Free-ranging Mammals Research Articles

Development of a multisensor biologging collar and analytical techniques to describe high-resolution spatial behavior in free-ranging terrestrial mammals.

Biologging has proven to be a powerful approach to investigate diverse questions related to movement ecology across a range of spatiotemporal scales and increasingly relies on multidisciplinary expertise. However, the variety of animal-borne equipment, coupled with little consensus regarding analytical approaches to interpret large, complex data sets presents challenges and makes comparison between studies and study species difficult. Here, we present a combined hardware and analytical approach for standardizing the collection, analysis, and interpretation of multisensor biologging data. Here, we present (i) a custom-designed integrated multisensor collar (IMSC), which was field tested on 71 free-ranging wild boar (Sus scrofa) over 2 years; (ii) a machine learning behavioral classifier capable of identifying six behaviors in free-roaming boar, validated across individuals equipped with differing collar designs; and (iii) laboratory and field-based calibration and accuracy assessments of animal magnetic heading measurements derived from raw magnetometer data. The IMSC capacity and durability exceeded expectations, with a 94% collar recovery rate and a 75% cumulative data recording success rate, with a maximum logging duration of 421 days. The behavioral classifier had an overall accuracy of 85% in identifying the six behavioral classes when tested on multiple collar designs and improved to 90% when tested on data exclusively from the IMSC. Both laboratory and field tests of magnetic compass headings were in precise agreement with expectations, with overall median magnetic headings deviating from ground truth observations by 1.7° and 0°, respectively. Although multisensor equipment and sophisticated analyses are now commonplace in biologging studies, the IMSC hardware and analytical framework presented here provide a valuable tool for biologging researchers and will facilitate standardization of biologging data across studies. In addition, we highlight the potential of additional analyses available using this framework that can be adapted for use in future studies on terrestrial mammals.

Sex differences in the relationship between maternal and foetal glucocorticoids in a free-ranging large mammal

Sex differences in the relationship between maternal and foetal glucocorticoids in a free-ranging large mammal

Diving into old age: exercise and aging affect cardiovascular control in a long-lived mammal, the Weddell seal

The central component of the mammalian dive response is bradycardia, which, in combination with other physiological mechanisms, conserves intrinsic oxygen stores and facilitates longer submersion. Several factors are hypothesized to affect diving heart rate ( fH) and its variability (HRV) through a shift in autonomic balance. This study aimed to elucidate how dive duration, aging, and exercise influence fH and HRV (calculated as root mean square of successive RR interval differences) of free-ranging Weddell seals ( Leptonychotes weddellii). We expected that mean dive fH and HRV would differ with dive duration, advancing age, and exercise intensity due to a shift in autonomic balance. We collected ECG data from free-ranging female Weddell seals in Erebus Bay, Antarctica (n=10 seals, n=120 dives, age range 9-25 years old). To increase the cost of transport, we affxed a “drag block” to three seals for a portion of their deployment period (n=30 dives). Linear mixed effects model selection identified the effects of dive behavior (duration and depth), seal age, and drag block presence on mean dive fH and HRV. As dive duration increased, mean dive fH decreased (F1,107=227.91, p<0.0001) while HRV increased (F1,103=84.47, p<0.0001), suggesting increased parasympathetic tone. HRV was reduced in older seals (F1,8=8.73, p=0.018), indicating attenuation of parasympathetic influence on bradycardia with advancing age. Consistent with this interpretation, HRV increased with dive duration more steeply in younger animals (age*duration: F1,103=10.31, p=0.002). When exercise effort was experimentally modified by attaching a drag block to free-ranging seals, both mean dive fH (F1,107=6.07, p=0.015) and HRV (F1,103=4.34, p=0.039) were affected; dive HRV was significantly higher when seals dove with a drag block. However, this result should be interpreted with caution until the effects of swimming effort on fH and HRV can be determined. There was a significant interaction between animal age and factors affecting cardiovascular control (age*drag: F1,107=5.16, p=0.028); mean dive fH increased with age when seals did not carry a drag block, but decreased with age when a drag block was present. Taken together, our results point to cardiovascular aging as a physiological element that could affect the foraging ability, fitness, and life history of a long-lived free-ranging mammal. Funding by the National Science Foundation (#0649609, #0440715, #2020706). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Circulation of picobirnavirus in Neotropical free-ranging mammals.

