Optimal foraging in seasonal environments: implications for residency of Australian flying foxes in food-subsidized urban landscapes

Bats provide important ecosystem services such as pollination of native forests; they are also a source of zoonotic pathogens for humans and domestic animals. Human-induced changes to native habitats may have created more opportunities for bats to reside in urban settings, thus decreasing pollination services to native forests and increasing opportunities for zoonotic transmission. In Australia, fruit bats (Pteropus spp. flying foxes) are increasingly inhabiting urban areas where they feed on anthropogenic food sources with nutritional characteristics and phenology that differ from native habitats. We use optimal foraging theory to investigate the relationship between bat residence time in a patch, the time it takes to search for a new patch (simulating loss of native habitat) and seasonal resource production. We show that it can be beneficial to reside in a patch, even when food productivity is low, as long as foraging intensity is low and the expected searching time is high. A small increase in the expected patch searching time greatly increases the residence time, suggesting nonlinear associations between patch residence and loss of seasonal native resources. We also found that sudden increases in resource consumption due to an influx of new bats has complex effects on patch departure times that again depend on expected searching times and seasonality. Our results suggest that the increased use of urban landscapes by bats may be a response to new spatial and temporal configurations of foraging opportunities. Given that bats are reservoir hosts of zoonotic diseases, our results provide a framework to study the effects of foraging ecology on disease dynamics.This research was supported by the State of Queensland, the State of New South Wales and the Commonwealth of Australia under the National Hendra Virus Research Program and by an IDEAS RCN research exchange grant awarded to D.P. to visit O.R. R.K.P. and O.R. are supported by National Science Foundation DEB-1716698; R.K.P. is supported by funding from the Defense Advanced Research Projects Agency (DARPA; D16AP00113), the National Institute of General Medical Sciences of the National Institutes of Health under Award Number P20GM103474 and P30GM110732, and SERDP RC-2633

Environmental variation across multiple spatial scales and temporal lags influences Hendra virus spillover

1. Pathogens can spill over and infect new host species by overcoming a series of ecological and biological barriers. Hendra virus (HeV) circulates in Australian flying foxes and provides a data-rich study system for identifying environmental drivers underlying spillover events. The frequency of spillover events to horses has varied interannually since the virus was first discovered in 1994. These observations suggest that HeV spillover events are driven, in part, by environmental factors, including loss of flying fox habitat and climate variability. 2. We explicitly examine the impact of environmental variation on the risk of HeV spillover at three spatial scales relevant to this system. We use a dataset of 60 spillover events and boosted regression tree methods to identify environmental features (including concurrent and lagged temperature, rainfall, vegetation indices, land cover, and climate indices) at three spatial scales (1-km, 20-km, 100-km radii) associated with horse contacts and reservoir species ecology. 3. We find that temperature, local (1-km radius) human population density, and landscape (100-km radius) forest cover and pasture are the most influential environmental features associated with HeV spillover risk. By including multiple spatial scales and temporal lags in environmental features, we can more accurately quantify risk across space and time than with models that use a single scale. For example, high quality vegetation at the local scale and within a foraging radius (20-km) in the concurrent month and previous years, combined with poorer quality vegetation at the landscape scale in the concurrent month increase risk of HeV spillover. These and other environmental associations likely influence the dynamic foraging behaviour of reservoir flying foxes and drive contacts that facilitate spillover into horse populations. 4. Synthesis and application: Current management of HeV spillover focuses on local-scale interventions – primarily through vaccination and detection of infected horses. Our study finds that HeV spillover risk is also driven by environmental changes over much larger scales and demonstrates management practices would benefit from incorporating landscape interventions alongside local interventions

Effects of logging and fire on small mamals in Mumbulla State Forest near Bega, New South Wales

