Are mist nets a menace for threatened insects? A first attempt to gather quantitative data

We attempt to identify the threat to flying beetles imposed by mist nets deployed for bird studies in an area of Mediterranean mosaic of evergreen scrub and deciduous forest in Italy. The present paper is the first attempt to identify the non-target species which die in these artificial traps. A large number of large scarab beetles was entangled in mist nets during a complete ringing session. The seasonal trend of beetle populations and their daily flight activity were also recorded. The results lead us to suggest that the populations of some threatened dung beetles can be impoverished at local level and represent a bycatch of mist net techniques, especially in early spring and at sunrise, when their swarming and reproductive activity is high. When summed with other factors affecting these beetles, such as habitat loss and fragmentation, this tool may represent a threat for vulnerable insect populations. Trapping effects may also represent a depletion of food resource for some insectivorous birds. For these reasons we recommend cooperative research between ornithologists and entomologists to fully study the bycatch effects of mist netting on flying insects and their effects on food availability for insectivorous birds.