The Breeding of Birds in the Aldinga Scrub Conservation Park, South Australia
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VOL. 12 (3) SEPTEMBER 1987 73 AUSTRALIAN BIRD WATCHER 1987, 12, 73-82 The Breeding of Birds in the Aldinga Scrub Conservation Park, South Australia By C.B. ASHIDN, P.O. Box 125, Aldinga Beach, S.A., 5173 Summary The breeding of birds in the Aldinga Scrub Conservation Park, coastal South Australia, is examined from data on 990 nest record submissions to the RAOU Nest Record Scheme over the period 1979-1986, predominantly the 1984 and 1985 seasons. Sixty-four species were recorded breeding, the highest seasonal breeding total being 470 nests. Species breeding totals corresponded fairly well with previously assessed species abundance. Some differences in incubation and nestling periods and clutch sizes from those given in standard reference books are noted. Introduction This paper supplements a previous one on the status and abundance of birds in the Aldinga Scrub Conservation Park, previously known as the Aldinga-Sellicks Beach Scrub (Ashton 1985), by summarising data from 990 nest record submissions to the RAOU Nest Record Scheme (NRS) for 64 species in the 1979-1986 breeding seasons. The Conservation Park (35 "17 'S, 138 OZ7 'E), consisting of about 7:15 hectares 45 km south of Adelaide, is the sole remnant of coastal dune vegetation of any significant size on the eastern side of St Vincent's Gulf south of Adelaide. Its vegetation formations (for details see Ashton 1985) consist mainly of dry sclerophyll woodland with some grassland and fernland, low and tall shrubland (a 400 m wide belt between coastal and secondary dunes) and swampland. Methods The Scrub was traversed using eight well-defmed tracks: four in a north-south direction, four in an east-west direction with excursions made in between these. In the 1985 season nest searching and monitoring was done for about four hours nearly every morning, and at some other times, between mid July 1985 and the end of January 1986. Ground observations of nests were occasionally supplemented by the use of a stick and mirror, stool, ladder and climbing of the nest tree. Disturbance was kept minimal early in breeding in the belief that it is then that birds are most likely to desert nests, hence in some cases only approximate building and laying times were obtained. The highest seasonal totals, 215 and 470 nests, were in the 1984-85 and 1985-86 seasons respectively. For some species the largest number of nests found in a season is compared with the number of groups or pairs believed to be present, e.g. Golden Whistler: total 25 nests (max. 13 nests/season, 12-17 pairs). This estimate of groups or pairs was based on the results of entering sightings on to maps over a period of four years. In general there was a correlation between the largest number of nests found in a season and the estimated abundances (Ashton 1985). The following definitions are used in the systematic list (following Marchant 1984). Breeding season (BS): time period during which clutches were started. For this determination, where the actual start oflaying was not observed nests were aged from the date of hatching, estimated age of young in the nest or date of fledging where incubation and, if necessary, nestling periods had been determined during the course of this survey. Clutch size: the criteria for acceptance were (a) laying followed through until the same number of eggs '.vas found after successive laying intervals appropriate to the particular AUSTRALIAN 74 ASHTON BIRD WATCHER species; (b) finding an incomplete clutch and then later finding a number of eggs in the nest that according to the laying routine of the species must have been laid in a shorter period than the intervals of observation. Clutch size is presented as C/1, C/2, C/3 etc. and the number of such clutches preceded by x, e.g. Mistletoebird C/2 x 3, C/3 X 6, C/4 X 1. Incubation period (IP): period from laying of last egg to hatching of last young. Nestling period (NP): hatching of last young to fledging of same. Where IP and NP criteria are not met an explanation is given concerning the nature of the entry. IP and NP values refer to single nests. Nest success rate (NSR): percentage of nests producing fledglings. Breeding success rate (BSR): young fledged per egg laid. Table 1 presents data for species with more than 20 nests and at least nine known clutch sizes followed to final result. DY: dependent young only. Such records are disregarded in nest success rate calculations. Results The results are presented in Thbles 1-3 and in the annotated list below. Table 1 shows breeding success for those species which provided sufficient data. Table 2 shows breeding records on the basis of dependent young