Observations of overwintering nymphalid butterflies in underground shelters in SW and W Bohemia (Czech Republic) (Lepidoptera: Nymphalidae: Nymphalini)

Abstract

The results from ten years of surveys and observations of overwintering nymphalid butterflies in various types of underground shelters in SW-W Bohemia, Czech Republic are presented. During these surveys, three species of nymphalid butterflies were encountered; the most commonly observed species was Inachis io (Linneaus), followed by Aglais urticae (Linneaus). Nymphalis polychloros (Linneaus) was encountered in the ten year period only twice. The typical overwintering sites for Inachis io were the ceilings of unheated cellars of buildings, and the entrances of mining tunnels/galleries or natural caves. A special category of underground shelters in the study area was abandoned World War 2 military bunkers. Inachis io frequently hibernates in aggregations of several individuals and Aglais urticae does so less often. The lowest ambient air temperature measured in these underground shelters was –1.1° C. It is believed that these observations represent the longest continuous record of hibernating nymphalid butterflies in underground (or other) shelters in Czech Republic.