Picobirnavirus (PBV) is a family of non-enveloped double-stranded RNA viruses with bisegmented genomes. Segment 1 encodes the capsid protein and segment 2 encodes RNA-dependent RNA polymerase. They exhibit high genomic heterogeneity and infect a wide range of vertebrate hosts, including humans. The objective of this study was to expand our knowledge of the circulation of PBV in free-living animals from two regions (Brazil and Argentina) of the Atlantic Forest. Fecal samples were analyzed from free-living animals: tapir, brocket deer, peccary, and different species of rodents and marsupials. A total of 133 samples were collected and analyzed by RT-PCR, of which 44 (33.08%) were PBV-positive. Nine amplicons were sequenced, five species from Argentina and four from Brazil, and phylogenetic analysis was performed. The nucleotide and amino acid identities of the PBV strains detected in animals from Argentina and Brazil were between 66.3% and 82.5% and between 55.3% and 74.2%, respectively. The analysed strains presented conserved nucleotide blocks without distinction of the host species. The phylogenetic tree showed that PBV strains from Atlantic Forest animals belonging to genogroup I were grouped into different clusters, without defining groups according to host species (human or animal) or the geographical area of detection. This is the first study on PBV in free-living animals in the Atlantic Forest. Our analysis suggested that PBV strains can infect different animal species, leading to PBV transmission between animals and humans. This reinforces the hypothesis of previous crossover points in the ecology and evolution of heterologous PBV strains.

Zoonoses in endemic, free-ranging mammals

Zoonoses are diseases and infections that can be transmitted naturally between animals and humans. Direct and indirect contact of humans with wildlife occur during hunting activities, when diseased wildlife is found and treated, and in shared fields, forests, parks, gardens, and homes. Zoonoses can only be understood and controlled when ecosystems, animals, and humans are considered holistically. This paper presents important zoonotic pathogens that are currently present in wild mammals as reservoirs in Germany. The literature was searched to determine the prevalence of zoonotic pathogens currently occurring in wild mammals. Viral zoonotic agents currently present in free-ranging, mammalian animals in Germany as reservoirs of natural origin are bornaviruses, lyssaviruses, hepatitisE virus genotype3, and Puumala orthohantavirus. Bacterial zoonotic agents beyond typical wound and foodborne pathogens include Brucella suis Biovar2, Francisella tularensis ssp. holarctica, Leptospira interrogans sensu latu, Mycobacterium caprae, and Yersinia pseudotuberculosis. In particular, parasitic zoonotic agents common in wildlife are Alaria alata, Baylisascaris procyonis, Echinococcus multilocularis, Sacoptes scabei, and Trichinella spp. The presence of zoonotic infectious agents of risk groups2 and3 has to be regularly expected in numerous endemic wildlife species, especially canines, small bears, rodents, insectivores, and bats. Animal caretakers, hunters, veterinarians, and human health professionals should be aware of this risk and take protective measures appropriate to the situation.

Cryptic behavior and activity cycles of a small mammal keystone species revealed through accelerometry: a case study of Merriam’s kangaroo rats (Dipodomys merriami)

BackgroundKangaroo rats are small mammals that are among the most abundant vertebrates in many terrestrial ecosystems in Western North America and are considered both keystone species and ecosystem engineers, providing numerous linkages between other species as both consumers and resources. However, there are challenges to studying the behavior and activity of these species due to the difficulty of observing large numbers of individuals that are small, secretive, and nocturnal. Our goal was to develop an integrated approach of miniaturized animal-borne accelerometry and radiotelemetry to classify the cryptic behavior and activity cycles of kangaroo rats and test hypotheses of how their behavior is influenced by light cycles, moonlight, and weather.MethodsWe provide a proof-of-concept approach to effectively quantify behavioral patterns of small bodied (< 50 g), nocturnal, and terrestrial free-ranging mammals using large acceleration datasets by combining low-mass, miniaturized animal-borne accelerometers with radiotelemetry and advanced machine learning techniques. We developed a method of attachment and retrieval for deploying accelerometers, a non-disruptive method of gathering observational validation datasets for acceleration data on free-ranging nocturnal small mammals, and used these techniques on Merriam’s kangaroo rats to analyze how behavioral patterns relate to abiotic factors.ResultsWe found that Merriam’s kangaroo rats are only active during the nighttime phases of the diel cycle and are particularly active during later light phases of the night (i.e., late night, morning twilight, and dawn). We found no reduction in activity or foraging associated with moonlight, indicating that kangaroo rats are actually more lunarphilic than lunarphobic. We also found that kangaroo rats increased foraging effort on more humid nights, most likely as a mechanism to avoid cutaneous water loss.ConclusionsSmall mammals are often integral to ecosystem functionality, as many of these species are highly abundant ecosystem engineers driving linkages in energy flow and nutrient transfer across trophic levels. Our work represents the first continuous detailed quantitative description of fine-scale behavioral activity budgets in kangaroo rats, and lays out a general framework for how to use miniaturized biologging devices on small and nocturnal mammals to examine behavioral responses to environmental factors.

