Variety is the spice of life : flying-foxes exploit a variety of native and exotic food plants in an urban landscape mosaic

Generally, urbanization is a major threat to biodiversity; however, urban areas also provide habitats that some species can exploit. Flying-foxes (Pteropus spp.) are becoming increasingly urbanized; which is thought to be a result of increased availability and temporal stability of urban food resources, diminished natural food resources, or both. Previous research has shown that urban-roosting grey-headed flying-foxes (Pteropus poliocephalus) preferentially forage in human-modified landscapes. However, which land-use areas and food plants support its presence in urban areas is unknown. We tracked nine P. poliocephalus roosting in Adelaide, South Australia, between December 2019 and May 2020, using global positioning systems (GPS), to investigate how individuals used the urban landscape mosaic for feeding. The most frequently visited land-use category was “residential” (40% of fixes) followed by “road-side,” “reserves” and “primary production” (13–14% each). However, “reserves” were visited four times more frequently than expected from their areal availability, followed by the “residential” and “road-side” categories that were visited approximately twice more than expected each; in contrast, the “primary production” category was visited approximately five times less than expected. These results suggest that while residential areas provide most foraging resources supporting Adelaide’s flying-fox population, reserves contain foraging resources that are particularly attractive to P. poliocephalus. Primary production land was relatively less utilized, presumably because it contains few food resources. Throughout, flying-foxes visited an eclectic mixture of diet plants (49 unique species), with a majority of feeding fixes (63%) to locally indigenous Australian native species; however, in residential areas 53% of feeding visits were to non-locally indigenous species, vs only 13% in reserves. Flowering and fruiting phenology records of the food plants visited further indicated that non-locally indigenous species increase the temporal availability of foraging resources for P. poliocephalus in urban Adelaide. Our findings demonstrate the importance of residential areas for urban-roosting P. poliocephalus, and suggest that the anthropogenic mixture of food resources available in the urban landscape mosaic supports the species’ year-round presence in urban areas. Our results further highlight the importance of conserving natural habitats within the urban landscape mosaic, and stress the need for accounting for wildlife responses to urban greening initiatives

Senescence Is More Important in the Natural Lives of Long- Than Short-Lived Mammals

Senescence has been widely detected among mammals, but its importance to fitness in wild populations remains controversial. According to evolutionary theories, senescence occurs at an age when selection is relatively weak, which in mammals can be predicted by adult survival rates. However, a recent analysis of senescence rates found more age-dependent mortalities in natural populations of longer lived mammal species. This has important implications to ageing research and for understanding the ecological relevance of senescence, yet so far these have not been widely appreciated. We re-address this question by comparing the mean and maximum life span of 125 mammal species. Specifically, we test the hypothesis that senescence occurs at a younger age relative to the mean natural life span in longer lived species.We show, using phylogenetically-informed generalised least squares models, a significant log-log relationship between mean life span, as calculated from estimates of adult survival for natural populations, and maximum recorded life span among mammals (R2=0.57, p<0.0001). This provides further support for a key prediction of evolutionary theories of ageing. The slope of this relationship (0.353+/-0.052 s.e.m.), however, indicated that mammals with higher survival rates have a mean life span representing a greater fraction of their potential maximum life span: the ratio of maximum to mean life span decreased significantly from >10 in short-lived to approximately 1.5 in long-lived mammal species.We interpret the ratio of maximum to mean life span to be an index of the likelihood an individual will experience senescence, which largely determines maximum life span. Our results suggest that senescence occurs at an earlier age relative to the mean life span, and therefore is experienced by more individuals and remains under selection pressure, in long- compared to short-lived mammals. A minimum rate of somatic degradation may ultimately limit the natural life span of mammals. Our results also indicate that senescence and modulating factors like oxidative stress are increasingly important to the fitness of longer lived mammals (and vice versa)

Thermoregulatory behaviour of tree-roosting chocolate wattled bats ('Chalinolobus morio') during summer and winter

The thermal physiology of tree-roosting bats has been rarely studied in the wild. I used temperature telemetry to locate and record the skin temperature (Tskin) of chocolate wattled bats ('Chalinolobus morio', Vespertilionidae) roosting in tree cavities. In summer, male 'C. morio' (n = 4) used torpor on 88% (15 of 17) of days. Bats entered torpor before or near sunrise, remained torpid for 7.3 h ± 3.8 SD (range: 0.8–13.2 h), and aroused midmorning. Torpor bout duration was negatively related to minimum torpid Tskin (R² = 0.94,

Winter activity of Australian tree-roosting bats: influence of temperature and climatic patterns

Many bats hibernate to overcome a critical energy shortage in winter. However, unlike strictly seasonal hibernators, bats sometimes alternate prolonged torpor bouts with increased activity coinciding with periods of mild weather. Winter activity may be especially common in hibernating tree-roosting bats because they are less insulated from external conditions than cave-roosting species and must also leave their roosts to drink, socialize or mate. To test this hypothesis, I measured the activity of a community of tree-roosting bats by recording echolocation calls at four sites on 18 nights throughout winter in south-eastern Australia. I also measured insect activity using light traps at each site. I recorded some bat activity on most nights, typically at dusk. Greater bat and insect activity occurred on nights of warmer temperatures, moderate wind speeds and falling barometric pressure, indicating the approach of low-pressure cold fronts. Thus, winter activity of tree-roosting bats is linked to short-term mild conditions caused by a specific, reoccurring weather pattern. Climatic shifts that reduce the frequency of such weather events, such as the El Niño Southern Oscillation phenomenon and future human-induced climate change, may also reduce winter activity and/or increase the cost of necessary arousal periods by hibernating tree-roosting bats

