DISTRIBUTION AND ABUNDANCE OF BROLGAS AND BLACK-NECKED STORKS IN THE ALLIGATOR RIVERS REGION, NORTHERN-TERRITORY

Aerial surveys between 1981 and 1984 were used to identify monthly tre nds in the abundance of Brolgas Grus rubicundus and Black-necked Stork s Ephippiorhynchus asiaticus on five floodplains of the monsoonal, sub coastal Northern Territory. Ground surveys were conducted during the s ame period on one of the plains, the Magela floodplain. Aerial surveys indicated that Brolgas were significantly more abundant in the dry se ason than the wet; they congregated particularly on the Cooper floodpl ain, were of intermediate abundance on the Magela and Nourlangie flood plains, and occurred only sporadically on the East Alligator floodplai n and Boggy Plain (a backswamp of the South Alligator River). Ground s urveys indicated that aerial surveys under-estimated abundance; based on rough correction factors calculated from ground surveys, peak numbe rs on the five floodplains were estimated at about 24 000. Black-necke d Storks were seen in low numbers on all floodplains, and did not vary significantly in abundance throughout the year. The total population was estimated at about 1800 birds.