Monitoring of Cape Barren Goose Populations in South Australia

184 SOUTH AUSTRALIAN ORNITHOLOGIST, 30 MONITORING OF CAPE BARREN GOOSE POPULATIONS IN SOUTH AUSTRALIA. II. THE 1987 BREEDING SEASON AND FURTHER BANDING RECOVERIES L. B. DELROY, A. C. ROBINSON AND M. H. WATERMAN INTRODUCTION to limitations on boat availability. On 21 to 23 July 1987four observers landed on 10islands in The South Australian National Parks and the Sir Joseph Banks Group and systematic Wildlife Service conducted ecological studies of counts of adults, chicks and eggs of Cape Barren the Cape Barren Goose Cereopsis novaehollan Geese on each island were undertaken. The diae in its breeding habitat in 1974, 1979and 1985 observers made successive parallel sweeps, with and two surveys of its summering habitats in 1979 one member using a compass, until the whole and 1985. These surveys involved counts of island had been completely covered. Observers adults, chicks, eggs and nests in the major counted within approximately a 30 metre wide breeding habitat of the Cape Barren Goose in the strip, zig zagging constantly within the strip so Sir Joseph Banks Group islands offshore from that the distance of scan was as low as two or Port Lincoln, and the monitoring of the three metres in dense vegetation or where summering habitat around lakes Alexandrina and numbers were high, but up to 15 metres in open Albert. Details of this work have been reported country. This level of observation was in Robinson et at. (1982) and Robinson & Delroy approximately the same as that used in previous (1986). surveys. As the line moved across an island, all In the 1985 survey of the Sir Joseph Banks nests sighted were inspected for eggs (and to Group, rainfall in theIate autumn and early ensure that they contained down and were not winter had been low and numbers of adult birds, nests from previous years) and chicks were eggsand chicks wereless than in the two previous recorded as they were seen. Adults were recorded surveys. A further survey of Partney Island in by one person who attempted to ensure that the September 1985, following exceptionally heavy same group was not counted again in another rain in August, showed that both unfledged location. On many islands, chicks tended to be juveniles from the early breeding attempts and concentrated at the edges of islands and detailed chicks from later nestings werepresent. This was inspections of beaches, cliffs and adjacent areas contrary to the pattern in the two previous years were made, especially where there was any when breeding was synchronized with late evidence of this occurring. Some nests and chicks autumn rains. wereundoubtedly missed using this technique, so In July 1987 a further surveyof nesting activity estimates would be somewhat lower than the on some islands in the Sir Joseph Banks Group actual population size. was undertaken at the standardized time in the Banding Recoveries hope that the results would be more directly comparable with the 1974 and 1979 data. A total of 1104 Cape Barren Geese were Unfortunately the opening rains in the autumn banded in South Australia between 1966 and of 1987 were again below average. This paper 1979. Banding involved the attachment of a reports the results of that survey and recoveries colour-coded plastic collar, and a numbered leg of banded Cape Barren Geese in South Australia band (see Robinson et at. 1982, Appendix 1). In further to those reported in Robinson et at. addition, one of us (M. H. Waterman) has been (1982). co-ordinating a programme of leg-banding 776 METHODS Cape Barren Geese since 1964. The majority of these birds have been banded at Rocky River in Breeding Island Surveys Flinders Chase National Park, Kangaroo Island. Methods were similar to those outlined The details of this additional banding programme previously but fewer islands were surveyed due are given in Table 1. MARCH,1989 185 TABLE 1. Cape Barren Geese banded by Max Waterman and assistants from 1964-1986 Date Area No. Banded Leg Band Nos. September 1964 Waldegrave I. 5 140-25974 to 140-25978 July 1970 Rocky River 52 140-06601 to 140-06652 August 1971 Rocky River 48 140-06653 to 140-06700 April 1973 Victor Harbor 1 130-03956 April 1974 Rocky River 21 140-32501 to 140-32521 September 1974 Langton I. 4 140-06747 to 140-06750 April 1975 Rocky River 75 140-32522 to 140-32596 April 1976 Rocky River 62 140-32597 to 140-32658 September 1976 Rocky River 42 140-32659 to 140-32700 July 1978 Rocky River 14 150-27801 to 150-27814 September 1980 Rocky River 29 150-27915 to 150-27943 May 1982 Rocky River 4 150-27944 to 150-27947 October 1982 Rocky River 53 150-27948 to 150-28000 October 1983 Rocky River 130 150-'31011 to 150-31140 October 1984 Rocky River 82 150-31141 to 150-31171 150-31191 to 150-31224 150-31251 to 150-31267 October 1985 Rocky River 62 150-31172 to 150-31189 150-31225 to 150-31244 150-31268 to 150-31291 October 1986 Rocky River 92 150-31190 150-31245 to 150-31250 150-31301 to 150-31315. 