A Ten-year Study to Monitor Populations of the Regal Fritillary, Speyeria Idalia, (Lepidoptera: Nymphalidae) in Wisconsin, U.S.A.

Document Type

Peer-Review Article


We present analyses of our transect survey data from consecutive years at 11 sites in Wisconsin during 1990-99 for the regal fritillary (Speyeria idalia), which is listed under state law as endangered, and the closely related but more widespread and abundant Aphrodite fritillary (Speyeria aphrodite). Within year, the date of peak survey numbers at each site ranged over a period of several weeks or more for each fritillary. Within year and site, the Aphrodite fritillary peak was typically a few days to a week prior to the regal fritillary's peak. Both fritillaries exhibited large annual fluctuations which were significantly correlated between the two species. Relatively larger regal fritillary densities were consistently associated with active non-fire managements (grazing cutting), relatively lower densities with burning, and widely varying den- with non-management. More unfavorable outcomes from burning oc­curred at sites where the entire habitat patch was fire-managed. Similar but less sensitive was the Aphrodite fritillary, which did not respond as strongly or clearly to burning, although higher densities were associated with unintensive non-fire managements. In Wisconsin and adjoining areas, the Aphrodite fritillary appears useful as a substitute in tests of techniques for habitat restoration or reintroduction for the regal fritillary. Since the Aphrodite fritillary may be less sensitive than the regal fritillary, success with the former certainly doesn't prove suitability for the latter. But unless and until the method works for the Aphrodite fritillary, it is almost certainly unsuitable for the regal fritillary.

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