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The non-breeding status of the Little Egret in Britain A. J. Musgrove Mike Langman ABSTRACT The Little Egret Egretta garzetta, formerly a rare vagrant in Britain, has undergone a remarkable range expansion following a large influx in 1989, and at the end of 1990 it was removed from the list of species considered by the British Birds Rarities Committee. Single-site counts in excess of 100 were made in autumn 1995, with the first site count of more than 200 in autumn 1998.The Little Egret was confirmed as a new British breeding bird in 1996, and by 1999 at least 30 breeding pairs were recorded at a total of nine sites. This paper documents the change in the species’ non-breeding status in Britain. Using data from the Wetland Bird Survey, with supplementary counts from roost surveys and county bird reports, it is estimated that more than 1,650 Little Egrets were present in September 1999, over 40% of these between Swanage Bay, Dorset, and Pagham Harbour,West Sussex. A further increase in the British population is expected.The increase in Britain has been mirrored in adjacent areas of northwest Europe. 62 © British Birds 95 • February 2002 • 62-80 Non-breeding status of Little Egret ormerly a rare vagrant in Britain, the Palearctic, very few were reported in the nine- Little Egret Egretta garzetta has undergone teenth century and in the first half of the twen- Fa remarkable range expansion in recent tieth century. In fact, certain well-watched years. Following a large influx into Britain in counties did not record the species until com- 1989, and continued high numbers during paratively recently, with first county records for 1990, the British Birds Rarities Committee took Sussex in 1952 (James 1996), Norfolk in 1952 the decision to remove the Little Egret from the (Taylor et al. 1999), Kent in 1957 (Taylor et al. list of species which it considers. Records of this 1981), Hampshire in 1957 (Clark & Eyre 1993) species occurring after the end of 1990 are no and Somerset in 1965 (Palmer & Ballance longer assessed by the BBRC, but are dealt with 1968). by the committees of individual local ornitho- Owing to its rarity, records of Little Egrets logical societies. were assessed by the British Birds Rarities Com- The Little Egret continued to be recorded in mittee. Fig. 1 shows the number of accepted increasing numbers in Britain throughout the records in each year from 1958 to 1988, and 1990s. By the autumn of 1995, counts in excess demonstrates a clear influx in 1970 and a more of 100 had been registered at individual sites, general increase through the 1980s. During that and three years later, in autumn 1998, the first period, 403 individuals were seen in Britain single-site count of more than 200 was made. (although some duplication cannot be ruled Moreover, breeding was confirmed in 1996, the out), which represents a huge increase com- first British breeding record ever for the species pared with the early part of the twentieth (Lock & Cook 1998), and by the summer of century and an average of 13 per year. Pre- 1999 it was nesting at nine different sites, with dictably, there was a strong southerly bias, with an estimated total of at least 30 pairs (Ogilvie et about half of all records coming from only six al. 2001). counties: Devon, Cornwall, Dorset, Kent, Sussex The increase in Britain has been mirrored in and Hampshire (listed in descending order of Ireland (Smiddy & O’Sullivan 1998), in the recorded numbers). Fig. 2(i) depicts the Channel Islands (Atkinson & Wells in prep.; monthly distribution during 1958-88, which Jersey Bird Report) and on the near Continent reveals a peak in May similar to that observed (van den Berg & Bosman 1999; Bijlsma et al. for many other Mediterranean species, such as 2001). Night Heron Nycticorax nycticorax and Squacco This paper documents the change in the Heron Ardeola ralloides. Although small non-breeding status of the Little Egret in numbers occurred in autumn, Little Egrets were Britain in the period from 1958 to the end of notably scarce in Britain in winter at that time. the 1990s. Using data from the Wetland Bird Survey, with supplementary counts from roost The first influx: 1989-92 surveys and county bird reports, it is estimated The events of 1989 have been described previ- that more than 1,650 Little Egrets were present ously (Combridge & Parr 1992). In summary, a in Britain in September 1999, over 40% of these marked arrival of Little Egrets occurred in May, between Swanage Bay, Dorset, and Pagham followed by, as usual, few in June, but in mid Harbour, West Sussex. 