The San Clemente Bell’s Sparrow (Artemisiospiza belli clementeae) is a federally threatened subspecies endemic to San Clemente Island, California. Previous research suggested dependence on boxthorn (Lycium californicum) as breeding habitat and nesting substrate; however, this conclusion was based on data collected when introduced feral ungulates had severely degraded the soil and vegetation cover. Since removal of the ungulates, native vegetation has gradually increased and the San Clemente Bell’s Sparrows have expanded into areas where habitat had been unsuitable. To explore how Bell’s Sparrows use these areas, we examined reproductive metrics associated with habitat covariates gathered at 214 nest sites used by Bell’s Sparrows from 2014 to 2016. We found that nest success in boxthorn habitat, previously considered an essential habitat for Bell’s Sparrow nesting, was similar to success in alternative habitat types. Our findings contradict previous conclusions that Bell’s Sparrows were boxthorn-dependent. We believe this previously documented relationship was likely due to the lack of available alternative nesting habitat following years of feral ungulate degradation, and Bell’s Sparrows now reproduce in multiple habitat types and throughout most of San Clemente Island. Furthermore, our findings illustrate the importance of long-term monitoring and corresponding adaptive management when monitoring species in changing and recovering landscapes.

中文翻译：

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受威胁的圣克莱门特·贝尔麻雀（Artemisiospiza belli clementeae）在恢复栖息地方面的繁殖成功与历史栖息地的成功相似

圣克莱门特贝尔麻雀（Artemisiospiza belli clementeae）是加利福尼亚州圣克莱门特岛特有的受到联邦威胁的亚种。先前的研究表明对盒棘（Lycium californicum）作为繁殖栖息地和筑巢基质；但是，该结论基于收集的数据，当时引入的野生有蹄类动物严重破坏了土壤和植被的覆盖。自从除去有蹄类动物以来，当地植被逐渐增加，圣克莱门特贝尔的麻雀已扩展到栖息地不合适的地区。为了探索贝尔的麻雀如何利用这些区域，我们研究了与2014年至2016年间在贝尔的麻雀所使用的214个巢点收集的栖息地协变量相关的繁殖指标。我们发现，在以前被认为是贝尔的麻雀筑巢必不可少的栖息地的盒棘栖息地中筑巢成功，与其他栖息地类型的成功相似。我们的发现与先前的结论“贝尔的麻雀”是依赖于黄刺的结论相矛盾。我们认为，这种先前记录的关系很可能是由于多年的有蹄有蹄类动物退化后缺乏可用的筑巢栖息地而引起的，而贝尔的麻雀现在在多种栖息地类型和整个圣克莱门特岛的大部分地区繁殖。此外，我们的发现说明了在监测物种变化和恢复景观时长期监测和相应的适应性管理的重要性。