The role of exotic mammals in the diet of native carnivores from South America

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Not all predators are equal: a continent‐scale analysis of the effects of predator control on Australian mammals

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Marine mammal culling programs: review of effects on predator and prey populations

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Global patterns in seed germination after ingestion by mammals

1. Mammals play an important role in seed germination through the ingestion of fruits and seeds. Since seed germination is a basic step in seedling recruitment, understanding how mammals affect germination improves our understanding of the effect of loss of mammal populations on the dynamics of plant communities.
2. We used meta-analytical methods to describe global patterns in the effect of seed ingestion by mammals on seed germination success and rate. We collected data from 154 studies that included 115 mammal species and 448 plant species.
3. Our results showed a positive cumulative effect of mammals on seed germination. However, this effect differed between mammalian orders; thus, some groups such as elephants, primates, and new world marsupials emerged as important enhancers of seed germination. Also, the effect varied depending on the plant family and the bioregion. Increased seed germination after ingestion was positively related to fast germination.
4. This meta-analysis, the first to synthesise and compare most of the information presently available on how mammals affect seed germination after ingestion, shows a global positive effect of mammals as enhancers of seed germination. However, behind that positive effect lies a diversity of neutral, negative, and positive effects of different magnitudes, which may have multifactorial explanations. We hope that the patterns presented here open up new questions and help guide future research efforts.

     

Mammals,agri‐environment schemes and set‐aside – what are the putative benefits?

• 1 The impacts of agricultural intensification on farmland wildlife have been the subject of increasing concern, particularly over the last two decades. Population declines have occurred for a number of mammalian species, sometimes drastically so, and changes in farming practice are believed to be significant contributory factors.
• 2 The major policy instruments for delivering environmental benefits on farmland are agri‐environment schemes. These encourage farmers to adopt more environmentally sensitive farming practices to promote farmland biodiversity. Additionally, compulsory set‐aside, which reduces agricultural surplus, could also have positive impacts on wildlife. In this paper we consider some of the putative benefits of agri‐environment schemes and set‐aside for mammals.
• 3 We review how establishment and management options within agri‐environment schemes and set‐aside might affect habitat resources for mammals. For example, conservation headlands increase plant and invertebrate resources within the crop edge for mammals such as wood mice. Grassy field margins can support communities of smaller mammals, and hedgerows may act as important commuting and hunting routes. Their potential will depend on factors such as seed mixtures used, timing and severity of cutting, and length of time they have been in place.
• 4 At a farm level, habitat heterogeneity may be increased through organic agriculture, which is supported by some agri‐environment schemes. Studies suggest significant benefits to mammals, including wood mice and bats. However, it is increasingly recognized that effective conservation of farmland mammals must seek solutions at the landscape scale, addressing such issues as habitat connectivity between farms. One approach may be the better targeting of scheme agreements.
• 5 We suggest that agri‐environment schemes and set‐aside can contribute to the conservation of mammals on farmland. Recent policy changes are likely to have further positive impacts on farmland wildlife but appropriate mammal monitoring programmes must be developed rigorously to assess their effects.

     

Iophenoxic acid as a bait marker for wild mammals: efficacy and safety considerations

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Macroscopic prey remains in the winter diet of foxes Vulpes vulpes in rural Britain

• 1 The winter diet of foxes Vulpes vulpes was quantified in seven landscape types in Britain, using faecal samples from 87 sites.
• 2 Medium‐sized mammals (0.1–5.0 kg) were consistently the most important prey group in arable and pastural landscapes, occurring in 44–72% of scats and comprising 50–75% of the mass of prey ingested. Birds and small mammals (< 0.1 kg) were important secondary prey groups.
• 3 Small mammals were the most frequently recorded prey group in marginal upland (42% of scats) and upland landscapes (75%), followed by large mammals (33% and 23%, respectively). In terms of mass ingested, small mammals (38%) and large mammals (52%) were the most important prey groups in these landscapes.
• 4 In all landscapes, field voles Microtus agrestis, lagomorphs, sheep/deer and passerines/galliforms dominated their respective prey groupings.

     

What can whiskers tell us about mammalian evolution,behaviour, and ecology?

