Hilbre Bird Observatory - Half A Century of Bird Ringing and Recording

by Bob Anderson and Steve Williams

The tidal Hilbre islands consist of some six hectares of land and rock in the Dee estuary, about 1km from the nearest point of the mainland at Red Rocks. Their location in the rich feeding grounds of the estuary make them important as a roost site for waders. Hilbre itself is the largest of the group, at something less than five hectares; most of its surface consists of rough grassland and some bare rock, but a cluster of buildings of various ages occupies the lower, east side of the island. Their associated (private) gardens and paddocks provide shelter for passerine migrants. The main island’s position at the extreme north-west point of Wirral means that, along with the peninsula’s north shore, it affords opportunities for seawatching not otherwise found in Cheshire.

The islands have long attracted attention from naturalists, with records of society visits going back to the nineteenth century. In the first half of the twentieth century a succession of well-known Wirral and Cheshire writers (e.g. Coward, Boyd and Ellison) visited Hilbre, while the opportunities for wader photography were exploited first by Farrar and later by Hosking and others. Drawing upon these sources, and the increasing number of records available from local societies and individuals, Ellison and Craggs (1) produced a checklist of the birds of the islands in 1955. Hilbre was therefore already a well-known and well-recorded site even before the inception of the Bird Observatory.

Nevertheless, a group of local birders who were already visiting the islands regularly felt that more could be learned by systematic observation and ringing, and the Observatory came into being early in 1957. The annual report produced that year was the first of an unbroken sequence extending to the present day (2). It should be said that, from the start, the interest was not wholly in birds but in all aspects of the islands’ natural history: for example, there is a fifty-year sequence of counts of the Grey Seal population, while light trapping of moths is a more recent development. This is reflected in the comprehensive volume on Hilbre edited by Craggs in 1982 (3) and in the annual reports, but such activities are beyond the scope of the present paper.

The Observatory

The main movers in the creation of the Hilbre Bird Observatory (HiBO) were John Gittins, a dynamic West Kirby man with a long association with the island, and Professor J D Craggs, who was already ringing House Sparrows Passer domesticus on Hilbre as part of his long-term study of the small colony then resident there. Fuller appreciations of the work and character of these two memorable and much-loved personalities can be found in obituary notices in CAWOS Bird News (4) and HiBO reports (2-1999 and 2-2001). They were joined by seven other founder members, four of whom were products of the then flourishing Birkenhead School Natural History Society, and over the next few years a succession of Wirral-based birders and ringers was added to the membership.

Birding in 1957 was very different from today, and more localised. The leisure market had yet to take off; equipment was more basic; information was much more limited; travel was far more restricted, and expensive. Ringing probably represented a more exciting option for young birders than it does in 2007. The beginnings of the Hilbre Bird Observatory have to be seen in this context. The primary motivation of the founder members was to learn more about the birds passing through the island and the waders feeding around its shores, but there was also the attraction of contributing to wider knowledge. The network of major observatories was, by now, established; a case was recognised (notably by Kenneth Williamson at the British Trust for Ornithology, who offered early encouragement to Hilbre) for smaller “mini-observatories” to supplement information by filling the geographical gaps in the network.

The two key developments which enabled the Observatory to take off in 1957 were permission to construct a small Heligoland trap in one of the gardens, and the use of a tiny hut in the grounds of one of the holiday bungalows for overnight accommodation and as a base for ringing activities. The original Heligoland site is still in use, though the trap has been rebuilt several times, and subsequently two further Heligolands were constructed in the east-side paddocks. In 1962 Hoylake UDC, recognising the value of the group’s work, provided a rather larger hut just north of the Canoe Club; though the building has now gone, its enclosed garden still provides a mist-netting site. In 1989 HiBO was fortunate to obtain, thanks to the previous occupants, the Dixon family, the tenancy of the southernmost bungalow on the island which continues to provide reasonably comfortable accommodation – far removed from the original 6’x4’ garden shed.

