Andy Musgrove - BTO
The October speaker was Andy Musgrove, who is Research Manager for the BTO's Wetland and Coastal Ecology Unit, and National Co-ordinator for the Wetland Bird Survey (WeBS). WeBS is a collaborative project between the BTO, RSPB, WWT and JNCC (Joint Nature Conservation Committee). Its principal aims include determining population sizes, together with trends in numbers and distribution, of non-breeding waterbirds in the UK. The main focus is on autumn and winter, but records are collected throughout the year. Synchronised "core counts" are made every month at as many wetland sites as possible (including rivers, estuaries, marshes, reservoirs, etc.), whilst Low Tide Counts are made on about 20 estuaries each winter to identify important feeding areas. Data is collected by 3000 volunteer counters who monitor sites throughout the UK. It was WeBS that first drew attention to a significant increase in Little Egret numbers in the 1990s. Andy is also involved with other work associated with water birds, including monitoring off-shore Scoters, and preparing data for public inquiries such as the Cliffe Airport project. He also fields enquiries from government on issues such as Avian Influenza.
Little Egrets are fairly easy to identify: males are the same as females - snowy white with black legs, yellow feet, dark bill and lores, and are about half the size of a Grey Heron. In the breeding season, the feet and lores go pinkish, and the birds develop plumes on their chests, back of head and scapulars. Their preferred habitat is open water such as lagoons, marshes, gravel pits, river valleys, etc. In spite of their striking appearance, they are easy to miss on saltmarshes as they disappear into the creeks. They feed in shallow water and on mudflats, on frogs and other amphibians, fish, shrimps, worms and other invertebrates, and occasionally small birds and mammals. They sometimes feed amongst cattle, eating the insects disturbed by the animals' feet, but they do not perch on the animals as Cattle Egrets do. They are very widespread in the Old World throughout southern Europe, Asia, and Africa. They can disperse over large distances, and are capable of crossing the Atlantic.
The early history of the Little Egret in the UK is uncertain. A 14th century document showing the prices of "poultry" gives "Egret 18 pence" but there are no fully documented records of Little Egret until a Yorkshire record in 1826. It is known that Bitterns and Spoonbills were common in the Middle Ages, and possible that Little Egret was too. A record that "many white herons do breed" in Dousdale Holt in Huntingdonshire in about 1600 is thought to refer to Spoonbills which we know did nest there at that time. It is possible that the species was present in the Middle Ages, and disappeared in the so-called "Little Ice Age" (c1550-1850).
Throughout most of the nineteenth century and the beginning of the twentieth, Little Egret populations in Europe were at a very low ebb, due to the popularity of their plumes with the fashion industry; indeed they were totally wiped out in France. However the recolonisation of France started in the Camargue, where there were about 1000 pairs by the early 1950s. They spread from there in the mid 1970s, moving up the western French coast. Their expansion took the form of wintering for a few years in a new territory, then starting to breed there, and then dispersing again northwards. The expansion is still continuing: the French breeding bird surveys show that the species occupied 110 of the French survey squares in 2003, and 190 (an increase of 73%) in 2004. The reasons for this increase are not entirely understood, but it is believed to be linked to increased protection since 1962 coupled with fewer harsh winters (there were no harsh winters in the west coast of France in the whole of the 1970s). It is estimated that the mid-winter population in western France is 8000 birds.
For the UK the spread has recently been equally dramatic. After that first Yorkshire record in 1826, there were then very few until the middle of the 20th century. Some counties had a long wait for their first records, for example, 1952 for both Sussex and Norfolk, 1957 for Kent and Hampshire, and 1965 for Somerset . Numbers then steadily increased and by 1988 there were about 40 records annually in the UK, virtually all of which were in the months April to August with a big peak in May. The first big influxes occurred in both 1989 and 1990 when there were about 120 records in each of those years. These birds were believed to come from post-breeding dispersal from French colonies, as most records were coming in August with now a much smaller May peak. At this stage, the status of the species was still summer non-breeding visitor.
The WeBS project as we know it today started in 1993 as an amalgamation of other schemes including the National Wildfowl Count and the Birds of Estuaries Enquiry. That year there was a peak total of 185 Little Egrets with over half of them coming from three sites: the Tamar complex (48), Chichester Harbour (44) and the Taw-Torridge estuary (11). The increase continued from 1993-2000, with peak numbers in August to October, and an increase in numbers staying throughout the winter.
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It was known that daytime counts give an underestimate of numbers, because of the difficulty in locating birds in creeks and gullies, so attempts were made to count them at their roosts. In September 1999, the estimated total number in Britain was 1650 birds, and in January 2000 the count was still as high as 850.
The first successful breeding record of Little Egret was on Brownsea Island in Poole Harbour in 1996 when they raised 3 young. In 1997 came the first successful nest in Eire, with unconfirmed breeding elsewhere. By 2004 there were 30 confirmed breeding colonies, totalling 366 pairs. It is predicted that there could be 600 pairs in 2006 (this compares with 10,000 pairs of Grey Heron). Breeding is moving northwards, up to Frodsham in Cheshire in the west and Holkham in Norfolk in the east. They are also spreading inland. There are no breeding Little Egrets in Yorkshire yet but it is only a matter of time before they arrive. Holkham is one of the most northerly colonies, and is also one of the biggest, with 30 pairs. Little Egrets nest in trees either deciduous or evergreen, and can be very difficult to see.
The WeBS core counts take place every month, and gave nearly 3000 Little Egrets in January 2004. In the winter of 2004/5 it was found that the counts at most sites on the west and east coasts were reaching new peaks, whereas counts along the south coast appeared to have stabilised. The northern boundary for winter colonies in the UK at present seems to be south of the Humber estuary in the east and the Ribble in the west. It is not known whether or not these boundaries will be breached. Inland spread is quite rapid, particularly along river valleys.
The following table summarises the progress of Little Egrets:
The expansion is thought to be due to increased protection and warmer winters. Where will they stop? If they reach the Humber, there is then a big step to the next major estuary, namely the Tees. On the west coast, there are more river estuaries, so expansion beyond the Ribble could be easier.
Andy finished his talk with a summary of the fortunes of other members of the heron family in the UK. The Bittern is now doing quite well: after being reduced to 11 booming males in 1997, there were about 55 in 2004. Spoonbills historically bred in the fens, but is thought to have disappeared in the seventeenth century. Of recent years there has been the odd breeding pair, but the expected increase in their population has not happened. Cattle Egrets are spreading northwards through France quite quickly, whilst the Great White Egret has increased dramatically in the Netherlands, where it is much more common than the Little Egret. There are increasing numbers of both these species in the UK, and it now seems possible that they may overtake Spoonbills as the next colonisers of the UK.
Andy was thanked for his most interesting account of the long absence of this attractive species from the UK, and its rapid northward march. His talk amply illustrated the value of monitoring bird populations, and he asked us to get out there and do our bits. The BTO has an enviable reputation for its independent and accurate research, and this is only possible with the help of the literally thousands of volunteers who work with the BTO staff to do the fieldwork. The BTO runs many and diverse surveys, not just the general ones like WeBS, the Breeding Bird Survey, Nest Record Scheme, etc. but also surveys of individual species such as Barn Owls and Herons.
Wendy Thomson |
