Rodent Predation Research Articles

Effects of seed traits and seed production on the seed predation and dispersal behavior of rodents.

To deeply understand the foraging behavioral strategies of the rodents in response to seeds of different sizes and tannin contents under different seed densities and its relationship with plant regeneration, field experiments were conducted to explore the effects of artificial seeds of different sizes (large and small) and tannin (T) contents (0%T, 2%T, 8%T, and 15%T) on seed predation and dispersal behavior of rodents during simulated non-mast and mast seeding year in Larix principis-rupprechtii plantation of Liupan Mountains in Ningxia. The results showed that seeds were consumed rapidly by rodents in non-mast seeding year but relatively slow in mast seeding year. No significant difference of in situ predation rate (ISPR) was observed between non-mast and mast seeding year. The predation rates of seeds after dispersal (PRAD) by rodents in non-mast year were significantly higher than those in mast year, while the hoarding rate of seed after dispersal (HRAD) of the former was significantly lower than the latter. Both seed predation distance after dispersal (PDAD) and hoarding distance after dispersal (HDAD) by rodents in non-mast year were substantially higher than those in mast year. In non-mast year, both PDAD and HDAD of large seeds were longer than those of small seeds. Significant difference of the former was observed between large and small seeds for all tannin content seeds, but significant difference of the latter between large and small seeds was detected only for seeds of 2% and 15% tannin. In mast year, significant difference of PDADs and HDADs between large and small seeds was found in all other seeds of tannin contents except for 0% Tannin seeds. The ISPR maximized in medium tannin seeds and minimized in high tannin seeds. Maximums of PRAD were observed in high tannin seeds in non-mast year and 0% tannin seeds in mast year respectively. High tannin seeds had the highest HRAD while medium tannin seeds had the lowest HRAD in both mast and non-mast year. Our results suggested that mast seeding year could delay the seed consumption rate of rodents and increase the HRAD, but reduce the dispersal distance. Hoarding preference of the rodents on large seeds was demonstrated in both mast and non-mast years and the dispersal distance of large seeds was longer than those of small ones. It is probably that rodents prefer to predate in situ seeds of medium tannin and disperse high tannin seeds during both mast and non-mast years.

Novel landscape elements within natural gas fields increase densities but not fitness of an important songbird nest predator

Identifying the elements within human-altered landscapes most associated with population and community changes is critical for conservation and management of sensitive species. We investigated which features of habitat change from natural gas development best explained the density of deer mice (Peromyscus maniculatus), an important nest predator of declining sagebrush-obligate songbirds. During 2014–2016, we quantified the spatial extent of habitat change (well pads, roads, and reclaimed areas [i.e., reseeded soils]) surrounding 12 sites spanning two natural gas fields in Wyoming, USA. We further tested whether the altered plant communities within reclaimed areas provided benefits to deer mice, by assessing multiple fitness indices. Deer mouse density increased with surrounding reclaimed area. Powder tracking and dietary analyses confirmed that mice moved through and consumed plant species found exclusively within reclaimed areas. Concomitant fitness metrics of mice, however, were neutrally or negatively related to the amount of surrounding reclaimed area. Mice therefore did not derive any apparent fitness benefits associated with living near reclaimed areas, despite the presence of novel food resources, indicating that increased abundance may be a product of mice dispersing toward reseeded soils. Our study contributes mechanistic insights into the complexities of how human-induced changes to landscapes can influence community dynamics. Minimizing total habitat disturbed during construction, expediting reclamation practices, and using only native and regionally-local seed mixes would likely help minimize increases in synanthropic rodent predators within energy fields. More efficient restoration of disturbed habitat, moreover, may help ameliorate altered predator-prey relationships that affect the success of sensitive species.

Evaluation of “Stress Relief” Dietary Supplement on Animal Stress Level and Locomotion

