Pteropus Poliocephalus Research Articles

Flying-fox (Pteropus spp.) sperm membrane fatty acid composition, its relationship to cold shock injury and implications for cryopreservation success

The very large acrosome of Pteropus species spermatozoa is prone to damage during cooling procedures. Cryogenic succuss has been linked to membrane composition, therefore the lipid composition of five Pteropus species sperm acrosomal and plasma membranes were investigated to provide insight into reasons for cold shock susceptibility. Rapid chilling and re-warming of spermatozoa from three Pteropus species resulted in a decrease (P<0.05) in acrosomal integrity. Biochemical analysis of lipids revealed that stearic acid (18:0) was the predominant saturated fatty acid and oleic acid (18:1, n-9) the predominant unsaturated fatty acid in both acrosomal and plasma membranes. Linolenic acid (18:3, n-3) was only detected in plasma membranes of Pteropus hypomelanus and was detected in acrosomal membranes of all Pteropus spp. studied (except Pteropus giganteus). Although detected in both plasma and acrosomal membranes of Pteropus vampyrus, docosahexaenoic acid (22:6) was not detected at all in Pteropus poliocephalus, only in trace levels in the acrosomal and plasma membranes of P. giganteus and P. hypomelanus and not in acrosomal membranes of Pteropus rodricensis. No difference was seen in the levels of polyunsaturated fatty acids (PUFAs) within plasma membranes, however PUFAs were lower (P<0.05) in acrosomal membranes of P. giganteus compared with P. vampyrus. Pteropus spp. spermatozoa have a very low ratio of unsaturated/saturated membrane fatty acids (<0.5). Membranes containing more PUFAs are more fluid, so the use of cryogenic media which improves membrane fluidity should improve Pteropus spp. spermatozoal viability post-thaw.

The haemosporidian parasites of bats with description ofSprattiella alectogen. nov., sp. nov.

Four species of Haemoproteidae were found in Pteropus alecto Temminck, 1837 in Queensland, Australia: i) Johnsprentia copemani, Landau et al., 2012; ii) Sprattiella alecto gen. nov., sp. nov., characterised by schizonts in the renal vessels; iii) Hepatocystis levinei, Landau et al., 1985, originally described from Pteropus poliocephalus Temminck, 1825 and, experimentally from Culicoides nubeculosus and found in this new host and for which features of the hepatic schizonts are reported; iv) gametocytes of Hepatocystis sp. which are illustrated but cannot be assigned to a known species. A tentative interpretation of phylogenetic characters of haemosporidians of bats is provided from the morphology of the gametocytes and localisation of the tissue stages with respect to recent data on the phylogeny of bats.

Life Expectancy, Causes of Death and Movements of the Grey-Headed Flying-Fox (Pteropus poliocephalus) Inferred from Banding

This study was designed to generate information on demography and movements in large flying-foxes, information that is critical to management planning. Between 1989 and 2002, 2,244 wild grey-headed flying-foxes, Pteropus poliocephalus, were harp-trapped, banded and released at sites across south-eastern Australia; 918 hand-reared orphans were also banded and released at four sites. Retraps of wild animals were few (n = 10) and are not discussed here. Recoveries (n = 86) from the public reporting dead wild flying-foxes (total 4.27%) and 38 hand-reared orphans (4.13%) are discussed. Recovery data were analysed via standard multiple regression; there was no difference between the sexes of wild P. poliocephalus in age at death or distance travelled, but hand-reared animals, on average, lived less than half as long as their wild counterparts (P < 0.001) and did not travel as far (P < 0.01). The average age of wild P. poliocephalus at death was 7.1 3.9 years ( ± SD, n = 86); the oldest flying-fox was 18 years of age. Generation length is estimated at 7.4 ± 3.76 years. Major causes of death of 86 wild P. poliocephalus were: hyperthermia (33.7%); electrocution (18.6%); entanglement in fruit-tree netting (5.8%); entanglement in barbed wire (4.7%); unknown (32.6%). 77% of recoveries of wild-banded P. poliocephalus were within 20 km of where they were banded; the longest movement recorded was 978 km. 1,632 wild black flying-foxes, P. alecto were trapped and banded; 27 were retrapped; seven were recovered dead (0.42%); from another 136 banded as hand-reared orphans, three were recovered (2.2%). Of 583 wild little red flying-foxes, P. scapulatus, trapped and banded, none were retrapped; one was recovered (0.2%). Data from P. alecto and P. scapulatus were too few for statistical analysis.