Hilbre Bird Observatory buildings: 1957-1962 (right) and 1989 to present day (left) (Steve Williams)

Possession of a permanent base led to improved coverage. HiBO members will normally be present on most weekends, with added effort (early morning visits and full-time residence on the island) at peak migration periods. Typically, the island will now be visited for ringing or recording purposes by members on 250 or more days in the year.

Ringing Activity

Despite the time and expense involved in their maintenance, the Heligoland traps remain a mainstay of ringing at Hilbre. They are sited in the limited cover available on the island, and are effective on an exposed site even when weather conditions limit mist net use. They are supplemented, for passerine trapping, by mist nets and some small wire (Potter) traps. Early wader ringing involved S-traps, clap-nets and dazzle-netting (the last a somewhat hazardous activity, utilising Aldis lamps and wet-cell batteries on slippery rocks) before the advent of rocket nets to catch roosting waders. The latter led to a brief period of relatively large wader catches, but the practice was discontinued in the 1970s. Before the organisation of the Dee Estuary Voluntary Wardens the roosting flocks at the mouth of the estuary were subject to serious disturbance by various public activities; the Dee became known as an “aerial roost” (the birds spending the tide in the air), and HiBO concluded that cannon netting on the islands would not help this situation. Limited wader ringing continues, primarily using mist nets but only at night.

It was always accepted that (waders briefly apart) Hilbre would never produce large ringing totals: a presentation on the HiBO’s work at the North-West Ringers’ Conference in March 2007 took as its theme the statement that “size isn’t everything” - that even a small site could contribute something to ornithological knowledge.

However, since 1957, HiBO has ringed over 32,000 birds (excluding early rocket netting of Oystercatchers Haematopus ostralegus which involved several thousand birds) of almost 100 species, but this modest total includes some useful results.

Of these 32,000 birds the pie chart below indicates that a very high proportion, almost 88%, is of passerines.

Figure 1 (left): Pie chart showing percentage of passerines, waders and other species ringed by HiBO 1957-2006.

Willow Warbler Phylloscopus trochilus is clearly the dominant passerine species with over 10,000 now ringed at Hilbre (representing about 1% of those ringed by the BTO), and is interesting on a number of counts.

The numbers illustrate how ringing expanded knowledge of the birds of an already well-watched site: in 1957 it was known that a few could be seen frequenting the gardens, but nobody then guessed that fifty, sixty or a hundred individuals could be present, and ringed, in a single day.

Moreover, bearing in mind its size and overall totals, Hilbre punches above its weight when compared with the national average for recoveries of many of the species ringed at Hilbre and this includes the Willow Warbler.

Not surprisingly, HiBO members have taken a particular interest in patterns of Willow Warbler movements.

Figure 2 (right): Map indicating some of the British recoveries and controls of Willow Warblers obtained by HiBO.

The pattern of recoveries and controls from HiBO is interesting; we have had a number of recoveries/controls from Scotland and Northern Ireland. This has led us to believe that the majority of Willow Warblers passing through Hilbre (particularly in August) are from these breeding areas and, to a lesser extent, northern England. This is emphasised by birds ringed in these areas during the breeding season and then captured on Hilbre during the August return migration or in some instances the following spring.

There is also evidence to suggest that birds use the same west coast migration routes with several recoveries/controls each from Portland, Bardsey and Calf of Man Bird Observatories, including birds ringed and captured in subsequent springs. However, interestingly, we have only had one from the east coast (ringed at Holme Bird Observatory in Norfolk on 12 May 1969 and controlled at Hilbre on 8 May 1970). We have several examples of Willow Warblers that have presumably overshot their intended destinations as they have been ringed on Hilbre (for example, one bird on 20 April 1988) and subsequently controlled further south (e.g. the same bird retrapped on Bardsey three days later on 23 April 1988).

There are also several foreign recoveries and/or controls of Willow Warblers and these have helped add to the ‘bigger picture’ that the BTO is compiling. A couple of examples are a bird ringed in Switzerland on 9 April 1980 and caught on Hilbre six days later, another ringed in Belgium on 23 April 1987 and captured at Hilbre on its return south on 17 August 1989 and one ringed at Hilbre on 12 September 2002 and captured in southern Spain on 6 October 2002. This latter bird was captured at a traditional feed-up area and was probably its last stop before it made its trans-Saharan crossing.