Marine mammal morphometrics: 3D modeling and estimation validation

Techniques of 3D modeling have earned increasing popularity in scientific studies as they offered unprecedented traits in representing objects. As with all mathematical models, the 3D model will be useful once its accuracy has been validated with direct measurements and the robustness of its predictive capability tested. Although measures of body mass and volume are essential to comprehend the life history of animals, such morphometrics, especially total volume, are challenging to obtain from marine mammals due to their elusive nature, aquatic lifestyle, and large size. In this study, accurate measurements of body volume were directly detected from fresh carcasses of eleven finless porpoises (Neophocaena asiaeorientalis sunameri) and used to validate 3D models recreated from the same animals using Blender 3D graphics. Published models using truncated cones or elliptical shapes, based on 3, 5, 8, or 19 measurements of girths or heights &amp;amp; widths along the body, were also applied to porpoises to verify their accuracy. The Blender-generated 3D model produced the most accurate estimates of body volume compared to conventional truncated models, with a mean error of only 2.5% to the direct volume measurements. When photogrammetric images are available, the model can predict the body volumes based on total length alone. Similar accuracy was possible with the elliptical model using 19 height &amp;amp; width measurements (5% increments in total length). However, significant (p &amp;lt; 0.001) inaccuracy resulted from truncated models with 3, 5, or 8 girth measurements and elliptical models with 3 or 5 height &amp;amp; width measurements, and the accuracy of these models also decreased significantly as the number of measurement sites was reduced. Moreover, Blender 3D models can be extrapolated to animals with images absent, and such predicted volumes were tested to be trustworthy (overall skill = 0.998, r = 0.998, p &amp;lt; 0.01). Therefore, we recommend that researchers use either digital 3D models or elliptical models with 5% increments sectioning the torso to obtain accurate estimates of the body volumes of free-ranging marine mammals.

Out of the stable: Social disruption and concurrent shifts in the feral mare (Equus caballus) fecal microbiota.

The disruption of animals' symbiotic bacterial communities (their microbiota) has been associated with myriad factors including changes to the diet, hormone levels, and various stressors. The maintenance of healthy bacterial communities may be especially challenging for social species as their microbiotas are also affected by group membership, social relationships, microbial transfer between individuals, and social stressors such as increased competition and rank maintenance. We investigated the effects of increased social instability, as determined by the number of group changes made by females, on the microbiota in free-living, feral horses (Equus caballus) on Shackleford Banks, a barrier island off the North Carolina coast. Females leaving their groups to join new ones had fecal microbial communities that were similarly diverse but compositionally different than those of females that did not change groups. Changing groups was also associated with the increased abundance of a several bacterial genera and families. These changes may be significant as horses are heavily dependent upon their microbial communities for nutrient absorption. Though we cannot identify the particular mechanism(s) driving these changes, to the best of our knowledge, ours is the first study to demonstrate an association between acute social perturbations and the microbiota in a free-ranging mammal.

Establishment of killer whale (Orcinus orca) primary fibroblast cell cultures and their transcriptomic responses to pollutant exposure

