David Priddel

An experimental translocation of brush-tailed bettongs (Bettongia penicillata) to western New South Wales

A total of 85 brush-tailed bettongs (Bettongia penicillata) from Western Australia and two sites in South Australia were translocated to Yathong Nature Reserve (YNR) in western New South Wales in October 2001. Aerial baiting to control the introduced red fox (Vulpes vulpes) had been undertaken on YNR since 1996. Thirty-one bettongs were fitted with radio-transmitters at the time of release, and two subsequently. Trapping took place at irregular intervals after the translocation. In all, 73% of telemetered bettongs died within the first six months; all were dead within 13 months. Eight bettongs died within the first eight days immediately following their release, due to causes other than predation. These eight all originated from St Peter Island (SPI), South Australia. A low incidence of breeding on SPI supports the belief that this source population was in poor condition and unsuited for translocation. Overall, 19 of the 33 telemetered bettongs were killed by predators: 14 (74%) by feral house cats (Felis catus), two (11%) by birds, and three (16%) by predators, which, although they could not be fully identified, were not foxes. One month after release, surviving bettongs weighed less than they did at the time of their release (mean decrease in mass = 9.7%, range 2.6–22.4%, n = 11). Within two months of their release most had regained any lost mass (mean change in mass since release = –0.3%, range –5.9 to 10.5%). Food resources on YNR appeared sufficient to sustain adult brush-tailed bettongs, despite a period of severe drought. Small pouch young present at the time of release were subsequently lost. Females gave birth and carried small pouch young (up to 50 mm), but no young-at-foot were recorded. Bettongs did not disperse further than 10 km from their release site. Overall, 50% of aerial-tracking locations were no further than 3.2 km from the release site, and 92% no further than 7.0 km. This experimental translocation of brush-tailed bettongs failed due to predation by cats. It demonstrated that foxes were no longer a threat to wildlife on YNR and identified cats as the major impediment to the restoration of locally extinct fauna.

High prevalence of Salmonella and IMP-4-producing Enterobacteriaceae in the silver gull on Five Islands, Australia

Objectives The objective of this study was to investigate the silver gull as an indicator of environmental contamination by salmonellae and carbapenemase-producing Enterobacteriaceae (CPE) in south-east Australia. Methods A total of 504 cloacal samples were collected from gull chicks at three nesting colonies in New South Wales, Australia [White Bay (n = 144), Five Islands (n = 200) and Montague Island (n = 160)] and were examined for salmonellae and CPE. Isolates were tested for carbapenemase genes and susceptibility to 14 antibiotics. Clonality was determined by PFGE and MLST. Genetic context and conjugative transfer of the carbapenemase gene were determined. Results A total of 120 CPE of 10 species, mainly Escherichia coli (n = 85), carrying the gene blaIMP-4, blaIMP-38 or blaIMP-26 were obtained from 80 (40%) gulls from Five Islands. Thirty percent of birds from this colony were colonized by salmonellae. Most isolates contained the gene within a class 1 integron showing a blaIMP-4-qacG-aacA4-catB3 array. The blaIMP gene was carried by conjugative plasmids of variable sizes (80–400 kb) and diverse replicons, including HI2-N (n = 30), HI2 (11), A/C (17), A/C-Y (2), L/M (5), I1 (1) and non-typeable (6). Despite the overall high genetic variability, common clones and plasmid types were shared by different birds and bacterial isolates, respectively. Conclusions Our data demonstrate a large-scale transmission of carbapenemase-producing bacteria into wildlife, likely as a result of the feeding habits of the birds at a local waste depot. The isolates from gulls showed significant similarities with clinical isolates from Australia, suggesting the human origin of the isolates. The sources of CPE for gulls on Five Islands should be explored and proper measures applied to stop the transmission into the environment.

