NORTHERN TERRITORY N ATURALIST NT Field Naturalist’s Club NO. 7 THE NORTHERN TERRITORY FIELD NATURALIST CLUB FOUNDED 1977 Officers for 1984/85 President: John Estbergs Secretary: Keith Fisher Librarian: Sue Wills Treasurer: Greg Wills Editor of the N.T. Naturalist: Stephen Swanson The objects of this club are to promote the study of and interest in the flora and fauna of the Northern Territory and in its conservation. The club provides opportunities for discussion and dissemination of information among its members by regular meetings, publications and fieldwork. It works in close contact with scientific institutions wherever possible, and encourages the publication of scientific and informed popular literature in the various fields of natural history. N.T.F.N.C. Subscription Rates: $12.00, Family membership $15.00 All members receive the regular newsletter Nature Territory and the NT NATURALIST. The Club holds monthly general meetings and field excursions. P.O. BOX 39565 WINNELLIE N.T. 5789 Advice to Contributors Contributions to the N.T. Naturalist need not be members of the N.T.F.N.C., although all members are urged to contribute. Contributions may take one of the following forms: Letter to the Editor A letter should be a short comment on a previous publication in the N.T. NATURALIST, a comment on an issue of topical interest in natural history, or a brief report of a field trip. Letters may be handwritten provided they are well presented. Only one copy of a letter is required. Notes If you have made a series of observations (for example, on the behaviour of a bird or other animal) or have notes on something new or unusual in the field, then this is the place to report your findings. Contributions should be in the order of 200-500 words and provided with a title. Articles An article should run to a maximum of about 1500 words (four to five double-spaced typed, A4 pages) and deal with a topic in the sciences. It should be written in a manner intelligible to readers without a specialist knowledge of the subject. Articles should be appropriately illustrated by clear, black ink graphs, diagrams or photographs. Cover: Curl Snake Denisonia suta Northern Territory Naturalist 3 LETTER TO THE EDITOR/ ^ Dear Sir, Sewage treatment tanks, words that conjure up rather unhealthy preconceptions in the minds of most people, are often exceptionally happy hunting-grounds for bird-watchers. Wading-birds that nest in remote areas of the Northern Hemisphere during the spring months (March to May) make long migrations southwards. Many species arrive in Australia, either on purpose, or sometimes because inclement weather makes them overshoot their intended destination. This latter category seems to have an uncanny knack of finding refuge at nice, peaceful sewage tanks, often metamorphosing into giant ‘ticks' (ticks = a new bird for the list) for lucky members of the birding fraternity! Alice Springs sewage tanks provide an interesting freshwater habitat, just a few kilometres south of the town centre. On 12 November 1983 1 had just started around the perimeter of the tanks when I saw what looked like a tiny gull, floating very bouyantly on the water. Through the binoculars the bird’s needle-like bill became visible, deftly picking at the surface while the bird delicately pirouetted about. This bird had to be a species of the family Phalaropodidae. These birds typically feed while swimming, propelled by lobed-toes. Dense feather- masses on the belly account for the pronounced bouyancy, and the birds' gyrations are to create a turbulence which brings their invertebrate food closer to the surface. They breed mostly in the Arctic circle, the larger females instigating courtship and defending the nest against other females while the males incubate the eggs and then care for the young. This individual had grey upperparts and pale underparts. The top of the crown and back of the long neck was dark, and a blackish ear-streak was present on an otherwise pale head. The eye was dark, and the straight bill was totally black, about the same length as the head. When the bird flew a pale bar was seen clearly along the margins of the upper wing coverts; the tail was a dark colour. During the flight the call was uttered, which I wrote down as ‘tsic’. This, then, was a red-necked phalarope, Phalaropus lobatus , an unusual bird to see on the coastline of Australia, let alone in such an inland place many hundreds of kilometres from the sea. I did not see this red-necked phalarope ever touch land; it was always milling about on the water in close proximity to a flock of red-necked Avocets, Recurvirostra novaehollandiae, and even flew with these considerably larger waders. (Unbeknown to me then, Mike Fleming of the Conservation Commission had seen this individual a few days before Ian Archibald and myself. The bird left the area shortly after our visit.) David Percival Museum and Art Galleries of the Northern Territory 4 Northern Territory Naturalist NOTES ON