Weather patterns have also been closely studied at Hilbre by HiBO and here are two weather charts which indicate the classic fall conditions required for the arrival of large numbers of Willow Warblers (and other species are involved in much smaller numbers) at Hilbre in spring (figure 3) and autumn (figure 4).

Figure 3 (left): Classic spring weather conditions for a large fall of passerines on Hilbre.

The chart for spring (figure 3 left) shows high pressure centred over North Africa and the Iberian peninsula moving north-eastwards. This produces south-easterly winds off the Continent. A front moving north to south arrives at Hilbre after dawn producing cloud cover and/or rain which downs lots of nocturnal migrants (typically involving Willow Warblers). The autumn chart (figure 4 below) is taken from the largest fall of Willow Warblers to ever occur on Hilbre (5 August 2006) when high pressure north of and over Scotland produces ideal conditions for birds to leave their breeding grounds (clear skies and light winds) and a north-easterly airstream. A front moving west to east across the Irish Sea arrives at Hilbre at dawn ‘grounding’ literally hundreds of Willow Warblers. For more detailed analysis of the autumn chart readers are referred to CAWOS Bird News (5).

Figure 4 (left): Classic autumn weather conditions for a large fall of passerines on Hilbre.

Other birds, though ringed in smaller numbers, have added to local knowledge and/or produced interesting recoveries. Grasshopper Warbler Locustella naevia is a good example. A species not recorded at Hilbre prior to the establishment of the Bird Observatory in 1957, a remarkable 225 birds have been ringed at Hilbre in the 50 years since. This represents just over 1% of Grasshopper Warblers ringed in the UK during that time and the recovery in Scotland of a Hilbre-ringed bird was an early reward for our work in 1963.
 
Grasshopper Warbler Locustella naevia (right), 225 have been ringed on Hilbre 1957-2006 (Steve Williams).

So far as waders go, attention has always been concentrated on Purple Sandpipers Calidris maritima - a speciality of the island, though sadly reduced in numbers in recent years (e.g. a maximum of only 29 birds during 2006, against a peak of over 70 in the 1960s). Colour ringing demonstrated the return of individuals year after year, and in 1964 a bird ringed at Hilbre five years earlier was shot (allegedly by an Eskimo hunter) in Greenland. This was something that encouraged HiBO members for many years, being the first overseas recovery of a British-ringed Purple Sandpiper and early evidence of the origins of our wintering west coast birds.

Turnstone Arenaria interpres (left), one of many colour ringed on Hilbre over the last decade (Steve Williams).

Similarly, with our colour ringing of Turnstones Arenaria interpres we have had a number of birds seen or captured on passage in Iceland as well as numerous sightings of our birds around the west coast of Britain.

Clearly, there is not enough space to celebrate the ringing achievements of HiBO despite its size. These are just a few illustrations that suggest that the Observatory has succeeded, as a ringing station, in terms of its original ambitions. Additionally, the founders’ hopes for the occasional rarity have been met over the years, and several species have been added to the county list. These are discussed further in the next section.
 

Figure 5: Sample of interesting recoveries/controls from HiBO ringing efforts 1957-2006

Records and Observations

A crude but significant measure of the Observatory’s contribution to knowledge of Cheshire’s birds is that in 1957 the total number of species recorded on Hilbre stood at 157; by the end of 2006 it had risen to 260 (this on an island which had been well watched, and in the opinion of one noted county ornithologist, speaking not long after HiBO was established, was “over-watched”). The current figure includes an impressive list of rarities and/or birds new to the county, some of which might not have been discovered had it not been for the ringing effort.