Abstract Search of new approaches for harmless, non-medication treatment of body dysfunctions is still on the agenda of vet and human practitioners and researchers as well. This study presents evaluation of the effect of “Stress Relief” dietary supplement (SR) on mice behaviour under different acute short-term stress conditions and treatment duration. Five experiments were performed and in each 40 animals were randomly split into four (I–IV) groups, where I and II — non-stressed mice, III and IV — stressed animals, I and III received water with trace mineral solution (TMS), II and IV received water with SR. As stress factors, forced swimming, rodent predator odour or both together were applied. Locomotor activity under normal and stress conditions in Open Field were observed and measured by a SMART video-tracking system. Blood glucose level was measured as well. SR showed a reversal of stress-decreased locomotor activity in all stress models — distance walked increased almost twice (p < 0.0001), central zone crossings and time spent in it were 2–4 times greater than in the control group (p < 0.0001 and p = 0.0002, respectively), and fast movement episodes and maximal speed increased by 50–200%. In addition, complete normalisation of stress-induced elevation of blood glucose level (p < 0.0001) was noted. These results demonstrate for the first time that the effect of “Stress Relief” formula (water additives–minerals processed by know-how way in Vital Force Technology using Dr. Yury Kronn method) can be observed in laboratory animals, and that the effects are significant and repeatable. SR shows fear- and stress-reducing activity, which does not sufficiently differ between 7-, 9-, 14-, 28- and 32-day treatment regimes.

Land snails benefit from human alterations in rural landscapes and habitats

AbstractMetapopulation functioning in the context of landscape and habitat structure is generally well understood. However, in human‐transformed landscapes, human disturbance may affect not only a species of interest but also biotic interactions in which that species is engaged, which has been rarely studied at multiple spatial scales. We tested (1) the associations between local (habitat and micro‐habitat) and landscape factors and the occurrence and abundance of the land snail Cepaea nemoralis and two of its predators (thrushes and mice); and (2) the hypothesis that human disturbances modify associations between C. nemoralis and its predators. We surveyed snail colonies in rural landscapes of Poland. Generalized linear mixed models were used to test the stated hypotheses. At the landscape scale, the occurrence of C. nemoralis colonies was positively related to the cover of suitable habitats, fallow/waste land, and road length in the surrounding landscape. Bird predator abundance was positively correlated with the occurrence of snail colonies, mostly at sites with a high human impact, and was negatively correlated with snail abundance at sites with low human disturbance. Snail occurrence and abundance at the micro‐habitat scale were positively correlated with variables describing the proximity of shelter and humidity. Avian predation pressure was negatively correlated with forest and settlement cover, whereas rodent predation pressure was positively associated with snail abundance and was negatively correlated with bird abundance. Human disturbance at the habitat and landscape scales benefited C. nemoralis through the creation of suitable habitats and scaling down of avian predation pressure. Conditions related to shelter and humidity were linked to the distribution and abundance of snails at the micro‐habitat scale.

Seed re‐dispersal of four myrmecochorous plants by a keystone ant in central China

AbstractSeed re‐dispersal following initial harvesting by ants may have important implications for the distribution and fate of myrmecochorous seeds. However, the probability of seed re‐dispersed by ants and the effect it may have on subsequent survival appear variable, the functional role of diaspore, disperser and seed predator to the fate of discarded seeds remain unclear. To clarify the ecology, we compared the consequences of seed re‐dispersal by a keystone seed‐dispersing ant (Myrmica ruginodis Nylander) for four sympatric myrmecochorous plants common to the temperate deciduous forests in Qinling Mountains, central China. Plants varied in the probability of re‐dispersal and in elaiosome condition. Ants preferred seeds with residual elaiosomes, while rodents only consumed the two larger‐seeded species, regardless of the elaiosome presence. The scattered distribution of discarded seeds increased the probability of ant re‐harvesting and, to some extent, reduced rodent predation. Thus, difference in the probability of seed re‐dispersal and its subsequent effect on seed fate in relation to ants and rodents was attributed primarily to the elaiosome condition, seed size and seed spatial pattern. The results imply that seed re‐dispersal could affect the fitness of plants and ultimately influence the plant abundance and distribution pattern. This highlights the necessity to incorporate re‐dispersal into myrmecochory to advance our understanding of the benefits of myrmecochory to plants.

Fluctuation in seed abundance has contrasting effects on the fate of seeds from two rapidly germinating tree species in an Asian tropical forest.

The seed predator satiation hypothesis states that high seed abundance can satiate seed predators or seed dispersers, thus promoting seed survival. However, for rapidly germinating seeds in tropical forests, high seed abundance may limit dispersal as the seeds usually remain under parent trees for long periods, which may lead to high mortality due to rodent predation or fungal infestations. By tracking 2 species of rapidly germinating seeds (Pittosporopsis kerrii, family Icacinaceae; Camellia kissi, family Theaceae), which depend on dispersal by scatter-hoarding rodents, we investigated the effects of seed abundance at the community level on predation and seed dispersal in the tropical forest of Xishuangbanna Prefecture, Southwest China. We found that high seed abundance at the community level was associated with delayed and reduced seed removal, decreased dispersal distance and increased pre-dispersal seed survival for both plant species. High seed abundance was also associated with reduced seed caching of C. kissi, but it showed little effect on seed caching of P. kerrii. However, post-dispersal seed survival for the 2 plant species followed the reverse pattern. High seed abundance in the community was associated with higher post-dispersal survival of P. kerrii seeds, but with lower post-dispersal survival of C. kissi seeds. Our results suggest that different plant species derive benefit from fluctuations in seed production in different ways.