THE SCINCID LIZARD Cryptoblepharus litoralis (Mertens, 1958) IN THE NORTHERN TERRITORY Paul G. Horner Division of Natural Sciences Museum and Art Galleries of the Northern Territory Cryptoblepharus litoralis was first recorded in the N.T. by Gow, 1981. This record was based on two specimens collected by the present author and G. Gow, from Cape Wessel Island (11°00'S 136°46'E, October 1979). Subsequent field work along the Arnhem Land coast by the author, has shown that the species is present on both New Year Island (10°55'S 133°02'E) and Oxley Island (10°59'S 132°50'E). These records extend the species distribution westwards, almost to Croker Island (figure 1). The skink was previously known only from the coastal fringes of northeastern Queensland. Torres Strait Islands and New Guinea. The genus Cryptoblepharus is composed of active, diurnal lizards which are normally arboreal or saxicoline in habit. The lower eyelid is fused to the upper, leaving the eye covered by a transparent disc. This character gives the genus its vernacular name of ‘Snake-eyed skinks’. Cryptoblepharus litoralis is a large, dark coloured species, which is known from a variety of habitats in the supralittoral (foreshore) zone. Of the eight N.T. specimens collected, only the specimen from New Year Island was found amongst beach debris. Other specimens were active on or around rock outcrops, close to the water’s edge. Observations on the behaviour of C. litoralis from Oxley Island provided interesting results. They are agile, fast moving animals which, in a suitable habitat, tend to congregate in smalt groups. Several specimens were observed foraging amongst rocks in the intertidal zone, one of which, upon collection, disgorged a polychaete worm of the family Nereidae. Cogger (1983) lists their usual diet as amphipods and other small marine animals. When confronted by an incoming tide the lizards retreated to the fringing vegetation. However, a few specimens were observed on rocks completely surrounded by water. When cornered these animals leaped into the sea and rapidly swam to the shore or another rock. I consider this to be atypical behaviour, as it would possibly leave them susceptible to predation by fishes. The N.T. specimens showed little variation in morphological characters when compared to a similar sized sample from northeastern Queensland (table 1). There are slight differences between the two populations, specifically in the mid body scale count and the number of lamellae under the fourth toe. These two characters were compared for similarities or differences between the two populations, using a Mann Whitney U-test. The results indicate that there are significant differences between N.T. and Old. specimens. Cryptoblepharus litoralis is generally characterised by its foreshore dwelling habits, but other species of Cryptoblepharus also may be found in close proximity to the shore. Table 2 lists some of the taxonomic characters which may be used to differentiate N.T. species of Cryptoblepharus. Northern Territory Naturalist 5 Material examined: N.T. Museum: R7761-62 Cape Wessel I.; R10905 New Year 1.; R10923-27 Oxley I. Old Museum: J20434-35 Lizard I.; J25448-49 Johnstone River; J27680 Magnetic I.; J32562-63 Townsville; J32565 Magnetic I. Acknowledgements My thanks go to Ms J. Covacevich. Curator of Reptiles at the Queensland Museum, for the loan of specimens in her care. Special thanks go to Mr J.N.A. Hooper who critically read the final draft. References COGGER, H.G. (1983) Reptiles and Amphibians of Australia, AH. & A.W. Reed Pty. Ltd. GOW, G.F. (1981) Checklist of Reptiles and Amphibians of the Northern sector of the N.T., N.T. Naturalist No. 4. Table 1: COMPARISON OF BODY PROPORTIONS AND SCALE COUNTS OF Cryptohlepharus litoralis IN THE N.T. AND QLD. Feature N.T. n=8 Qld. n=8 hindlimb length, % SVL 38.6-52.6 mean = 44.1 41.5-46.7 mean = 43.8 axilla to groin length, % SVL 43.5-54.9 mean = 50.3 48.3-57.6 mean = 53.0 forelimb to snout length, % S VL 35.3-45.1 mean = 39.3 35.6-40.0 mean = 37.8 mid body scale rows 27-30 mean = 28.1 26-27 mean = 26.3 paravertebral scale rows 49-56 mean = 51.9 49-55 mean = 51.6 no. of lamellae under 4th toe 17-19 mean = 18.1 19-24 mean = 20.6 6 Northern Territory Naturalist Table 2: COMPARISON OF SOME MORPHOLOGICAL CHARACTERS OF N.T. MEMBERS OF THE GENUS Cryptoblepharus species subdigital lamellae lower surfaces of hands & feet number of supraciliary scales max. snout/ vent, length carnabyi finely keeled whitish 5 40 mm litoralis smooth black 5 55 mm megastictus smooth whitish 6, rarely 5 40 mm plagiocephalus smooth light brown/ whitish 6,rarely 5 47 mm FIGURE 1: MAP SHOWING THE N.T. ISLANDS WHERE Cryptoblepharus litoralis HAS BEEN RECORDED Northern Territory Naturalist 1 Figures 3 and 4: Cryptoblepharus litoralis — N.T.M. R7762, from Cape Wessel Island , N. T. Scale in mm. 8 Northern Territory Naturalist FIRST SIGHTING OF THE SPOTTED REDSHANK Tringa erythropus IN AUSTRALIA John L. McKean and Alan R. Dampney