Temperature effects on metabolic rate and torpor in southern forest bats (Vespadelus regulus)

I measured the metabolic rate (MR) of four male southern forest bats (Vespadelus regulus; 5.5g) exposed to a diurnal increase in air temperature (T a) from 13 to 26°C, simulating conditions in natural tree roosts. Three bats remained in torpor throughout the day, despite the rise in T a, whereas one bat aroused at a T a of 25.2°C and was normothermic for 108min until re-entering torpor when T a declined in the afternoon. All bats aroused shortly after lights off. Torpid MR increased exponentially with rising T a, yet even at 26°C remained only 16% of minimum resting MR at the same T a. Rest-phase energy expenditure (12h), including the estimated cost of an evening arousal, ranged from 0.62 to 1.23kJ. Thus, torpor provides these small bats with an enormous reduction in energy consumption even at T a close to their thermoneutral zone

Hibernation by tree-roosting bats

In summer, long-eared bats ('Nyctophilus' spp.) roost under bark and in tree cavities, where they appear to benefit from diurnal heating of roosts. In contrast, hibernation is thought to require a cool stable temperature, suggesting they should prefer thermally insulated tree cavities during winter. To test this prediction, we quantified the winter thermoregulatory physiology and ecology of hibernating tree-roosting bats, 'Nyctophilus geoffroyi' and 'N. gouldi' in the field. Surprisingly, bats in winter continued to roost under exfoliating bark (65%) on the northern, sunny side of trees and in shallow tree cavities (35%). Despite passive re-warming of torpid bats by 10–20°C per day, torpor bouts lasted up to 15 days, although shorter bouts were also common. Arousals occurred more frequently and subsequent activity lasted longer on warmer nights, suggesting occasional winter foraging. We show that, because periodic arousals coincide with maximum roost temperatures, when costs of rewarming and normothermic thermoregulation are minimal, exposure to a daily temperature cycle could largely reduce energy expenditure during hibernation. Our study provides further evidence that models of torpor patterns and energy expenditure from hibernators in cold temperate climates are not directly applicable in milder climates, where prolonged torpor can be interspersed with more frequent arousals and occasional foraging

Thermal physiology of pregnant and lactating female and male long-eared bats, 'Nyctophilus geoffroyi' and 'N. gouldi'

During roosting in summer, reproductive female bats appear to use torpor less frequently and at higher body temperatures (Tb) than male bats, ostensibly to maximise offspring growth. To test whether field observations result from differences in thermal physiology or behavioural thermoregulation during roosting, we measured the thermoregulatory response and energetics of captive pregnant and lactating female and male long-eared bats (Nyctophilus geoffroyi 8.9 g and 'N. gouldi' 11.5 g) during overnight exposure to a constant ambient temperature (Ta) of 15°C. Bats were captured 1–1.5 h after sunset and measurements began at 21:22±0:36 h. All 'N. geoffroyi' entered torpor commencing at 23:47±01:01 h. For 'N. gouldi', 10/10 males, 9/10 pregnant females and 7/8 lactating females entered torpor commencing at 01:10±01:40 h. The minimum Tb of torpid bats was 15.6±1.1°C and torpid metabolic rate (TMR) was reduced to 0.05±0.02ml O2 g⁻¹ h⁻¹. Sex or reproductive condition of either species did not affect the timing of entry into torpor (F=1.5, df=2, 19, P=0.24), minimum TMR (F=0.21, df=4, 40, P=0.93) or minimum T b (F=0.76, df=5, 41, P=0.58). Moreover, sex or reproductive condition did not affect the allometric relationship between minimum resting metabolic rate and body mass (F=1.1, df=4, 37, P=0.37). Our study shows that under identical thermal conditions, thermal physiology of pregnant and lactating female and male bats are indistinguishable. This suggests that the observed reluctance by reproductive females to enter torpor in the field is predominantly because of ecological rather than physiological differences, which reflect the fact that females roost gregariously whereas male bats typically roost solitarily

Ethnography in work integrated learning research

This paper introduces and discusses ethnography as a methodological approach to investigate phenomena at the place of practice in WIL. The commensurability of ethnography for examining WIL \u27in situ\u27 is presented in order to delve deeper into WIL phenomena on placement through greater temporal and physical proximity. Part of the reason we haven\u27t been able to fully understand student learning on placement, for example, is because of a lack of awareness and uptake of methodologies that employ direct observation in WIL spaces. Ethnography could open the door to investigating a range of research areas previously obscured or inaccessible by methodologies that keep the researcher at a distance. This paper offers practical implications for researchers in WIL by highlighting methods and future research areas conducive with an ethnographic approach

Distribution and abundance of the south-eastern form of the greater long-eared bat 'Nyctophilus timoriensis'

In south-eastern Australia, the greater long-eared bat ('Nyctophilus timoriensis') has been rarely captured and is considered uncommon, although large areas within its range have received little survey effort. We collate existing capture records and present new data on 'N. timoriensis' captures from recent fauna surveys across the western slopes and plains of New South Wales (NSW). From 1628 trap nights at 39 study areas, 118 'N. timoriensis' were captured out of a total of 8266 bats. In larger remnants in the Brigalow Belt South Bioregion, N. timoriensis was captured at a rate of 0.1 to 0.6 per trap night and made up 7 to 9% of bat captures. This was approximately an order of magnitude greater than in other study areas throughout western NSW. There were no captures from the Darling Riverine Plains Bioregion. These surveys show that the large vegetation remnants of Goonoo, Pilliga West and Pilliga East study areas were a distinct stronghold in the distribution of the south-eastern form of 'N. timoriensis'