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<p>Local populations of rare and declining species assume particular interest for their conservation value, as models for studying the dynamics of vulnerable populations and for insights into the successful maintenance of populations at risk. The Harris’ checkerspot <i>Chlosyne harrisii</i> (Nymphalidae) is a small orange and black butterfly whose populations have rapidly declined in recent years along the southern edge of its geographic range in New England, USA. Its larvae feed exclusively on the tall flat-topped white aster <i>Doellingeria umbellata</i>, a plant of old fields and roadsides. Here, I evaluate the dynamics of a population of this butterfly, whose numbers have fluctuated markedly over 19&#xa0;years, with maximum and minimum yearly counts varying over 30-fold during that period, and exhibiting little suggestion of constancy. I focused on several life-cycle stages, including numbers and fate of egg masses and success in overwintering. Nearly two-thirds of the egg masses produced some young that entered hibernation, but only a few of these individuals survived the winter. Warm overwinter temperatures were associated with especially low overwintering success and wet, cold weather during the period of oviposition was associated with poor reproductive success. Little direct evidence existed in support of density dependence as a factor limiting population numbers over the period of this study. Checkerspots exhibited poor success as colonizers, for we found only one small satellite population likely emanating from the focal population.</p>

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Fluctuations of a Large Harris’ Checkerspot Chlosyne harrisii Population in 19 Years

  • 期刊论文

  • 发表日期：

    2025年3月6日

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  • Douglass H. Morse

摘要

Local populations of rare and declining species assume particular interest for their conservation value, as models for studying the dynamics of vulnerable populations and for insights into the successful maintenance of populations at risk. The Harris’ checkerspot Chlosyne harrisii (Nymphalidae) is a small orange and black butterfly whose populations have rapidly declined in recent years along the southern edge of its geographic range in New England, USA. Its larvae feed exclusively on the tall flat-topped white aster Doellingeria umbellata, a plant of old fields and roadsides. Here, I evaluate the dynamics of a population of this butterfly, whose numbers have fluctuated markedly over 19 years, with maximum and minimum yearly counts varying over 30-fold during that period, and exhibiting little suggestion of constancy. I focused on several life-cycle stages, including numbers and fate of egg masses and success in overwintering. Nearly two-thirds of the egg masses produced some young that entered hibernation, but only a few of these individuals survived the winter. Warm overwinter temperatures were associated with especially low overwintering success and wet, cold weather during the period of oviposition was associated with poor reproductive success. Little direct evidence existed in support of density dependence as a factor limiting population numbers over the period of this study. Checkerspots exhibited poor success as colonizers, for we found only one small satellite population likely emanating from the focal population.