Samuel K Wasser

• PhD
• Executive Director at University of Washington

After a long-standing debate, African elephants, listed as Vulnerable on the IUCN Red list of Threatened Species, are now considered by the IUCN as two distinct species: savannah elephants ( Loxodonta africana ) and forest elephants ( Loxodonta cyclotis ), the latter being severely threatened by forest loss, fragmentation and degradation due to agr...

Pangolins are among the most highly trafficked animals, with shipments of pangolin scales and products weighing several metric tonnes being seized at various ports. These large seizures are challenging to process and comprehensively genotype for both upstream provenance tracing and species identification for prosecution. In this study, we implement...

The 14-carbon in animal tissues records the time that the tissues are formed; since the 1960s, using the "bomb curve" for 14C, the age of animal death can be determined accurately. Using animal tissue samples of known collection and formation dates for calibration, we determine the age of ivory samples from four ivory seizures made by law enforceme...

Transnational ivory traffickers continue to smuggle large shipments of elephant ivory out of Africa, yet prosecutions and convictions remain few. We identify trafficking networks on the basis of genetic matching of tusks from the same individual or close relatives in separate shipments. Analyses are drawn from 4,320 savannah (Loxodonta africana) an...

After a long-standing debate, African elephants are now considered by the IUCN as two distinct species: savannah elephants (Loxodonta africana), listed as endangered on the IUCN Red List of Threatened Species, and forest elephants (Loxodonta cyclotis), critically endangered. Both are severely threatened by forest loss, fragmentation and degradation...

Understanding baseline hormone levels, the magnitude of intra-individual variability, and their variation as a function of life history is difficult in toothed whales (e.g. dolphins and porpoises) because of the effects of capture stress. To determine the endocrine profile of the common bottlenose dolphin (Tursiops truncatus) as a function of seaso...

Social structure is a fundamental aspect of animal populations. In order to understand the function and evolution of animal societies, it is important to quantify how individual attributes, such as age and sex, shape social relationships. Detecting these influences in wild populations under natural conditions can be challenging, especially when soc...

Accurate dietary inference of wild carnivores is essential to understand their impacts on the ecosystem and manage carnivore-livestock conflicts. Diet analysis with fecal DNA metabarcoding technology can help deliver valuable insights with fine-grained resolution. The recovery of wolves in Washington, USA offers an excellent opportunity to study th...

The maternal gut microbiota can influence and be affected by the substantial physiological changes taking place during the periparturition period. However, little information is known about the changes in the maternal gut microbiota and hormonal variations during this period in nonmodel organisms. Tibetan antelope (Pantholops hodgsonii) provide a u...

We describe a primer pair that amplifies a 203 base pair fragment containing 4 single nucleotide polymorphisms (SNPs) within the cytochrome b region of the mitochondrial DNA that, when sequenced, conclusively distinguishes Washington state gray wolves from domestic dogs. The method is more efficient and cost-effective than other established methods...

The most comprehensive data on poaching of African elephants comes from the Monitoring the Illegal Killing of Elephants (MIKE) program, which reports numbers of illegally killed carcasses encountered by rangers. Recent studies utilizing MIKE data have reported that poaching of African elephants peaked in 2011 and has been decreasing through 2018. C...

The maternal gut microbiome can influence and be affected by the substantial physiological changes taking place during the perinatal period. However, little information is known about the changes in the maternal gut microbiome during this period. Tibetan antelope (Pantholops hodgsonii) provide a unique system to address this issue because their sum...

Non-invasive stress and nutritional hormone analysis in relation to ecological and other biological indices have tremendous potential to address environmental disturbance impacts on wildlife health. To this end, we examined the relation between glucocorticoid (GC) and thyroid (T3) hormone indices of disturbance and nutritional stress in response to...

The recovery of apex predators relies on restoring the full suite of trophic interactions within the ecosystem. Diet analysis with DNA metabarcoding technology can help deliver insights into these trophic interactions with fine-grained resolution. The recovery of wolves in Washington state offers an excellent case to study the trophic cascade impac...

Background: Limited studies have investigated the microbial diversity of wild marine mammals. Objectives: This study characterized Escherichia coli isolates collected from fresh faecal samples of endangered southern resident killer whales (Orcinus orca) located by detection dogs. Methods: WGS of each strain was done to determine ST (using MLST...

African elephants are under threat, especially from poaching for illegal ivory trade. New monitoring data show a dramatic increase in elephant poaching in northern Botswana, where the largest remaining population of African elephants resides.

Population reduction is generally assumed to reduce the population's genetic diversity and hence its ability to adapt to environmental change. However, if life history traits that promote gene flow buffer populations from such impacts, conservation efforts should aim to maintain those traits in vulnerable species. Tibetan antelope (Pantholops hodgs...