Comments on Point:Counterpoint: High altitude is/is not for the birds!

TO THE EDITOR: The debate between Scott et al. (6) and Llanos et al. (4) highlights the remarkable ability of birds and mammals to adapt and survive at high altitudes and cope with reduced oxygen (O2) availability. Scott and colleagues (6) make a compelling argument that birds are far superior to mammals at adapting and thriving in hypoxic environments, both at rest and during exercise. While their argument is supported by comparisons between birds and terrestrial mammals, it ignores marine mammals. Marine mammals such as seals are routinely exposed to and tolerate long bouts of hypoxia during breath-hold diving. For example, elephant seals may dive to depths of nearly 1,600 m and occasionally remain submerged for 2 h (3). Moreover, marine mammals can be exposed to partial pressures of arterial oxygen (PaO2) as low as 12 mmHg during free dives (5), which is less than the 20 mmHg observed in the bar-headed goose (6). Interestingly, a PaO2 of 12 mmHg observed in elephant seals corresponds to arterial saturations and O2 content of only 8% and 2.7 ml O2/dl (5). Thus marine mammals such as the elephant seal demonstrate a remarkable hypoxia tolerance. The integration of several key physiological adaptations including 1) substantially greater myoglobin concentrations compared to other mammals, 2) reductions in metabolism, 3) a greater reliance on aerobic metabolism (i.e., less lactate production), 4) a host of dramatic acute cardiovascular adjustments; and 5) an increased intrinsic cerebral hypoxia tolerance allow marine mammals to thrive in hypoxic environments and enable long deep dives (1–3).

Deliberate Insectivory by the Fruit BatPteropus poliocephalusby Aerial Hunting

The diet of the Old World fruit bats (Pteropodidae) has been well studied with a large inventory of nectar and fruit bearing plant species known to be consumed. It is far less certain, however, whether pteropodid bats intentionally supplement their diet with insects in a similar fashion to many other frugivorous and nectivorous species, including some New World fruit bats of the family Phyllostomidae. Several reports of pteropodid bats consuming insects in captivity exist, and insects have been found in the faeces and digestive tracts of some wild pteropodid bats, although their ingestion was initially thought to be accidental. However, more recent observations of large insects in faeces of wild bats, coupled with two reports (one anecdotal) of observed intentional insectivory in the wild, suggest that intentional insectivory by pteropodid bats may be more common than previously thought. In addition, reports of intentional insectivory to date have been of bats catching insects from a stationary position, and a large question still remains as to the ability of pteropodid bats to catch insects in flight without the use of laryngeal echolocation. Here, we report on an observation of intentional insectivory by a group of grey-headed flying foxes (Pteropus poliocephalus) actively preying on, and consuming, numerous (> 20) cicadas (Psaltoda sp.) by aerial hunting in southeastern Australia. We conclude that deliberate insectivory is likely an evolved and fixed component of the grey-headed flying fox's dietary ecology, and suggest that this may be an adaptation more common among pteropodid bats than previously thought.

