Alarm Call of Common Coot in Response to Ground Predator Common Redshanks Using Trees As High-Water Roost

NOTES Alarm call of Common Coot in response to ground predator On 30th August 1993, at Eavestone Lake, North Yorkshire, I observed a family of two adult and two juvenile Common Coots Fulica atra feeding at the edge of a small clump of reeds. Between 08.45 and 09.30 BST, a Stoat Alustela erminea made repeated attempts to entice the juveniles on to land by characteristic 'dancing' among the reeds. Each time the young were attracted towards the Stoat, one of the adult coots would emit a loud wailing call, often interspersed with short, deep rasping sounds. I recorded these calls (fig. 1); Fig. 1. Sonagram of alarm call of Common Coot Fulica atra in response to ground predator, North Yorkshire, August 1993 (prepared by Richard Ranft, British Library of Wildlife Sound, National Sound Archive) they are similar to, but much louder than, the species' nocturnal flight call, and may also resemble the 'sobbing' or 'weeping' alarm of the female Common Coot in response to birds of prey (see BWP vol. 2). I could not identify the sex of the individual whose voice I recorded. SIMON T. ELUOTT 103 Kenton Road, Gosforth, Newcastle upon Tyne NE3 4NL Common Redshanks using trees as high-water roost On 18th August 1993, at Isley Marsh on the River Taw, Devon, I saw 35 Common Redshanks Tringa totanus perched in two small dead trees surrounded by the waters of the high tide. Resting about 2 m above the water's surface, most with their bills tucked beneath their mantle feathers, they allowed an unusually close approach and were obviously settled to roost out the tide. The adjacent saltmarsh and estuary were water-covered, and other waders were roosting on or near grassy and stone embankments. At high tide on 1st September 1993, a single Common Redshank was perched in one of the trees. This species frequently uses elevated perches when breeding, but roosting in trees away from breeding sites, while it may not be unusual, does not appear to be well documented. BWP (vol. 3) specifically mentions two instances, the circumstances in both cases suggesting that the waders had no alternative. The Common Redshanks in Devon, however, were using trees in preference to embankments and nearby grassy fields. R. M, R. JAMES 10 Eastbrae Road, Httkover, Derby DE23 7WA [Bnt. Birds 91: 139-145, April 1998] © British Birds Ltd 1998 139 140 Notes Reaction of Common Greenshanks and Eurasian Curlew to Grey Squirrel On 2nd September 1991, beside the Beaulieu estuary, Hampshire, a Grey Squirrel Sciurus carolinemis appeared at the edge of a pool and made its way across the dried-up mud to the edge of a water channel, finally swimming across and climbing the grass bank opposite. At one point it passed close behind a Eurasian Curlew Numenius arquata, which immediately turned around and trotted after it through the water. On 6th September 1991, at the same pool, a squirrel again appeared and moved towards the water channel. Before it could reach the water's edge, however, three Common Greenshanks Tringa nebularia, which were feeding in the water, intercepted the squirrel by immediately taking up a precise close formation about 0.5 m from each other, one on each side and the third behind. With necks lowered approximately to the horizontal and bills outstretched, they then escorted the squirrel at a trot back across the mud for some 35 m until it entered the fringing vegetation; any deviation from the most direct line of retreat was immediately countered by the wader formation. After the squirrel had cleared the mud, the three Common Greenshanks separated and walked the length of the vegetation, a distance of about 25 m, apparently to check that it had gone, during which time they called continuously in a subdued manner. They then flew back to the water channel and returned to feeding normally. J- J- GARR 1 Widbury Road, Pennington, Lymington, Hampshire S041 SEF EDITORIAL COMMENT This behaviour by the Common Greenshanks seems very unusual, and nothing similar is mentioned in BWP (vol. 3). Dr K. E. L. Simmons has queried, however, whether the waders were perhaps feeding communally and, in so doing, simply happened initially to move the squirrel on, but this seems unlikely since J. J. Garr (in litt.) has stated that the waders flew towards the squirrel. Common Terns nesting on roofs in Suffolk Common Terns Sterna hirundo breed in a wide variety of habitats, from shingle or sandy beaches to heath and even rocky shorelines. They also adapt readily to artificial sites, such as man-made islets on inland gravel-pits, rafts and low platforms over water. Since at least 1993, at Lowestoft, Suffolk, Common Terns have nested on the roof of the