Rapid growth in world trade has enabled transnational criminal networks to conceal their contraband among the 1 billion containers shipped worldwide annually. Forensic methods are needed to identify the major cartels moving the contraband into transit. We combine DNA-based sample matching and geographic assignment of tusks to show that the two tusk...

Several hormones are potential indicators of stress in free-ranging animals and provide information on animal health in managed-care settings. In response to stress, glucocorticoids (GC, e.g. cortisol) first appear in circulation but are later incorporated into other tissues (e.g. adipose) or excreted in feces or urine. These alternative matrices c...

Genotyping ivory samples can determine the geographic origin of poached ivory as well as the legality of ivory being sold in ivory markets. We conducted a series of experiments to determine where the DNA is most concentrated in ivory samples and how best to increase DNA yield from groups of samples likely to vary in DNA concentration. We examined v...

Significance Mammals harbor communities of gut bacteria that regulate host health, requiring an understanding of the processes that govern the evolution of gut microbiotas. We investigated the diversification of mammalian gut microbiotas by surveying the gut microbiotas of 136 pairs of wild mammalian species living throughout the Americas. These co...

OBJECTIVE To evaluate the impact of oral megestrol acetate (MA) administration on adrenal function in male bottlenose dolphins ( Tursiops truncatus ). DESIGN Serial cross-sectional study. ANIMALS 8 adult male dolphins, all of which were receiving MA at various daily doses (range, 0 to 60 mg, PO) for the control of reproductive behavior. PROCEDURES...

The Southern Resident killer whale population (Orcinus orca) was listed as endangered in 2005 and shows little sign of recovery. These fish eating whales feed primarily on endangered Chinook salmon. Population growth is constrained by low offspring production for the number of reproductive females in the population. Lack of prey, increased toxins a...

Raw data. (XLSX)

Timing and abundance of Columbia River (orange) and Fraser River (blue) Chinook runs based on DART (2015) and Albion Test fisheries (Catch Per Unit Effort, Albion 2015), respectively (see also Lundin 2015). (TIFF)

Significance C-14 dating methods can be used to determine the time of death of wildlife products. We evaluate poaching patterns of elephants in Africa by using ¹⁴ C to determine lag time between elephant death and recovery of ivory by law enforcement officials. Most ivory in recent seizures has lag times of less than 3 y. Lag times for ivory origin...

Stress hormones, released into circulation as a consequence of disturbance, are classically assayed from blood samples but may also be detected in a variety of matrices. Blubber and fecal samples can be remotely collected from free-ranging cetaceans without the confounding hormone elevations associated with chase, capture, and handling required to...

Persistent organic pollutants (POPs), specifically PCBs, PBDEs, and DDTs, in the marine environment are well documented, however accumulation and mobilization patterns at the top of the food-web are poorly understood. This study broadens the understanding of POPs in the endangered Southern Resident killer whale population by addressing modulation b...

Estimating diet composition is important for understanding interactions between predators and prey and thus illuminating ecosystem function. The diet of many species, however, is difficult to observe directly. Genetic analysis of fecal material collected in the field is therefore a useful tool for gaining insight into wild animal diets. In this stu...

Distance matrix of number of nucleotide differences among species in the baseline. (CSV)

Table of sampling dates and associated sample groups for the 175 fecal samples used in the analysis. (CSV)

Description of methods for estimated daily salmon abundance. (DOCX)

Alignment of the primer regions. (DOCX)

BLAST results of Pacific salmon 16s sequences from GenBank against our baseline. (CSV)

Dietary habits of free-ranging animals are essential for understanding their ecology, conservation and management. Carnivore diet is most frequently estimated using morphological analysis of prey remains found in scats. However, genetic methods may identify prey in scats when parts are too small to identify by morphological methods. We developed an...

Knowledge regarding stress hormones and how they vary in response to seasonality, gender, age, and reproductive status for any marine mammal is limited. Furthermore, stress hormones may be measured in more than one matrix (e.g., feces, blood, blubber), but the relationships between levels of a given hormone across these matrices are unknown, furthe...

The African elephant consists of forest and savanna subspecies. Both subspecies are highly endangered due to severe poaching and habitat loss, and knowledge of their population structure is vital to their conservation. Previous studies have demonstrated marked genetic and morphological differences between forest and savanna elephants and despite ex...

Biologic sample collection in wild cetacean populations is challenging. Most information on toxicant levels is obtained from blubber biopsy samples; however, sample collection is invasive and strictly regulated under permit, thus limiting sample numbers. Methods are needed to monitor toxicant levels that increase temporal and repeat sampling of ind...