Latitudinal range shifts in Australian flying‐foxes: A re‐evaluation

AbstractRecent range shifts towards higher latitudes have been reported for many animals and plants in the northern hemisphere, and are commonly attributed to changes in climate. Relatively little is known about such changes in the southern hemisphere, although it has been suggested that latitudinal distributions of the fruit‐batsPteropus alectoandPteropus poliocephaluschanged during the 20th century in response to climate change in eastern Australia. However, historical changes in these species distributions have not been examined systematically. In this study we obtained historical locality records from a wide range of sources (including banding and museum records, government wildlife databases and unpublished records), and filtered them for reliability and spatial accuracy. The latitudinal distribution of each species was compared between eight time‐periods (1843–1920, 1921–1950, five 10‐year intervals between 1950 and 2000, and 2001–2007), using analyses of both the filtered point data (P. alecto870 records,P. poliocephalus2506) and presence/absence data within 50 × 50 km grid cells. The results do not support the hypothesis that either species range is shifting in a manner driven by climate change. First, neither the northern or southern range limits ofP. poliocephalus(Mackay, Queensland and Melbourne, Victoria respectively) changed over time. Second,P. alecto's range limit extended southward by 1168 km (approximately 10.5 degrees latitude) during the twentieth century (from approximately Rockhampton, Queensland to Sydney, New South Wales). Within this zone of southward expansion (25–29°S), the percentage of total records that wereP. alectoincreased from 8% prior to 1950 to 49% in the early 2000s, and local count data showed that its abundance increased from several hundred to more than 10 000 individuals at specific roost sites, as range expansion progressed.Pteropus alectoexpanded southward at about 100 km/decade, compared with the 10–26 km/decade rate of isotherm change, and analyses of historical weather data show that the species consequently moved into recently‐colder regions than it had previously occupied. Neither climate change nor habitat change could provide simple explanations to explainP. alecto's observed rapid range shift. More generally, climate change should not be uncritically inferred as a primary driver of species range shifts without careful quantitative analyses.

The Grey-headed Flying-fox in Castlemaine

The Grey-headed Flying-fox in Castlemaine

Deaths and injuries to Grey-headed Flying-foxes,Pteropus poliocephalusshot at an orchard near Sydney, New South Wales

For several years, animal welfare concerns have been raised over the practice of shooting Greyheaded Flying-foxes (GHFF) in commercial fruit orchards in Australia, and the role of government agencies in licensing the kill. In NSW the practice is poorly monitored and insufficient evidence has been available to assess welfare concerns. This study reports the first systematically acquired data on flying-foxes shot under licence in NSW. In the 2006/07 season the average number of GHFFs licensed to be harmed was <40 individuals per licence. Despite this, a total of 164 dead or injured flying-foxes were collected (n = 146) or observed (n = 18) from an orchard in western Sydney over two weeks in spring 2007, after shooting had occurred at the orchard to protect fruit crops. Detailed information, including sex, reproductive state, age and description of injuries, was compiled on 136 collected bats. The sex ratio was strongly skewed towards females (1:1∙73), of which 54 (65%) were lactating at the time. Thirteen of these were shot while carrying their dependent young, while 41 neonates would have been left behind in the camp to die. Hence, the total estimate of flying-foxes that died due to shooting in the orchard over the two-week period was 205. Collected bats suffered from various injuries, and at least 30% (44% including the neonates left in the camp) were alive and unattended more than 8.5 hours after shooting. This is in contravention of the definition of ‘humane killing’ and the Prevention of Cruelty to Animals Act 1979. Importantly, the GHFF is vulnerable under NSW and Federal legislations and the killing of reproducing females in crops contributes to its declining numbers, making Sydney Basin an ecological trap for this species.

Fit females and fat polygynous males: seasonal body mass changes in the grey-headed flying fox

When females and males differ in their timing of maximum reproductive effort, this can result in sex-specific seasonal cycles in body mass. Such cycles are undoubtedly under strong selection, particularly in bats, where they affect flying ability. Flying foxes (Old World fruit bats, Pteropus spp.) are the largest mammals that can sustain powered flight and therefore face critical trade-offs in managing body reserves for reproduction, yet little is known about body mass dynamics in this group. I investigated body mass changes in relation to reproductive behaviour in a large colony of grey-headed flying foxes (Pteropus poliocephalus). In this polygynous mammal, females were predicted to maximise reproductive effort during lactation and males during the breeding season. As predicted, female body condition declined during the nursing period, but did not vary in relation to sexual activity. By contrast, males accumulated body reserves prior to the breeding season, but subsequently lost over 20% of their body mass on territory defence and courtship, and lost foraging opportunities as they also defended their day roost territories at night. Males in better condition had larger testes, particularly during territory establishment, prior to maximum sexual activity. Thus, the seasonality of female mass reflected the high metabolic load that lactation imposes on mothers. However, male mass followed a pattern akin to the "fatted male phenomenon", which is commonly observed in large polygynous mammals with seasonal reproduction, but not in bats. This shows the importance of body reserves for reproduction in flying foxes, despite their severe constraints on body mass.