only, Table 3 lists the species of vegetation most commonly used for nest sites and Figure 1 shows the breeding periods for 20 species having a reasonable number of nests with known starting dates for clutches. Annotated list Totals refer to number of nests observed. White-faced Heron Ardea novaehollandiae Total 10. Earliest record of brooding 17 August, latest nest containing young Z7 December. Black-shouldered Kite Elanus notatus Total 7. One season bred twice in same nest: two fledged on 7 September, next seen brooding again 17 October, two fledged 26 December. Two nests used in two successive years (cf. Hollands 1984: 'Nest normally used once only but one nest . .. used twice'). Brown Goshawk Accipiter fasciatus Total 2. Same nest fledged young in 1984 and 1985. In the second year the male was a different bird, in immature plumage. Brown Falcon Falco berigora Total l. Bred in an Australian Magpie nest in which the latter fledged young in October 1981, the falcon young fledging on 13 December of the same year. Australian Kestrel Falco cenchroides Total 3. Used same nest in two successive years. Stubble Quail Cotumix novaezelandiae Total 2. DY2. C/9 x l. Masked Lapwing JUnellus miles Total 3. Earliest hatching l3 August, latest 10 November. Sitting bird rose to drive off Marsh Harrier Circus aeruginosus. In one nest two chicks were heard cheeping in the eggs 48 hours before they hatched. The two young were brooded for longer than 24 hours from the hatching of the second young. Banded Lapwing JUnellus tricolor Total 3. Earliest brooding recorded 28 July. An association of a sitting bird with a partly eaten three-week-old embryo was noted (field notes): 'Now only three (previously four) eggs. 3.0 em from nest is the fresh, moist, naked head and neck of embryo with a little shell attached. Other eggs warm. No sign of predator. Cows nearby'. When chicks were 36 days old one parent was a road kill; one young seen with remaining parent a month later. VOL. 12 (3) SEPTEMBER 1987 Breeding of Birds, Aldinga Scrub Conservation Park, S.A. 75 Red-capped Plover Charadrius ru.ficapillus Total 4. Earliest brooding recorded 19 August. Black-fronted Plover Charadrius melanops Total I. Hatched 26 September. One egg pipped at 0700 h, three downy young (one not completely dry)) at 1630 h. Still being brooded Tl September at 0700 h, no sign of adult or young at 1120 h. Black-winged Stilt Himantopus himantopus Total 15. Earliest record of brooding 16 September, latest hatching 24 October. One bird resumed sitting early in brooding after eggs covered by water for seven days and successfully hatched four young (one found floating dead below nest). Australian Pratincole Stiltia isabella Total 1 (C/2). Start of laying 23 September, egg hatched 13 November, IP 19 days ± 1 day. Spotted Turtle-Dove Streptopelia chinensis Total 65. Success 21, failure 36, NSR 35%. BS 30 August to 23 January, peak laying October and November. C/1 x 1, C/2 x 50. Flushing was often hasty, resulting occasionally in a damaged egg. Young often brooded to fledging. Twice, young that fledged on approach returned to the nest for a further day. Once a second brood in the same nest (intervals from loss of young to laying of next egg 41 days). Two New Holland Honeyeaters were observed eating a clutch of two eggs. A brooding adult was caught by a cat. Nest site: catholic in choice. Crested Pigeon Ocyphaps lophotes Total 30. Largest number of nests recorded in a season 17. DY 1. Success rate 13, failure 13, NSR 48%. BS: 21 September (first nest-building observed 23 August) to 26 December, peak laying October December. C/1 x 1, C/2 x 16. Young often brooded to fledging (more tightly than Spotted Thrtle-Dove), and a brooding bird repelled an immature Australian Magpie. This was at a nest 9 m high in a eucalypt that had been used in another season by Australian Magpie and Brown Falcon. Also escaped predation whereas a House Sparrow nest 1 m distant in the same bush did not. Once, young that fledged on approach returned to the nest for a further day. Experience before this survey showed that this species readily deserts nests if disturbed early in breeding. Once brooded on nil contents for at least 10 days. A building adult was caught by a Brown Goshawk. Thwny Frogmouth Podargus strigoides Total 3. DY 1. Earliest recorded brooding 6 September, latest fledging 25 October. Same nest used in three successive years, then nested in adjoining tree after a road was built alongside the first site. Laughing Kookaburra Dacelo novaeguineae Total 5. First inferred brooding 19 September, latest fledging 30 December. Same nest hole used in two successive years twice, each time being displaced by Honey Bees Apis m!dlifera; new nest site made available by recent fall of hollow limb.