Some of the more interesting examples include the first Cheshire and Wirral Yellow-browed Warbler Phylloscopus inornatus on 13 October 1973 – Hilbre has since had seven more records of this delightful, once much sought after, rarity. 2007's fine male Subalpine Warbler Sylvia cantillans was the second for Hilbre but only the fourth for Cheshire and Wirral. Two each of Melodious Hippolais polyglotta and Icterine Warblers Hippolais icterina, the latter species occurring twice on Hilbre in spring (1970 and 1973), were rare events on the west coast and constituted the first and second records for Cheshire and Wirral. Other good passerines have included two Woodchat Shrikes Lanius senator (of five county records), Pallas’s Warbler Phylloscopus proregulus, Dartford Warbler Sylvia undata, and Red-rumped Swallow Hirundo daurica (all third county records).

One of the most incredible records for Hilbre was probably the Yellow-breasted Bunting Emberiza aureola on 7 September 1994. Very much a Shetland speciality, this was one of the first west coast mainland records. Obviously, seabirds are also emphasised with the first county records of Great Shearwater Puffinus gravis (October 1971) and Cory’s Shearwater Calonectris diomedea (August 1980). Other notable species include Laughing Gull Larus atricilla, two White-winged Black Terns Chlidonias leucopterus and Collared Pratincole Glareola pratincola (another first record for the county).

The rarities apart, regular observation has led to improved knowledge of frequency of occurrence, and/or fluctuation in numbers of all species that occur on or around the Hilbre islands group.

Many examples of species’ status that have changed considerably in the time that HiBO has been running are from a positive perspective – Storm Petrel Hyrdobates pelagicus, Brent Goose Branta hrota/bernicla, Sparrowhawk Accipiter nisus, Osprey Pandion haliaetus, Marsh Harrier Circus aeruginosus, Little Egret Egretta garzetta, Long-tailed Skua Stercorarius longicaudus and Little Gull Larus minutus. Some of these are simply as a result of the species increasing within and/or expanding their range but other reasons, such as better identification awareness (e.g. Long-tailed Skua) and observer awareness of when and where to look (e.g. Storm Petrel and Little Gull) may also have played a part.

Figure 6 below indicates the dramatic rise in numbers of Pale-bellied Brent Geese Branta hrota at Hilbre in the last decade or so. Prior to the early 1990s Pale-bellied Brent Goose was very scarce at Hilbre but before this Dark-bellied Brent Goose Branta bernicla was the more regular of these two closely related species.

Figure 6: Peak counts of Pale-bellied Brent Geese at Hilbre from winter 1995/96 to 2006/07.

Similarly, figure 7 below indicates the dramatic increase in Sparrowhawk records at Hilbre in the last 50 years (shown in five-year periods). It has had a particularly significant increase since the early 1980s, mirroring its general recovery on the mainland.

Figure 7: Number of Sparrowhawk records at Hilbre in five-year periods 1957-2006 (50 years)

Those species that have been affected with a downward turn in recent times sadly include two of our favourite species, namely Willow Warbler and Purple Sandpiper. The former has seen a decline nationally and the latter has seen numbers dwindle in the last few winters. The reasons for the Purple Sandpiper decline are possibly partly due to more movement between wintering sites in north Wirral (with better feeding habitat available at Wallasey and Leasowe), but more likely that birds are staying further north in winter, although this latter suggestion is yet to be proved.

Seawatching has always attracted birders to Hilbre, and no seabird more than Leach’s Petrel Oceanodroma leucorhoa – adopted as the symbol for CAWOS as well as HiBO. Long associated with autumn north-westerly gales there is perhaps no better place on the ‘mainland’ of Britain to watch this enigmatic petrel, in terms of location, ambience and views of the birds themselves (but of course we are biased!). However, all of the other important seabird sightings and counting that HiBO carries out should not be passed over. Hilbre, and HiBO in particular, is particularly significant in county terms for providing data for divers, grebes, shearwaters, sea-ducks, gulls, terns and auks (as well as waders and passerines as already discussed above).

