegetation mosaics on a fire-prone landscape under stochastic climatic conditions which culminated in stable and high nest survival. Broadly, our findings provide a unique depiction of organism response strategies to fire at scales relevant to a critical life-stage, a topic that has been previously understudied and poorly understood. We also demonstrate how doing so can better inform conservation practices aimed at restoring fire regimes on grassland and shrubland landscapes.

干扰对于全球草原牧场生态系统的保护至关重要，且多数此类生态系统均为火依赖型系统。尽管已有充分研究证实，将火作为生态过程恢复可提升草原与灌丛地的生物多样性，但对于火频发景观中的动物类群而言，驱动群落格局形成的潜在机制仍未得到充分阐释。此类认知缺口大多源于现有研究的匮乏——现有研究鲜少在契合生物生活史特征的尺度上开展火效应相关调查。本研究针对一种非迁徙性地栖鸟类，在为期4年的周期内评估其对干扰（即受控火烧（prescribed fire））与环境随机性的响应，该周期涵盖了历史性干旱与破纪录降雨的年份。具体而言，我们以美国俄克拉荷马州西部一处混灌丛草原为研究区域，针对山齿鹑（Colinus virginianus，后文简称山齿鹑）的繁殖巢生态学展开调查，以期阐明该物种在关键繁殖阶段（即筑巢期）如何响应动态景观格局。研究结果显示，山齿鹑在不同火烧后时间类别（Time Since Fire，简称TSF）下的巢址基质选择表现出极强的可塑性，且整体维持了较高的巢存活率（范围为57%至70%）。山齿鹑在不同TSF类别下的巢址选择呈现机会主义特征：火烧后0-12个月内，72%的巢址位于灌丛中；而火烧后超过36个月时，71%的巢址则位于草本植被中。不过无论处于何种TSF类别，山齿鹑的筑巢决策首先会受到巢址周边相似结构特征（即垂直与水平覆盖度）的筛选。尽管山齿鹑属于非迁徙性且活动能力相对较弱的地栖筑巢鸟类，但在随机气候条件下的火频发景观中，其仍能适应动态变化的植被镶嵌格局，最终实现了稳定且较高的巢存活率。总体而言，本研究的发现为阐释生物在契合关键生活史阶段的尺度下对火的响应策略提供了全新视角——该主题此前尚未得到充分研究与认知。此外，本研究还展示了此类研究如何能够为旨在恢复草原与灌丛地火制度（fire regimes）的保护实践提供更具针对性的科学参考。