Small Mammal Predators Research Articles

Collection methods of wild barn owl pellets at low environmental contamination and proposals of microbiological and ecological investigations

BackgroundThe barn owl Tyto alba is a medium-sized nocturnal raptor, predator of small mammals, birds, reptiles, and insects, distributed all over the world. Environmentally uncontaminated wild barn owl pellets are hard and rare to find and provide a natural matrix for biological investigations.ResultsDifferent solutions for collecting wild barn owl pellets at low environmental contamination are proposed. These solutions are based on a daily sanitized surface for sample retrieval, followed by rapid analysis. As an example of the possible investigations that can be carried out on these matrices, with the aim to highlight the relevance of the obtained results also from a biotechnological perspective. Two rare pellet samples from wild barn owl T. alba, appropriately collected in a rural area of central Italy, were analyzed using culture-dependent, molecular (Next-Generation Sequencing), and enzyme profile analysis techniques. The osteological observations of the bone remains provided useful information for identifying the prey, mainly rodents (Apodemus sp.). Under our experimental conditions, the results revealed both a wide heterogeneity between the pellet microbiota and a great percentage of uncultured bacteria not classified at the species level. Furthermore, microbial cultures of Malbranchea albolutea, Debaryomyces hansenii, and Lactobacillus sp. were isolated and studied.Finally, we quantified the environmental impact of our experimental work in terms of CO2 equivalent release. To compensate for the release of 300 kg/CO2 eq., three Taxus. baccata L. were planted.ConclusionsThis work provides a starting point for developing an effective strategy to study and characterize wild barn owl pellets at low environmental contamination. It presents a simple and easy technique/protocol for collecting the pellets. The microbiota heterogeneity found in the two analyzed samples suggests that barn owl pellets can represent a potential natural reservoir for the discovery of new microorganisms to be used in various biotechnological applications. This could open the way for further large-scale studies on a greater number of samples and populations.Graphical

Forest disturbance and occupancy patterns of American ermine (Mustela richardsonii) and long-tailed weasel (Neogale frenata): results from a large-scale natural experiment in Maine, United States

Abstract Weasels are small mustelid carnivores that play an important role as predators of small mammals in a wide array of ecosystems. However, their response to land use, such as forest harvest for timber products, is seldom the subject of focused research and management projects. Both the American ermine, also known as the short-tailed weasel (Mustela richardsonii), and the long-tailed weasel (Neogale frenata) are native to Maine, United States, where commercial timber harvesting is widespread. The effects of this forest disturbance on weasels are poorly understood, so to contribute toward filling this knowledge gap, we conducted a 4-year, large-scale field study: specifically, our objective was to assess the effects of forest disturbance caused by timber harvest on occupancy patterns of ermines and long-tailed weasels occupancy patterns in Maine. We collected data from 197 survey sites (three camera traps each) over 4 years and analyzed over 7,000 images of weasels using dynamic false-positive occupancy models. We found that American ermines were widely distributed across the state (naïve occupancy at 54% of sites), while long-tailed weasels were rarer (naïve occupancy at 16% of sites). Both species responded positively to forest disturbance, with higher occupancy probabilities as disturbance increased, especially at the larger scales. American ermines were more likely to occupy stands with a higher percentage of conifer trees, while no such relationship was found for long-tailed weasels. We conclude that current forest harvest practices in Maine are not detrimental to weasel populations, but that the two species warrant continued monitoring.

