Greg Johnston

Phytohaemagglutinin (PHA) response and bill-hue wavelength increase with carotenoid supplementation in Diamond Firetails (Stagonopleura guttata)

Abstract Carotenoids cannot be synthesised by vertebrates and must be derived from the diet. A growing amount of research has focussed on the role of carotenoids in immune function, as well as the signalling function of carotenoids in the colour of the integument (skin, bill and legs) and feathers. We used an experimental approach to examine the effects of experimental reduction and supplementation of dietary carotenoids on phytohaemagglutinin (PHA) response (as an estimate of cell-mediated immune response) and colour of the bill in the Diamond Firetail (Stagonopleura guttata). To demonstrate the biological relevance of our study, we first show that carotenoid concentrations of our captive experimental birds did not differ significantly from those of wild birds. We found that carotenoids circulating in the plasma of captive Diamond Firetails dropped to 50% of the original concentration in less than 5 days when on a carotenoid-free diet. The mean level of total carotenoids in the plasma stabilised at 6% of the original concentration after 26 days. Finally, Diamond Firetails showed a significant increase in PHA response and increased bill-hue wavelength while on either a lutein or a zeaxanthin supplemented diet. Our results show rapid signalling of carotenoid concentration in the integument (as measured here in the bill) that we suggest complements the longer term signalling potential of feathers.

Sexual Dimorphism and Ecology of the Gecko, Ptyodactylus guttatus

Abstract Geckos are generally nocturnal and show no sexual dichromatism, and males are usually smaller than females. Ptyodactylus guttatus is an unusual gecko. It is active by day and night and is sexually dichromatic, and males are larger than females. We studied P. guttatus at two sites in southern Israel. Eggs were laid between May and October at Haluqim, where we studied eggs in natural caves. At a second site, Hazeva, P. guttatus occur on buildings at a density of 390 ha−1. This is 195 times the density that the species occurs in natural habitats. At Hazeva, adult males inhabited large home ranges, which generally overlapped with one or more smaller home ranges of females. The pattern of home-range overlap presumably reflects the opportunities for mating. A path analysis was consistent with the hypothesis that females spaced themselves to gain access to insects (which they eat) attracted to wall lights on the buildings, and that males space themselves to gain access to female mates. We did not find evidence of territoriality in this population but observed males guarding females. Large male body size may provide priority access to mates, and the distinct male dorsal pattern may have arisen because light does not constrain the use of visual signals in these unusual, largely diurnal geckos, to the same extent as it may in nocturnal geckos.

Identification of protected avian species using a single feather barb.

Abstract:  We report on the unambiguous identification of protected avian species from as little as one barb of a feather. Many avian species are protected by international agreements and national legislation, yet they are traded illegally because of their high value. Two sections of the avian mitochondrial genome were chosen to identify bird species, being a 561‐bp section of ND2 gene and a 921‐bp section of the ND5 gene. Two different DNA extraction methods were compared for their ability to reliably isolate sufficient DNA to be detected in a subsequent PCR. Using a commercial kit supplied by QIAGEN, a complete sequence was obtained from one barb for the ND2 gene, whereas two barbs were required to reliably sequence the 921‐bp section of the ND5 gene. The process worked on all species tested using feathers from archival museum specimens, resulted in minimal damage to the specimen and can readily be adopted by a forensic science laboratory.

Morphological Sex Determination in Black-Faced Cormorants (Phalacrocorax fuscescens)

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.

Predation by snakes thwarts trial reintroduction of the Endangered woma python Aspidites ramsayi.

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.

Habitat selection by an arboreal lizard in an urban parkland: not just any tree will do.

The nocturnal, arboreal Marbled Gecko, Christinus marmoratus, is a common reptile in urban areas in southern Australia. This study compared the demographics and the distribution of geckos occupying different tree species in a modified urban park, the Adelaide Parklands, with those of a population occurring in Ferguson Conservation Park, a nearby native vegetation remnant surrounded by suburbia. The geckos in the modified urban and native remnant parks demonstrated different demographic characteristics. These differences were explained by tree circumference and the amount and type of bark cover on the tree trunk. In the Parkland, geckos were limited by the availability of thick exfoliating bark, its clearly preferred microhabitat as demonstrated by a laboratory choice experiment. The preference for trees with larger circumference, more cover, and thick bark were probably linked to thermoregulation, predator avoidance, and food resources. This study supports the premise that to support populations of urban animals, tree species selection needs careful consideration with regard to its microhabitat capabilities as well as food provision and other resource supports it can provide.

Susceptibility of Bush Stone-curlews (Burhinus grallarius) to sodium fluoroacetate (1080) poisoning

Abstract Although baiting for feral predators with sodium fluoroacetate (1080) benefit native fauna over much of Australia by reducing the abundance of those predators, there is a potential risk of poisoning to non-target species. Bush Stone-curlews (Burhinus grallarius) have declined over much of mainland southern Australia owing to predation by Red Foxes (Vulpes vulpes), but they have the potential to eat and be affected by 1080 baits. This paper explores the extent to which 1080-baiting programs may have an adverse effect on extant or reintroduced populations of Bush Stone-curlews. Our study used Bush Stone-curlews from a population that was not adapted to naturally occurring 1080, so our results are likely to be relevant throughout the range of the species. We determined the approximate lethal dose (ALD) of 1080 for Bush Stone-curlews to be 10–15 mg kg−1. Thus a Bush Stone-curlew weighing 700 g would need to eat between three and four baits, each containing 3 mg of 1080, to receive an ALD. In unforced trials, the Bush Stone-curlews in our study did not eat (undosed) meat or grain baits. Dying food blue did not deter Bush Stone-curlews from eating it. Thus, sole reliance on blue dyes to deter non-target species from taking baits seems unwise. Our results indicate that reintroduction programs for Bush Stone-curlew are unlikely to be affected by concurrent 1080-baiting for feral animal control.

The structure of the male proboscis in the New Guinean tree frogs, Litoria pronimia and Litoria havina (Anura : Hylidae)

Abstract. 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.

Observations of a large colony of bats roosting in a church

The nightly and seasonal activity patterns of a large colony of bats roosting in a country church are described. In summer 400–700 bats from two species – southern freetail bat (Mormopterus sp. 4) and chocolate wattled bat (Chalinolobus morio) – left the roost beginning around civil twilight. Bats emerged at a rate of up to 40–50 min–1, and took 30 min or longer to clear the roost.