Greg Johnston
South Australian Museum, Vertebrates, Department Member
- Flinders University of South Australia, Biological Sciences, Faculty Memberadd
- Greg Johnston is a semi-retired wildlife biologist, originally from Eyre Peninsula, Australia. He has worked in the ... moreGreg Johnston is a semi-retired wildlife biologist, originally from Eyre Peninsula, Australia. He has worked in the mining industry, universities, zoos, and with conservation NGOs. Between 2000 and 2010 he established the research and conservation program at Zoos SA's Adelaide and Monarto Zoos, where he was Head of Science. Prior to that Greg worked at the Blaustein Institute for Desert Research in Israel and the Smithsonian Tropical Research Institute in Panama. He has extensive field experience in Australia and in Papua New Guinea.Greg has degrees in zoology and anatomy and a PhD in biology. He has published over 60 books, book chapters and scientific papers. He holds honorary positions at the South Australian Museum, Flinders University and the University of Adelaide, where he is an adjunct Associate Professor.Greg lives in Adelaide and is a keen amateur photographer. He plays banjo badly, although his family would rather he didn’t!edit
A unit of The University of South Australia and the University of Adelaide,
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Globally, pelican populations have decreased, with three species being of conservation concern. Australian pelicans (Pelecanus conspicillatus) are not regarded as endangered, but have declined across south-eastern Australia. Information... more
Globally, pelican populations have decreased, with three species being of conservation concern. Australian pelicans (Pelecanus conspicillatus) are not regarded as endangered, but have declined across south-eastern Australia. Information on their movements and causes of mortality are required to interpret the importance of these regional declines to the species’ global population. We explored patterns of movement and causes of mortality by analysing recoveries from 14 615 Australian pelicans banded over 37 years between 1969 and 2006. Data from 243 leg band recoveries showed that Australian pelicans move distances of up to 3206 km, and travel across the species’ entire geographic range, within a year of fledging. We found little evidence for the popular notion that these birds move en masse from the coast to inland areas in response to flooding rains. Maximum recorded age of a banded Australian pelican was 15 years. The banding data suggest that the regional pelican declines could re...
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Leg bands are one of the oldest and most widespread of methods used to mark individual birds for study, but different kinds of bands may infl uence results obtained. We compared recoveries from closed aluminium and butt-ended stainless... more
Leg bands are one of the oldest and most widespread of methods used to mark individual birds for study, but different kinds of bands may infl uence results obtained. We compared recoveries from closed aluminium and butt-ended stainless steel leg bands deployed on Australian Pelicans Pelecanus conspicillatus between 1968 and 2004. All 64 recoveries from the 2123 closed aluminium bands deployed exhibited wear, whereas none of the 162 recoveries from the 12 427 butt-ended stainless steel bands deployed were worn. Closed aluminium bands resulted in 2.3 times as many recoveries overall, but half the recoveries within one year of deployment compared to butt-ended stainless steel bands. Only butt-ended stainless steel bands were recorded as “band only found”, suggesting they became dislodged from pelicans. This was confi rmed with pelicans that were simultaneously marked with leg bands and patagial tags. Together these data show that butt-ended stainless steel bands, while offering greater durability, result in less useful data than closed aluminium bands. A leg band that combines the durability of stainless steel bands and reliability of closed aluminium bands would provide a better proposition for the future studies of Australian Pelicans.
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Context Introduced mammalian predators have been responsible for population declines in native prey species around the world. Many conservation programs rely on control or eradication of introduced mammalian predators, but the impact of... more
Context Introduced mammalian predators have been responsible for population declines in native prey species around the world. Many conservation programs rely on control or eradication of introduced mammalian predators, but the impact of environmental variation on the efficacy of this approach is rarely documented. Aims The present paper describes (1) the impact of introduced European foxes (Vulpes vulpes) on breeding Australian pelicans (Pelecanus conspicillatus) in South Australia and (2) the responses of both species to a fox-eradication program using a before-after-impact framework. Methods The impact of foxes on breeding Australian pelicans was studied on a near-shore island. An index of fox abundance and direct measurements of breeding pelicans and mortality of pelican eggs and young were compared before foxes were established on the island, while foxes were resident and during a fox-eradication program. A path analysis was used to explore the causal relationships between fox a...
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Introduced predators have had, and continue to have, severe impacts on Australian biodiversity. At a recently established conservation reserve, Witchelina, in arid South Australia, we assessed the diet of feral cats (Felis catus) (404... more
Introduced predators have had, and continue to have, severe impacts on Australian biodiversity. At a recently established conservation reserve, Witchelina, in arid South Australia, we assessed the diet of feral cats (Felis catus) (404 samples), red fox (Vulpes vulpes) (51 samples) and dog (Canis familiaris) (11 samples) over a 3-year period. There was marked overlap (98.5%) in dietary composition between cats and foxes. Rabbits (Oryctolagus cuniculus) comprised a major dietary item for all three predators. Invertebrates contributed the largest number of prey items for foxes and cats, but mammals comprised the bulk, by weight, for all three predators. Birds and reptiles had a higher frequency of occurrence in the diet of cats than of foxes or dogs. The size of mammal prey taken was least for cats and greatest for dogs. The diets of cats and foxes showed significant seasonal variation, with reptiles and invertebrates being least common in the diet in winter. The threatened thick-bille...
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At least three species of New Guinean tree frogs (Litoria) are sexually dimorphic in that the snout of the male is projected into a proboscis, which is poorly developed or absent in females. In this paper the anatomy of the proboscis in... more
At least three species of New Guinean tree frogs (Litoria) are sexually dimorphic in that the snout of the male is projected into a proboscis, which is poorly developed or absent in females. In this paper the anatomy of the proboscis in the male Litoria pronimia is described and compared with the structure of the smaller proboscis of Litoria havina, described previously. We note that it appears to be erectile, speculate on the possible method of erection and suggest directions for future research.