Polyglucosan Inclusions (Lafora Bodies) in a Gray-Headed Flying Fox (Pteropus Poliocephalus)

Polyglucosan bodies (Lafora bodies) were identified in a juvenile gray-headed flying fox (Pteropus poliocephalus) with neurological signs. The structures were only noted in the brain stem, and no associated degenerative changes were present. These structures have not been previously identified in any species in the order Chiroptera.

Growth, bimaturation, and sexual size dimorphism in wild gray-headed flying foxes (Pteropus poliocephalus)

In many mammals large size is more important for male than female fitness, which may select for bimaturation with males maturing later and attaining a larger size. In bats, however, sexual dimorphism in size tends to be reversed, with females being larger. Exceptions to this can be found, notably in the genus Pteropus. I examined growth, maturation, and sexual size dimorphism in free-ranging gray-headed flying foxes (Pteropus poliocephalus) to better understand the links between life history, behavior, and ecology of this large, polygynous Australian fruit bat. Juveniles left the colony independently at dusk when their forearm length and body mass exceeded 130 mm and 301 g, or 79% and 39% of mean adult dimensions, respectively. Mean forearm length and mass of these volant juveniles increased by 0.72 mm and 4.9 g per week, independent of sex. However, significant dimorphism and bimaturation were observed: adult males averaged 1.8–4.5% larger for skeletal measurements and 25% heavier than adult females, but 40% heavier at the start of the breeding season. Males also were sexually mature at a larger skeletal size and at a higher mass (604 g) than females (514 g). Sexual size dimorphism in P. poliocephalus likely results from prolonged male growth and delayed maturation. Intrasexual selection among males for fighting ability is implicated as the cause for dimorphism, together with a release of female size from the constraints posed by carrying heavy young. Bimaturation likely results from the high costs of maintaining mating territories that confer few reproductive benefits for small males.

Growth, bimaturation, and sexual size dimorphism in wild gray-headed flying foxes (Pteropus poliocephalus)

In many mammals large size is more important for male than female fitness, which may select for bimaturation with males maturing later and attaining a larger size. In bats, however, sexual dimorphism in size tends to be reversed, with females being larger. Exceptions to this can be found, notably in the genus Pteropus. I examined growth, maturation, and sexual size dimorphism in free-ranging gray-headed flying foxes (Pteropus poliocephalus) to better understand the links between life history, behavior, and ecology of this large, polygynous Australian fruit bat. Juveniles left the colony independently at dusk when their forearm length and body mass exceeded 130 mm and 301 g, or 79% and 39% of mean adult dimensions, respectively. Mean forearm length and mass of these volant juveniles increased by 0.72 mm and 4.9 g per week, independent of sex. However, significant dimorphism and bimaturation were observed: adult males averaged 1.8–4.5% larger for skeletal measurements and 25% heavier than adult females, but 40% heavier at the start of the breeding season. Males also were sexually mature at a larger skeletal size and at a higher mass (604 g) than females (514 g). Sexual size dimorphism in P. poliocephalus likely results from prolonged male growth and delayed maturation. Intrasexual selection among males for fighting ability is implicated as the cause for dimorphism, together with a release of female size from the constraints posed by carrying heavy young. Bimaturation likely results from the high costs of maintaining mating territories that confer few reproductive benefits for small males. DOI: 10.1644/09-MAMM-A-157R.1.