Динамика населения мелких млекопитающих пирогенных сообществ в степном бору

In 2008–2021 we studied small mammals annually using zoological ditches in the Tsasucheysky steppe pine forest (Zabaikalsky Region, Russia). Before the 2012 high-severity fire we captured small mammals in a typical pine forest, either old-growth or old-burnt sites, and after the 2012 fire—in sites of fresh primary and repeated burns as well as in survived areas. The undisturbed steppe pine forest was characterised by small numbers of mammals, dominated by Myodes rutilus. In the first-burnt sites mainly Cricetulus pseudogriseus individuals were captured during the first decade after the fire. This species also rapidly invaded the re-burnt sites; however, in the third or fourth year the small mammal community became polydominant. In the old post-fire area (more than 10 years after the fire) small mammals were most abundant and the community was more diverse. In the post-fire sites С. pseudogriseus, Lasiopodomys raddei, Sorex tundrensis and S. minutissimus were the most numerous; Alexandromys mongolicus was also common in the old burnt sites. The total number of small mammals decreased significantly only in the first year after the fire. The total abundance of small mammals in the sites of old and repeated burns was significantly higher than in the undisturbed pine forests and first burned areas. In parallel, the total numbers of small mammals in the pyrogenic and relevant preceding communities were not statistically different. The number of M. rutilus decreased and the number of C. pseudogriseus increased in the burns compared to the pine forest. Despite the changes in the composition and structure of the community, the fire led to no significant changes in the overall abundance of small mammals in the Tsasucheysky Pine Forest during the first following decade. Subsequently, when the burns became overgrown, the small mammal community became richer in both number of species and their abundance. This indicates the resilience of small mammal populations to fires in the forest-steppe and, thus, the stability of the food base for small mammal predator populations.

Frequency of Occurrence and Ingested Biomass of Different Prey of the Barn Owl Tyto alba in an Island Ecosystem

The Barn Owl Tyto alba is commonly reported as a non-selective predator of small mammals, and its diet has been thoroughly analyzed also to assess the small mammal assembly composition in many study areas. The aim of this work was to analyze the diet of the Barn Owl in the Elba island through the analysis of 161 pellets collected in September 2020. Undigested fragments were isolated and compared with reference collections. We confirmed that the Barn Owl is a typical predator of field mice (62% of relative frequency), with synanthropic murid rodents as the second category of prey. The frequency of consumption of shrews increased by 9% with respect to the previous work, suggesting that the natural environment of Elba island is still in a good health status. Moreover, fragments of two newborn hares were detected, increasing the knowledge on the local trophic spectrum of the Barn Owl. Finally, the skull of a Geoffroy’s Myotis Myotis emarginatus confirmed the presence of this species in Elba island after over 60 years from the first unconfirmed record. Repeated studies conducted in the same study site may provide useful information on prey population trends and local environmental status.

Diet of the eastern barn owl (

The eastern barn owl (Tyto delicatula) is a significant native predator of small mammals in Australia. Regurgitated pellets can provide important data on species presence, current or historical changes in mammal fauna over time, or data on cryptic or threatened species. We collected 125 pellets from Cravens Peak reserve, Simpson Desert, Queensland, and examined the contents, including changes in diet over time (using age of pellet as a proxy) and the relative importance of different prey. In total, 642 unique prey items were recorded, 92% of which were mammals. Small rodents were the dominant prey – Mus musculus and Pseudomys hermannsburgensis, and the presence of Notomys cf. fuscus, Pseudantechinus cf. mimulus and Dasycercus blythi were all significant, being range extensions. Such data add to more traditional or novel techniques to record community changes over time.

Ants in the diet of Collared Anteater, Tamandua tetradactyla (Linnaeus, 1758) (Pilosa, Myrmecophagidae), in the state of Rio de Janeiro, Brazil

The Collared Anteater, Tamandua tetradactyla (Linnaeus, 1758), is a small mammal predator of ants. There are few studies describing which species are in fact consumed by them. This study was aimed to investigate the diversity and abundance of local species of ants preyed by the T. tetradactyla. Eight samples of stomach contents collected in the period from 2009 to 2014 were analyzed and identified at the lowest possible taxonomic level. We found 5,906 ants distributed in 16 species. The most abundant samples were number 2 and 4 with almost 2,000 individuals and the highest richness and abundance was Myrmicinae subfamily with eight species and 3,721 individuals. The ant richness found in this research demonstrates that the anteaters are generalists and opportunistic about their diet, not having a preference for a particular species, but rather for those insects that are available in their habitat.