A trial translocation of Gould's Petrel ( Pterodroma leucoptera leucoptera )

Abstract Aside from a few pairs recently discovered breeding on nearby Boondelbah Island, the Goulds Petrel (Pterodroma leucoptera leucoptera) is limited to a single breeding colony located on Cabbage Tree Island, New South Wales. The translocation of birds from Cabbage Tree Island to establish a new colony elsewhere, or to augment the small colony on Boondelbah Island, is an option currently being considered to aid the long-term conservation of this endangered species. We undertook a trial translocation of nestlings within their current breeding grounds on Cabbage Tree Island. This involved removal of the nestlings from the natal nest, denying them further parental care, relocating them to an artificial nest box and feeding them artificially. Thirty nestlings were translocated between gullies on Cabbage Tree Island after they had attained specific plumage characteristics thought to occur just prior to their first emergence from their nests. The translocated nestlings were confined to their adopted nest boxes for the first 3 days and artificially fed every third day until they fledged. The experimental translocation and the associated use of artificial feeding resulted in a small increase in fledging weight, but caused no reduction in fledging success, and had no effect on the timing of departure of the fledglings. Three translocated fledglings have returned to Cabbage Tree Island since their departure in April 1995; all returned to their adopted nest site, one being recovered only a few metres from the nest from where it fledged. This study demonstrated that translocations of Goulds Petrel nestlings can be achieved without any discernible detriment to the individual birds involved.

Nesting activity and demography of an isolated population of malleefowl (Leipoa ocellata)

Nesting activity of a population of malleefowl (Leipoa ocellata), isolated within a small mallee remnant in central New South Wales, was monitored annually between the summers of 1986–87 and 1998–99. A total of 148 nesting events was recorded. Only once was a new mound constructed rather than an old one reworked. Birds began and finished work on the mound progressively later each month (October to January). Nest-site fidelity was highly variable; some pairs persisted with the same mound for up to nine years while others relocated between a cluster of two, three or four mounds. Males displayed greater nest-site fidelity than females. After the loss of a partner, males tended to continue to use mounds they had used previously whereas females often relocated to a new mound. All individuals were monogamous. Pair bonds were maintained for life but, following the death of a partner, new bonds were quickly established with another unattached individual. Established pairs occasionally failed to breed, all such failures being coincident with years of low rainfall. Pairs that did not breed generally began construction of a nest but failed to complete the task. As far as can be ascertained, unpaired birds did not construct nests. The malleefowl population was characterised by a rapid turnover of breeding individuals, a high rate of adult mortality and a lesser rate of recruitment. The maximum longevity recorded for breeding adults was 12 years; average longevity was 7.5 years. Twenty-five adults were lost from the breeding population over a period of 9 years; meanwhile, 14 birds entered the breeding population. Thus, the ratio of adult mortality to recruitment was 1.79 : 1.00. Between 1986–87 and 1997–98 the population declined from at least 32 breeding adults to 14, at an average exponential rate of decrease of 0.075. Large population decreases were coincident with years of low rainfall. This population of malleefowl is predicted to become extinct by 2008.

Population size, breeding success and provenance of a mainland colony of Little Penguins (Eudyptula minor)

Abstract Although most Little Penguins (Eudyptula minor) breed on offshore islands, several small colonies occur on the mainlands of New Zealand and Australia, including mainland Tasmania. Unlike island colonies, most mainland colonies have declined over recent decades, several having gone extinct. A mainland colony of Little Penguins in North Harbour, Sydney, Australia, was monitored over three consecutive breeding seasons (2002–03 to 2004–05). The number of known nesting pairs was 49–56 per annum. The mean number of eggs laid per pair (2.45), eggs hatched per pair (1.84), fledglings produced per pair (1.71), hatching success (0.72) and breeding success (0.70) were among the highest reported from Australian colonies. Underlying these figures was a particularly high proportion of pairs that double-brooded (14–31% per annum, mean 24%). Fledging mass as a percentage of mean adult mass (103%) was also high. Together, these results suggest that food at the North Harbour colony was abundant during the period of study. Fledglings first returned to the colony at 1–4 years of age and first bred at 2–4 years of age. The recruitment rate of fledglings produced at the North Harbour colony was up to 15%, much higher than that recorded elsewhere. Banding recoveries (1997–2005) show that the North Harbour colony contains a substantial number of immigrants that have come from as far afield as Phillip Island, 761 km south of Sydney. Individuals banded at North Harbour have been recovered as far away as Sydenham Inlet, Victoria, 485 km to the south. The mixed provenance of the North Harbour population demonstrates that it is not isolated, either demographically or genetically, from other colonies in south-eastern Australia.

