Ecological Studies on the Butterfly Maniola jurtina in Britain. II. Population Dynamics: The Present Position

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Abstract
Capture-recapture experiments were performed to investigate the population dynamics of M. jurtina. The main study site was at Hightown near Liverpool [Great Britain, UK] with additional sites in this area and in central-eastern Scotland. Adult survival at Hightown was lowest in the hot and dry summer of 1976. The estimates of expectation of life for males and females in all experiments varied between 5 and 12 days. The mean number of eggs laid by a female was estimated from fertility and survivorship data as 66. This is 0.37 of the mean total egg production in the laboratory. Analysis of the capture rate of newly emerged butterflies at Hightown suggested that the emergence of each sex occurred in > 1 peak in 1977 and 1978. Total emergence at Hightown estimated using 2 capture-recapture models declined from 1380-1850 insects ha-1 in 1976 to 235-250 insects ha-1 in 1977. This change was probably due to exceptionally high mortality of hatching larvae in the dry late summer of 1976. A generally lower population density was found in Scotland than in England. The results are compared with those of other authors. Factors which introduce error into the estimates are examined.