Population ecology of the endangered butterfliesMaculinea teleiusandM. nausithousand the implications for conservation

Abstract

Butterflies of the genus Maculinea are highly endangered in Europe. The cuckoo species M. rebeli has been thoroughly investigated through both empirical and modelling studies, but less is known about the population ecology of predatory Maculinea. We present the findings of a 2‐year research study on sympatric populations of two endangered butterflies: Maculinea teleius and M. nausithous in the Kraków region, southern Poland. The study comprised mark–release–recapture sampling and laboratory rearing of butterflies from larvae collected in the field. For both species the sex ratio was slightly, but consistently, female‐biased and there was little year‐to‐year change in the seasonal population sizes. Daily numbers showed greater variation between the 2 years of the study due to the differences in daily survival rate. The average life span of laboratory‐raised butterflies kept in ideal conditions was more than 6 days, compared to only 2–3 days in the field. The recruitment of both males and females consistently followed a bimodal pattern. A small proportion of individuals (maximum 25%) changed sites, in spite of relatively short distances of ca. 100 m separating them. The results indicate that populations of both species are typically stable within their sites, possibly due to larval polymorphism, but there is little inter‐site mobility and thus landscape corridors seem necessary to enhance metapopulation viability. A further problem to be considered in the conservation of Maculinea butterflies is the fact that their very short life span in relation to flight‐period length reduces the effective population size.

Resource use in two contrasting habitat types raises different challenges for the conservation of the dryad butterfly Minois dryas

“…Mowing should be conducted either in the spring, at the end of May, or in the fall, in mid-September at the earliest (Johst et al 2006;Grill et al 2008;Wynhoff et al 2011). In wet meadows, however, mowing should only take place in the late autumn, because they are also an important habitat for endangered Maculinea (= Phenagris) butterflies (Nowicki et al 2005(Nowicki et al , 2007. Mowing is necessary not only to sustain the nectar and host plants favorable to the butterflies, but also to prevent the invasion of some notorious alien plants, such as goldenrods Solidago sp.…”

Adult longevity and its relationship with conservation status in European butterflies

“…physiological longevity. This is because when butterlies are raised in enclosures or laboratories, their recorded longevity is known to overestimate the life span actually achieved in nature (Karlsson and Wiklund 2005;Nowicki et al 2005b). We likewise excluded mark-recapture estimates of butterly residence time assessed in clearly open populations, which are subject to substantial emigration and thus considerably underestimate butterly longevity (Nowicki et al 2005a).…”

“…It has recently been pointed out that the extinction risk of butterly populations is likely to depend not only upon classic spatial fragmentation of their habitats, but also upon their fragmentation over time (Nowicki et al 2005b). The latter derives from the fact that the individual life span of the adult butterlies is usually much shorter than is the length of adult occurrence season dubbed as the light period.…”

“…earlier emergence of males in the season as compared with females, which is typical for butterlies (Wiklund and Fagerström 1977). The extent of and a temporal fragmentation (sensu Nowicki et al 2005b) depends upon adult life span and light period length and so it is highly variable among butterlies. Surprisingly, the efects of temporal fragmentation on butterly species extinction risk have not been investigated so far.…”

“…Butterlies that have short life spans and long light season length will have fewer opportunities for males and females representing diferent daily cohorts to meet together (Nowicki et al 2005b). Consequently, we hypothesised that a higher level of threat should be associated with: (a) shorter adult life span; (b) longer light period length; and (c) higher values of the temporal fragmentation index.…”