Non-linear relationship between body size of terrestrial carnivores and their trophic niche breadth and overlap

Studying food partitioning of mammalian predators is important for understanding trophic structures and interactions between coexisting carnivore species. This is particularly pertinent in the light of expanding ranges of populations of generalist species whose habitat and diet overlap with more specialized species. Here, we tested the resource partitioning hypothesis in terrestrial carnivores, predicting that trophic niche breadth and overlap relate positively to body mass. We used dietary data from 18 terrestrial carnivore taxa in four families (Canidae, Mustelidae, Felidae and Ursidae; body mass 0.1–173.6kg) in three regions in Central and Eastern Europe, i.e. deciduous forest and forest-steppe region (DFR), temperate deciduous and mixed forest region (MFR) and transitory mixed forest regions (TFR). We ranked carnivores along an axis of trophic niche (breadth and overlap), and analysed the relationship between trophic niche and body mass (or pair-wise difference in body mass). A hierarchical cluster analysis of diet composition divided carnivores into four ecological groups: wild ungulate predators; small-mammal predators; amphibians and small mammal predators and omnivores. The relationship between body mass of predators and both trophic niche breadth and trophic niche overlap were hump-shaped. The trophic niche breadth to body mass ratio was significantly lower in DFR than in TFR and trophic niche overlap was significantly higher in DFR than in MFR and TFR. The predominant food resource is small mammals whose abundance is related to local agricultural and forestry management practices. Modifications of management techniques can affect population dynamics and community composition of carnivore species, especially in the case of small-mammal predators.

Indirect commensalism between an introduced apex predator and a native avian predator

In ecosystems, some organisms facilitate others indirectly, by interacting with one or more common mediator organisms. Thus, the indirect effects of introducing or removing species can be resonant, sometimes leading to successional extinctions. The dingo (Canis dingo) is the apex predator in Australian deserts and was introduced to the continent between 3000 and 5000 years ago. Dingoes suppress the abundances of introduced mesopredators, the red fox (Vulpes vulpes) and feral cat (Felis catus) and in so doing mitigate small mammal declines wreaked by these mesopredators. Given the positive association between the abundances of dingoes and small mammals, we predicted that dingoes indirectly facilitate a specialised native predator of small mammals, the Barn owl, Tyto alba. We tested our prediction by monitoring the abundances of dingoes, foxes, cats, small mammals and barn owls and investigating barn owl diets in areas where dingoes were common versus areas where dingoes were functionally extinct on either side of the dingo barrier fence (DBF) in the Strzelecki Desert. Foxes and cats were less abundant in areas where dingoes were common. Conversely, small mammals and barn owls were more abundant where dingoes were common. Owls in areas where dingoes were common fed almost exclusively on small mammals, but owls in areas where dingoes were functionally extinct fed on greater proportion of birds and invertebrates. The findings of our study provide evidence that an introduced apex predator may indirectly facilitate a native predator and illustrates the myriad of far-reaching indirect effects that can result from apex predator suppression.

Effect of Predation, Competition, and Facilitation on Tree Survival and Growth in Abandoned Fields: Towards Precision Restoration

Tree seedlings planted in abandoned agricultural fields interact with herb communities through competition, tolerance, and facilitation. In addition, they are subject to herbivory by small mammals, deer or invertebrates. To increase the success of forest restoration in abandoned fields and reduce management costs, we should determine which species are tolerant to or facilitated by herbaceous vegetation and those which require protection from competition and predation. Eight native tree species were planted in plots covered by herbaceous vegetation, plots where herbaceous vegetation was removed, and plots where seedlings were surrounded by an organic mulch mat. Half of the seedlings were protected against small mammal damage. Results showed that two non-pioneer and moderately shade-tolerant species (yellow birch and red oak) were inhibited by herbaceous vegetation. Birch species were particularly affected by small mammal predation. No effects of predation or herbaceous competition were observed for conifer species. Rather, herbaceous vegetation had a positive effect on the survival and the height growth of tamarack (Larix laricina). None of the tested herb communities had a stronger competitive effect on tree growth than another. Restoration of abandoned fields using multi-tree species should be designed at the seedling scale rather than at the site scale to account for different tree responses to predation and competition as well as variable site conditions. An approach resembling precision agriculture is proposed to lower costs and any potential negative impact of more intensive vegetation management interventions.

