Species Spotlight - Little Tern Sterna albifrons
Little Terns are a declining species in Britain and Ireland and they are amber listed in the Bird of Conservation Concern list (1). It is estimated that they have declined from about 2,850 pairs in 1987 to less than 2,000 today, a worrying trend. The RSPB reckon that this drop in numbers is due to poor productivity at the nesting colonies, mainly because of an increase in fox numbers (2). However, it is not all doom and gloom as our local colony at Gronant is doing very well as demonstrated in the graph below, this shows the numbers of pairs and young fledged each year since 1975 when the RSPB started wardening here.
As is typical of tern colonies nesting success can vary greatly from year to year, and that has always been the case at Gronant with the difference between 2001, when just one young fledged, and 2003, when a record breaking 190 young fledged, an extreme example of this.
Why is nesting success so varied? Two factors in particular are important, weather and predators. If the weather is bad at crucial times, such as when the bulk of the terns first arrive, when they first lay eggs and when the eggs first hatch; this can make a huge difference, with sand blowing over the nests the most harmful effect of windy conditions.
The three main predators at Gronant are crows, kestrels and foxes. Crows can certainly take a large number of eggs, but are relatively easy to scare away so this is where wardening is crucial, particularly early morning when they are most active. One of the problems in recent years is that as the colony has grown the area to cover has got bigger - if you are scaring a crow at one end of the colony you haven't a hope of stopping one taking eggs at the other end, so the relatively recent innovation of having more than one warden on duty is essential. In contrast a determined Kestrel is very difficult to stop, a male in 2001 with a hunting technique more like a Sparrowhawk took around 60 chicks, that's an average of two successful hunting trips a day over a thirty day period. But even a Kestrel can be deterred by distracting it with a loud whistle just as it is diving down towards the colony, and again the role of the wardens is crucial here. The Little Terns themselves can be pretty effective chasing away avian predators, they can get particularly aggressive after the chicks have hatched. Even more effective are Oystercatchers, we usually have a couple of pairs within the colony, it is quite amusing to see a crow suddenly turn tail with a couple of very annoyed Oystercatchers in chase!
Foxes take both eggs and chicks and if a couple get into the colony they can more or less wipe it out in one night, if given the chance. But here we have a big success story at Gronant with the introduction of a new and very effective electric fence three years ago, since when foxes have gone from being the most serious predator to not one single record of fox predation within the fenced area for three years!
The first Little Terns arrive back at Gronant late April/early May, although no serious nesting attempts are made until the last week in May. By the second week in June there is usually a significant increase in birds, called the 'second wave' by the wardens, and these soon get down to egg laying. The incubation and fledgling period are each around 20 days, with the first chicks fledged around the first week in July and the majority flying by the end of the month. It is during July we get a third wave of birds arriving, in 2005 numbers increased from the 150 or so breeding birds to over 400 in total. Some of these may be from colonies further north, but the majority are likely to be returning two year old birds not yet ready to breed. In 2005 these two year old birds will have been fledged from the record breaking 2003 season when 190 chicks successfully flew. From mid-July onwards numbers in the Dee Estuary itself start to increase, with peak numbers usually occurring in the first two weeks of August. The calm shallow waters of the estuary act as a nursery for the terns with the sand banks around Hilbre being particularly attractive, 300 or so are often recorded here at this time with good size flocks also seen at Point of Ayr, West Kirby and Hoylake - no doubt many of these will be from Gronant.
The Gronant Little Tern colony is one of the most productive in the UK as shown in the bar chart above, 2004 was a particularly good year at Gronant, 2003 even better, and even though 2005 was relatively poor the terns still produced 35 fledglings. The selection of other colonies from the UK in 2004 shown in the bar chart were actually some of the best in the country, the original table (3) showing all the main colonies make depressing reading with 18 out of 32 colonies not producing a single chick. Colonies in Ireland, however, fared much better with a similar success to that obtained at Gronant.
I hope I have made it clear the vital role the wardening scheme has played in the success at Gronant. Denbighshire Countryside Service are organising the wardens this year, so if you want to volunteer email Garry Davies at firstname.lastname@example.org. Garry can also be contacted by phone - 01745 356197 or 07884490345.
May Bird News
fresh westerly wind blowing for much of the month sea-watching was good
with plenty of Gannets, Kittiwakes, Manx Shearwaters and Common Scoters in
sight, but the most unusual record was of a Sooty Shearwater seen from
Leasowe on 28th May. Although we usually
get one or two each year they are always seen August to October, so this
could be our first ever May record. Another good sea bird was a Laughing
Gull flying past Hilbre on 14th, perhaps
the one which spent the winter in Portmadog. A full summer plumaged
Black-throated Diver off Hoylake on 24th
was another good bird.