The limited land area of the islands makes it relatively easy to study, and ring, the limited population of resident birds. The House Sparrow colony which attracted Craggs, and was the subject of two papers by him (6), (7) was largely dependent on livestock foodstuff, and disappeared many years ago. However, a number of passerine species breed on the islands, and are studied through five-year cycles using territory mapping methods. Of particular interest are the flourishing Linnet Carduelis cannabina colony (the subject of an ongoing study) and Wren Troglodytes troglodytes (the island having once been regarded as unsuitable breeding habitat). Additionally, about 15 pairs of Shelduck Tadorna tadorna now breed – a significant increase from the two or three pairs to be found when the Observatory began, and consistent with changes elsewhere in the county.

The observation work carried out by HiBO is not restricted to the daily log of species and numbers and the ringing efforts, but also includes provision of data to CAWOS and other organisations, the Winter Gull Survey, Wetland Bird Survey, Breeding Bird Survey, Brent Goose Survey, CAWOS Wintering and Breeding Atlas surveys and the BTO Atlas survey work planned to commence in the winter of 2007.

Conclusion

Has it worked out as the founder members hoped, and has it been worthwhile? This brief account of fifty years’ work on the islands suggests that the answer to both questions should be in the affirmative. The twin aims of finding out more about the birds using the islands and making a contribution, however modest, to wider ornithological knowledge, have been achieved. As changes take place over the years, there are always new questions to answer, and new trends to be identified. There seems no need to stop work, and no reason to lose interest, even after half a century. Fortunately, the Observatory is better housed, better equipped and perhaps most significantly, better manned and covered than it has ever been – we are looking forward, with eager anticipation, to what the next fifty years might produce.

Bob Anderson and Steve Williams

References:

(1) Craggs J D & Ellison N F (1955), The Birds of Hilbre Islands, Cheshire, Northwest Naturalist
(2) Hilbre Bird Observatory (1957-2006), Hilbre Bird Observatory Report, HiBO
(3) Craggs J D, Ed (1982), Hilbre – The Cheshire Island, Liverpool University Press
(4) Anderson R (2002) Bird News No 53, CAWOS
(5) Williams S (2004), Bird News No 64, CAWOS
(6) Craggs J D (1967) Bird Study volume 14, pp53-60
(7) Craggs J D (1976) Ibid volume 23, pp 281-284

Acknowledgements:

Many thanks are due to Chris Williams for providing data on ringing, recoveries and controls and also to Pete Williams for commenting on an early draft and reviewing the final draft of this article.

Editor: this article first appeared in the Cheshire and Wirral Bird Report 2007 and appears here with the kind permission of the Editors and Authors.

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January Bird News
 

Cattle Egret at Neston, Jan 8th 2008, Steve Round ©

The Christmas period saw an influx of Cattle Egrets into the country, at least 30, and one of these duly turned up here. Although news only reached birders on the 3rd apparently it had been present on farmland next to the A540 near Neston at least a week before that. This is the second record for Wirral. It, or possibly a second bird, was seen on Burton Marsh on 25th and 26th. The following day a Great White Egret was observed flying inland at the same site at dusk, and was relocated off Neston Reed Bed on the 30th.

A look at the Brent Geese graph in the above article (figure 6) demonstrates the dramatic rise in numbers of these birds on the Dee Estuary since the winter of 99/00. Well, they are still increasing in number with a remarkable 172 counted on a flat calm sea off Little Eye on 12th. These are mostly of the pale-bellied race, the main population winter in Ireland and apparently a record number of 29,500 were present at Strangford Lough (near Belfast) in October 2007 with 30% young, so this population is obviously doing very well. Pink-footed Geese are another species doing well. We sometimes get large movements over the estuary with birds moving from Norfolk to Lancashire, max count this month was 500 on 14th over West Kirby. But we also have an over-wintering flock on the marshes, this flock seems to be increasing slowly each year and max count was 320 on the 25th giving good views from Parkgate and Neston, they seem to be very active at high tide flying off the edge of the marsh. Whooper Swan is another bird which is increasing, the 61 counted on Shotwick Fields on the 1st is almost certainly a record high count for that site. Other wildfowl of note was a first winter male Long-tailed Duck seen off Hilbre on several days at the start of the month, up to 450 Pintail spent most low tides in the channel off Thurstaston and at least 300 Common Scoters were off Point of Ayr on 26th, no doubt just a very small portion of the total Liverpool Bay flock.

