Web placement in sympatric linyphiid spiders (Arachnida, Araneae): Individual foraging decisions reveal inter-specific competition

The distribution of two sympatric web spiders, Frontinellina frutetorum (C. L. Koch) and Neriene radiata (Walckenaer) (Araneae: Linyphiidae) was studied on an area of forest regrowth in eastern Austria. Both species utilised significantly different heights on young conifer trees to construct their webs. F. frutetorum selected higher vegetation layers, whereas N. radiate constructed its webs closer to the ground. This distribution may either be evidence of competition for web space or it may reflect specific distribution patterns unrelated to spider density. An experiment showed that when spiders of either species were released onto vacant trees they selected similar vegetation heights for web construction. On trees already occupied by a heterospecific individual however, F. frutetorum placed its webs significantly higher and N. radiate significantly lower compared to web placement on vacant trees suggesting that F. frutetorum and N. radiata compete for web space.