Kingfishers often drift towards the coast in winter, often spending the season on the estuaries before moving back upstream to breeding areas. This movement was more marked when winters were colder and ponds more likely to be frozen over, forcing birds to move in search of food.
Cumulative number of records per week in Pembrokeshire since 2000, taken from BirdTrack. Birds are more widespread during the autumn dispersal period, and also in winter when there are fewer leaves on the trees.
Greylag geese were rarely recorded in Pembrokeshire prior to 2000 but since 2011-12 they have been seen more regularly. Counts of 100+ birds are now not unusual on the upper parts of the Cleddau Estuary. They are thought to be descendants of a population introduced by wildfowlers to the Kidwelly area in Carmarthenshire.
The main flock of greylags spend their time commuting between the upper parts of the Cleddau Estuary, especially the Langwm-Hook-Eastern Cleddau area, and the surrounding fields where they feed. However, small numbers may be encountered on bodies of water of any size elsewhere.
Herons disperse widely in the autumn, and small parties of juveniles have been seen flying due west out to sea. Thus, the herons seen on the estuary system in winter may or may not be from local colonies. On WeBS sites, the total numbers drop from around 30-40 in autumn to around twenty in mid-winter.
The overall population trend seems to be for an increase in all parts of the UK for breeding herons, and a general increase in wintering herons except in Wales where there has been a slow decline since 2001-02. The results of WeBS in Pembrokeshire is consistent with this.
Typically, peak numbers of greenshank in Britain are recorded in August as birds move from their northern European (including Scottish) breeding sites to winter in south-west Europe and north and west Africa. The pattern seen in Pembrokeshire largely follows this regime, with generally higher numbers (usually 30-40, but over 70 in 1995 and 2005) seen in the July-September period compared with the November-February mid-winter period. (Note there were no migration period counts in the early 1990s).
Most of the birds have moved on by the end of October, but those remaining tend to stay put for the rest of the winter. This is generally around 20-30 birds although 58 were present in January 2019.
The Cleddau Estuary is of National Importance for its greenshank population, and is the second-most important Welsh site (the Burry Inlet has higher counts) for the species.
The June records are likely to be of failed breeders, returning south early. The main migration takes place from July to October. Birds arriving from October onwards are likely to stay the winter, moving on in March, back to (probably) their Scottish breeding grounds. Spring migration of birds that have wintered further south and will be breeding further north takes place in April-May.
Annie Haycock (BBS & WeBS local organiser)
HODGES J E. (2010-2020) Daugleddau Estuary and Milford Haven Waterway: annual surveillance of summer shelduck populations. Reports to the Milford Haven Waterway Environmental Surveillance Group.
Mareca strepera – HWYADEN LWYD – Winter visitor, has bred
The gadwall has been increasing in numbers and distribution in winter since the 1960s. However, there was a lack of birds in Pembrokeshire (and in Wales) during the early-mid 1990s, and again in 2007-08. Recent winters have again shown a decline in numbers. The reason for this is not clear, although as this is primarily a freshwater species, it is possible that its occurrence in this part of the country may depend on whether lakes further north are frozen over or otherwise unaccessible.
Gadwall are kleptoparasitic on species such as coot and swans that feed on submerged vegetation – bringing it to the surface where the gadwalls can reach it. It is therefore possible that the recent decline in gadwall here is related to the decline in coot since 2010.
Adult Buzzards in Britain are highly sedentary and territorial, rarely moving out of their breeding territory once established. In contrast, some continental populations migrate well south for the winter. Thus the distribution of buzzards in Pembrokeshire in winter is pretty much the same as in the breeding season.
Young Buzzards, dispersing from natal sites, tend to wander the countryside in search of food and their own territories. They often gather in autumn and winter wherever invertebrate and carrion food is plentiful. Groups of 20-30 birds in stubble or ploughed fields are not uncommon.
Impressive movements of these nomadic immature birds are occasionally noted, for example, 58 flying west over Treginnis, near St Davids, on 5 October 2005.
Ringing studies in the BTO Migration Atlas suggest that most first winter birds typically stay within 20km of their natal sites, but some do go further in their initial explorations. An extreme example is a female nestling ringed near Lampeter (Ceredigion) in June 1977, and found in Northumberland in May 1990, while a bird tagged in Dumfries, Scotland, in 1994 turned up in Caernarfonshire a year later. As most ringing recoveries are of dead birds, it may be worth checking any road casualties and other corpses for rings to further this knowledge locally.
The BTO Atlas 2007-11 shows no change in winter distribution across Pembrokeshire (or most of Wales) and their relative abundance here is similar to that across the rest of Wales (though it is lower in the mountains)and south-west England.
Annie Haycock (BBS & WeBS local organiser)
BALMER D, GILLINGS S, CAFFREY B, SWANN B, DOWNIE I, FULLER R. 2014. Bird Atlas 2007-11: The Breeding and Wintering Birds of Britain and Ireland. HarperCollins. UK