Introduction Larger than usual numbers of waders visited the Darwin area during the 1983/84 summer. Exceptional numbers were recorded for the less common species such as Oriental Plover Charadrius veredus, Long-toed Stint Calidris subminuta, and Wood Sandpiper Tringa glareola. Rarieties observed included Ruff Philomachus pugnax, Little Ringed Plover Charadrius dubius, Little Stint Calidris minuta, Pectoral Sandpipers Calidris melantos, Pin-tailed Snipe Gallinago stenura, Redshanks Tringa totanus, the first record for Northern Territory of Bairds Sandpiper Calidris bairdii (McKean, in press 1984). and the first reported sighting of the Spotted Redshank Tringa erythropus in Australia, which is the subject of this note. The Spotted Redshank breeds in the northern Palearctic from Scandinavia to far eastern U.S.S.R., migrating south to 'winter’ in Africa, South and Southeast Asia to the Malay Peninsula (Medway and Wells, 1976). It occasionally occurs further east, (e.g. at least thirteen sight records from Borneo; Smythies, 1981) and recently (August 1983) a single bird was seen on Halmahera, Moluccas (Peter Kaestner, pers. comm.). It is, perhaps, surprising that this species has not previously been recorded in Australia. Field Notes On 16 November 1983. at 0615 hours we were watching waders at Darwin, N.T. McKean's attention was drawn to a wader flying in from the sea uttering a whistled ‘chu-eet, chu-eet'. Although McKean had heard Spotted Redshanks previously in Hong Kong he could not immediately identify the call but knew that it was not that of a wader normally found in the Northern Territory. In flight the bird appeared about the size of a Greenshank Tringa nebularia with a similar white rump patch extending in a wedge up the back. The upper surface of the wings were plain except for some lighter mottled areas on the wing coverts and the bird lacked any indication of a wing stripe. The bird landed in front of us. but with the sun directly behind it viewing conditions, despite the use of a 20X telescope, were not optimal. The following identification points were noted. The bill was long, straight and dark but paler at the base. It was proportionally longer than that of a Redshank. The legs were also longer than those of a Redshank but the poor light prevented us from being sure of th§ir true colour. We though they could have been blackish red. A noticeable white superciliary stripe was present, throat white; well marked brown grey pectoral gorget; belly and rump white; tail end dark, and dorsal plumage brown grey exactly the shade of the bird in figure 3 of plate 50 in Cramp etal. (1983). When the bird lifted its wing the underwing coverts were seen to be whitish. The bird appeared very nervous and vanished while we were clambering down the rocky cliff for a closer view. At 1530 hours on the same day McKean revisited the area and heard the bird call from behind some rocks. He did not disturb the bird as other observers had been notified and he hoped they would see it later on. The bird Northern Territory Naturalist 9 was seen again by McKean, briefly between rain squalls at 0715 hours the following day and the legs were noted to be orange and the dark end of the tail was seen to actually consist of barring. The Spotted Redshank has not been seen subsequently. References CRAMP, S. et al. (1983) Handbook of the Birds of Europe, the Middle East and North Africa, Vol. 3, 913 pp. Oxford Univ. Press: London. McKEAN, J.L. (1984) A Northern Territory sighting of the Baird’s Sandpiper, Aust. Bird Watcher (in Press). MEDWAY, Lord and WELLS, D.R. (1976) The Birds of the Malay Peninsula, Vo. 5, 448 pp. Witherby: London. SMYTHIES, B.E. (1981) The Birds of Borneo, 3rd Ed. 473 pp. Sabah Society: Kota Kinabalu. 10 Northern Territory Naturalist STREAKED SHEARWATER Calonectris leucomelas IN THE NORTHERN TERRITORY David Percival c/- N.T. Museum G.P.O. Box 4646, Darwin N.T. 5794 Carter (1983) has drawn attention to the regular occurence of this species in Northern Australian waters. Observations made on 17 February 1984 from T.S.M.V. Febrina, which was cruising between Darwin and Gove, (10° 53'.49s, 133°39'.89e) additionally confirm this. The conditions were cloudy, with slight drizzle, and wave-height was about 1.5 metres. At 16.40 a single Streaked Shearwater was seen flying past the vessel. Single birds and groups of three or four were seen regularly after this, until 17.15 hours, when a large group of birds was seen. A small cloud of fifty Sooty terns Sterna fuscata were working fifteen to twenty metres over a large ‘raft’ of about one hundred and fifty Streaked Shearwaters. They were settled on the ocean surface, which was erupting with tuna of about 0.5 kilo. As the tuna moved off to another area, the whole mass of birds would fly over to where the fish reappeared. The only other Procellariidae seen with the Streaked Shearwaters were a Tahiti Petrel Pterodroma rostrata and a heavy, all dark-brown bird, of a similar size to Calonectris