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.

Seedling predation of Quercus mongolica by small rodents in response to forest gaps

Although the importance of gaps in forest dynamics has been well documented, the influence of gap size on the foraging behavior of small rodents and seedling predation has received little attention. In this study, we explored the foraging behaviors of seedling predators and seedling survival in the artificial gaps with different sizes and the associated closed canopy forest, to see the influence of rodent predation on seedling establishment of Quercus mongolica. Our results showed that small rodents (Apodemus peninsulae, Clethrionomys rufocanus, Tamias sibiricus and Sciurus vulgaris) tended to avoid recently created gaps in comparison with the associated closed canopy forests. As a consequence, lower levels of seedling predation (i.e., cotyledon removal and shoot clipping) and higher levels of seedling survival were observed in the gaps than in the closed canopy forests. In addition, gaps with large size tended to provide a better shelter for seedlings of Q. mongolica, possibly due to higher predation risks on small rodents in large gaps than in small gaps and the associated closed canopy forests. Our one-year study indicates that small rodents exert strong impacts on the recruitment of Q. mongolica through clipping young seedlings both in the gaps and closed canopy forests. Our study also implies that seedling predation by small rodents is regulated by gap size.

Fast-growing seeds and delayed rodent predatory activity in the seeding season: A combined mechanism to escape and survive rodent predation in Quercus ilex subsp. ballota L. acorns and seedlings

Holm-oak is a sclerophyllous Mediterranean species that presents relatively fast growing, non-dormant, desiccation-sensitive seeds. We investigated the importance of this trait for decreasing acorn predation risk and increasing seedling predation tolerance in combination with delaying the maximal predatory activity of rodents within the seeding season. The study was conducted in a Mediterranean savannah-like forest ecosystem. Temporal changes in acorn availability and predation by mice were studied during the acorn fall period. In a second experiment, propagules at different stages of development (acorns, rooted but un-emerged seedlings and emerged seedlings of different heights) were exposed to rodent predation at the end of the seeding season (end of winter). The results indicated that temporal changes in acorn availability (19–0.05acornsm−2) and predation rate (0–0.11acornsday−1) were negatively correlated; the lowest predation rate occurred when the food resource was at its highest (peak acorn fall). The developmental stage reached by propagules at the end of the seeding season significantly affected their ability to escape predation: 52–16% of emerged seedlings escaped predation by mice, but only 6% of rooted, un-emerged seedlings and 2% of acorns did so. Rodent predation of seedlings mostly consisted of cotyledon consumption and its effect on seedling survival was also significantly affected by developmental stage: 70% of emerged seedlings survived predation while only 17% of rooted, un-emerged seedling did so. The acorns did not survive at all. The results reinforce the ecological significance of non-dormancy and the associated rapid seed germination and seedling development facing early recruitment in holm-oak. We suggest that, in environments subject to high rodent predatory activity, early sowing of acorns during the seeding season should be considered in order to maximize the success of forest restoration.

Trade-off between seed defensive traits and impacts on interaction patterns between seeds and rodents in forest ecosystems

Plants often have two kinds of defensive traits against animal predation: physical and chemical defenses, but the trade-off between them is heavily debated, and their impacts on relationship between plants and animals are largely unknown. We investigated seed traits of 23 tree species and their impacts on seed fates or hoarding behaviors under predation from 16 rodent species in four forest types in China. We provide clear evidence that there is a strong nonlinear trade-off between physical (as measured by seed coat thickness) and chemical (as measured by tannin content) defensive traits in seeds. This trade-off was closely associated with nutritional traits, resulting in coordinated defense syndromes in seeds. The seed fate and hoarding behavior patterns were largely determined by the trade-off-related seed traits and the body mass of rodents, respectively, not by the phylogenetic relations of species. Tree species showed more conservative evolution in seed traits of high starch content, high tannin content, and thin seed coat, but they showed more convergent/divergent evolution in seed traits of high protein content, high fat content, and thick seed coat under rodent predation. Our results suggest that trade-off-related seed traits may play a predominant role in shaping the relationship between plants and animals.