Poaching of elephants is now occurring at rates that threaten African populations with extinction. Identifying the number and location of Africa's major poaching hotspots may assist efforts to end poaching and facilitate recovery of elephant populations. We genetically assign origin to 28 large ivory seizures (≥0.5 tons) made between 1996-2014, als...

The winter diet of barren-ground caribou may affect adult survival, timing of parturition, neonatal survival, and postpartum mass. We used microhistological analyses and hormone levels in feces to determine sex-specific late-winter diets, pregnancy rates, group composition, and endocrine-based measures of physiological and nutritional stress. Liche...

Poaching and habitat loss has caused a massive decline in the number and range of African elephants over the past few decades, with the greatest post ivory ban losses occurring since 2006. Poaching targets the largest individuals for their greater tusk sizes. This should also bias poaching towards males. We hypothesized that elephant sex ratios fro...

Wide-ranging species with large spatial requirements can rarely be supported in protected areas alone, yet most species face greater threats outside reserves. The need to consider conservation of large mammals in landscape mosaics is very relevant to the Brazilian Cerrado, which is the world's most biologically diverse and threatened savanna. The m...

We examined the potential influences of existing social housing arrangements on captive sun bear female reproductive cycling. Three social conditions were studied: 1.2, 1.1, and 0.2. Fecal hormone metabolites of total estrogens, progestins and glucocorticoids were compared between the three social conditions and were analyzed along with vaginal cyt...

We examined fecal glucocorticoid (fGC) measures of nutrition and thermoregulatory demands on wild bears in Glacier National Park, Montana, and assessed how these measures changed in samples left in the field. Both ambient temperature and exposure can impact thermoregulation and sample degradation. Bear diets vary markedly with season, affecting bod...

There is widespread concern about impacts of land-use change on connectivity among animal and plant populations, but those impacts are difficult to quantify. Moreover, lack of knowledge regarding ecosystems before fragmentation may obscure appropriate conservation targets. We use occurrence and population genetic data to contrast connectivity for a...

Objective: To determine the effect of natural exposure to domoic acid (DA) on eosinophil counts and adrenal gland function in California sea lions (Zalophus californianus). Design: Cross-sectional prospective study. Animals: 39 California sea lions. Procedures: Adult female sea lions admitted to a rehabilitation hospital during 2009 were cla...

State and federal actions to conserve northern spotted owl (Strix occidentalis caurina) habitat are largely initiated by establishing habitat occupancy. Northern spotted owl occupancy is typically assessed by eliciting their response to simulated conspecific vocalizations. However, proximity of barred owls (Strix varia)-a significant threat to nort...

Northern Spotted Owl Occupancy Model Using Forward Model Selection. (DOCX)

Northern spotted owl occupancy plotted as a function of habitat quality. Habitat quality is based on amount of old growth and mature forest (see Carroll and Johnson 2008). Dotted lines are 95% confidence intervals. (DOCX)

Northern spotted owl (NSO) and barred owl (BO) roosts located by detection dog versus vocalization surveys. (DOCX)

Barred Owl Occupancy Model Using Forward Model Selection. (DOCX)

Background/Question/Methods Wildlife populations are simultaneously regulated by a number of ecological processes, including forage availability, competition, and predation. These mechanisms commonly interact. Thus, scientific or management approaches that emphasize a single process can lead to misinformation and undesired outcomes. The situation...

Managing endangered species often involves evaluating the relative impacts of multiple anthropogenic and ecological pressures. This challenge is particularly formidable for cetaceans, which spend the majority of their time underwater. Noninvasive physiological approaches can be especially informative in this regard. We used a combination of fecal t...

Most species of bears exhibit a reproductive strategy that includes a highly defined breeding season, delayed implantation, pseudopregnancy, and no postpartum estrus. Sun bears (Helarctos malayanus), a tropical lowland species, represent a potential departure from the typical ursid reproductive pattern. We studied reproductive timing in captive sun...

One of the worst threats currently confronting the federally threatened northern spotted owl (Strix occidentalis caurina) is the ongoing range expansion of the closely related barred owl (Strix varia). In addition to outcompeting spotted owls for territories, barred owls also attack spotted owls directly. As a result, spotted owls call less frequen...

Baleen whales (Mysticeti) communicate using low-frequency acoustic signals. These long-wavelength sounds can be detected over hundreds of kilometres, potentially allowing contact over large distances. Low-frequency noise from large ships (20-200 Hz) overlaps acoustic signals used by baleen whales, and increased levels of underwater noise have been...

