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Comparisons to the Century Before: The Legacy of R. C. L. Perkins and Fauna Hawaiiensis as the Basis for a Long-Term Ecological Monitoring Program

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Title:Comparisons to the Century Before: The Legacy of R. C. L. Perkins and Fauna Hawaiiensis as the Basis for a Long-Term Ecological Monitoring Program
Authors:Liebherr, James K.
Polhemus, Dan A.
Date Issued:Oct 1997
Publisher:University of Hawaii Press
Citation:Liebherr JK, Polhemus DA. 1997. Comparisons to the century before: the legacy of R. C. L. Perkins and Fauna Hawaiiensis as the basis for a long-term ecological monitoring program. Pac Sci 51(4): 490-504.
Abstract:As one means of assessing the impact of the past 100 yr of development
and biological alteration in Hawai'i, the damselfly (Odonata: Coenagrionidae) and
carabid beetle (Coleoptera: Carabidae) collections of R. C. L. Perkins made in the
l890s are compared with similar collections made one century later during the
1990s. Two islands that have experienced very different histories of development
are compared: O'ahu and Moloka'i. Of eight native damselfly species originally
inhabiting O'ahu, one has been extirpated from the island, another is now reduced
to a single population, and three more are at risk. Of the eight species originally
found on Moloka'i, by contrast, there is only one species that has not been rediscovered,
although there is reasonable probability that it has simply eluded capture
because of inherent rarity, whereas the remaining species retain large and stable
populations. Capture frequencies (based on specimens collected per decade) are
lower now than in the preceding century for most species on O'ahu, even allowing
for modem collectors retaining fewer specimens. The only species on O'ahu for
which captures have increased between the l890s and the 1990s are those that
breed away from lotic and lentic habitats, indicating a severe negative impact from
introduced aquatic biota for species that breed in such freshwater situations. On
Moloka'i, all damselfly species except one have higher capture rates now than in
the l890s, explainable in large part to improved access to previously remote terrain.
Among the Carabidae studied, 1990s surveys on Moloka'i have found 12 of 15
species Perkins sampled in the 1890s. Overall, recent surveys have failed to rediscover
five species, all of which have been relatively rarely encountered over all
decades of the past century. Recent surveys on O'ahu have recollected 17 of the
21 species Perkins found in the 1890s. The most dramatic change in the O'ahu
carabid fauna over the past 100 yr is the extinction of the most common O'ahu
species of the 1890s, Colpocaccus tantalus (Blackburn). This species was broadly
distributed across the island, possessed a well-developed flight apparatus, and
accounted for 39% of the specimens captured in the 1890s. It has not been collected
since 1940 in spite of intensive collecting during the 1950s and 1990s. The elevational
preference of C. tantalus was lower than that for the aggregate balance of the O'ahu
carabid fauna, suggesting an altitudinally associated factor in the extinction: most
likely ants such as Pheidole megacephala (F.). The loss of a previously dominant
generalist species is viewed as an ecological catastrophe, substantially different in
quality from extinction of geographically restricted island specialists.
Appears in Collections: Pacific Science Volume 51, Number 4, 1997

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