NOTES

MELOMYS RUB/COLA , AN ENDANGERED MURID ENDEMIC TO THE OF

THE BRAMBLE CA Y (Melo­ had obtained from the natives of E rub 1 'vVe rnys rubico/a Thomas, 1924) is a little sent pa rties to 11·atch for turtle t 11·o night s but known A ustralian rodent recorded on ly from 11·ithout success, hm1·ever 11·e found the Spinach o f Raine's Island abundant here also, and 11·ha t Bramble (9°09'S, 143 o 52' E) , a s mall 11·ith this and the eggs and a fe11· fish from the vegetated cora l cay at the extrem e northern reef, made a ve ry tolerable addition to our e nd of the Great Barrie r Reef (Tate 195 1). 'Sa lt -horse'." The presence of the rats was reported by Sweatman when Europeans. on HiVIS Bramble , When Bramble Ca y was visited in D ecembe r. discovered the island in early April , 1845. The 1977 a nd 1978, the rats p rinc ipally inhabited ext ract from his diary (Vol. 2, C h. 16 w hi c h the dense 40 c m hig h g ro und cove r of g rass. is unpublished ) refe ring to is Lepturus repens a nd the herbaceous Boerhavia as foll ows: repens and Susaviwn portulacas/rum ( F ig. I). By spo tlig ht at night they were seen fo raging " We found a large key or rather islet to thro ugh the vegeta ti o n a nd o ut o nto the 11·hi ch 11·e gave the name of 'Bramble Cay' but beach to a bo ut the spring high tide level ll'hich is ca ll ed by the nati ves of Erub ' Kaedha', a nd 11·hi ch being a con ve nient isolated spot and w here they we re freque ntly seen in the vicinity free from the presence of natives was fixed o f logs. Whe n disturbed. they gene rall y re­ upon fo r our Northern base Station. It put me trea ted into the vegetation or beneath logs, very much in mind of Raine's lsle.t being lik e but they occasio nally retreated cl own crab it composed of a plateau of soft stone with a (Ocypode sp. ) burrows. There was no indica­ high sa nel y beach thrown up round it a nd a tio n that this rat dug burrows for itself. The fringing coral reef stretching out nearly a mile tota l rat po pula tio n o n B ramble Cay was esti­ to the S.E. but very na rro\\' to the N .W. o f the mated at a m aximum of severa l hundred islet which is a lso like Raine's Islet covered individua ls in December. 197R. T he re was no ll'ith coarse green vegetat ion and frequented by inumerable quantities o f sea birds. whose eggs indica tio n that this ra t prevs on the eggs o r were a rare prize to us. Unlike Raine's lslet young of a n y of the numerous sea birds o r however, Bra mble Cay was not based upon a turtles that breed on the island. coral reef, but upon a mass of igneous rock simila r to that of Darnley Isla nd , a large patc h The cay is o n the m ove. Sweatman recorded of whi ch 20 or 30 feet high and some 50 or a reef fl a t surro unding the island. Tn desc ribing 60 across, appears above the coral reef at the the geology of Bramble Cay in 1924, Ja rdine S. E. end of the is·'et, while anoth er patch o f ( 192R) illustrated a cay extending over the the sa me frin ge d with coral, drie.s at low water northwestern edge of the reef. H e m easured about four miles to the S.W. the depth between the axes of the cay at a pproxima te ly 20 the two bein g 20 to 25 fms, in which ancho rage c hains lo ng and 8 c hains broad (402 x 161 m ). may be obta in ed a ll round. The islet is about By 1976 the Cay ha d moved to li e at the a furlong across and 15 feet above low water mark, there is no fresh water on it but it edge of the reef platform and its sand was appea rs to be visit ed occasiona ll y by the na ti ves spilling off over the no rthweste rn reef edge for the purpose of taking fish and turtle : of into d eep water. Tn 1958 a te mpo ra ry scaffold the latter they must obta in a plentiful supply tube and c lip struc ture supporting a naviga­ for we found upward of 60 shell s arrange d in tion li ght a nd gu yed by fo ur steel wire ro pes regular order, head to ta il , round the south to conc re te blocks was e rected on the sou th­ end of the isl et, for what purposes we could easte rn e nd o f Bramble Cay. A t that time not imagin e but I fan cy through some mere the outer ed ge o f the scaffold foundation idle whim. On capsizing them numbers o f was 6. I m inla nd from the m a rgin o t' the large rats made their escape from beneath them, and our people, who (bein g Sunday) had phosphatic rock platfo rm. By 1972 the south­ an aft ernoon's leave on shore to coll ect eggs eastern end of the isla nd had e roded back for their messes, amused themselves with to the scaffo ld foundations a nd this caused shooting them with the bows and a rrows they the re placem e nt o f the a bove " te mpora ry 78 AUSTRALIAN MAMMALOGY light" with the present stainless steel naviga­ with certainty" (Thomas 1924) . No rats were tion li ght in 1973. Thus during t he 14 years seen during a superficial examination of the commencing 1958 there was a nett e rosion sand and shingle ramparts on the western of the southeastern margin of the rock plat­ side of Long Island in December, 1978. The form of 0.44 mfyr. status of the Long Island !v!e/omys is depen­ dent on specimens of this rodent being Erosion has continued. Tn October. 1978, a recollec ted. portion of the concrete foundat ions of the " temporary li ght" fell onto the beach. T here A ll other Me/umys spec imens coll ected is no nett growth of the island in other direc­ (Dowar Island, 9' 55'S, !44' 04'E and Hanni­ tions and sand is being lost irretrievably from bal island, 11 ' 36'S, 142'56'El were referable the northeastern end where it fal ls away into to At/. burtoni (based on skin and skull deep water. If this trend continues, Bramble characters; E. Knox, pers. comm.). Cay wi ll eventua ll y be lost from the reef flat. Studies of the blood proteins of Me/omys Thus the type locali ty of M . rubico/a may be lost by e rosion. Tn December, 1977 a nd rubico/a (unpublished observations CHSW. specimen numbers: lMVS MR I and 2) show 1978, the cay measured approximately 750 111 that it is most closely a llied to in circumference (lo ng axis 340m, short axis M . capensis 150m) at the spring high tide level. and it is probably an island race of this species. However, pending further biochemical Attempts by the a uthors in recent years and morphologica l study of tl1e M . cervinipesf to find this rodent on other islands in eastern 1\11. capensis taxonomic complex, we feel it and the northern Great Ba rrier is premature, and not the place here, to for­ Reef have proved unsuccessful. Thomas, in mally suggest synonomy of M. capensis and M. describing M . rubico/a, mentions a single rubico/a. This complex includes a numbe r of specimen of a .Me/omvs from Long Island (a isolated forms, either on offshore islands or la rge mangrove island in central Torres Strait, in pockets of closed-forest along the east 10' 02'S , 142 '50'E) collected presumably in coast of . A taxonomic reviSIOn J 845 which ". appears to be M. rubico/a, would be better based on study of these forms but is not in a condition to be determined as we ll as those noted above