Hyena as a predator of small mammals? Taphonomic analysis from the site of Bois Roche, France

AbstractFeeding behaviors may differ between past and current predators due to differences in the environments inhabited by these species at different times. We provide an example of this behavioral variability in spotted hyena (Crocuta crocuta), for which our analysis of a late Pleistocene micromammal assemblage indicates that hyenas preyed upon small rodents, a feeding habit that is rarely observed today among hyenas.The Bois Roche cave site is situated at the edge of a low bluff overlooking the floodplain of a small stream in Cherves-Richemont (Charente, France). The deposits are dated by electron spin resonance (ESR) to about 69.7 ± 4.1 Ka. Excavations at the site recovered fossil bones and teeth of large and small mammals, together with hyena coprolites. Water screening of the sediments produced large accumulations of rodent remains with low taxonomic diversity. Small mammal bones were recovered from hyena coprolites as well. Descriptions of small mammal bone modification, both from the sediments and coprolites, are reported here. The analysis yielded a distinct taphonomic pattern representative of large carnivores (over 30 kg), which differs from any other modern or fossil predator-accumulated microfaunal assemblage taphonomically analyzed to date. To our knowledge, previous studies of hyena diet have not recorded high concentrations of a single-rodent prey species. We conclude that the low species diversity of this small mammal assemblage most likely relates to a local abundance of the prey species due to an outbreak in the rodent population, rather than from specialist predator behavior and hunting technique.

Seasonal variation in prey composition and digestion in small mammal predator assemblages

AbstractMany aspects of taphonomy have a time dimension which affects the way modifications develop. Weathering is an obvious aspect of this, and for this there is an added aspect of variations by geography or latitude. A long‐term taphonomy project in Wales was set up to investigate how small mammal assemblages may have changed in relation to seasonal and climatic variation. A collection of 304 pellets produced by a single pair of tawny owls (Strix aluco) spanned 40 months from 1982 to 1986, and pellets were collected from the roosting site on a monthly basis. The project ended in March 1986, when the owls left their roosting place, with a follow‐up collection from the same site but from a different owl individual in 1987. Both the species composition of the owls' prey, and the digestion of their prey, differed from month to month, with the major differences being between summer and winter and variations in the local climate. Earthworms were the most abundant prey, but they were more abundant during the summer months and during mild winters. Microtus agrestis was the most abundant mammal species in the pellets and the next most common prey species, closely followed by Apodemus and a large beetle species. Digestion of arvicolid teeth and post‐crania was greater during the winter months, but no difference was found for murid teeth between summer and winter collections because the summer sample was too small. Amphibian bones were also more digested in winter. Digestion of Apodemus molars was about half that of Microtus, but digestion of incisors was the same, and where both occurred in the same pellets they were on average one stage behind that of Microtus molars. It is concluded that seasonality and local climate are important factors both in the prey composition and the degrees of digestion of prey in tawny owl assemblages.

The Research Strategy for a ‘Predator Free’ New Zealand

Author(s): Tompkins, Daniel M. | Abstract: The goal to make New Zealand ‘Predator Free,’ articulated as the eradication of rats, stoats, and possums by 2050, was announced as a New Zealand government initiative in 2016 and became a founding initiative for the International Union for Conservation of Nature (IUCN) Honolulu Challenge on Invasive Species. A new government owned company, Predator Free 2050 Limited (PF2050 Limited), was formed to coordinate partnership approaches to large landscape projects and breakthrough science. Consultation of both the general public and conservation stakeholders in New Zealand has given strong confidence of majority support for the Predator Free 2050 initiative, and both its target species focus (rats, stoats, and possums) and goal (landscape-scale eradication for the outcome of native biodiversity protection and restoration). A logical and robust process of research strategy development to help realise the Predator Free goals has been ongoing since 2012, when seven priority strategy and research areas were identified at a ‘Pest Summit’ workshop of researchers and stakeholders convened by the New Zealand Department of Conservation. The workshop also highlighted that past improvements in the ability to manage small mammalian pests have been driven by multiple complementary and often synergistic strands of research. The critical learning from such back-casting is that if the Predator Free 2050 goals are to be achieved, a similarly diverse research portfolio is essential moving forwards to drive the paradigm shift from current mainland predator suppression approaches to mainland predator eradication. This learning was implemented in construction first of a research project on small mammal management in the New Zealand’s Biological Heritage National Science Challenge, and, more recently, of PF2050 Limited’s research strategy. With the remit of focusing research efforts to achieve a breakthrough science solution capable of eradicating at least one small mammal predator by 2025, the strategy has four programmes (‘Environment and Society,’ ‘Best Use of Existing Approaches,’ ‘Exploring New Approaches,’ and ‘Computer Modelling’) designed to complement existing efforts to give the whole portfolio of relevant research the best chance of achieving the 2025 goal.

