Though all are Charadriiformes & share a common structural/behavioural theme, waders are a fairly diverse group of birds.
Scotland holds a wide range of species -many of which breed here. Some are amongst our rarest breeding birds whilst others are only passage migrants & winter visitors.
In addition to Western Palearctic waders a number of nearctic (& even eastern palearctic) species are also sometimes encountered. Pectoral Sandpipers are regular, Spotted Sandpipers have tried to breed & others such as Lesser Yellowlegs & American Golden Plover are more or less annual.