Tachybaptus ruficollis – GWYACH FACH – Breeding resident and winter visitor
Little Grebe counts for the Wetland Bird Survey (WeBS) in Pembrokeshire. Note that data prior to 1995-96 are incomplete.
The distribution and the breeding population of little grebe in Pembrokeshire have increased dramatically in the past twenty years, but this has not been reflected in the wintering population on the estuary system.
The decline on the estuary is largely accounted for by the decline in the wintering population on Westfield Pill, which was considered a stronghold for the species after being dammed in the late 1980s. It is possible that, as the Pill has matured and stabilised as a slightly saline lagoon, conditions may not be quite as suitable for little grebe.
From the mid-1990s, numbers wintering on WeBS sites in the county appeared reasonably stable at around 100 birds, but the total on the estuary has declined. This was almost certainly linked to the milder winters since then. If smaller ponds are not freezing over, then birds are not forced to move to the estuary to feed. In 2013-14 there has been a further decline to around 65 birds. It is likely that there are more birds in the county, particularly on the more recently-created ponds which are not counted for WeBS.
During the cold winter of 2010-11, numbers in the county reached the highest level recorded on WeBS sites. This could be the result of local movements away from small water bodies that are not regularly monitored, or from other parts of the country. Across the UK, numbers declined that year, suggesting that birds either moved further south, and/or succumbed to the bad weather.
The slow but steady increase in Little Grebes across Britain, that appeared to begin in the early 1990s soon after the species was first routinely monitored, has continued in recent years; a period during which numbers have risen concurrently in The Netherlands. This increase has led to large changes in the levels of international and national importance for this species, and the Cleddau Estuary now falls well below the national threshold.
Why the wintering little grebe population in Pembrokeshire as a whole has not increased in line with that in the rest of the UK is unknown.
Annie Haycock (BBS & WeBS local organiser)