BIC differences for various giant armadillo, giant anteater, maned wolf, jaguar, and puma resource selection models. (DOCX)

Conserving animals beyond protected areas is critical because even the largest reserves may be too small to maintain viable populations for many wide-ranging species. Identification of landscape features that will promote persistence of a diverse array of species is a high priority, particularly, for protected areas that reside in regions of otherw...

Woodland caribou (Rangifer tarandus caribou) and moose (Alces alces) populations in the Alberta oil sands region of western Canada are influenced by wolf (Canis lupus) predation, habitat degradation and loss, and anthropogenic activities. Trained domestic dogs were used to locate scat from caribou, moose, and wolves during winter surges in petroleu...

The ability to noninvasively detect the presence of species and assess physiological health by DNA and hormone analysis makes scat a valuable tool for ecology and conservation. We assessed factors associated with DNA and hormone degradation in a four-season study that employed detection dogs to collect scats from maned wolf (Chrysocyon brachyurus)...

Linear dominance hierarchies are thought to form within groups of social animals to minimize conflict over access to resources. Dominance in both male and female African elephants (Loxodonta africana) is based mostly on intrinsic factors relating to age, and dominance hierarchies have been described within and between family groups of females. Very...

We used data from 78 individuals at 26 microsatellite loci to infer parental and sibling relationships within a community of fish-eating ("resident") eastern North Pacific killer whales (Orcinus orca). Paternity analysis involving 15 mother/calf pairs and 8 potential fathers and whole-pedigree analysis of the entire sample produced consistent resul...

Climate change and industrial development are contributing to synchronous declines in Rangifer populations across the Arctic. Chronic stress has been implicated as a proximate factor associated with decline in free-ranging populations, but its role in Rangifer is unspecified. Analysis of glucocorticosteroid (GC) concentration in feces, and more rec...

The use of scat surveys to obtain DNA has been well documented in temperate areas, where DNA preservation may be more effective than in tropical forests. Samples obtained in the tropics are often exposed to high humidity, warm temperatures, frequent rain and intense sunlight, all of which can rapidly degrade DNA. Despite these potential problems, w...

Stress physiologists posit that multiple simultaneous demands faced by an organism may have non-additive effects on the magnitude of their response to disturbance. The environmental assessment literature emphasizes a similar phenomenon at the population level, arguing that populations can compensate for perturbations up to a threshold, beyond which...

ABSTRACT  Noninvasive scat sampling methods can generate large samples sizes, collected over vast landscapes, ideal for addressing wildlife conservation and management questions. However, the cost of genotyping scat samples limits the accessibility of these techniques. We describe detection-dog methods for matching large numbers of scat samples to...

Avian endocrinology is a productive field that could benefit from increased application of non-invasive techniques. Although assay protocols vary, most studies that measure hormone metabolites in avian feces struggle with an artificial effect of sample mass on steroid metabolite concentration. Hormone metabolite concentrations measured in small sam...

Most protected areas are too small to sustain populations of wide-ranging mammals; thus, identification and conservation of high-quality habitat for those animals outside parks is often a high priority, particularly for regions where extensive land conversion is occurring. This is the case in the vicinity of Emas National Park, a small protected ar...

Walker and Stiles argue that elephant populations are not declining. The facts say otherwise. Loxodonta africana numbers have plummeted by more than 50% continent-wide in the past 40 years, a reduction now compounded by increases in range loss, conflict with humans, and resurgence in poaching ([ 1

Recovery plans for endangered southern resident killer whales Orcinus orca have iden- tified reduced prey availability as a risk to the population. In order to better assess this risk, we stud- ied prey selection from 2004 to 2008 in 2 regions of the whales' summer range: San Juan Islands, Washington and the western Strait of Juan de Fuca, British...

Tanzania and Zambia are petitioning the Convention on International Trade in Endangered Species (CITES) to “downlist” the conservation status of their elephants to allow sale of stockpiled ivory. But just 2 years after CITES placed a 9-year moratorium on future ivory sales (1), elephant poaching is on the rise. The petitioning countries are major s...

Poaching removed adult female elephants, Loxodonta africana, from a social system centred on kin support and female philopatry, creating a natural experiment in many matrifocal African elephant populations. We hypothesized that core groups lacking kin display less cohesion and cooperate and compete with elephants outside of their core group more fr...

Variation in concentrations of thyroid hormones shed in feces may help to identify physiological states of animals, but the efficacy of the technique needs to be validated for each species. We determined whether a known physiological alteration to thyroid hormone production was reflected in hormone concentrations in the feces of Steller sea lions (...

The illegal slaughter of African elephants for ivory is now worse than it was at its peak in the 1980s. New forensic tools based on DNA analysis can help stop the cartels behind this bloody trade