Grey Heron – Winter 2021

Ardea cinerea – CREYR GLAS – Breeding resident

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.

Distribution

This map was produced by the West Wales Biodiversity Information Centre using data collected between November and February for the BTO Atlas 2007-11, with additional data collected in 2011-12 winter to fill gaps in coverage.

The main sites are:

While herons can be found at almost any wetland (open water or marshy grassland) sites in winter, they are probably most easily observed on the estuaries and at Bosherston Lily Ponds.


Wetland Bird Survey

Herons were not regularly counted for WeBS until 1993.

Data for June and July are collected by Jane Hodges during the annual surveillance of summer shelduck populations on the Cleddau Estuary complex. There are no counts in August. The September to March data is collected from sites across Pembrokeshire (including the Teifi Estuary) for the BTO Wetland Bird Survey.

Maximum counts are usually in the autumn, coinciding with dispersal from nest sites. This graph will be updated as more counts come in.


Pattern of occurrence

Cumulative number of records per week in Pembrokeshire since 2000, taken from BirdTrack. As herons are considered to be a resident species, they can be seen at any time of year. However, sightings peak in September-October, coinciding with autumn dispersal.

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.

More about the Grey Heron in Pembrokeshire