Predation of pitfall-trapped rodents by the ghost bat, Macroderma gigas

Pitfall trapping for wildlife research is accompanied by the risk of predation of captured animals. However, predation events are sometimes difficult to observe and not subsequently reported. We describe the first known records of predation of pitfall-trapped animals by ghost bats. We discuss these observations in the context of ghost bat hunting behaviour and the implications for pitfall trapping studies in northern Australia.

Predator–rodent–plant interactions along a coast–inland gradient in Fennoscandian tundra

Spatial variation in the strength of trophic cascades in arctic tundra has been related to flows of subsidies across ecosystem boundaries. Here, we ask whether the input of marine subsidies in tundra systems would cause spatial variation in the strength of rodent–plant interactions between coastal areas, where predators have access to marine‐derived resources, and non‐subsidized inland areas of northern Fennoscandia. We present a detailed evaluation of predator–rodent–vegetation interactions along a coast‐inland gradient, during the 2011 rodent outbreak and the two following decline years, by using direct assessments of rodent impacts and tracing of marine‐derived nutrients in the food web. Our results revealed that the main rodent predator during summer, the long‐tailed jaeger Stercorarius longicaudus, did not benefit from marine resources while breeding (relative dietary proportion in chicks’ diet = 0–3%). Contrary to this pattern, parasitic jaegers S. parasiticus, bred exclusively near the coast and preyed effectively on both marine resources (41% of chicks’ diet) and rodents (12%). Mammalian predators also showed a higher activity during winter near the coast. Despite overall higher predator numbers, no evidence was found for lower rodent population growth rates during the three monitoring summers and for weaker rodent grazing impacts in the coastal area. Instead, we documented pronounced damages caused by lemmings and voles on bryophytes and vascular plants, especially dwarf shrubs (e.g. Vaccinum myrtillus) all along the coast–inland gradient. Taken together, our results did not support the hypothesis that marine subsidies would trigger a trophic cascade in coastal tundra areas of northern Fennoscandia during a major rodent outbreak, probably due to a relatively low diversity of marine‐subsidized predators in the region. Comparative observational and experimental studies at large spatial scales in various arctic regions are absolutely necessary for a better understanding of factors causing regional variations in the functioning of arctic food webs.

Towards a mechanistic understanding of human‐induced rapid environmental change: a case study linking energy development, nest predation and predators

Summary Demographic consequences of human‐induced rapid environmental change (HIREC) have been widely documented for many populations. The mechanisms underlying such patterns, however, are rarely investigated and yet are critical to understand for effective conservation and management. We investigated the mechanisms underlying reduced avian nest survival with intensification of natural gas development, an increasing source of human‐induced rapid environmental change globally. We tested the hypothesis that energy development increased the local activity of important nest predator species, thereby elevating nest predation rates. During 2011–2012, we surveyed predators and monitored 668 nests of Brewer's sparrows Spizella breweri (BRSP), sagebrush sparrows Artemisiospiza nevadensis (SASPs) and sage thrashers Oreoscoptes montanus (SATHs) breeding at twelve sites spanning a gradient of habitat loss from energy development in western Wyoming, USA. Nine species, representing four mammalian and three avian families, were video‐recorded depredating eggs and nestlings. Important nest predator species differed across songbird species, despite similar nesting habitats. Approximately 75% of depredation events were by rodents. Consistent with our predictions, detections of most rodent nest predators increased with surrounding habitat loss due to natural gas development, which was associated with increased probability of nest predation for our three focal bird species. An altered nest predator assemblage was therefore at least partly responsible for elevated avian nest predation risk in areas with more surrounding energy development. Synthesis and applications. We demonstrate one mechanism, that is the local augmentation of predators, by which human‐induced rapid environmental change can influence the demography of local populations. Given the accelerating trajectory of global energy demands, an important next step will be to understand why the activity and/or abundance of rodent predators increased with surrounding habitat loss from energy development activities.