leucomelas, which I could not identify. M. Carter (in litt. to J.L. McKean, Mss. in prep.) has a number of unpublished sightings of P. rostrata off the N.T. The tuna were identified by Helen Larson (N.T. Museum), also on the boat, as being probably Northern Bluefin Thunnus tonggol. These typically school and drive their food (fish and squid) to the surface. Reference CARTER, M. ‘Streaked Shearwaters in Northern Australia’, Australian Birdwatcher 10(4): 113-121. Northern Territory Naturalist 11 Figure 1: Streaked Shearwater — underwing and side-view. The painting was taken from a study-skin at the N. T. Museum. The dead bird was presented to the museum anonymously. Any information about the location of collection and date would be appreciated. 12 Northern Territory Naturalist THE CURL SNAKE Denisonia suta (Peters) A DANGEROUS ELAPID IN THE NORTHERN TERRITORY Mike W. Gillam Conservation Commission of the Northern Territory Alice Springs, N.T. 5750 Owen J. Williams Arid Zone Research Institute Department of Primary Production Alice Springs, N.T. 5750 Summary The Curl snake Denisonia suta (Fig. 1) has previously been disregarded as a species potentially dangerous to man. A venom toxicity study undertaken on Northern Territory specimens reveals a subcutaneous LD. (| of 20.68 /jl. g. in 20 gram mice. Variation is evident in the total lengths of adult snakes collected from three geographically isolated populations and this feature is correlated with venom yields of adult specimens representing two of these populations (Fig. 3). Some aspects of D. suta natural history in the Northern Territory are considered in the assessment of its threat to man in this state. Introduction Throughout its distribution Denisonia suta is entirely nocturnal in habit and shelters during the day beneath rocks and debris or in deep ground crevices. Probably because of its small size, D. suta has not been regarded as dangerous to man. Most authors agree that it is capable of inflicting an extremely painful bite or that care should be taken with large specimens (Kinghorn, 1964, P. 176; Kellaway, 1934; Worrell, 1966, P. 146; Cogger, 1979, P. 404; Gow, 1976, P. 65; McPhee, 1979, P. 70) however it has also been inferred to be an innocuous species (Flouston, 1973). In November 1979 a domestic cat sustained a fatal bite while eating a juvenile D. suta in a residential area of Alice Springs. Details of this case are presented below. Following this incident a study was initiated to assess the potential of D. suta as a snake dangerous to humans. In this assessment we have examined snake length, venom yield and venom toxicity combined with relevant information on the distribution, behaviour and ecology of the species. Northern Territory Naturalist 13 Fig 1: Typical adult from Alice Springs district. Methods To determine venom yields, captive specimens were deprived of food for a week prior to venom extraction. During early trials it was discovered that captive snakes readily expelled venom for about the first 20 seconds they were handled but any prolonged attempt to individually ‘milk' both glands usually resulted in a poor yield from the second fang. To overcome this bias a pipette was used to milk venom from the right side fang only and this venom weight was then doubled to provide the total yield. The LD. () determination was calculated using the Spearman-Karber method (Finney; 1964) with venom obtained from snakes collected from the Barkly Tableland and Alice Springs districts. Fresh and freeze-dried, reconstituted venom was used. Eighteen to twenty one gram laboratory white mice were injected subcutaneously in the flank with a 0.2 ml saline solution of a range of dilutions of fresh venom. The range of doses given was from 8 p.g. to30p.g. in a dose interval of 1:1 'A. Deaths were recorded over a 48 hour period. Results Distribution and Habitat: In the Northern Territory this species is represented by three geographically isolated populations (Fig. 2). Throughout the central Alice Springs district it inhabits rocky ranges and adjacent riverine and woodland areas. In the Barkly Tableland district, it occurs throughout the 'black soil’ tussock grass plains. The two Victoria River district specimens were collected from an alluvial flood plain with grass tussocks and cracking soil. 14 Northern Territory Naturalist Fig. 2: Distribution of Denisonia suta in the Northern Territory. Geographic Variation in Snake Lengths: Twelve specimens collected from the Alice Springs district ranged from 31-56 cm in total lengths with a mean of 43.5 (s.d. = 8.3). Twelve specimens collected from the Barkly Tableland district ranged from 57-75 cm in total lengths with a mean of 70.3 (s.d. = 5.4). Only two specimens, measuring 52 and 54 cm in total lengths, have been collected from the Victoria River district. The tails of all snakes measured, were complete. Northern Territory Naturalist 15 70 60 50 VENOM YIELD 40 Wet 3 o Weight (mg) 20 10 0 r = 094 yield = 1.4 (length) -44.7 * O