assembly shop of the former Brooke Marine shipbuilding yard. Although similar behaviour has been recorded in Finland (Hakala & Jokinen, 1971, Ornis Fennica 48: 135-137), where Common Terns nested on the sand-covered roof of a factory in Tampere, this may be the first reported instance of roof-nesting by this species in Britain & Ireland. Least Terns 5. antillarum have used similar sites in North America (BWP, vol. 4). The building used in Lowestoft, on a quay beside the saltwater inner harbour, is about 176 m long and 23 m wide, and aligned approximately east British Birds, vol. 91, no. 4, April 1998 141 to west. The roof, 15 m above ground level along the edges, is of corrugated asbestos sloping upwards at about 5° to a central ridge at 16 in; 24 rectangular ventilation hatches projecting about 30 cm at intervals along the ridge provide some shelter from the wind. Possible breeding on the roof was reported in 1992 {Suffolk Bird Report; see also editorial comment below), and on 3rd July 1993 I saw a pair of Common Terns feeding three half-grown chicks near one of the rooftop ventilators. In 1994, I made more-detailed observations using a telescope at distances of 200-300 m (direct access to the roof is not possible): all the north-facing half of the roof could be examined in this way, but the terrain and other buildings restricted views of the south side to about 60%. A total of eight pairs of terns attempted to breed, seven on the north side and one on the south side. Nests were spaced over a distance of about 36 m in the middle section of the roof, all on the upper half of the slope; the main cluster of four nests had a minimum spacing of 5 m. When incubating and brooding, the adults generally preferred to sit across, rather than along, the axis of corrugation. The furrow of each corrugation is about 25 cm wide, thus forming an apparently comfortable substitute for a scrape (but, of course, lacking the sides). Lichens and other vegetation form a thin cushion in the troughs, and in places may allow compression into a shallow scrape. In 1994, eggs were laid in late May and early June, hatching during 17th- 27th June. Two nests failed at the chick stage, probably through predation. Of the six other clutches, three produced three chicks each and three each hatched two. At least nine chicks fledged in late July, giving a minimum productivity of 1.1 young per pair: at least as good as success rates quoted in the literature (e.g. BWP, vol. 4) for more-conventional colonies. NEVILLE SKINNER 60 Gunton Drive, Lowestoft, Suffolk NR32 4QB EDITORIAL COMMENT We have also received a report on this same rooftop colony from Andrew Easton, who provided the following additional information. Both sides of the central section of the roof are heavily covered with mosses and lichens, with a few clumps of Biting Stonecrop Sedum acre, while much of the guttering is overgrown with grass. In June-July 1992, he saw up to at least eight adult Common Terns on the roof, some of which regularly brought in fish, but breeding could not be proved. In 1993, at least eight adults returned to the roof, and on 27th June the three recently hatched chicks were being brooded on the north-facing side against the upslope of a stonecrop plant (which may have been the original nest site, as it would have prevented eggs from rolling away); other adults were again carrying fish to the less viewable south side of the roof; the young were first seen to fly on 17th July. Oystercatchers Haematopus ostralegus, domesticated Rock Doves Columba livia and Red-legged Partridges Alecioris rufa visiting the roof were tolerated, but all the adult terns very vigorously drove away from the site any aerial predators, such as Common Kestrels Falco tinnunculus and numerous gulls Lams. The greatest danger is that the slanting corrugations channel rainwater through all potential nest sites, creating a much greater risk of chicks or eggs becoming chilled. 142 Notes Fighting Magpies surrounded by others watching A letter sent to me in October 1993 by Mr B. C. Doughty described how he and his wife came across six Magpies Pica pica standing silently and regularly spaced in a circle 2-3 m in diameter and all facing the centre, where two more Magpies were locked in combat. It sounds strangely human: bystanders gathering around a fight in curiosity, neither helping to separate the combatants nor offering encouragement. As with other birds, fights between Magpies sometimes result in a stalemate, where both individuals are equally motivated and equally unwilling to break off and retreat. I have read of two Magpies falling 10 m out of a tree, locked beak to beak, and continuing to struggle on the ground.

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