Norris Andrea R, Martin Kathy
Department of Forest and Conservation Sciences, University of British Columbia, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada.
Science & Technology Branch, Environment and Climate Change Canada, 60 Front Street, Nanaimo, BC, V9R 5H7, Canada.
Sci Rep. 2025 Mar 18;15(1):9338. doi: 10.1038/s41598-025-93109-y.
We investigated the impact of two natural pulses (food and nesting resources) on intra- and inter-specific territorial behaviour of species that co-occur year-round in multi-species groups. We simulated conspecific and heterospecific territorial intrusions in two cavity-nesting species using 974 model presentations with territorial song playbacks during and after a dual resource pulse of insect (bark beetle) prey and nest cavities across 5 years in British Columbia, Canada. As beetle abundance increased, both species increased aggression toward conspecific intruders. At peak beetle abundance the (typically) subordinate generalist insectivore, mountain chickadee (Poecile gambeli), attacked model intruders more frequently than did the dominant bark insectivore, red-breasted nuthatch (Sitta canadensis), and responded more aggressively to nuthatch intruders than to conspecifics. The reversal in the inter-specific dominance hierarchy suggests that behavioural mechanisms governing community structure may change during resource pulses. Overall, we suggest that social interactions between chickadees and nuthatches are dynamic with high complexity and flexibility to major ecological changes. Future work that examines the fitness consequences of temporal variation in community dynamics and resiliency could help to reveal evolutionary mechanisms by which these species co-exist.
我们研究了两种自然脉冲（食物和筑巢资源）对常年共存于多物种群体中的物种的种内和种间领地行为的影响。我们在加拿大不列颠哥伦比亚省，利用974次模型展示并在5年期间昆虫（树皮甲虫）猎物和巢穴的双重资源脉冲前后播放领地性鸣叫，模拟了两种洞巢物种的同种和异种领地入侵情况。随着甲虫数量的增加，两个物种对同种入侵者的攻击性都增强了。在甲虫数量达到峰值时，（通常）处于从属地位的杂食性食虫鸟——美洲山雀（Poecile gambeli），比占主导地位的树皮食虫鸟——白胸䴓（Sitta canadensis）更频繁地攻击模型入侵者，并且对䴓的入侵者比对同种入侵者反应更激烈。种间优势等级的逆转表明，在资源脉冲期间，控制群落结构的行为机制可能会发生变化。总体而言，我们认为山雀和䴓之间的社会互动是动态的，对主要生态变化具有高度的复杂性和灵活性。未来研究群落动态和恢复力的时间变化对适应性影响的工作，可能有助于揭示这些物种共存的进化机制。
