Date of Award

4-1-1998

Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

Biology

First Advisor

Dr. Thomas Bragg

Abstract

I investigated the relationship between nectar source diversity and regal fritillary (Speyeria idalia Drury) butterfly populations at ten native tallgrass prairie sites in eastern Nebraska. Walking-transect surveys were used to establish regal fritillary population-density indices in 1996 and 1997. Flowering-plant surveys were also conducted, coincident with the butterfly surveys, and were used to develop blossom-density, and abundance indices. Spearman rank correlation was used to examine relationships between regal fritillary density indices and plant survey variables. Two significant, positive correlations were identified between (1) 1996 population-density indices and 1996 blossom-diversity indices for known nectaring sources of the regal fritillary (n = 10, r = 0.903, P < 0.000) and between (2) 1997 population-density indices and 1996 blossom-diversity indices for known nectaring sources of the regal fritillary (n = 10, r = 0.770, P = 0.009). No significant relationship was found between 1997 population-density indices and 1996 blossom-diversity indices for known nectaring sources of regal fritillary (n = 10, r = 0.726, P = 0.018), and in 1997 (n = 10, r = 0.646, P = 0.044). I used intraclass correlation to see if there was greater variation in population-density indices between sites or years. The calculated intraclass correlation coefficient of 0.648 (P = 0.012) suggests that differences in population-density indices are more attributed to differences between years. Approximately half of all nectar visits were to Asclepias spp. This study showed that positive relationships do exists between regal fritillary densities and nectar source diversity, although this relationship may vary from year to year. Further, large site size appears to be beneficial to regal fritillary populations.

Comments

A Thesis Presented to the Department of Biology and the Faculty of the Graduate College University of Nebraska In Partial Fulfillment of the Requirements for the Degree Master of Arts University of Nebraska at Omaha. Copyright 1998 Jeffrey J. Huebschman.

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