Populations of killer whale (Orcinus orca) contain some of the most polluted animals on Earth. Yet, the knowledge on effects of chemical pollutants is limited in this species. Cell cultures and in vitro exposure experiments are pertinent tools to study effects of pollutants in free-ranging marine mammals. To investigate transcriptional responses to pollutants in killer whale cells, we collected skin biopsies of killer whales from the Northern Norwegian fjords and successfully established primary fibroblast cell cultures from the dermis of 4 out of 5 of them. Cells from the individual with the highest cell yield were exposed to three different concentrations of a mixture of persistent organic pollutants (POPs) that reflects the composition of the 10 most abundant POPs found in Norwegian killer whales (p,p’-DDE, trans-nonachlor, PCB52, 99, 101, 118, 138, 153, 180, 187). Transcriptional responses of 13 selected target genes were studied using digital droplet PCR, and whole transcriptome responses were investigated utilizing RNA sequencing. Among the target genes analysed, CYP1A1 was significantly downregulated in the cells exposed to medium (11.6 µM) and high (116 µM) concentrations of the pollutant mixture, while seven genes involved in endocrine functions showed a non-significant tendency to be upregulated at the highest exposure concentration. Bioinformatic analyses of RNA-seq data indicated that 13 and 43 genes were differentially expressed in the cells exposed to low and high concentrations of the mixture, respectively, in comparison to solvent control. Subsequent pathway and functional analyses of the differentially expressed genes indicated that the enriched pathways were mainly related to lipid metabolism, myogenesis and glucocorticoid receptor regulation. The current study results support previous correlative studies and provide cause-effect relationships, which is highly relevant for chemical and environmental management.

Does artificial feeding impact neonate growth rates in a large free-ranging mammal?

Variation and disparity in resource access between individuals in an animal population within human-dominated landscapes require attention as artificial selection processes may be at work. Independent, recreational human-wildlife feeding interactions constitute an increasingly prevalent, yet understudied, food resource for birds and mammals living in our cities. However, only a limited number of risk-taking individuals may access it. Using urban fallow deer as our model species, we hypothesized that if these interactions result in positive effects for the engaging individual, e.g. increased milk quality and yield, then this would result in the increased growth rates of their offspring. Alternatively, if these individuals were prioritizing investing time in engagement with humans, resulting in decreased maternal care, then this would result in slower growth rates in their offspring. We found that the offspring of those females that regularly interacted with humans displayed significantly faster growth rates than their risk-adverse counterparts. This advantage for fearless mothers in terms of boosted neonatal growth rates could be mirrored in birds accessing garden feeders, seagulls or pigeons utilizing urban resources, or seals approaching city harbours. Here, we add a new piece to the complex puzzle of how humans are impacting wildlife living within human-dominated landscapes.

Early onset of postnatal individual vocal recognition in a highly colonial mammal species.

Mother-young vocal recognition is widespread in mammals. The features of vocal recognition are known to be shaped by the ecological constraints faced by each species. In some species, a rapid establishment of mother-young vocal recognition is crucial for offspring's survival. However, knowledge of the precise features of this recognition system, especially the timing of the onset in the first hours after birth, is often lacking. Here we show that Cape fur seal females can recognize their pup's voice 2-4 h after parturition and that pups develop this aptitude 4-6 h after birth. This study is the first to investigate this mechanism in a wild and free-ranging mammal from only 2 h after birth. We report the fastest establishment of mother-young vocal recognition for any mammalian species, including humans, described to date. Such early vocal identification in pups suggests an in utero vocal imprinting. These findings highlight the synergistic role of environmental constraints and biological traits in optimizing the timing of individual vocal recognition onset in vertebrates.

Pervasive exposure of wild small mammals to legacy and currently used pesticide mixtures in arable landscapes

Knowledge gaps regarding the potential role of pesticides in the loss of agricultural biodiversity worldwide and mixture-related issues hamper proper risk assessment of unintentional impacts of pesticides, rendering essential the monitoring of wildlife exposure to these compounds. Free-ranging mammal exposure to legacy (Banned and Restricted: BRPs) and currently used (CUPs) pesticides was investigated, testing the hypotheses of: (1) a background bioaccumulation for BRPs whereas a “hot-spot” pattern for CUPs, (2) different contamination profiles between carnivores and granivores/omnivores, and (3) the role of non-treated areas as refuges towards exposure to CUPs. Apodemus mice (omnivore) and Crocidura shrews (insectivore) were sampled over two French agricultural landscapes (n = 93). The concentrations of 140 parent chemicals and metabolites were screened in hair samples. A total of 112 compounds were detected, showing small mammal exposure to fungicides, herbicides and insecticides with 32 to 65 residues detected per individual (13–26 BRPs and 18–41 CUPs). Detection frequencies exceeded 75% of individuals for 13 BRPs and 25 CUPs. Concentrations above 10 ng/g were quantified for 7 BRPs and 29 CUPs (in 46% and 72% of individuals, respectively), and above 100 ng/g for 10 CUPs (in 22% of individuals). Contamination (number of compounds or concentrations) was overall higher in shrews than rodents and higher in animals captured in hedgerows and cereal crops than in grasslands, but did not differ significantly between conventional and organic farming. A general, ubiquitous contamination by legacy and current pesticides was shown, raising issues about exposure pathways and impacts on ecosystems. We propose a concept referred to as “biowidening”, depicting an increase of compound diversity at higher trophic levels. This work suggests that wildlife exposure to pesticide mixtures is a rule rather than an exception, highlighting the need for consideration of the exposome concept and questioning appropriateness of current risk assessment and mitigation processes.