Histomorphometric changes in the wing bones of the fruit bat,Pteropus poliocephalus, (Megachiroptera: Pteropidae) in relation to increased bone strain and the failure of a good (?) hypothesis

Fluorochrome labelling of bone formation was used to examine the effect of exercise (flight) on the wing skeleton of fruit bats, Pteropus poliocephalus, over a 194 day period. The bats in this study had been born and raised in captivity and it was hypothesised that the large increases in bone strain that accompanied active flight would result in bone formation at the periosteal bone surface, leading to increased mechanical stiffness and strength. This hypothesis was not supported by the results. Bone formation rates, percentage mineralising surface and mineral apposition rates at the mid-shaft periosteal surface of the radius, metacarpal III and metacarpal V were small. The proximal phalanx of digit V did not display any bone formation at this surface. Bone appositional activity was not significantly different between baseline, control (non-flight) and treatment (flight) groups at any time-point of the experiment. Apposition, although limited, occurred primarily at the endocortical surface in all bones of all animals. No correlation was found between activity and bone formation. Active intracortical remodelling (a total of four secondary osteons) was only seen in three individuals.There was evidence of earlier remodelling activity in most bones, although there was no evidence of any secondary remodelling in the proximal phalanx.

Non-invasive genetic sampling of faecal material and hair from the grey-headed flying-fox (Pteropus poliocephalus)

Remote-sampling DNA from animals offers obvious benefits for species that are difficult to sample directly and is less disruptive for species of conservation concern. Here we report the results of a pilot study investigating non-invasive DNA sampling of the grey-headed flying-fox (Pteropus poliocephalus), a threatened species that is restricted to the east coast of Australia. We successfully extracted DNA from fresh scats and hair, each of which was of sufficient quality for amplifying mitochondrial DNA markers and microsatellites. A single-locus multitube approach was used to investigate amplification success and genotyping reliability. Faecal samples yielded a higher proportion of successful amplifications and consensus genotype assignments than hair samples. We outline measures that may be utilised to minimise microsatellite genotyping error for future studies. These indirect approaches to obtaining genetic data show much promise given the difficult nature of directly sampling flying-foxes and related species.

Microclimate preferences of the grey-headed flying fox (Pteropus poliocephalus) in the Sydney region

The population size of the grey-headed flying fox (Pteropus poliocephalus) has decreased dramatically as a result of a variety of threatening processes. This species spends a great proportion of time in roosting large social aggregations in urban areas, causing conflict between wildlife and humans. Little is known about why these bats choose to roost in some locations in preference to others. Roost selection by cave-dwelling bats can be greatly influenced by microclimatic variables; however, far less is known about microclimate selection in tree-roosting species despite the direct management implications. This study aimed to determine the microclimate characteristics of P. poliocephalus camps. Temperature and humidity data were collected via data-loggers located both in six camps and the bushland immediately adjacent to the camps in the greater Sydney region. We found significant differences between the microclimate within the camps and the surrounding bushland. In general, areas within the camps had a greater variance in temperature and humidity than the alternative locations. We hypothesise that camps may be specifically located in areas with high microclimate variance to accommodate a range of individual preferences that vary depending on demography.

Testosterone is associated with harem maintenance ability in free-ranging grey-headed flying-foxes, Pteropus poliocephalus

Males of many vertebrate species aggressively defend their reproductive interests by monopolizing females, and the 'challenge hypothesis' predicts that testosterone levels in reproductive contexts rise to facilitate males' competitive behaviours necessary for meeting social challenges. The hypothesis is successful in explaining patterns of testosterone secretion in many avian species, but remains comparatively unexplored in mammals. 'Circulating plasma testosterone levels (T)' were studied in relation to harem maintenance in grey-headed flying-foxes, Pteropus poliocephalus. In this species, harems provide mating opportunities and so a male's ability to maintain a harem is likely to correlate with his fitness. We hypothesized that if T reflect a male's ability to withstand challenges from competitors, then T should be linked to successful harem maintenance. To test this, we temporarily removed males from their territories prior to and during the short mating period, recording their harem sizes both before removal and after reintroduction. Most males successfully reclaimed their territory and a harem, but during the mating period, males with higher T had harems closer to their original size, and males with lower T suffered reduction in harem size. Our findings highlight the role of T in harem maintenance in a major mammalian taxon with complex forms of social organization.