Diet of the Tawny Owl Strix aluco in the area of Slovenske gorice (NE Slovenia)

Abstract The diet of Tawny Owl Strix aluco was studied in the area of Slovenske gorice - NE Slovenia. The analysis was carried out by examining pellets collected at ten locations in the period from 1984 to 2015. From the pellets, 2,121 prey units were isolated. The predominant prey were mammals (Mammalia, 84.8%), followed by birds (Aves, 8.3%), insects (Insecta, 4.7%), frogs (Anura, 1.6%) and earthworms (Oligochaeta, 0.5%). Four orders of mammals were found: rodents (Rodentia), insectivores (Insectivora), bats (Chiroptera) and carnivores (Carnivora). The most frequent prey in the owls’ diet were voles (Arvicolinae, 46.6%) and mice (Murinae, 28.8%), while the number of shrews (Soricidae) was low (4.5%). The obtained results are in concordance with the conclusions of other studies. In the area of Slovenske gorice, the Tawny Owl is an opportunistic predator of small mammals with an emphasis on voles and mice. Prey frequencies differ significantly among some localities. Variability in proportions of prey species among localities can also be the result of sampling carried out in different seasons and variability in the population dynamics of small mammals among years. Challenges for future research are to describe seasonal variability of the diet and to evaluate interspecific competition within the guild of night predators of small mammals: Tawny Owl, Long-eared Owl Asio otus, and Barn Owl Tyto alba, which are sympatric in this area.

Habitat heterogeneity affects predation of European pine sawfly cocoons.

Habitat heterogeneity is thought to affect top‐down control of herbivorous insects and contribute to population stability by providing a more attractive microhabitat for natural enemies, potentially leading to reduced population fluctuations. Identifying the parameters that contribute to habitat heterogeneity promoting top‐down control of herbivorous insects by natural enemies could facilitate appropriate management decisions, resulting in a decreased risk of pest insect outbreaks because of a higher level of predation. In our study, we measured the top‐down pressure exerted by small mammals on the cocoons of a notorious pest insect in pine forests, the European pine sawfly (Neodiprion sertifer), which is known to be regulated by small mammal predation. The forest stands used differed in heterogeneity measured in terms of differences in tree diversity and density, understory vegetation height, presence/absence, and density of dead wood. We found higher predation in more dense spots within forest stands. Further, the effect of dead wood on sawfly cocoon predation depended on the pine proportion in forest stands. The addition of dead wood in a manipulation experiment had a slight positive effect on cocoon predation, while dead wood removal caused a clear decrease in predation rate, and the decrease was more pronounced when the proportion of pine increased. Our results show that habitat heterogeneity affects predation by generalist predators on herbivorous insects. This knowledge could be applied to reduce the risk of insect outbreaks by applying management methods that increase heterogeneity in perennial systems such as forests and orchards, thus decreasing the levels of insect damage.

SEMICE: An unbiased and powerful monitoring protocol for small mammals in the Mediterranean Region