Risk-taking neonates do not pay a survival cost in a free-ranging large mammal, the fallow deer (Dama dama).

Recent debate has focused on whether variation in personality primarily reflects variation in resource allocation or resource acquisition of individuals. These two mechanisms predict different relationships between personality and survival. If personality mainly reflects variation in resource allocation, then bold (i.e. risk-taking) individuals are expected to live shorter lives, whereas the opposite pattern is expected with resource acquisition. Here we studied the relationship between neonate personality and early-life survival in 269 juveniles of a population of fallow deer (Dama dama). We found that bolder individuals paid no apparent survival cost. Interestingly, among-individual differences in the physiological response at capture (heart rates, which covary with the behavioural response, i.e. latency to leave) were linked to survival, where individuals with lower heart rates when handled by humans had a higher probability of early-life survival. This suggests that bolder individuals may be of higher state than their shyer counterparts. As the first study linking neonate personality to survival in a free-ranging mammal, we provide novel insights into drivers behind early-life individual variation.

Plague and Trace Metals in Natural Systems.

All pathogenic organisms are exposed to abiotic influences such as the microclimates and chemical constituents of their environments. Even those pathogens that exist primarily within their hosts or vectors can be influenced directly or indirectly. Yersinia pestis, the flea-borne bacterium causing plague, is influenced by climate and its survival in soil suggests a potentially strong influence of soil chemistry. We summarize a series of controlled studies conducted over four decades in Russia by Dr. Evgeny Rotshild and his colleagues that investigated correlations between trace metals in soils, plants, and insects, and the detection of plague in free-ranging small mammals. Trace metal concentrations in plots where plague was detected were up to 20-fold higher or lower compared to associated control plots, and these differences were >2-fold in 22 of 38 comparisons. The results were statistically supported in eight studies involving seven host species in three families and two orders of small mammals. Plague tended to be positively associated with manganese and cobalt, and the plague association was negative for copper, zinc, and molybdenum. In additional studies, these investigators detected similar connections between pasturellosis and concentrations of some chemical elements. A One Health narrative should recognize that the chemistry of soil and water may facilitate or impede epidemics in humans and epizootics in non-human animals.

Draft Genome Sequences of Erysipelothrix sp. Strains Isolated from Stranded Septic Bottlenose Dolphins in Alabama, USA

ABSTRACTWe report the genome sequences of two Erysipelothrix isolates from fatal cases of sepsis in bottlenose dolphins (Tursiops truncatus). The genomes were found to be most closely related to Erysipelothrix rhusiopathiae and Erysipelothrix piscisicarius. This information expands our knowledge of the genetic characteristics of this pathogen, which can affect free-ranging marine mammals.

An accelerometer-derived ballistocardiogram method for detecting heart rate in free-ranging marine mammals.

ABSTRACTPhysio-logging methods, which use animal-borne devices to record physiological variables, are entering a new era driven by advances in sensor development. However, existing datasets collected with traditional bio-loggers, such as accelerometers, still contain untapped eco-physiological information. Here, we present a computational method for extracting heart rate from high-resolution accelerometer data using a ballistocardiogram. We validated our method with simultaneous accelerometer–electrocardiogram tag deployments in a controlled setting on a killer whale (Orcinus orca) and demonstrate the predictions correspond with previously observed cardiovascular patterns in a blue whale (Balaenoptera musculus), including the magnitude of apneic bradycardia and increase in heart rate prior to and during ascent. Our ballistocardiogram method may be applied to mine heart rates from previously collected accelerometery data and expand our understanding of comparative cardiovascular physiology.

Seroprevalence to Rabies Virus in Wildlife in Brazil.

