The Worm, the Holms and the Mumbles - Gower - page 175

FIG 96. 'Holmes Island', as depicted on the Tithe Map of 1848, showing the Iron Age earthwork that bisects the site.
(West Glamorgan Archive Service)
On the exposed rock surface around deep rock pools in the lower portion of the cliff there is an algal
zone consisting of various brown seaweeds, including a variety of wracks Fucus spp., knotted wrack
Ascopyllum nodosum and channelled wrack. Higher up in the spray zone are two lichens, leafy yellow
scales and Lecanora atra . Above the lichens, where soil forms in the clefts in the rock, the dominant
plants are thrift, rock samphire Crithmum maritimum and common scurvygrass, the presence of scurvy-
grass being affected by gulls, whose droppings and food remains add nitrogenous material to the soil.
Twenty pairs of herring gulls were recorded nesting on the island during a census in 1959, although only
a few pairs remain today. The rock crevices also contain sea campion and golden samphire together with
orpine Sedum telephium and rock sea-spurrey.
Around sixty plant species have been recorded from the island as a whole. Windblown sand from
LlangennithBurrowstotheeastcoversthelandwardslopesandisdominatedbymarramgrass.Incontrast
the cliff tops to the west support Yorkshire-fog, curled dock, lady's bedstraw Galium verum , common
bird's-foot-trefoil, spear thistle Cirsium vulgare and carline thistle Carlina vulgaris . In spring the north-
west of the island is covered in spring squill. The ditches of the earthwork contain a rich community of
plants including cock's-foot and germander speedwell Veronica chamaedrys , together with salad burnet,
common centaury Centaurium erythraea and cleavers Galium aparine . The well-used paths across the is-
landaremarkedbyseastorksbill,buck'shornplantain,sheep'ssorrelandtheveryvariableautumnhawk-
bit Leontodon autumnalis .
Thefewinvertebraterecordsincludegreentigerbeetle Cicindela campestris ,anactive,ground-dwell-
ing beetle of sandy places (Fig. 98) and white-tailed bumblebee, one of the commonest and most wide-
spread bumblebees. A monarch butterfly Danaus plexippus was seen in October 1995 and marbled white
and clouded yellow Colias croceus have also been recorded. Mammals are restricted to rabbit and short-
tailed vole Microtus agrestis , while birds recorded on the island, in addition to herring gulls, include sky-
lark Alauda arvensis , meadow pipit, jackdaw Corvus monedula , wheatear Oenanthe oenanthe and stock
dove Columba oenas .