Although changes, particularly declines, in Australian terrestrial insects and other invertebrates have long been suspected and well‐documented for some species, the magnitude, rate and spatial extent of decline remain unclear. Here we use a combination of alternative, qualitative approaches (expert opinion, historical records and temporal replication of surveys) to standardised monitoring and mapping programs to investigate the extent of change of a peri‐urban butterfly assemblage. This assemblage, comprising 52 species, of which 46 are residents or seasonal immigrants, was studied at three spatial scales (local ~0.01 km², intermediate ~9 km² and regional ~100 km²) in the Eltham district near Melbourne based on presence/absence data over the past 40 (1981–2020) and 80 years (1941–2020). We then consider the causal factors or drivers that have led to changes, and we explore the timing and ecological patterns underpinning extirpations. Long‐term records reveal substantial changes (mostly decline) in composition and species richness of the 46 breeding species at all spatial scales and time frames analysed. Although the magnitude and rate of decline were higher at the smaller, local to intermediate scales (29–43% decline over 40 years, loss rate of 0.20–0.25 species/year) compared with the larger, regional scale (26% decline over 80 years, loss rate of 0.15 species/year), extirpations at the larger scale were more alarming because they are indicative of widespread population collapse. Declines in relative abundance and occupancy were also recorded at the intermediate and regional spatial scales. Further decline (extinction debt) is anticipated for several ecological specialists currently known from very few sites. Historical extirpations mostly involved obligate myrmecophilous lycaenids and appear to have been largely driven by a combination of urbanisation (habitat loss, degradation and fragmentation) and vegetation encroachment. More recent extirpations consist mainly of grass‐feeding and mistletoe‐feeding specialists and are more worrying because they have predominantly occurred within the past 20–30 years. An interaction of urbanisation (tree canopy death and decline of mistletoes and their host trees from ecosystem dysfunction) and climate change (water stress and heat waves) are considered to be the most likely drivers for these ecological guilds.

中文翻译：

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澳大利亚墨尔本附近80年来郊区蝴蝶组合的变化

尽管长期以来人们一直怀疑澳大利亚陆生昆虫和其他无脊椎动物的变化，特别是下降，但某些物种的变化有据可查，但下降的幅度，速度和空间范围仍不清楚。在这里，我们使用替代性，定性方法（专家意见，历史记录和调查的时间重复）的组合来标准化监测和制图程序，以研究城郊蝴蝶组合的变化程度。从三个空间尺度（本地〜0.01 km ²，中级〜9 km ²和区域〜100 km ²）研究了该组合，包括52种，其中46个是居民或季节性移民。）基于过去40年来（1981–2020）和80年来（1941–2020）的在场/不在场数据，在墨尔本附近的Eltham区进行了调查。然后，我们考虑导致变化的因果因素或驱动因素，并探讨了根除的时机和生态模式。长期记录表明，在所有空间尺度和时间范围内，46种育种物种的组成和物种丰富度均发生了重大变化（大部分呈下降趋势）。尽管规模较小，但局部到中等规模的下降幅度更大（在40年中下降了29-43％，损失率为0.20-0.25种/年），而较大的区域规模（在80年代下降了26％年，损失率为0.15种/年），更大规模的灭绝是更令人震惊的，因为它们表明人口普遍崩溃。在中间和区域空间尺度上也记录了相对丰度和占有率的下降。预计目前很少有站点的几位生态专家将进一步下降（灭绝债务）。历史上的灭绝大多涉及专性的嗜温性lycaenids，并且似乎在很大程度上是由于城市化（栖息地的丧失，退化和破碎）和植被侵占的共同驱动。最近的物种灭绝主要是由草食和槲寄生食专家组成，并且更加令人担忧，因为它们主要发生在过去20-30年内。