The Wetland Bird Survey (WeBS) Special Surveys

Update on Little Egrets in the UK

A few years ago, the BTO looked in detail at the explosion in non-breeding numbers of Little Egrets occurring in the UK. This research, involving counts of nocturnal communal roosts by many volunteers, along with data from other sources, was published in full in the journal British Birds (vol. 95, pp 62-80). In summary, within the course of roughly a decade, the Little Egret had gone from being a rare spring vagrant to being a locally numerous species, especially at southern estuaries from south Wales around to the Thames. By the end of the 1990s, Little Egrets were resident year round in the UK, although numbers peaked in the late summer and early autumn, following post-breeding dispersal from French breeding colonies. By September 1999, an estimated 1,650 Little Egrets were present in the UK. In addition, substantial numbers were now remaining throughout the winter, with about 800-900 birds in January 2000. Meanwhile, the northwards expansion of breeding colonies in France finally resulted in the first documented UK breeding pair in 1996 at Brownsea Island in Dorset.

In 2003, the Special Protection Area Scientific Working Group (SPA SWG) asked the BTO for an update on the status of the Little Egret in the UK, to ensure that satisfactory provision was being made for this species within the conservation framework afforded by the “Birds Directive” (EU Directive on the Conservation of Wild Birds (79/409/EEC)). Data were reviewed for both non-breeding and breeding Little Egrets for the period up to the end of 2001, mostly WeBS Core Counts, county bird reports and information contributed by individual observers.

Non-breeding Little Egrets

It was found that the numbers of non-breeding Little Egrets have continued to increase, with an autumn 2001 peak total of the order of 2700 birds. Moreover, the data already available suggest that continued increases have occurred in 2002 and 2003, especially notable around the periphery of the range (e.g. in north Wales and in Norfolk).

Estimated peak autumn numbers of Little Egrets in GB: 1989 to 2001:

Over the five years 1997 to 2001, a total of 12 sites supported mean peak numbers in excess of 50 birds, with a further 12 sites supporting over 50 Little Egrets on at least one occasion up to 2001 (and at least three more sites having done so since). The majority of these sites are already designated as SPAs (although mostly not specifically for Little Egrets) and most of the remainder are designated as SSSIs.

Mean and peak numbers of Little Egrets at key GB sites. Only those counts (mean or peak) in excess of 50 birds are shown. Note that most data for 2002 and 2003 were not yet available.

Breeding Little Egrets

As a new breeding species, a degree of confidentiality should be maintained with regard to Little Egret nesting sites. However, much information has been generously donated by individual observers, both directly and through various recording schemes and confirms that the population has increased rapidly since colonisation. The number of confirmed colonies rose from one in 1996 to 16 in 2001, whilst the overall number of pairs has risen from one in 1996 to at least 116 in 2001.

Confirmed numbers of Little Egret breeding colonies and breeding pairs in GB: 1996 to 2001.

Interestingly, although the original site of colonisation at Brownsea Island was, in 2001, the most important, with 45 pairs, numbers appear to have levelled out here. At least five other colonies have held in excess of 10 pairs, including Northward Hill in Kent and Fort Elson in Hampshire, whilst the breeding range has extended as far north as Cheshire.

Implications for the SPA suite

To date, the SPA suite for non-breeding Little Egrets consists of three SPAs: Chichester and Langstone Harbours; Poole Harbour; and the Tamar Estuaries Complex. No SPAs are currently designated for breeding Little Egrets, although the species is protected all year round on the SPAs selected for non-breeding birds. The SPA SWG considered the updated information on breeding and non-breeding egrets, as summarised above. The group decided that, with the continued high rate of population growth and expansion, identifying the most suitable areas to protect for Little Egrets would be extremely difficult. A future review of the species will be carried out in around five years time. Many of the important sites for Little Egrets are already within (or adjacent to) existing SPAs and SSSIs which, although designated on the basis of their value to other species, already impart a degree of protection to Little Egrets.

Future

It is intended that the Little Egret population will be kept under review for the time being. Observers are encouraged to continue to submit their observations to county bird recorders, as well as continuing to support such schemes as WeBS, the BTO Heronries Census and the Rare Breeding Birds Panel. Coordinated counts of nocturnal roosts are particularly valuable, as is information on regular flight lines between feeding and roosting areas. If you have any observations of interest concerning Little Egrets, or have any questions about the species, please contact Andy Musgrove.

Thank you to the many observers who have contributed data, by whatever route, to enable us to keep an eye on this fascinating colonisation. Particular thanks go to John Marchant and Malcolm Ogilvie for providing information from the Heronries Census and the Rare Breeding Birds Panel, respectively, and to JNCC for funding this piece of work.