Wildlife near Cosham

Birds, butterflies and chalk grassland habitats

The Cosham area is surprisingly rich in wildlife, thanks to the chalk grassland of Portsdown Hill, the coastal habitats of Portsmouth and Langstone Harbours, and the proximity of Farlington Marshes nature reserve.

Portsdown Hill's south-facing chalk grassland is one of the most important wildlife habitats in the Portsmouth area. The thin, alkaline soils support a specialised plant community that in turn supports a rich insect fauna. Chalkhill blue butterflies can be seen on the slopes in July and August, feeding on horseshoe vetch. Common blue, marbled white, small heath, meadow brown and skipper butterflies are also present. Wildflowers including wild thyme, kidney vetch, common spotted orchid, pyramidal orchid, cowslips and harebells colour the grassland from spring through summer.

Birds of prey are regularly seen over the hill, including kestrels hovering above the slopes, buzzards circling on thermals and, occasionally, peregrine falcons hunting over the ridge. Skylarks sing above the chalk grassland in spring and summer, and yellowhammers can be heard in the hedgerows on the northern side of the hill.

Farlington Marshes, to the east of Cosham, is a nationally important site for wintering and migrating birds. Brent geese arrive from Arctic Russia in October and feed on the mudflats and grazing marsh through to March. Wading birds including dunlin, redshank, curlew, oystercatcher and grey plover are present throughout the year, with numbers peaking in winter. In spring and autumn, migrating warblers, wheatears and other passerines pass through. Avocets breed at the reserve in some years.

The harbour mudflats, visible from the lower parts of Cosham and from the hill, support large populations of invertebrates that in turn feed the birds. The combination of chalk grassland, coastal wetland and harbour mudflats within a few miles of each other makes the Cosham area one of the best for wildlife observation in an urban setting.