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 428C 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 42.08C are predicted. The effects of temperature extremes on flying-foxes highlight the complex implications of climate change for behaviour, demography and species survival.

Climate change is expected to have significant influences on terrestrial biodiversity at 21all system levels, including species-level reductions in range size and abundance, 22 especially amongst endemic species 1-6 . However, little is known about how mitigation of 23 greenhouse gas emissions could reduce biodiversity impacts, particularly amongst 24 common and widespread species. Our global analysis of future climatic range change of 25 common and widespread species shows that without mitigation, 57±6% of plants and 26 adaptation. 34The IPCC 3 estimates that 20-30% of species would be at increasingly high risk of 35 extinction if global temperature rise exceeds 2-3°C above pre-industrial levels. However, 36 since quantitative assessments of the benefits of mitigation in avoiding biodiversity loss are 37 lacking, we know little about how much of the impacts can be offset by reductions in 38 greenhouse gas emissions. Furthermore, despite the large number of studies addressing 39 extinction risks in particular species groups, we know little about the broader issue of 40 potential range loss in common and widespread species, which is of serious concern as even 41 small declines in such species can significantly disrupt ecosystem structure, function and 42 services 7 . 43Here we quantify the benefits of mitigation in terms of reduced climatic range losses 44 in common and widespread species, and determine the time early mitigation action can "buy" 45 3 for adaptation. In particular, we provide (i) a comprehensive analysis of potential climatic 46 range changes for 48,786 animal and plant species across the globe, using the same set of 47 global climate change scenarios for all species; and (ii) a direct comparison of projected 48 levels of potential climate change impacts on the climatic ranges of species in six 21 st century 49 mitigation scenarios, including a 'no policy' baseline scenario in which emissions continue to 50 rise unabated (Fig. 1, Table 1). To calculate the climatic range changes, we employed 51MaxEnt, one of the most robust bioclimatic modelling approaches for cases where only 52 presence data (as opposed to presence-absence) are available 8 . MaxEnt models the 53 probability of a species' presence, conditioned on environment 8 so that in this paper 'climatic 54 range change' specifically refers to the change in the modelled probability of a species' 55 occurrence, conditioned on climatic variables. Eighty percent of the species studied have 56 climatic ranges in excess of 30,000 km 2 , which is the range size used by Bird Life 57International to delineate 'restricted range species', whilst less than 7% have ranges 58 occupying less than 20,000 km 2 ( Supplementary Fig. S1). Our study therefore focuses on 59 quantifying the effects on widespread species, which are in general more common and less 60 likely to become extinct than restricted range species 9 , in contrast to previous studies that 61 have only speculated that there may be effects such species [1][2][3][4][5][6] . In projecting future...

Refugia – areas that may facilitate the persistence of species during large‐scale, long‐term climatic change –are increasingly important for conservation planning. There are many methods for identifying refugia, but the ability to quantify their potential for facilitating species persistence (ie their “capacity”) remains elusive. We propose a flexible framework for prioritizing future refugia, based on their capacity. This framework can be applied through various modeling approaches and consists of three steps: (1) definition of scope, scale, and resolution; (2) identification and quantification; and (3) prioritization for conservation. Capacity is quantified by multiple indicators, including environmental stability, microclimatic heterogeneity, size, and accessibility of the refugium. Using an integrated, semi‐mechanistic modeling technique, we illustrate how this approach can be implemented to identify refugia for the plant diversity of Tasmania, Australia. The highest‐capacity climate‐change refugia were found primarily in cool, wet, and topographically complex environments, several of which we identify as high priorities for biodiversity conservation and management.

Coevolutionary arms races, where adaptations in one party select for counter-adaptations in another and vice versa, are fundamental to interactions between organisms and their predators, pathogens, and parasites [1]. Avian brood parasites and their hosts have emerged as model systems for studying such reciprocal coevolutionary processes [2, 3]. For example, hosts have evolved changes in egg appearance and rejection of foreign eggs in response to brood parasitism from cuckoos, and cuckoos have evolved host-egg mimicry as a counter-response [4-6]. However, the host's front line of defense is protecting the nest from being parasitized in the first place [7-10], yet little is known about the effectiveness of nest defense as an antiparasite adaptation, and its coevolutionary significance remains poorly understood [10]. Here we show first that mobbing of common cuckoos Cuculus canorus by reed warblers Acrocephalus scirpaceus is an effective defense against parasitism. Second, mobbing of cuckoos is a phenotypically plastic trait that is modified strategically according to local parasitism risk. This supports the view that hosts use a "defense in-depth strategy," with successive flexible lines of defense that coevolve with corresponding offensive lines of the parasite. This highlights the need for more holistic research into the coevolutionary consequences when multiple adaptations and counter-adaptations evolve in concert [11].

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Coevolutionary arms races between brood parasites and hosts involve genetic adaptations and counter-adaptations. However, hosts sometimes acquire defenses too rapidly to reflect genetic change. Our field experiments show that observation of cuckoo (Cuculus canorus) mobbing by neighbors on adjacent territories induced reed warblers (Acrocephalus scirpaceus) to increase the mobbing of cuckoos but not of parrots (a harmless control) on their own territory. In contrast, observation of neighbors mobbing parrots had no effect on reed warblers' responses to either cuckoos or parrots. These results indicate that social learning provides a mechanism by which hosts rapidly increase their nest defense against brood parasites. Such enemy-specific social transmission enables hosts to track fine-scale spatiotemporal variation in parasitism and may influence the coevolutionary trajectories and population dynamics of brood parasites and hosts.

The similarity between many Old World parasitic cuckoos (Cuculinae) and Accipiter hawks, in size, shape and plumage, has been noted since ancient times. In particular, hawk-like underpart barring is more prevalent in parasitic than in non-parasitic cuckoos. Cuckoo-hawk resemblance may reflect convergent evolution of cryptic plumage that reduces detection by hosts and prey, or evolved mimicry of hawks by parasitic cuckoos, either for protection against hawk attacks or to facilitate brood parasitism by influencing host behaviour. Here, we provide the first evidence that some small birds respond to common cuckoos Cuculus canorus as if they were sparrowhawks Accipiter nisus. Great tits and blue tits were equally alarmed and reduced attendance at feeders during and after the presentation of mounted specimens of common cuckoos and sparrowhawks, but not in response to control presentations of collared doves or teal. Plumage manipulations revealed that the strong alarm response to cuckoos depended on their resemblance to hawks; cuckoos with barred underparts were treated like hawks, while those with unbarred underparts were treated like doves. However, barring was not the only feature inducing alarm because tits showed similarly strong alarm to barred and unbarred hawks, and little alarm to barred doves. These responses of tits, unsuitable as hosts and hence with no history of cuckoo parasitism, suggest that naive small birds can mistake cuckoos for hawks. Thus, any cuckoo-hawk discrimination by host species is likely to be an evolved response to brood parasitism.