Establishment of a new, secure colony of Endangered Bermuda Petrel Pterodroma cahow by translocation of near-fledged nestlings

Until recently, Bermuda Petrel Pterodroma cahow (IUCN Category: ‘Endangered’) bred only in sub-optimal habitat on four small islets in north-east Bermuda. Although intensive management of the population since 1962 has led to a substantial increase in population size (now approaching 100 pairs), the nesting habitat on these four islets is being increasingly inundated, eroded and destroyed by high seas associated with hurricanes and storms. To ensure the long-term conservation of the species a decision was made to establish a new colony at a more secure site on nearby Nonsuch Island, where they once bred in large numbers. Between 2004 and 2008, 104 near-fledged nestlings were translocated to artificial burrows on Nonsuch Island, where they were hand-fed meals of fish and squid. All but three translocated birds fledged successfully, with the first returning to Nonsuch Island in February 2008. The first Bermuda Petrel egg on Nonsuch Island in more than 300 years was laid in January 2009, and the resultant fledgling departed in June of the same year. By the end of the 2009/10 breeding season, a total of 18 Bermuda Petrels have been recorded on Nonsuch Island, 17 were translocated as near-fledged nestlings, and one bird came from the existing colonies. A total of five eggs have been produced, resulting in two fledglings. The establishment of this new colony, at a site that is much more secure than the existing nesting sites, greatly enhances the conservation prospects of the species and demonstrates the importance of translocation as a tool for the conservation of threatened seabirds.

An evaluation of three field techniques for sexing Gould's Petrels (Pterodroma leucoptera) (Procellariidae)

Abstract Many petrels show no obvious sex-linked dimorphism in plumage or size and consequently many researchers fail to sex the living individuals they study. Several methods of sex discrimination that do not rely on plumage- or obvious size-dimorphism can be used to sex live petrels. The effectiveness of three such techniques was evaluated: body condition at the time of laying, cloacal inspection, and discriminant function analysis (DFA) of external morphometrics. Goulds Petrel (Pterodroma leucoptera leucoptera) was used as the subject species. Sexing of breeding adults on the basis of body condition at laying proved to be highly accurate (100% of birds sexed correctly) but required detailed knowledge of the breeding biology. Following training, cloacal inspection proved to be an accurate (96%) method of determining the sex of breeding adults, but not of chicks. Unlike molecular sexing, the latter two methods of sex discrimination provide immediate knowledge of the sex of individuals in the field. DFA of external morphometrics predicted the sex of adults with an accuracy of 73% and the sex of near-fledged chicks with an accuracy of 66%. However, the probability of correct assignment of sex was low in most cases and, therefore, this is the least useful of the three techniques assessed here.

Breeding biology and population increase of the Endangered Bermuda Petrel Pterodroma cahow