This study of the effects of logging on small mammals in Mumbulla State Forest on the south coast of New South Wales included the effects of a fire in November 1980 and a drought throughout the study period from June 1980 to June 1983. Rattus fuscipes was sensitive to change: logging had a significant impact on its numbers, response to ground cover, and recapture rate; fire had a more severe effect, and drought retarded the post-fire recovery of the population. The three species of dasyurid marsupials differed markedly in their response to ground cover, canopy cover, logging and fire. Antechinus stuartii was distributed evenly through all habitats and was not affected by logging, but fire had an immediate and adverse effect which was sustained by the intense drought. A. swainsonii markedly preferred the regenerating forest, and was not seen again after the fire, the failure of the population being attributed to its dependence on dense ground cover. Sminthopsis leucopus was found in low numbers, appeared to prefer forest with sparse ground cover, and showed no immediate response to logging or fire; its disappearance by the third year post-fire suggests that regenerating forest is inimical to the survival of this species. Mus musculus showed no response to logging. In the first year following the fire its numbers were still very low, but in the next year there was a short-lived plague which coincided with the only respite in the 3-year drought and, importantly, occurred in the intensely burnt parts of the forest. The options for managing this forest for the conservation of small mammals include minimising fire, retaining unlogged forest, extending the time over which alternate coupes are logged and minimising disturbance from heavy machinery

Temporal

An evolving meditation upon the complex, periodic processes that mark Australia’s seasonality, and our increasing ability to disturb them. By amplifying and shining light upon a myriad of mysterious lives lived in blackness, the work presents a sensuous, deep engagement with the rich, irregular spectras of seasonal forms: whilst hinting at a far less comforting background increasingly framed by anthropogenic climate change. ’Temporal’ uses custom interactive systems, illusionary techniques and real time spatial audio processes that draw upon a rich array of media, including seasonal, nocturnal field recordings sourced in the Bundaberg region and detailed observations of foliage & flowering phases from that region. By drawing inspiration from the subtle transitions between what Europeans once named ‘Summer’ and ‘Autumn’ and the multiple seasons recognised by other cultures, whilst also including bodily disturbances within the work, ’Temporal’ creates a compellingly immersive environment that wraps audiences in luscious yet ominous atmospheres beyond sight and hearing. This work completes a two year long project of dynamic mediated installations that have been presented in Sydney, Beijing, Cairns and Bundanon, that have each been somehow choreographed by environmental cycles; alluding to a new framework for making works that we named ‘Seasonal’. These powerful, responsive & experiential works each draw attention to that which will disappear when biodiverse worlds have descended into an era of permanent darkness – an ‘extinction of human experience’. By tapping into the deeply interlocking seasonal cycles of environments that are themselves intimately linked with social, geographical & political concerns, participating audiences are therefore challenged to see the night, their locality & ecologies in new ways through extending their personal limits of perception, imagery & comprehension

Temporal: The artwork

The interactive artwork Temporal arose from a series of art-science investigations with some of Australia’s leading flying fox ecologists. It was designed as a gently evolving meditation upon the complex, periodic processes that mark Australia’s often irregular seasonal changes. In turn these changes directly govern the migratory movements of Australia’s keystone pollinating mammals - the mega bats (Flying Foxes). Temporal further called attention to our increasing capacity to profoundly disturb these partners within Australia’s complex, life-supporting system

Measuring Habitat Restoration using the Darwin and "Event" Cores: Australian examples powered by BioCollect

Habitat decline and fragmentation are major factors in biodiversity loss across the globe and can be difficult to measure, particularly at landscape scale (Brooks et al. 2002, Fahrig 2003, Ritchie and Roser 2019). In Australia, rural, coastal and urban communities have been undertaking habitat restoration activities since the mid-1980s to protect and restore ecological balance on private land and in local shared and natural spaces. Much of the restoration effort has centered around hands-on activities as a mechanism for building community with environmental benefits. Over such a time span, thousands of locations throughout the country have been transformed from degraded and highly disturbed landscapes into resemblances of more-or-less natural areas. However, collecting and analysing data for these activities was given little attention until quite recently, as governments, philanthropists and other investors have become increasingly interested in measuring the value and outcomes from investment. To measure the effectiveness of the restoration effort, it is essential to to benchmark the environmental state and species composition before the restoration begins, but surprisingly or unsurprisingly, this is rarely done (Hale et al. 2019).Responding to this call for better documentation of restoration outcomes, over 30 groups have been using the Atlas of Living Australia’s BioCollect platform to capture complex information about current and past restoration work. The BioCollect platform enables each type of monitoring, establishment, and follow-up activity to have its own data collection schema and associated metadata structured around using a hierarchy of sampling events based on the Event class in the Darwin Core standard, which allows relationships between types of event records to be specified. When event records are created through use of an activity-based template, each occurrence of a species is also parsed and configured as a Darwin Core occurrence record. Standard templates have been created for a range of activities, such as benchmarking assessments, site establishment, follow-up interventions and monitoring over time, which are being used by many different groups over large areas of the landscape. This allows each group to operate independently, yet collect standardised data that can be easily aggregated at larger temporal and spatial scales, quantifying change over time. The relationships between occurrences and the event context in which they were collected is also preserved and navigable.Here we present how Darwin Core and Event Core have been implemented in the BioCollect platform to enable this important data to be collected and stored in its full richness and resolution