Consequences of habitat disturbance on seed fate of a Brazilian tropical dry forest tree Cavanillesia arborea (Malvaceae)

AbstractWe compared seed fate (survival, mortality by rodent predators, desiccation and other causes) of the tree Cavanillesia arborea (Malvaceae) in preserved old‐growth tropical dry forests and in nearby abandoned pasturelands in Brazil. For this purpose, we performed an experiment where 15 seeds were placed in the surroundings of 15 parental individuals in each habitat. These 450 seeds were monitored over four months. At the end of the experiment, seed predation by rodents was higher in forest (56.5%) than in pasture (8.9%) areas, but seed desiccation showed the opposite pattern (8.9% vs. 80.4%). Mortality by desiccation was also faster in pasture than in forest areas, probably reducing their attractiveness to predators in these areas. None of the seeds placed in the pasture survived, whereas 26.2% of seeds became seedlings in forest areas. The absence of seedling recruitment of Cavanillesia arborea in pastures is likely a consequence of their incapacity to tolerate the harsh abiotic conditions in this habitat. Thus, forest conversion imposes a strong limitation to the long‐term population viability of this species. However, restoration and natural regeneration of abandoned pastures can recreate the forest structure and microclimatic conditions favourable to seed germination and seedling establishment. Remnant individuals of Cavanillesia arborea in agricultural landscapes may have a negligible contribution to current recruitment, but they can attract potential dispersers of pioneer species, with positive feedbacks to future recruitment during secondary succession.

Zoonosis in dogs and cats attended by the Birth Control Project: Toxoplasma gondii, Leishmania spp. and Leptospira spp., serodiagnosis and epidemiology

A proximidade da relação homem-animal tem aumentado o risco de transmissão de doenças de caráter zoonótico. O objetivo desse trabalho foi determinar a prevalência de anticorpos IgG anti-Toxoplasma gondii, anti- Leishmania spp. e anti- Leptospira spp. nos cães e gatos atendidos pelo Projeto Controle de Natalidade (PCN) nos anos de 2004 a 2012 e verificar a significância estatística de variáveis ambientais e da população de estudo à presença dos agentes infecciosos. Amostras de sangue de 271 cães e 415 gatos foram colhidas por venopunção jugular ou cefálica para a posterior obtenção dos soros. Estes foram submetidos à técnica de imunofluorescência indireta para detecção de anticorpos IgG anti-T. gondii e anti-Leishmania spp. e à técnica de soroaglutinação microscópica para detecção de anticorpos anti- Leptospira spp. A tabulação dos dados foi realizada utilizando-se o pacote estatístico EpiInfo (3.4.3). Dos soros caninos examinados, 20,6% (56/271), 1,3% (3/236) e 21,6% (51/236) foram positivos para T. gondii, Leishmania spp. e Leptospira spp., respectivamente. Encontrou-se maior prevalência de anticorpos anti- T. gondii em cães sem raça definida (p=0, 0009), em cães alimentados com carne crua ou mal cozida (p= 0,0101) e naqueles que não receberam vacina polivalente (p= 0,0147). Não houve associação estatística entre as variáveis avaliadas no questionário epidemiológico para leishmaniose e leptospirose. Dos soros felinos analisados, 20,9% (87/415) foram positivos para T. gondii. Maiores prevalências foram observadas nos felinos com hábito de caçar roedores (p= 0,0388) e que não recebem água tratada (p= 0,0294). Os resultados obtidos confirmam a importância dos fatores de risco ingestão de carne crua ou mal cozida, ingestão de água não tratada e predação de roedores para infecção por T. gondii. Demonstrou-se baixa prevalência ao sorodiagnostico para Leishmania spp. Os sorovares de Leptospira spp. mais frequentes foram Copenhageni, Canicola e Butembo.

Foraging activity of commensal Mus musculus in semi-captivity conditions. Effect of predator odours, previous experience and moonlight.

Mus musculus is a pest in urban and rural habitats where it consumes and contaminates food and may transmit diseases to human and domestic animals. Its control by anticoagulants is partially effective because of aversive behaviours and resistance. In this context, we wanted to assess the potential of the use of predator odours as repellents in experimental feeding trials using urine and faeces of domestic cats and faeces of geoffroyi cat, a wild small felid that is one of the main rodent predators in the study area. We also assessed the effect of previous experience and moonlight on foraging activity. We did not find an aversive response to cat odours in Mus musculus individuals. There was a trend to consume food in the same feeding stations over time, and the visit rate was lower in periods with high moonlight than in periods with low moonlight. Predator odours did not seem to be useful as rodent repellents, but maintaining illumination may lower rodent foraging activity. As rodents maintain their feeding sites over time, toxic baits may be more efficiently placed at sites previously known to be used by rodents.

