Roosting, foraging, preening, bathing and dust-bathing or anting are communal activities. Passive anting occurs when a bird rubs its wings and tail on an anthill. More than 200 species of song birds wipe ants, a behaviour known as anting. In total there are 24 ant species birds use for anting. Dusting with soil from ant-hills has been considered by some as equivalent to anting. The train was intercepted at Anting (several miles from Shanghai). Birds may also use 'substitutes' in active anting. These birds often focus much of the anting on their wings and tails. Anting to get rid of ectoparasites is another hypothesis for anting in songbirds. Some birds participate in this anting behaviour but with other organisms and even objects. This type of anting can last anywhere from just several minutes to half an hour. Birds indulge in a peculiar behaviour called anting that, as yet, is not fully understood. This type of anting is less common and is mostly seen in robins and ravens. The species has also been observed anting. Some studies have also suggested that anting serves as a sensual or sexual function.