40 Historical status Unlike a number of other wetland 30 species, such as Great Bittern Botaurus stellaris, Eurasian Spoon- 20 bill Platalea leucorodia and Common Crane Grus grus, the Little Egret was not a regular component 10 of the British avifauna in historical times. The first documented record 0 is of one shot in East Yorkshire in 1958 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1826 (Naylor 1996) but, despite the species’ widespread occurrence in Fig. 1. Annual numbers of Little Egrets Egretta garzetta the southern half of the Western recorded in Britain during 1958-88. British Birds 95 • February 2002 • 62-80 63 Non-breeding status of Little Egret in Britain 100 the south coast between Cornwall and West Sussex. The influx was evi- 80 dently the result of post-breeding dispersal, a process which had led to 60 a regular movement of Little Egrets to the north coast of Brittany since 40 about 1980 and which preceded an % of peak month increase in numbers and breeding 20 range in northwest France. Voisin 0 (1991) considered that the spread of i Little Egrets northwards along the Oct Jan Feb Apr Dec Sep Mar Nov Aug July May June west coast of France was due to species-specific protection mea- 100 sures, and to a lack of cold winters. 80 The 1989 influx was not a tem- porary phenomenon. During 1990, 60 BBRC amassed a further 113 British records and, at the end of that year, 40 removed Little Egret from the list of % of peak month ‘official’ rarities. The pattern of 20 occurrence was similar to that in 1989, with a large influx in May, 0 very few in June and then an Oct Jan Feb ii Apr Dec Sep Mar Nov Aug July May June increase in the late summer (fig. 2(ii)). The number of August 100 records in 1990 was, however, only about half that for August 1989. 80 Initially, records of Little Egret, 60 an attractive and striking species which is easy to identify, were well 40 documented in county bird reports. % of peak month Although detailed recording has 20 continued over much of central and northern Britain, the numbers of 0 sightings in many southern coastal Jul Oct Jan Feb iii Apr Jun Dec Sep Mar Nov Aug May counties rapidly grew so large that there was an inevitable decline in Fig. 2. Monthly distribution of records of Little Egret Egretta garzetta the precision with which the species in Britain during the three periods (i) 1958-88, (ii) 1989-90 and (iii) July 1993 to March 2000. was reported. This is partly because Data for 1958-1988 and 1989-90 are from BBRC, and those for a species which is present 1993-2000 are from monthly Wetland Bird Survey (WeBS) counts; throughout the year will inevitably comparable data are not available for 1991-92.The three be recorded less comprehensively datasets have been scaled to allow comparison. Note that BBRC (and less enthusiastically), and data refer to arrival dates, whereas WeBS counts are obtained on a predetermined date each month. partly because, in the case of the Little Egret, the difficulty of assessing duplication between sites July a large-scale influx began, with almost 50 has increased greatly. Despite the lack of a individuals present by late August. Numbers central database of records, an analysis of declined to single figures in October, but a county bird reports does, nevertheless, indicate second, smaller, influx was observed in that the numbers in Britain in 1991 and 1992 December. BBRC, while acknowledging the were at a similar level to those in 1989 and 1990 likelihood of some duplication of records, sug- (Fraser et al. 1997). In autumn 1993, however, gested that no fewer than 120 individuals were another major influx took place, making those seen in Britain that year. Most occurred along numbers seem small by comparison. 64 British Birds 95 • February 2002 • 62-80 Non-breeding status of Little Egret in Britain Further consolidation: 1993-99 As Little Egrets have become more abundant in Britain, the Wetland Bird Survey (WeBS) – a partnership of the British Trust for Ornithology, The Wildfowl & Wet- lands Trust, the Royal Society for the Protection of Birds and the Joint Nature Conservation Com- mittee – was well placed to monitor their spread. Each month, thou- sands of volunteers make a count of the birds using wetland habitats throughout Britain. Although the coverage is not 100% complete, it is certainly very high with regard to the wetlands frequented by Little Egrets, and the scheme provides the best comparative data on this species at a national level. These regular monthly counts are known as WeBS ‘Core Counts’, which, in their present form (the scheme is an amalgamation of two earlier surveys, National Wildfowl Counts and the Birds of Estuaries Enquiry), commenced in the summer of 1993. G. M.