Assessment of invasive rodent impacts on island avifauna: methods, limitations and the way forward

Bird conservation is nowadays a strong driving force for prioritising rodent eradications, but robust quantitative estimates of impacts are needed to ensure cost-effectiveness of management operations. Here, we review the published literature to investigate on what methodological basis rodent effects on island bird communities have been evaluated for the past six decades. We then discuss the advantages and limitations of each category of methods for the detection and quantification of impacts, and end with some recommendations on how to strengthen current approaches and extend our knowledge on the mechanisms of impacts. Impact studies (152 studies considered) emphasised seabirds (67%), black rats (63%) and the Pacific Ocean (57%). Among the most commonly used methods to study rodent impacts on birds were the observation of dead eggs or empty nests while monitoring bird breeding success, and the analyses of rodent diets, which can both lead to misleading conclusions if the data are not supported by direct field evidence of rodent predation. Direct observations of rodent–bird interactions (19% of studies) are still poorly considered despite their potential to reveal cryptic behaviours and shed light on the mechanisms of impacts. Rodent effects on birds were most often measured as a change or difference in bird breeding parameters (74% of studies), while estimates of bird population growth rates (4%) are lacking. Based on the outcomes of this literature review, we highlight the need for collecting unbiased population-level estimates of rodent impacts, which are essential prerequisites for predicting bird population growth scenarios and prioritising their conservation needs. This could be achieved by a more systematic integration of long-term monitoring of bird populations into rodent management operations and modelling bird population dynamics. We also strongly recommend including various complementary methods in impact assessment strategies to unravel complex interactions between rodents and birds and avoid faulty evidence. Finally, more research should be devoted to a better understanding of the cases of non-impacts (i.e. long-term coexistence) and those impacts mediated by mechanisms other than predation and ecosystem-level processes.

Rodent predation by Turdus leucomelas (Passeriformes: Turdidae)

Pale-breasted Thrush (Turdus leucomelas) is described as an omnivorous bird that forage solitarily or in pairs on the soil. This note reports a rodent predation event by T. leucomelas. The event was recorded on November 14th 2013, in a riparian Forest fragment of Grande River, in Igarapava Municipality, Sao Paulo, Brazil. Although the presence of small vertebrates on the diet of T. leucomelas is known, this is the first record of a mammal being predated by this bird species. This record is important because it contributes to a better understand of the natural history of Neotropical passerines.

High prevalence of pathogenic Leptospira in alien American mink (Neovison vison) in Patagonia

Background: Leptospirosis is an important zoonosis with worldwide distribution caused by pathogenic bacteria of the genus Leptospira. The North American mink (Neovison vison) has an important role in the environmental contamination with Leptospira, as minks live in aquatic environments and are the predators of rodents. Findings: Blood and kidney samples were obtained from 57 minks in Southern Chile 39° S to 45° S. Pathogenic species of Leptospira were detected by PCR on 31/57 minks. To determine the species, we sequenced the 16S ribosomal RNA (rRNA) gene on nine of the positive samples. We predicted two pathogenic species: Leptospira interrogans (five samples) and Leptospira borgpetersenii (four samples). Conclusions: This study showed that the American mink presents pathogenic species of Leptospira and confirm important environmental contamination of Patagonian rivers and lakes with pathogenic Leptospira.

Factors Constraining the Natural Regeneration of Alibangbang (Bauhinia malabarica Roxb.) in Carranglan Watershed, Nueva Ecija, Philippines

Field experiments on insect infestation, rodent predation and seed viability were conducted to determine the causes of natural regeneration failure of Bauhinia malabarica Roxb. in Carranglan Watershed. The larva of Caryedon serratus (Olivier) infested the pods and seeds of Bauhinia malabarica with a mean infestation rate of 78.32 % and 73.23 %, respectively. Other experimental trees recorded a mean infestation rate of 75.00 % on pods and 71.19 % on seeds. Examination conducted in different parts of the watershed obtained a mean infestation rate of 65.00 % and 67.80 % on pods and seeds, respectively. On the other hand, rodents were not eating ripened seeds of the species since no predation was observed. On viability test, only 47.50 % germination was obtained in seeds soaked in tap water for 24 hours. This treatment had the earliest germination period (7.75 days), longest total germination period (52 days) and highest germination value (3.32). Similarly, it recorded the highest root length (5.73 cm), total length (12.34 cm) and seedling vigor index (585.62).On the other hand, seeds alternately soaked in tap water and hot for 30 seconds had the highest germination energy (40.75 %). Therefore, serious infestation on Bauhinia malabarica seeds and low viability limits the regeneration of the species in the watershed