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Pitfall trapping in the National Park Thy, north-western Jutland, Denmark, in 2011 and 2013 revealed 3654 specimens of the harvestman Nelima gothica. In most European countries, including Denmark, this species has been considered rare and little information is available on its biology. The species was found predominantly in the yellow dune habitat close to the North Sea coast. Here it could be either very abundant or completely absent at localities only a few kilometres apart. It also occurred in lower numbers in the grey dunes and the dune heathland, and was rare in managed grassland; it disappeared from habitats further inland. In the yellow dunes high numbers were recorded especially in rather dense Ammophila arenaria vegetation not disturbed by sand shifting. The phenology follows the typical pattern of North-European Phalangiidae and Leiobuninae: an annual life-cycle with juveniles developing through late spring and summer months, reproduction in autumn and hibernation in the egg stage. The findings suggest that N. gothica may be found all along the coastal dunes of western Denmark and possibly the Wadden Sea area, though it may only locally reach high abundances. Earlier records also included the coasts of eastern Denmark.
Spiders leave draglines, faeces and other secretions behind when traveling through their microhabitat. The presence of these secretions may unintentionally inform other animals, prey as well as predators, about a recent and possible current predation risk or food availability. For a wolf spider, other spiders including smaller conspecifics, form a substantial part of their prey, and larger wolf spiders, again including conspecifics, are potential predators. We tested two hypotheses: that large wolf spiders may locate patches of potential spider prey through the presence of silk threads and/or other secretions; and that prey spiders may use secretions from large wolf spiders to avoid patches with high predation risk. We used large (subadult or adult) Pardosa saltans to provide predator cues and mixed dwarf spiders or small (juvenile) P. saltans to provide prey cues. Subadult wolf spiders were significantly attracted to litter contaminated by dwarf spiders or small conspecifics after 6 hours but no longer after 24 hours. In contrast, neither dwarf spiders nor small P. saltans showed significant avoidance of substrate contaminated by adult P. saltans. However, small P. saltans showed different activity patterns on the two substrates. The results indicate that wolf spiders are able to increase the efficiency of foraging by searching preferentially in patches with the presence of intraguild prey. The lack of a clear patch selection response of the prey in spite of a modified activity pattern may possibly be associated with the vertical stratification of the beech litter habitat: the reduced volume of spaces in the deeper layers could make downward rather than horizontal movement a fast and safe tactic against a large predator that cannot enter these spaces.