Schemes to monitor biodiversity change should detect properly target species without harmful effects on individuals and populations, and be powerful enough to detect expected population trends in the face of global change. Targeting is a key aspect of monitoring schemes since there is no single method able to detect unbiasedly all species of any given community, especially the rarest ones. Here we test whether SEMICE (SEguimiento de MIcromamíferos Comunes de España), a monitoring protocol for small mammal biodiversity in the Mediterranean Region, fulfil these requirements. The protocol aims at monitoring common species easy to catch with the two most widely used commercial live traps (18 Sherman and 18 Longworth traps alternated in position across 6×6 trapping grids spaced 15m, brought into operation for three consecutive nights in spring and fall). We used pilot data from twenty-two plots distributed along wide environmental gradients in Catalonia (NE Spain), sampled from 2008 to 2015. The wood mouse (Apodemus sylvaticus) was dominant throughout the study period (992 individuals, 39.0%), followed by the white-toothed shrew (Crocidura russula, 598 individuals, 23.5%) and the Algerian mouse (Mus spretus, 269 individuals, 10.6%). The two most common rodent species experienced strong population declines during the eight-year period (91% for A. sylvaticus and 83% for M. spretus). Regional community data obtained from diet studies of small mammal predators showed that common keystone prey and seed dispersers were sampled properly. No differences among trap types regarding community parameters and similarity indexes, sampling efficiency, detectability, trap-induced mortality, mean size and sex-ratio were detected, confirming previous results for a smaller pilot study. The method was sensitive enough for detecting expected population changes. We recommended extending the SEMICE protocol to sample common keystone small mammals along wide Mediterranean environmental gradients, since the method was sensitive enough to detect, and even test, expected population trends associated to global change for all them.

Diet of the common kestrel <em>Falco tinnunculus</em> in east Cork and west Waterford: an insight into the dynamics of invasive mammal species

The common kestrel Falco tinnunculus Linnaeus is chiefly a predator of small mammals, and breeding density and success often fluctuate in tandem with cyclic population changes of Microtus voles and the common shrew Sorex araneus Linnaeus. Ireland traditionally had four prey species to support its predatory birds and mammals—field mouse Apodemus sylvaticus (Linnaeus), house mouse Mus domesticus (Linnaeus), brown rat Rattus norvegicus (Berkenhout) and pygmy shrew Sorex minutus Linnaeus (indigenous species)—but the arrival of bank vole Myodes glareolus (Schreber) and greater white-toothed shrew Crocidura russula (Hermann) (invasive species) has taken the number to six. The wider range of prey species may positively affect birds of prey, but the impact of invasive species on the ecology of indigenous species may be negative, especially on field mice and pygmy shrews. Negative effects on indigenous species have been shown to be strong to the point of bringing about species replacement in some habitats, with no pygmy shrews present where both invasive species (bank voles and greater white-toothed shrews) were present.

Modeling Exposure of Mammalian Predators to Anticoagulant Rodenticides

Anticoagulant rodenticides (AR) are a widespread and effective method of rodent control but there is concern about the impact these may have on non-target organisms, in particular secondary poisoning of rodent predators. Incidence and concentration of AR in free-living predators in Denmark is very high. We postulate that this is caused by widespread exposure due to widespread use of AR in Denmark in and around buildings. To investigate this theory a spatio-temporal model of AR use and mammalian predator distribution was created. This model was supported by data from an experimental study of mice as vectors of AR, and was used to evaluate likely impacts of restrictions imposed on AR use in Denmark banning the use of rodenticides for plant protection in woodlands and tree-crops. The model uses input based on frequencies and timings of baiting for rodent control for urban, rural and woodland locations and creates an exposure map based on spatio-temporal modelling of movement of mice-vectored AR (based on Apodemus flavicollis). Simulated predator territories are super-imposed over this exposure map to create an exposure index. Predictions from the model concur with field studies of AR prevalence both before and after the change in AR use. In most cases incidence of exposure to AR is predicted to be greater than 90%, although cessation of use in woodlots and Christmas tree plantations should reduce mean exposure concentrations. Model results suggest that the driver of high AR incidence in non-target small mammal predators is likely to be the pattern of use and not the distance AR is vectored. Reducing baiting frequency by 75% had different effects depending on the landscape simulated, but having a maximum of 12% reduction in exposure incidence, and in one landscape a maximum reduction of <2%. We discuss sources of uncertainty in the model and directions for future development of predictive models for environmental impact assessment of rodenticides. The majority of model assumptions and uncertainties err on the side of reducing the exposure index, hence we believe the predictions to be robust and to indicate that the scale of the problem may be large.

