1. Spiders frequently disperse and colonise habitats through ballooning, a passive aerial dispersal process. Ballooning is pre-eminent in open habitat spider communities and its propensity can be modulated by habitat conditions and availability, and by life-history traits such as body size, degree of specialisation, and feeding behaviour.
2. Using spiders from the canopy and understorey of a north-temperate hardwood forest as a model system, our main objectives were to detect if foliage spiders of a mature forest disperse through ballooning, and identify life-history traits that influence ballooning propensity.
3. Our results demonstrate that foliage spiders living in the canopy and understorey of a mature forest do balloon, and in some cases have very high ballooning propensities similarly to open field spiders. Species level models showed that small body size had a strong positive effect on ballooning for juveniles of species with large-bodied adults, while individuals of small-bodied species initiated ballooning regardless of size, habitat or development stage. A generalised linear mixed model indicated that small size web-building spiders from the Retro Tibial Apophysis (RTA) and Orbicularia clades had the highest propensity for foliage spiders of this north-temperate hardwood forest.
4. In conclusion, we provide the first demonstration that forest spiders can have high ballooning propensities and that ballooning propensity is negatively affected by body size and positively affected by the prominent use of silk to catch prey. However, spiders originating from the canopy and understorey of a north-temperate hardwood forest did not differ in their ballooning propensities.