Herring Gulls establish colonies, with 10 to 30 nests relatively close together, usually on vegetated dune slopes, tops and ridges.  Great Black-backed Gulls also nest on the ground, but although a number of pairs nest in the the same general area, Black-back `colonies' are less well-defined spatially.  Occasionally a few Black-backed Gulls nest near or amongst the Herring Gulls.  Both species build nests of primarily beach grass with other materials (e.g. seaweed, horse hair, plastic scraps) occasionally added.  However, nest `design and housekeeping' differs somewhat - Herring Gull nests tend to be neat and compact; Black-back nests are usually larger, often higher, and a little scraggly.  

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