Prey composition modulates exposure risk to anticoagulant rodenticides in a sentinel predator, the barn owl

Worldwide, small rodents are main prey items for many mammalian and avian predators. Some rodent species have pest potential and are managed with anticoagulant rodenticides (ARs). ARs are consumed by target and non-target small mammals and can lead to secondary exposure of predators. The development of appropriate risk mitigation strategies is important and requires detailed knowledge of AR residue pathways. From July 2011 to October 2013 we collected 2397 regurgitated barn owl (Tyto alba) pellets to analyze diet composition of owls on livestock farms in western Germany. 256 of them were fresh pellets that were collected during brodifacoum baiting. Fresh pellets and 742 liver samples of small mammals that were trapped during baiting in the same area were analyzed for residues of ARs. We calculated exposure risk of barn owls to ARs by comparing seasonal diet composition of owls with AR residue patterns in prey species. Risk was highest in autumn, when barn owls increasingly preyed on Apodemus that regularly showed AR residues, sometimes at high concentrations. The major prey species (Microtus spp.) that was consumed most frequently in summer had less potential to contribute to secondary poisoning of owls. There was no effect of AR application on prey composition. We rarely detected ARs in pellets (2 of 256 samples) but 13% of 38 prey individuals in barn owl nests were AR positive and substantiated the expected pathway. AR residues were present in 55% of 11 barn owl carcasses. Fluctuation in non-target small mammal abundance and differences in AR residue exposure patterns in prey species drives exposure risk for barn owls and probably other predators of small mammals. Exposure risk could be minimized through spatial and temporal adaption of AR applications (avoiding long baiting and non-target hot spots at farms) and through selective bait access for target animals.

Paleoecological and microenvironmental aspects of the first European hominids inferred from the taphonomy of small mammals (Sima del Elefante, Sierra de Atapuerca, Spain)

Unit TE9 of the Sima del Elefante (Sierra de Atapuerca, Burgos, Spain), where the remains of Homo sp. have been discovered (1.2–1.3Ma), is also a level rich in small mammals. The taphonomic study of these small vertebrates sheds light on the landscape that provided the setting for the activities of these early hominids and allows us to describe what the cave was like during the formation of the level. Small mammal predators identified in the study indicate that during this period the Sierra de Atapuerca was part of a large biome consisting of semi-open riparian forests with meadows nearby. Postdepositional alterations reveal that the production of fossils took place outside the cave, being transported inside by water currents. During the formation of TE9, the cave presented conditions of high humidity, which made it difficult for hominids to establish occupations inside, although these conditions became somewhat less severe in TE9c, the sublevel where human remains are found.

Canopy gaps promote selective stem-cutting by small mammals of two dominant tree species in an African lowland forest: the importance of seedling chemistry

Abstract:Small mammals can impede tree regeneration by injuring seedlings and saplings in several ways. One fatal way is by severing their stems, but apparently this type of predation is not well-studied in tropical rain forest. Here, we report on the incidence of ‘stem-cutting’ to new, wild seedlings of two locally dominant, canopy tree species monitored in 40 paired forest understorey and gap-habitat areas in Korup, Cameroon following a 2007 masting event. In gap areas, which are required for the upward growth and sapling recruitment of both species, 137 seedlings of the long-lived, light-demanding, fast-growing large tropical tree (Microberlinia bisulcata) were highly susceptible to stem-cutting (83% of deaths) — it killed 39% of all seedlings over a c. 2-y period. In stark contrast, seedlings of the more shade-tolerant, slower-growing tree species (Tetraberlinia bifoliolata) were hardly attacked (4.3%). In the understorey, however, stem-cutting was virtually absent. Across the gap areas, the incidence of stem-cutting of M. bisulcata seedlings showed significant spatial variation that could not be explained significantly by either canopy openness or Janzen–Connell type effects (proximity and basal area of conspecific adult trees). To examine physical and chemical traits that might explain the species difference to being cut, bark and wood tissues were collected from a separate sample of seedlings in gaps (i.e. not monitored for stem-cutting). These analyses suggested that, compared with T. bifoliolata, the lower stem density, higher Mg and K and fatty acid concentrations in bark, and fewer phenolic and terpene compounds in M. bisulcata seedlings made them more palatable and attractive to small-mammal predators, likely rodents. We conclude that selective stem-cutting is a potent countervailing force to the current local canopy dominance of the grove-forming M. bisulcata by limiting the recruitment and abundance of its saplings. Given the ubiquity of gaps and ground-dwelling rodents in pantropical forests, it would be surprising if this form of lethal browsing was restricted to Korup.