Black Nectar

Black Nectar is a site-specific light & sound installation, that asks audiences to take slow, sensory walks through the inky-blackness of Bundanon’s forests at night, charting personal courses through seasons of change, animality and imagination – far beyond the blinding lights and howling tones of our contemporary existence. Gathering during a time Europeans once named as ‘spring’ audiences will leave the comfy lights and sounds of Bundanon’s homestead area, to take powerful, personal, silent journeys into the long darks of night, heading ultimately towards the place of ‘Black Nectar’. This most unusual of walks begins with impending darkness, and yet ultimately ends with the faintest, sweetest of glimmers – an en-lightening, re-sounding of our seasonal futures

Pest or Guest: The Zoology of Overabundance

How humans interact with the biotas of the world is critically determined by our ecological knowledge as well as our social goals and outlook. This symposium addresses the important question of how to deal with both exotic species and native species that turn into pests. We have to begin with a clear understanding of what a pest species is, and the general conundrum of overabundance. There is an underlying theme in many discussions about our environmental problems that the main pest is the human animal, and only when we learn to deal with this ever-expanding and overabundant species will we achieve some broad-scale conservation successes. But the conventional definition of a pest is any organism that interferes with humans

Climate change and the effects of temperature extremes on Australian flying-foxes

Little is known about the effects of temperature extremes on natural systems. This is of increasing concern now that climate models predict dramatic increases in the intensity, duration and frequency of such extremes. Here we examine the effects of temperature extremes on behaviour and demography of vulnerable wild flying-foxes (Pteropus spp.). On 12 January 2002 in New South Wales, Australia, temperatures exceeding 42°C killed over 3500 individuals in nine mixed-species colonies. In one colony, we recorded a predictable sequence of thermoregulatory behaviours (wing-fanning, shade-seeking, panting and saliva-spreading, respectively) and witnessed how 5–6% of bats died from hyperthermia. Mortality was greater among the tropical black flying-fox, Pteropus alecto (10–13%) than the temperate grey-headed flying-fox, Pteropus poliocephalus (less than 1%), and young and adult females were more affected than adult males (young, 23–49%; females, 10–15%; males, less than 3%). Since 1994, over 30 000 flying-foxes (including at least 24 500 P. poliocephalus) were killed during 19 similar events. Although P. alecto was relatively less affected, it is currently expanding its range into the more variable temperature envelope of P. poliocephalus, which increases the likelihood of die-offs occurring in this species. Temperature extremes are important additional threats to Australian flying-foxes and the ecosystem services they provide, and we recommend close monitoring of colonies where temperatures exceeding 42.0°C are predicted. The effects of temperature extremes on flying-foxes highlight the complex implications of climate change for behaviour, demography and species survival

Pest or guest : the cultural context of the zoology of overabundance

In this chapter, our aim is to draw attention to common themes, look historically at the subject, and to consider the use of words, particularly "pest", "abundant" and "overabundant". One of the important points is to note that the word "pest" is a label that can categorise an animal in a way that may preclude it from receiving humane treatment and/or being seen as a resource. Word use, values and wildlife management conflicts project us into the cultural domain of examining the zoology of overabundance. We present a chronology of the convolutions in thinking, decision-making and actions to manage the burgeoning koala population on Kangaroo Island in South Australia. While these dilemmas are often played out publicly for terrestrial vertebrates, we also draw attention to the importance of invertebrate pests, such as invading ants, and marine organisms in ships' ballast, and then discuss the ultimate pest species - humans. We regard the issue of overabundance as a challenge to the discipline of ecology. The burgeoning world population of people and the koalas on Kangaroo Island both reflect the same process, throwing up similar biological and ethical dilemmas