1. Most mammals have whiskers; however, nearly everything we know about whiskers derives from just a handful of species, including laboratory rats Rattus norvegicus and mice Mus musculus, as well as some species of pinniped and marsupial.
2. We explore the extent to which the knowledge of the whisker system from a handful of species applies to mammals generally. This will help us understand whisker evolution and function, in order to gain more insights into mammalian behaviour and ecology.
3. This review is structured around Tinbergen’s four questions, since this method is an established, comprehensive, and logical approach to studying behaviour. We ask: how do whiskers work, develop, and evolve? And what are they for?
4. While whiskers are all slender, curved, tapered, keratinised hairs that transmit vibrotactile information, we show that there are marked differences between species with respect to whisker arrangement, numbers, length, musculature, development, and growth cycles.
5. The conservation of form and a common muscle architecture in mammals suggests that early mammals had whiskers. Whiskers may have been functional even in therapsids.
6. However, certain extant mammalian species are equipped with especially long and sensitive whiskers, in particular nocturnal, arboreal species, and aquatic species, which live in complex environments and hunt moving prey.
7. Knowledge of whiskers and whisker use can guide us in developing conservation protocols and designing enriched enclosures for captive mammals.
8. We suggest that further comparative studies, embracing a wider variety of mammalian species, are required before one can make large-scale predictions relating to evolution and function of whiskers. More research is needed to develop robust techniques to enhance the welfare and conservation of mammals.

     

Comparative aspects of iodine conservation in mammals

• 1.1. Comparative aspects of iodine conservation in mammals were studied on the basis of published data on kidney and thyroid weights and function.
• 2.2. Very small mammals possessed an efficient reabsorption of iodide to compensate for the high glomerular nitration rate (GFR).
• 3.3. Humans and mammals of a similar and larger size had “lost” the ability to reabsorb iodide efficiently.
• 4.4. Very large mammals are protected against renal loss of iodide due to the relatively low GFR.
• 5.5. Thyroid weights in relation to body weight were highest in humans suggesting that humans and other mammals of a similar size are especially susceptible to iodine deficiency.

     

Spatial mapping memory: methods used to determine the existence and type of cognitive maps in arboreal mammals

1. Researchers have used multiple methods to understand spatial mapping memory used by arboreal mammals for orientation: the change-point test, measures of path tortuosity, field experiments with feeding platforms, nearest-neighbour feeding tree methods, complex calculations of travel route parameters, and theoretical models.
2. This literature review provides details of all of these methods, highlights previous results from spatial mapping memory studies, and discusses perspectives for future studies.
3. Previous studies have shown that various arboreal mammals, mostly in the order Primates, can memorise spatial environments using a cognitive map. Two types of maps are characterised: the topological map, based on landmarks and reused routes, and the Euclidean map, including the ability to create shortcuts by measuring distances and distinguishing between directions. Most of the studies showed that mammals do not travel randomly but, due to the difficulty of determining which spatial map is used, the use of cognitive maps remains hypothetical.
4. When studying spatial mapping memory, data collection and analysis should account for the species’ characteristics, such as the home-range size, food preferences, and types of movements. The role of sensory cues (visual, auditory, olfactory) is crucial to understanding spatial orientation. The most relevant way to determine how arboreal mammals orientate themselves in space is by using a mix of methods: random theoretical models, collecting data in a controlled environment, measuring different parameters of travel patterns, and considering the use of sensory cues and environmental factors of the study sites.
5. Research pertaining to spatial mapping memory in arboreal mammals and forest-dwelling mammals is important for understanding cognitive abilities in mammal species, and more studies are needed in mammals of various orders.

     

Emerging sex allocation research in mammals: marsupials and the pouch advantage

• 1 Adaptive adjustments in offspring sex ratios in mammals have long been reported, but the conditions and mechanisms that prompt shifts in the proportion of sons and daughters born are still unclear.
• 2 Empirical evidence indicates that offspring sex in mammals can be related to a diversity of environmental and maternal traits. However, the underlying assumptions regarding offspring and maternal fitness are rarely tested.
• 3 Physiological mechanisms of maternal selection of offspring sex may occur at many stages during the prolonged maternal investment stage, and a pluralistic approach to studying mechanisms might prove fruitful.
• 4 This review highlights the apparent frequency, in marsupial mammals, of sex ratio bias, which has largely been recorded as conforming to one of a few hypotheses.
• 5 Marsupials are ideally suited to experiments involving cross‐fostering of offspring, which can allow rigorous tests of the fitness consequences of rearing one sex vs. the other. The reproductive biology of marsupials lends the group to detailed studies of the timing and physiological correlates of offspring sex biases.
• 6 Many components of metatherian biology may prove advantageous in experimental studies of sex allocation in mammals, and together may provide a prosperous avenue for examining adaptive and mechanistic hypotheses in mammalian sex allocation.