The Bermuda Petrel Pterodroma cahow was thought to have become extinct early in the 17ᵗʰ century due to a combination of hunting by human colonists and predation by introduced rats, cats, dogs and pigs. However, single individuals were found on four occasions during the first half of the 20ᵗʰ century, and in 1951 a small population was discovered breeding on several rocky islets in north-east Bermuda. Recovery actions began in 1962 when the population numbered just 18 pairs, dispersed among five small islets. Although rats extirpated one of these five colonies in 1967, the population has grown steadily to 56 breeding pairs in 2000. We investigated the breeding phenology, productivity and population size of the Bermuda Petrel between 2000/2001 and 2007/2008. Each year, the birds began arriving in Bermuda around mid-October. They departed on a pre-breeding exodus between 19 November and 14 December, returning after 32–56 days to lay a single egg between 31 December and 31 January. Eggs hatched from 16 February to 26 March after a mean (± SD) incubation period of 53 ± 2 days, and young fledged from 15 May to 25 June after a mean fledging period of 91 ± 5 days. Between 2000/2001 and 2007/2008, reproductive output ranged from 29 to 40 fledglings per annum. Mean annual breeding success (62%) was reasonably high relative to other Procellariiformes, largely due to the provision of artificial (concrete) nesting burrows. In 2008, the population numbered 85 breeding pairs. Monitoring since 1961 indicates the population has been increasing exponentially, doubling approximately every 22 years. This rate of increase, together with the increased incidence of storm damage, is making it progressively more impracticable to construct sufficient concrete burrows on the current nesting islets to accommodate all breeding pairs. The vulnerability of these sites to accelerating storm damage and erosion as a result of anthropomorphic climate change is now the greatest threat to the Bermuda Petrel.

Does the integrity or structure of mallee habitat influence the degree of Fox predation on Malleefowl (Leipoa ocellata)

Abstract Malleefowl (Leipoa ocellata) are in decline across their range. Previous studies have found that the survival rate of young Malleefowl is low, the single greatest cause of mortality being predation by the introduced Red Fox (Vulpes vulpes). Many of these studies, particularly those in New South Wales (NSW), were conducted in habitats that were heavily modified by fire, exotic herbivores or plant harvesting. In this paper, we examine the survival of Malleefowl in relatively undisturbed mallee habitats within two conservation reserves in South Australia (SA). Both reserves were long unburnt and free of large exotic herbivores, but differed greatly in understorey structure. Fifteen young captive-reared Malleefowl were released into each reserve. In all, 70% of these individuals were dead within 40 days. Fox predation was the prime cause of mortality, accounting for at least 30%, and perhaps as much as 96%, of all deaths. The extent and causes of mortality were similar in the two reserves. The overall level of Malleefowl survival was (1) better than that recorded in more disturbed habitat in NSW in the absence of any Fox control, but (2) substantially less than that in NSW after widespread Fox control was implemented. This study indicates that Malleefowl in SA are subject to significant levels of Fox predation, even in relatively undisturbed habitats. Also, for the two mallee habitats examined, evidence suggests that understorey structure had no influence on the degree of predation. Available data indicate that during the past two decades Malleefowl populations in SA have declined at about the same rate as those in NSW. Current densities in SA are typically about one- quarter of what they were 15 years ago. We conclude that habitat integrity and structure have little effect on the interaction between Foxes and Malleefowl, and suggest that Malleefowl populations across Australia are threatened by Foxes, placing the species at substantial risk of extinction.

Differential rates of offspring provisioning in Gould's petrels: are better feeders better breeders

Procellariiformes (albatrosses and petrels) must accumulate substantial energy reserves to sustain them while incubating their single egg. They then produce a chick that is often more than 130% of their own body mass. Thus, despite the variable nature of resource availability in the marine environment, successful reproduction requires a considerable increase in foraging rates. Birds that are better foragers are, therefore, likely to be better parents. As surrogates of foraging ability, we assessed two parental traits that are separated temporally over the breeding season, body condition during incubation and provisioning performance, in Gould’s petrel (Pterodroma leucoptera). Although parental condition did not influence hatching success, we found significant positive correlations between the average body condition of a breeding pair and both the growth rate of chicks (g day–1) and the body condition of chicks at peak mass. Provisioning rate also correlated positively with chick condition. Chick condition was positively correlated with haemoglobin concentration [Hb] at peak mass, which was positively correlated with [Hb] at fledging. Because the probability of survival after fledging may be influenced by chick body condition and [Hb], the ability of parents to acquire additional resources for breeding is likely to be an important determinant of reproductive success.