Challenges and recovery actions for the widespread, threatened Grey‐headed Flying‐fox: A review from a New South Wales policy perspective

Summary The challenges of managing and conserving threatened species that have a widespread distribution operate at several levels and recovery of these species is a complex process. This paper provides an overview of how science is informing the management and conservation of the Grey‐headed Flying‐fox (Pteropus poliocephalus) in New South Wales. It outlines a series of research projects and activities the Department of Environment and Climate Change (New South Wales) has led or been involved in since the Grey‐headed Flying‐fox was listed as threatened in New South Wales in May 2001. This includes investigation of the species’ distribution and abundance; its roosting and foraging habitat requirements; assessment of horticultural damage and the mitigation techniques used; public attitudes towards the species; and development of policies and plans to guide the species’ conservation and management. Conservation gains for threatened species can be achieved through a sustained, focused programme of management, coordinated by dedicated individuals and informed by the available science. Scientists, policy‐makers and the general community must continue to strive together for the recovery of widespread, threatened species.

Fruit availability and utilisation by grey-headed flying foxes (Pteropodidae: Pteropus poliocephalus) in a human-modified environment on the south coast of New South Wales, Australia

Context. Extensive clearing and modification of habitat is likely to change many facets of the environment including climate and regional food resources. Such changes may result in changes in behaviour in highly mobile fauna, such as flying foxes. Aims.The availability of fruit resources was examined to determine whether grey-headed flying foxes (Pteropus poliocephalus) have feeding preferences related to habitat or dietary items, and whether human usage of the land around the colony site has affected the resources available. Methods. Fruit availability around a colony was monitored from December 2004 to March 2005. Night surveys and faecal analyses were undertaken to determine the distribution of feeding locations, the food species used and the food items consumed by P. poliocephalus. Key results.The amount of food available per hectare in each habitat was similar. However, we found differences in the composition of food trees and the distribution of food resources within each habitat. Ficus species were a major resource with flying foxes observed feeding in figs during every survey and figs identified in droppings over the whole period. Human-modified habitats were used throughout the study period with flying foxes observed in small patches of vegetation and in individual trees without any nearby vegetation. Conclusions. The need for maintaining vegetation, particularly Ficus species, in all areas where flying foxes are found, especially in human-modified habitats and rainforest remnants, is highlighted as this vegetation is of great importance to flying foxes. Other wildlife, such as birds and possums, may also benefit from the maintenance of this vegetation. Implications. Through management of urban resources there is the potential to prevent future conflict situations arising between humans and wildlife, such as can be seen when flying fox colonies are in close proximity to houses.

Spatio-temporal vigilance architecture of an Australian flying-fox colony

The social structure of animal aggregations may vary considerably in both space and time, yet little is known about how this affects vigilance. Here, we investigate the vigilance architecture of a colony of wild-living grey-headed flying-foxes (Pteropus poliocephalus) in Australia and examine how spatial as well as temporal variation in social organization influences social and environmental vigilance. We sampled color-marked individuals at different stages of the reproductive cycle and the year and at different locations in the colony to examine the effects of temporal and spatial factors on social and environmental vigilance. We found that vigilance architecture reflected the social structure of the colony, with the highest environmental vigilance being displayed by bats at the periphery of the colony, and the highest social vigilance by bats that roosted at intermediate distances from the colony’s edge. Furthermore, we found that vigilance levels reflected changes in reproductive state, with social vigilance increasing toward the mating season, particularly in males. Our findings show that spatial and temporal variation in social structure can have differential effects on social and environmental vigilance. This highlights the necessity to differentiate between functions of vigilance to understand fully vigilance architecture in aggregations of social animals.

Factors affecting the occupation of a colony site in Sydney., New South Wales by the Grey-headed Flying-fox Pteropus poliocephalus (Pteropodidae)

Factors affecting the occupation of a colony site in Sydney., New South Wales by the Grey-headed Flying-fox Pteropus poliocephalus (Pteropodidae)