Focus on Argynnis niobe in the dunes of North HollandMichiel
Wallis de Vries (De Vlinderstichting) The Niobe Fritillary
(Argynnis niobe) has shown an alarming decline since 1997; it is
now an endangered species in the Netherlands. As the coastal
dunes constitute the species’ stronghold, we carried out a
survey of the species distribution in the dunes of Kennemerland
with the help of volunteers. The Niobe Fritillary was found in
42 out of 107 km squares investigated. Distribution has shrunk
by more than 50% in the last two decades, and the survey
suggests that the decline is continuing. More research is needed
on host plant use in these calcareous dunes. It is clear,
however, that the main cause of decline lies in the vast
encroachment of tall grasses and scrub, especially Black Cherry
(Prunus serotina), facilitated by low rabbit numbers. Extreme
drought, such as in 2003, presents an additional threat. In
several areas, restoration measures are being taken. Nectar and
host plants will benefit from scrub cleara