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How sociality evolves and is maintained remains a key question in evolutionary biology. Most studies to date have focused on insects, birds, and mammals but data from a wider range of taxonomic groups are essential to identify general... more
How sociality evolves and is maintained remains a key question in evolutionary biology. Most studies to date have focused on insects, birds, and mammals but data from a wider range of taxonomic groups are essential to identify general patterns and processes. The extent of social behaviour among squamate reptiles is under-appreciated, yet they are a promising group for further studies. Living in aggregations is posited as an important step in the evolution of more complex sociality. We review data on aggregations among squamates and find evidence for some form of aggregations in 94 species across 22 families. Of these, 18 species across 7 families exhibited 'stable' aggregations that entail overlapping home ranges and stable membership in long-term (years) or seasonal aggregations. Phylogenetic analysis suggests that stable aggregations have evolved multiple times in squamates. We: (i) identify significant gaps in our understanding; (ii) outline key traits which should be the...
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ABSTRACT A new microhylid frog in the genus Oreophryne is described from southern New Guinea. It is a small species (males to 22 mm snout-urostyle length (SUL), females to 27 mm SUL) distinguished from congeners by having a cartilaginous... more
ABSTRACT A new microhylid frog in the genus Oreophryne is described from southern New Guinea. It is a small species (males to 22 mm snout-urostyle length (SUL), females to 27 mm SUL) distinguished from congeners by having a cartilaginous connection between the procoracoid and scapula, no webs between fingers, basal webs mainly between toes 3 and 4 and between toes 4 and 5, and the fifth toe slightly longer than the third. In life, most specimens have a conspicuous lime green (yellowish in preservative) bar between the eyes, a lime green and irregular longitudinal stripe on the flanks, and an irregular spot of the same colour above the insertion of the upper arms. The advertisement call is a pronounced rattle lasting about one second with a note repetition rate of 26-28 notes per second. Males of the new species guard the eggs of their mates on the underside of leaves hanging 30-400 cm above the ground (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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ABSTRACT Black-faced Cormorants (Phalacrocorax fuscescens) are endemic to marine environments in southern Australia and little is known of their biology. Development of a reliable and practical method for sexing adult birds in the field... more
ABSTRACT Black-faced Cormorants (Phalacrocorax fuscescens) are endemic to marine environments in southern Australia and little is known of their biology. Development of a reliable and practical method for sexing adult birds in the field is necessary to aid research into their behavior and life-history. Eleven measurements from museum specimens (27 male; 31 female) were used to document sexual dimorphism in Black-faced Cormorants using discriminant function analyses (DFA). A simultaneous DFA correctly sexed 81% of birds, while a stepwise DFA correctly sexed 85% of birds based on two measurements (bill length and mid tail length). However, terminal wear of the retrices make this measurement unreliable. A logistic regression using bill length correctly predicted the sex of 78% of individuals. Black-faced Cormorants with a bill ≤ 76 mm long are likely female and ≥ 77 mm long are likely male, therefore providing a reliable method for assigning sex in the field. Black-faced Cormorants exhibit the same pattern of sexual dimorphism found in all other cormorants studied to date: males are larger, more robust and have a longer bill compared to the smaller, relatively gracile and shorter-billed females. The use of this general rule to assign sex to adult Black-faced Cormorants was confirmed through the observation of mating behavior. Therefore, this study provides a dependable and practicable technique for assigning sex in the field without the need to capture birds and disturb their behavior.
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Case studies of well-documented snake reintroductions are limited, despite their potential value for conservation and ecosystem recovery. The Endangered woma Aspidites ramsayi is a large boid snake that has declined considerably and is... more
Case studies of well-documented snake reintroductions are limited, despite their potential value for conservation and ecosystem recovery. The Endangered woma Aspidites ramsayi is a large boid snake that has declined considerably and is now threatened throughout much of central Australia. We describe a trial release of captive-bred womas into the feral predator-free Arid Recovery Reserve in northern South Australia. All of the reintroduced womas were killed within 4 months, with predation by the mulga snake Pseudechis australis confirmed or implied in all cases. Lessons learned for the conditioning of captive-bred snakes for wild release and the role of the mulga snake in structuring Australian arid-zone snake assemblages are discussed.
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Abstract Rostral appendages occur in a very small number of species spread across the entire clade of iguanian lizards. The five species of Sri Lankan agamid lizards of the poorly known endemic genus Ceratophora show remarkable variation... more
Abstract Rostral appendages occur in a very small number of species spread across the entire clade of iguanian lizards. The five species of Sri Lankan agamid lizards of the poorly known endemic genus Ceratophora show remarkable variation in the morphology and development of rostral appendages, which are absent in two species and present in the other three. Parsimony and Bayesian comparative methods do not robustly resolve whether the appendage evolved once (with two losses), twice (with one loss) or thrice ...
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Page 1. NOTES STANCYK, SE 1982. Non-human predators of sea turtles and their control. In K. Bjorndal (ed.), Bi-ology and Conservation of Sea Turtles, pp. 139-152. Smithsonian Inst. Press, Washington, DC TINKLE, DW 1979. Long-term field... more
Page 1. NOTES STANCYK, SE 1982. Non-human predators of sea turtles and their control. In K. Bjorndal (ed.), Bi-ology and Conservation of Sea Turtles, pp. 139-152. Smithsonian Inst. Press, Washington, DC TINKLE, DW 1979. Long-term field studies. Biosci-ence 9:717. ...