Purple Sandpiper bravely coping with sea spray on rocks below the Lifeguard Station,
Wallasey Shore,  Jan 25th 2008, Matt Thomas ©

A mainly mild and windy month meant low numbers of waders, although 2,100 Black-tailed Godwits and six Spotted Redshanks at the Connah's Quay Reserve are not bad numbers. We've also had reasonable numbers of Purple Sandpipers with at least 40 on Hilbre, 11 on rocks by the Wallasey Lifeguard Station and seven on a platform on New Brighton Marine Lake at high tide. There seems to have been loads of Oystercatchers around although I haven't seen any total counts for the estuary, but we've had good numbers roosting on West Kirby Shore nearly every high tide ever since they returned from breeding in late summer, 6,000 was max this month. We've still got some overwintering Greenshank with singles seen at Heswall, Gilroy Nature Park and West Kirby Marine Lake, with two at Connah's Quay.

The same windy weather which suppressed wader counts brought in a pale phase Arctic Skua off West Kirby on 24th, I think this is the first ever Jan record for Wirral although we have had several December records in the past. There have been both Marsh Harriers and Hen Harriers of Burton, Heswall and Parkgate, usually only single birds have been noted but there were two Marsh Harriers off Burton on 2nd and Parkgate the following day, and two Hen Harriers off Neston Reedbed on 19th. At least three Peregrines and two Merlins were regularly observed through the month. Up to four Short-eared Owls have been on the marshes and there have been some good views of Barn Owls at dusk at Burton.

Two Snow Buntings took up residence on Little Eye towards the end of the month, with singles briefly at West Kirby and Hilbre. 15 Brambling were at Connah's Quay on 21st and 25 Twite was the max seen at Flint Castle. Cormorant numbers continue to increase, one day at West Kirby we counted a total of well over 1,000 on Bird Rock, Little Eye and flying south down the estuary.

Many thanks go to Richard Steel, Steve Liston, Neil McLaren, Jimmy Meadows, Matt Thomas, Andrew Wallbank, Paul Vautrinot, Roger Morgan, Mike Cocking, Tony Twemlow, John Kirkland, Pete Hilton, John Ferguson, David Haigh, Mike Hart,  John Jakeman, Henerz Cook, Iain Douglas, Graham Thompson, Allan Conlin, Dave Wild, Graham Jones, Steve Round,  Steve Williams, Dave Edwards, Chris Butterworth, Jane Turner, Charles Farnell, Paul Shenton, David Small, Gilbert Bolton, Steve Ainsworth, Damian Waters, David Thompson, Mark Gibson, Alec Thomasson, Colin Schofield, Allan Hewitt, John Tubb, Dave Harrington, Paul Roberts, Norman Hallas, Phil Woollen, Phil Liston, Colin Davies, Jason Stannage, Bernard Machin, Michael Clarkson, Mike Jones, Peter Poole, Nigel Young, James Smith, Rob Black, Ian Bedford, Steve Hassell, Bryan Joy, Steve Roberts, Richard Graham, Bernard East, Peter Poole, Graham Mercer, the Dee Estuary Voluntary Wardens and the Hilbre Bird Observatory for their sightings during December.  All sightings are gratefully received.

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Forthcoming Events

February Highest Spring Tides (Liverpool), also see Tides page.
10th February, 13.21hrs (GMT), 9.7m.
22nd February, 12.08hrs (GMT), 9.7m.

NOTE: Many of these forthcoming events are extracted from the 'Birdwatchers Diary 2008', which covers both the Dee and Mersey regions. Hard copies available from the visitor centre at Thurstaston, Wirral Country Park 0151 648 4371.

All material in this newsletter, and indeed the whole web site, has been written by myself, Richard Smith, unless specified.

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