Banded Cladorhynchus leuococephalus Attempting to Copulate with a Stick

On 12 December 1997, we visited the Tullakool Salt Evaporation Ponds, 30 km south of Moulamein, New South Wales, where we observed approximately 500 Banded Cladorhynchus leuococephalus and 300 Red-necked Recurvirostra novaehollandiae in one of the shallow lagoons. Most were standing in two roosting flocks (which consisted largely of single species), about 30 m apart, but a few were feeding around these flocks of roosting birds in a rather desultory manner. After a short while, our attention was drawn to a Banded Stilt which was going through the motions of a courtship display. The focus of this display was a piece of wood about 3 em in diameter and protruding, nearly vertically, about 30 em out of the water. The continuously walked around the stick, up to a metre away , with much head-bowing and opening and shaking of wings, in a typical pre-copulatory display (Marchant & Higgins 1993, CM pers. obs.). The Stilt circled the stick for about 5-10 minutes, then briefly mounted and attempted to copulate with it: the bird lowered its abdomen onto the top of the stick, with its legs bent, and rapidly flapped its wings as it tried to maintain balance. This behaviour lasted only a few seconds, in contrast with the real event which typically lasts from 30-45 seconds (CM pers. obs.). The attempted copulation was repeated another six or seven times during the next 10 minutes, between bouts of circling behaviour. This behaviour was maintained for a total of 20 minutes before the bird lost interest and began feeding. A similar record of a Red-necked apparently trying to copulate with an inanimate object has been described at Werribee Water Treatment Plant, Vic., in August 1991 (Weston & Rush 1992). It was suggested that the behaviour observed MINTON & COLLINS: AUSTRALIAN 344 Banded Stilt Unusual Copulatory Display BIRD WATCHER

there may have been as a result of the stick representing a super-normal stimulus or could possibly represent a 'practice' exercise. Long-legged species may need to practice to enable successful manipulation of awkward limbs into a complex position for successful copulation to take place (Weston & Rush 1992). Unlike Red-necked Avocets, Banded Stilts may get the opportunity to breed only once or twice each decade (Marchant & Higgins 1993). The Banded Stilt was in full breeding , as "Yere at least half of the birds in the flock; this is normal, even in non-breeding flocks of Banded Stilts (CM pers. obs.). The last known occasion that Banded Stilts were recorded breeding was from March to June 1989, at Lake Torrens, South Australia (Marchant & Higgins 1993). It is possible that undetected breeding in the more remote parts of north-eastern South Australia has occurred during wet periods since then, possibly during the autumn and winter of 1996, which were wetter than usual. At the time of our observation, the area around Moulamein was experiencing the first stages of a severe drought, and it is unlikely that breeding was imminent. The Tullakool Saltworks would not, incidentally, appear to be a suitable breeding location for Banded Stilts. Apart from a possible deficiency of food resources, it lacks the raised islands on which this species prefers to nest (Marchant & Higgins 1993). This observation falls outside both the probable breeding season and the usual breeding distribution of Banded Stilts, in contrast with the observation of the Red­ necked Avocet by Weston & Rush (1992). However, the question remains of why this Stilt, in the company of so many other Stilts, should display such behaviour, which was ignored by the remainder of the flock. Indeed, the observation of the Red­ necked Avocet was also made in a pond with many uninterested conspecifics nearby, some as close as 10 m (M .A. Weston pers. comm.). What stimulated this individual to direct its attention to an inanimate object remains a mystery. It did, however, give several people the opportunity to witness the copulatory display of the Banded Stilt without having to achieve the difficult task of finding and visiting a breeding colony, especially at the early stages of formation.

References Marchant, S. , & Higgins, P.J. (Eds) (1993), Handbook of Australian, New Zealand & Antarctic Birds, vol. 2, Oxford University Press, Melbourne. Weston, M. & Rush , M. (1992), ' Probable pseudo copulation of a Red-necked Avocet', Stilt 21, 28. By CLIVE MINTON' and PETER COLLINS2

1165 Dalgetty Road, Beaumaris, Victoria 3193 2507 Settlement Road, Cowes, Victoria 3922 Received 13 January 1998 •