Good numbers of Dunlin have been on passage with 2,000 counted on Hoylake shore together with a gorgeous flock of Grey Plover in breeding plumage, and 100 Sanderling at Gronant. 700 Bar-tailed Godwit on West Kirby Shore south of the Marine Lake was an excellent May record.
Two of the rarities which were present at the end of April put in an appearance early in May, this was the Great Grey Shrike near Leasowe Lighthouse which was seen again on the 1st, and the Subalpine Warbler stayed on Hilbre until the 8th May but was very elusive. Almost as rare as the 'subalp' was a Red-throated Pipit seen all too briefly as it flew over three birders near Leasowe Lighthouse, if accepted this will be Cheshire and Wirral's sixth record.
It continues to be a good spring for Ospreys with five flying over, although there is always the possibility that one has been seen more than once and is hanging around the area. Marsh Harriers have also been passing through with three or four around, I saw a female sitting on West Kirby Shore looking very miserable in pouring rain. A Red Kite over Dawpool Nature Reserve, Thurstaston, was well spotted by Matt Thomas, one of the Wirral Rangers. Someone saw a Turtle Dove on the nearby Wirral Way on 26th. Three drake Garganey were at Inner Marsh Farm towards the end of May.
What to expect in June
The summer begins, the summer ends. Whilst Sanderling are still passing through on their way north at the beginning of the month Curlew will already be returning to their wintering grounds on the estuary by the end, with several hundred to be seen on Heswall Shore. These first returning Curlew will be birds which have bred in this country with those breeding further afield coming back over the following couple of months. Green Sandpipers are also one of the first species to start returning, look out for them at Inner Marsh Farm. Of course most waders are absent from the estuary in June, but we do have quite a few non-breeders which stay here. Several hundred Black-tailed Godwits are to be found at Inner Marsh Farm, and despite not being fully mature birds many are in breeding plumage making for a great spectacle. Last summer we had around 1,000 Knot at Inner Marsh Farm which was most unusual, but these were definitely immature birds with only one or two in breeding plumage. Several hundred Oystercatchers stay here over summer with many roosting at Point of Ayr at high tide. A handful of Oystercatchers, Redshank and Ringed Plover nest around the estuary with the latter easily seen within the Little Tern colony at Gronant, look out for the tiny chicks running around - but please stay outside the fence!
It always surprises me just how many gulls we get here in June loafing around on the sand banks, flocks of a thousand or more are not uncommon - mainly immature Herring and Lesser Black-backed. Gronant, Point of Ayr, West Hoyle Bank and Hoylake seems to be their favourite sites. A prolonged west wind may well produce a Storm Petrel along with the more usual Gannets, Common Scoters and terns.
The odd rarity can turn up, we had a the Black Stork over Burton last year, Golden Orioles are occasionally seen and Quails heard, it's also a good month to expect a wandering Spoonbill or two.
Many thanks go to Matt Thomas, Steve Wrigley, Adrian Hibbert, David small, Graham Fergus, Tony Molloy, Phil Woolen, Katie Barrett, Tanny Robinson, Gilbert Bolton, Huw Pearson, Derek Pover, David Haigh, Dave Harrington, Damian Waters, Steve Round, Allan Conlin, Mike Hart, Dave Wild, Paul Green, Colin Wells, Steve Ainsworth, Bernard Machin, Colin Schofield, Clive Ashton, Neil Mclaren, Michael Clarkson, Steve Williams, Chris Butterworth, Dave and Emma Kenyon, Jane Turner, Kevin Smith, Frank Gleeson, Andy Jennings, Mark Turner, Dorothy Jebb, Laura Bimson, Andy Beech, Margaret Coles, Frank Huband, Mark Gibson, Andrew Metha and the Hilbre Bird Observatory for their sightings during May. All sightings are gratefully received.
Highest Spring Tides,
13th June, 13.12hrs 8.8m. BST.
Forthcoming Events (organised
by the Wirral Ranger Service,
Flintshire Countryside Service and/or the RSPB):
Sunday 4th June, 1:30pm.
Wednesday 21st June, 9pm – 11pm, Owl-tastic!
Tuesday 27th June, Sunset Walk to Hilbre.
Thursday 29th June, 8pm - 10.30pm, Night Owl Watch.
Sunday 2nd July, 10am - 12.30pm, Heswall
Thursday 13th July, Sunset Walk to Hilbre.
NOTE: Many of these forthcoming events are extracted from the 'Birdwatchers Diary 2006', 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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