     

Heterothermy,body size,and locomotion as ecological predictors of migration in mammals

1. Migration is ubiquitous among animals and has evolved repeatedly and independently. Comparative studies of the evolutionary origins of migration in birds are widespread, but are lacking in mammals. Mammalian species have greater variation in functional traits that may be relevant for migration. Interspecific variation in migration behaviour is often attributed to mode of locomotion (i.e. running, swimming, and flying) and body size, but traits associated with the evolutionary precursor hypothesis, including geographic distribution, habitat, and diet, could also be important predictors of migration in mammals. Furthermore, mammals vary in thermoregulatory strategies and include many heterothermic species, providing an alternative strategy to avoid seasonal resource depletion.
2. We tested the evolutionary precursor hypothesis for the evolution of migration in mammals and tested predictions linking migration to locomotion, body size, geographic distribution, habitat, diet, and thermoregulation. We compiled a dataset of 722 species from 27 mammalian orders and conducted a series of analyses using phylogenetically informed models.
3. Swimming and flying mammals were more likely to migrate than running mammals, and larger species were more likely to migrate than smaller ones. However, heterothermy was common among small running mammals that were unlikely to migrate. High-latitude swimming and flying mammals were more likely to migrate than high-latitude running mammals (where heterothermy was common), and most migratory running mammals were herbivorous. Running mammals and frugivorous bats with high thermoregulatory scope (greater capacity for heterothermy) were less likely to migrate, while insectivorous bats with high thermoregulatory scope were more likely to migrate.
4. Our results indicate a broad range of factors that influence migration, depending on locomotion, body size, and thermoregulation. Our analysis of migration in mammals provided insight into some of the general rules of migration, and we highlight opportunities for future investigations of exceptions to these rules, ultimately leading to a comprehensive understanding of the evolution of migration.

     

Support for a metapopulation structure among mammals

• 1 The metapopulation metaphor is increasingly used to explain the spatial dynamics of animal populations. However, metapopulation structure is difficult to identify in long‐lived species that are widely distributed in stochastic environments, where they can resist extinctions. The literature on mammals may not provide supporting evidence for classic metapopulation dynamics, which call for the availability of discrete habitat patches, asynchrony in local population dynamics, evidence for extinction and colonization processes, and dispersal between local populations.
• 2 Empirical evidence for metapopulation structure among mammals may exist when applying more lenient criteria. To meet these criteria, mammals should live in landscapes as discrete local breeding populations, and their demography should be asynchronous.
• 3 We examined the literature for empirical evidence in support of the classical criteria set by Hanski (1999 ), and for the more lenient subset of criteria proposed by Elmhagen & Angerbjörn (2001 ). We suggest circumstances where metapopulation theory could be important in understanding population processes in mammals of different body sizes.
• 4 The patchy distribution of large (>100 kg) mammals and dispersal often motivate inferences in support of a metapopulation structure. Published studies seldom address the full suite of classical criteria. However, studies on small mammals are more likely to record classic metapopulation criteria than those on large mammals. The slow turnover rate that is typical for medium‐sized and large mammals apparently makes it difficult to identify a metapopulation structure during studies of short duration.
• 5 To identify a metapopulation structure, studies should combine the criteria set by Hanski (1999 ) and Elmhagen & Angerbjörn (2001 ). Mammals frequently live in fragmented landscapes, and processes involved in the maintenance of a metapopulation structure should be considered in conservation planning and management.

     

Resource pulses affect prey selection and reduce dietary diversity of dingoes in arid Australia

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Impacts of hunting on mammals in African tropical moist forests: a review and synthesis

• 1 Available information on the consumption of wild meat in West and Central Africa is reviewed. We show that mammals are the prime source of bushmeat, and that ungulates and rodents make up the highest proportion of biomass extracted.
• 2 We present data on current knowledge of extraction patterns of wild mammals in West and Central Africa, and evidence that at current off‐take levels, within the range states, mammals as bushmeat are being depleted on an unprecedented scale. Extraction rates are orders of magnitude higher there than in comparable ecosystems like the Amazon, and much less likely to be sustainable.
• 3 However, basic knowledge of the biology of harvestable tropical moist forest mammals, and the consequences of hunting on mammalian communities, which permits accurate estimation of maximal production rate (the excess of growth over replacement rate), is largely unavailable, and this hinders estimation of hunting quotas and sustainability. Comparisons are made with the existing information available on Amazon basin mammals and hunting patterns reported there.