Serum samples of 638 free-ranging wild mammals from São Paulo state, Brazil, were tested for neutralizing antibodies against rabies virus by the rapid fluorescent focus inhibition test. Overall seroprevalence was 1.7% among 24 species surveyed, with individuals of six species having positive results indicating exposure to rabies virus.

Body size and canine size do not confer a competitive advantage in male rhesus macaques

Male armaments are hypothesized to have evolved under intrasexual selection. Such traits may function as signals, weapons, or both, in male–male mating competition. Primate sexually dimorphic canine teeth and body size are two potentially weaponized traits whose function as a signal and/or weapon remains unclear, largely due to the difficulty of collecting detailed measurements of morphology on large free-ranging mammals. Rhesus macaques, Macaca mulatta, are an interesting study system in which to investigate how such traits function because they experience relatively low levels of direct male–male mating competition compared to other members of their subfamily. Furthermore, male dominance rank is largely based on a queuing system rather than on the outcome of intermale aggressive encounters. We leveraged a novel data set of behavioural observations and morphometric data from free-ranging rhesus macaques to investigate the function of sexually dimorphic canine teeth and body mass as weapons and/or signals. We tested whether canine height or body mass was correlated with dominance rank, whether similarity in any of these factors influenced the occurrence or outcome of agonistic interactions between male–male dyads and whether either of these traits predicted the likelihood of winning an agonistic interaction. Neither canine height nor body mass was related to dominance rank. Similarity in dominance rank, but not in morphology, predicted the occurrence of agonism between dyads. Agonistic encounters between males more similar in dominance rank were more likely to be characterized by aggression rather than submission. Dominance rank, but not canine height or body mass, predicted the likelihood of winning an agonistic interaction. Our results suggest that canine height and body mass do not confer a strong competitive advantage in male rhesus macaques and add to a growing body of evidence indicating that weaponized traits do not always seem to function either in fights or as signals in male–male combat.

Occurrence of Microplastics in Harbour Seals (Phoca vitulina) and Grey Seals (Halichoerus grypus) from German Waters.

Simple SummaryIt is well known that the occurrence of microplastics (MP) is ubiquitous in both water compartments and in biota. Nevertheless, knowledge on the microplastic exposure of marine mammals is scarce. This study gives first evidence of microplastic burden in seal species inhabiting German waters of the North Sea and Baltic Sea. Accordingly, 63 gastrointestinal tracts (GIT) of harbour seal (Phoca vitulina) and grey seal (Halichoerus grypus) carcasses were analysed. This investigation is urgently needed since information on microplastic burden in grey seals, especially from the Baltic Sea, are still lacking. This information is particularly important as it allows a direct comparison of this species and its sympatric species, the harbour seal, from different waters. A slightly higher incidence of microplastics (>100 µm, here categorized as fibres and fragments) was found in specimen found in the Baltic Sea. Moreover, higher microplastic loads were detected in stomachs compared to the intestinal samples, with first evidence of fragment retainment within the GIT. Nevertheless, an accumulation of microplastics in marine mammals could not be excluded for all categories since the egestion of those subjects is documented and no significant differences in life history parameters such as sex and age, nor parasite infestation were revealed.The level of knowledge on microplastic exposure in marine mammals is limited by the access to dead and alive individuals. Focusing on the Northeast Atlantic area, some studies already confirmed the microplastic presence in free-ranging marine mammals, such as harbour porpoises or harbour seals inhabiting the North Sea (NS). In contrast, knowledge on the exposure to grey seals and particularly on specimen inhabiting the Baltic Sea (BS) are scarce. This study examined 63 gastrointestinal tracts (GIT) of harbour seals and grey seals originating from German waters (NS and BS) found between 2014 and 2019. Besides the documentation of microplastic findings, this study is dealing with life history and health parameters, attempting to identify correlations with microplastic presence. This study confirmed beside the presence, the egestion of microplastics (>100 µm; MPs) in the examined seals, without correlations in parasite infestations or inflammation responses. 540 suspected MPs were identified in 62 intestinal samples (42% fibres, 58% fragments), and 228 MPs in seven stomachs (28% fibres, 72% fragments). In accordance, first evidence of the retainment of fragments in the GIT were given. However, no significant difference in MP occurrence was indicated for different sex or age groups.

Effects of Chronic Exposure to Toxic Metals on Haematological Parameters in Free-Ranging Small Mammals

Effects of Chronic Exposure to Toxic Metals on Haematological Parameters in Free-Ranging Small Mammals