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

Klose, Stefan M.; Welbergen, Justin A.; Goldizen, Anne W.; Kalko, Elisabeth K. V.

doi:10.1007/s00265-008-0671-8

Cited by 29 publications

(26 citation statements)

References 50 publications

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“…Sleep is a prominent behaviour in bats (Klose et al ., ; Zhao et al ., ), as in most mammals (Lesku et al ., ). Since a sleeping animal is relatively unresponsive to the external environment, time spent asleep is often time spent at risk to predators (Lesku et al ., ).…”

Section: Predator Avoidance In An Ecological Contextmentioning

confidence: 99%

Do predators influence the behaviour of bats?

2013

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Many aspects of animal behaviour are affected by real-time changes in the risk of predation. This conclusion holds for virtually all taxa and ecological systems studied, but does it hold for bats? Bats are poorly represented in the literature on anti-predator behaviour, which may reflect a lack of nocturnal predators specialized on bats. If bats actually experience a world with minimal anti-predator concerns, then they will provide a unique contrast within the realm of vertebrate ecology. Alternatively, such predator-driven behaviour in bats may not yet be fully understood, given the difficulties in working with these highly mobile and nocturnal animals. We provide a wide-ranging exploration of these issues in bat behaviour. We first cover the basic predator-prey information available on bats, both on potential predators and the ways in which bats might perceive predators and respond to attacks. We then cover work relevant to key aspects of bat behaviour, such as choice of daytime roosts, the nature of sleep and torpor, evening roost departures, moonlight avoidance, landscape-related movement patterns, and habitat selection. Overall, the evidence in favour of a strong influence of predators on bat behaviour is equivocal, with the picture clouded by contradictory results and a lack of information on potential predators and the perception of risk by bats. It seems clear that day-active bats run a considerable risk of being killed by diurnal raptors, which are able to capture bats with relative ease. Thus, bats taking advantage of a pulse of insects just prior to sunset are likely taking risks to gain much-needed energy. Further, the choice of daytime roosts by bats is probably strongly influenced by roost safety. Few studies, however, have directly addressed either of these topics. As a group, insectivorous temperate-zone bats show no clear tendency to avoid apparently risky situations, such as activity on moonlit nights. However, some observations are consistent with the idea that predation risk affects choice of movement paths and feeding areas by temperate-zone bats, as well as the timing of roost departures. The behaviour of tropical bats, on the other hand, seems more generally influenced by predators; this is especially true for tropical nectarivores and frugivores, but also for insectivorous bats. Presumably there are more serious predators on bats in the tropics (e.g. specialized raptors or carnivorous bats), but the identity of these predators is unclear. More information is needed to assess fully the influence of predators on bat behaviour. There is much need for work on the ways in which bats perceive predators via auditory, visual, and olfactory cues, and whether bats have some knowledge of the risks posed by different predators. Also needed is information on how predators attack bats and how bats react to attacking predators. Difficult to obtain, but of critical value, will be information on the nature of the predation risk experienced by bats while away from roosts and during the full darkness of night.

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Section: Predator Avoidance In An Ecological Contextmentioning

confidence: 99%

Do predators influence the behaviour of bats?

2013

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“…P. poliocephalus is endemic to the southeastern forested areas of Australia (Hall and Richards 2000). During the day, it forms large colonies amongst the foliage and branches of canopy trees (Klose et al 2009a;Nelson 1965a;Welbergen 2005). At dusk, it emerges from the colony and flies up to 50 km foraging for fruit, nectar and pollen (Eby 1991;Spencer et al 1991;Welbergen 2006Welbergen , 2008.…”

Section: Introductionmentioning

confidence: 99%

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

Welbergen

2010

Oecologia

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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.

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“…At the beginning of the reproductive season, from January to April 2006 ('pre-mating period', late January to mid February; 'mating period', late March to mid April; Klose et al 2009), 36 roosting adult males (2 years old) actively defending mating territories were randomly selected from the central colony area, assigned to one of the two study periods and sampled independently. This was because residents were known to be centrally located (Welbergen 2005).…”

Section: Methodsmentioning

confidence: 99%

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

2009

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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.

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

Cited by 29 publications

References 50 publications

Do predators influence the behaviour of bats?

Do predators influence the behaviour of bats?

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

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

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