150-31321 to 150-31328 150-31331 to 150-31390 150-31292 to 150-31293 TOTAL 776 RESULTS Breeding Island Surveys number of adults was lower than in 1974 and 1979 but higher than in 1985. The distribution of nests and groups of chicks of Cape Barren Geese on 10of the islands in the Prior to the islands being managed for Sir Joseph Banks Group in late July are shown conservation in 1967 most had been used for in Figure 1. This can be compared with Figure sheep grazing. This encouraged the growth of 8 in Robinson et al. (1982), which shows the grasses and limited the growth of shrubs. The distribution in June 1979 and with Figure 1 in geese now prefer locations on islands where Robinson & Delroy (1986), which shows the grasses are abundant, such as the southern half distribution in July 1985. Details of actual counts of Partney Island and the western end of Langton of adults, chicks, eggs and nests counted in 1987 Island. The north-eastern end of Roxby has are shown in Table 2; the counts may be considerable scrub and Atriplex low shrubland compared with the 1974, 1979and 1985 data from and little grass and has few nesting geese. Robinson et al. (1982) and Robinson & Delroy Rangers reported that some geese remained on (1986). the mainland during the 1987winter: 38 at Little Very few eggs were present in 1987 and Swamp near Port Lincoln in early July and 26 numbers of chicks were considerably fewer than at Sleaford Bay on August 18 (P. Hollow, pers. in 1974 and 1979 but higher than in 1985. The cornm.). 'A limited inspection of lakes 186 SOUTH AUSTRALIAN ORNITHOLOGIST, 30 TABLE 2. Counts of adult birds, chicks and eggs of Cape Barren Geese on the islands of the Sir Joseph Banks Group, 1987. The corresponding counts for 1974, 1979 and 1985 are in Table 1 of Robinson & Delroy (1986). ISLAND EGGS CHICKS EGGS PLUS CHICKS NESTS ADULTS Blyth * * * * * Boucaut * * * * * Dalby 2 7 9 5 35 Duffield * * * * * English * * * * * Hareby 5 0 5 15 29 Kirkby 0 4 4 2 32 Langton 0 92 92 12 76. Lusby 0 1 1 7 19 Marum 0 0 0 8 76 Partney 0 46 46 33 234 Reevesby * * * * * Roxby 27 26 53 28 82 Sibsey 3 7 10 25 74 Stickney * * * * * Winceby 0 7 7 26 30 TOTALS 37 190 227 161 687 * indicates that a count was not made on these islands in 1987. Alexandrina and Albert on 12 August failed to The combined rainfall for April, May and June, locate any geese. the critical months for producing food for Banding Recoveries breeding birds, was 70/0 above normal in 1974, 8%above in 1979, 17% below in 1985 and 12% A total of 1,875Cape Barren Geese have been below in 1987. banded in South Australia between 1964 and 1986. Twenty-five recoveries were reported in Cape Barren Goose eggs take 35 days to Robinson et al. (1982, Table 3). An additional 30 incubate. There is a further six weeks before the recoveries are shown in Table3, bringing the total young form flocks of juveniles (Reader's Digest to 55 since banding in South Australia began in 1983). Because the opening rains of the 1987 1964. season did not occur before early May, it was impossible for the young to have fledged and joined the juvenile flocks at the normal time of early July. DISCUSSION It appears that the majority of geese move Breeding Island Surveys from their summering habitat to the breeding The comparisons of counts of eggs and chicks islands. The geese that spent the winter in the on the islands of the Sir Joseph Banks Group in Port Lincoln area would probably have been 1987with 1974, 1979and 1985indicate that both below the breeding age of three years. The 1985 and 1987 were poor breeding years relative presence of birds overwintering on the mainland to 1974 and 1979. Rainfall for Port Lincoln in may be due to a limited availability of suitable April was 62 mm in 1974. 95 mm in 1979,42 mm . breeding sites on the Sir Joseph Banks Group. in 1985 and 16 mm in 1987 (Table 4). This There could now be a continuing reduction in the indicates a poorer opening to the season in 1985 amount of suitable breeding habitat present and 1987. On 2 May 1987, 21mm of rain fell and because of the increasing growth of shrubs and this appears to have initiated growth of grasses, herbs and the reduction in the growth of grasses which led to the nesting recorded on the survey.

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