     

Is the loss of Australian digging mammals contributing to a deterioration in ecosystem function?

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Can recreational hunting contribute to pest mammal control on public land in Australia?

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Monitoring exposure to avian influenza viruses in wild mammals

• 1 Avian influenza (AI) viruses primarily circulate in wild waterfowl populations and are occasionally transmitted to domestic poultry flocks. However, the possible roles of other wildlife species, such as wild mammals, in AI virus ecology have not been adequately addressed.
• 2 Due to their habitat and behaviour, many wild mammals may be capable of transmitting pathogens among wild and domestic populations. Exposure to AI viruses has been reported in an array of wild and domestic animals. The presence of wild mammals on farms has been identified as a risk factor for at least one poultry AI outbreak in North America. These reports suggest the need for seroprevalence studies examining the exposure of wild mammals to AI viruses.
• 3 Serological tests are routinely used to assess domestic poultry, domestic swine and human exposure to influenza A viruses, but these tests have not been validated for use in wild mammals. As such, some of these protocols may require adjustments or may be inappropriate for use in serology testing of wild mammals. Herein, we review these serological techniques and evaluate their potential usefulness in AI surveillance of wild mammals. We call for care to be taken when applying serological tests outside their original area of validation, and for continued assay verification for multiple species and virus strains.

     

Employing statistical learning to derive species-level genetic diversity for mammalian species

1. The patterns of genetic diversity in several genomic regions have been used in mammalian systematics for decades. For instance, when studying closely related species, it is generally assumed that the mitochondrial cytochrome b gene (cytb) exhibits significant information that can be used for differentiation between intraspecies and interspecies variation in mammals. Because of sampling limitations, early analyses of this proposition were conducted mainly on rodents and bats.
2. Currently, more than 57000 cytb sequences are available covering all major lineages of mammals, and sequencing of several individuals per species is common practice in molecular systematics. We were thus prompted to carry out a large-scale analysis of the utility of cytb genetic variation as a predictor of whether a pair of sequences came from within-species or between-species comparisons.
3. Using predetermined species-level assignments, we employed standard methods from statistical learning to calculate the cut-off values able to classify genetic distances in either intraspecies or interspecies categories; we then measured the performance of such statistical classifiers to predict the species-level taxonomic rank as defined by experts.
4. Depending on the classifier, our results showed that when adopting cytb distance cut-off values of 7.3% and 5.5% for small mammals (Metatheria, Rodentia, Chiroptera, and Eulipotyphla) and 4.3% and 3% for medium-sized to large mammals (Primates, Carnivora, and Artiodactyla), the frequency of incorrect assignment of within-species divergences to the between-species category (type I error) varied from 7 to 11%.
5. In order to avoid over-splitting by future researchers, we calculated cut-off values using a more conservative evaluation and provided a list of mammalian species that are likely to consist of complexes of cryptic species. We show that our supervised method can provide practical guidelines to improve the performance of unsupervised algorithms for species delimitation. Finally, we discuss limitations of large-scale approaches (e.g. effects of misclassification in databases and the need for case-by-case evaluation of cryptic species complexes) and their consequences for conservation policies.

     

Litter size and latitude in a large mammal: the wild boar Sus scrofa

• 1 A positive relationship between clutch size or litter size and latitude exists in birds and many species of small mammal. Hitherto, however, analyses for large mammals have failed to provide evidence that litter sizes increase with latitude.
• 2 We collated data from published studies of wild boar in Europe, to analyse the relationship between litter size and latitude in this widely distributed terrestrial mammal.
• 3 Depending on the specific data set (whether only the most reliable data or all available data were included), latitude explained 58% to 72% of the variation in mean litter sizes across studies. On average, litter size increases by approximately 0.15 piglets per degree of latitude.
• 4 A strong correlation between litter size and latitude for wild boar in Europe provides a starting point for demographic modelling of this species of both ecological and economic importance.
• 5 The pattern for wild boar is consistent with Ashmole's explanation for the effects of latitude on reproduction. The contrast between our results and those generated for other large mammals may result from our focus on an herbivore in contrast to previous work which was focused on carnivores. Further work could usefully examine the extent of seasonality in the availability of resources for species of different dietary types.