Fig. 1. Bramble Cay, November, 1977. Melomy.1· rubicola inhabits the vege tated section. LIMPUS, PARMENTER and WATTS: MELOMYS RUB/COLA 79

The differs from assistance during the preparation of the manu­ mainland populations of M. capensis in the script. A copy of C hapter 16 of Sweatman's Iron Range and Mcl!wraith's ranges area by unpublished journal, Volume 2, was provided two out of thirty proteins ( personal observa­ by the Mitchell Library. This assistance is tion CHSW). The tail is a little longer a nd gratefully acknowledged. considerably rougher than in mainland M. capqnsis, due to the individua l scales standing R EFERENCES ou t from the tail. Although these differences J,\IWI NE, F., 1928. Bramble Cay, Torres Strait. - are slight, they are great enough to indicate Geological notes. Reports of th e Great that the Bramble Cay population is recognis­ Barrier Reef Commillee 2: 93-100, pi s 6-7. ably different from populations on the main­ SwEATMAN, J. (unpublished). " Journal of a sur­ land of Cape York. veyi ng voyage to the N .E. coast of Australia T he biology of M. capensis is poorly known and Torres' Strait in Her Maj. Schooner " Bramble", Lieut. C. B. Yule, Commander. (Watts and Aslin 1981). Most have been 1842-1847". Yo·! 2: 15-16. caught in the narrow scrubby transition zone between closed forest and grassland rather TATE, G. H. H., 1951. R esu lt s of the Archbold Expeditions. No. 65. The of Aus­ than inside the forest which is the u sua l tralia and . Ru/1. Amer. Mus. habita t of the related /11/ . cervinipes in Queens­ N at. His!. 97 : 296. land. This preference to live in seasonall y dry THOMAS, 0., 1924. Some new Australasian and relatively open habitat may go part way . Ann. Mag. Nat. His/. (Ser. 9). 12: to explaining the presence on Bramble Cay of 296-99. the closely re la ted M. rubico/a. W ATTS , C. H . S. AND ASLIN, H. J., 1981. " The The Bramble Cay Melomys is a n ecologi­ rodents of Australia". Angus and Robertson: e