Mark Pokras
Tufts University, IDGH, Faculty Member
SummaryA recent review of the management of hyperabundant macropods in Australia proposed that expanded professional shooting is likely to lead to better biodiversity and animal welfare outcomes. While the tenets of this general argument... more
SummaryA recent review of the management of hyperabundant macropods in Australia proposed that expanded professional shooting is likely to lead to better biodiversity and animal welfare outcomes. While the tenets of this general argument are sound, it overlooks one important issue for biodiversity and animal health and welfare: reliance on toxic lead‐based ammunition. Lead poisoning poses a major threat to Australia's wildlife scavengers. Current proposals to expand professional macropod shooting would see tonnes of an extremely toxic and persistent heavy metal continue to be introduced into Australian environments. This contrasts with trends in many other countries, where lead ammunition is, through legislation or voluntary programs, being phased out. Fortunately, there are alternatives to lead ammunition that could be investigated and adopted for improved macropod management. A transition to lead‐free ammunition would allow the broad environmental and animal welfare goals desi...
Research Interests:
This data package constitutes the demographic (time series) data used to assess the population scale impacts of lead toxicosis on Bald eagles (Haliaeetus leucocephalus) in the Northeast United States from 1990-2018. Three time series... more
This data package constitutes the demographic (time series) data used to assess the population scale impacts of lead toxicosis on Bald eagles (Haliaeetus leucocephalus) in the Northeast United States from 1990-2018. Three time series exist: (1) that of a hypothetical group of eagles in the Northeast that did not experience mortalities from lead toxicity, (2) that of a hypothetical group of eagles in the Northeast that did not experience mortalities from lead exposure, and (3) that empirical time series of the real group of eagles. Time series of the control group consists of the counts of breeding eagles in the study area from 1990-2018, while time series of the Pb-reduced and Pb-free data groups have been altered using veterinary data.This study was funded in part by the Morris Animal Foundation D18ZO-103, in part by the New York State Department of Environmental Conservation, and in part by the Federal Aid in Wildlife Restoration Grant W-178-R Wildlife Health. The views expressed do not necessarily reflect the views of the Morris Animal Foundation or the New York State Department of Environmental Conservation, their officers, directors, affiliates, agents, nor staff
Research Interests:
This packet contains the standardized veterinary (necropsy) used in the assessment of the population scale impacts of lead toxicosis in bald eagles in the Northeast United States from 1990-2018. The data is featured in the article... more
This packet contains the standardized veterinary (necropsy) used in the assessment of the population scale impacts of lead toxicosis in bald eagles in the Northeast United States from 1990-2018. The data is featured in the article entitled Environmental Lead Reduces the Resilience of Bald Eagle Populations, by B. Hanley, A. Dhondt, M. Forzán, E. Bunting, M. Pokras, K. Hynes, E. Domingues-Villegas, and K. Schuler. While this dataset contains only cleaned and standardized data used directly in the analysis, all data were originally sourced in raw (unstandardized) form from regional state and federal agencies, diagnostic laboratories, and other organizations. Raw data and their metadata are available at: https://doi.org/10.7298/jn80-e080, https://doi.org/10.7298/qg9d-9p17, https://doi.org/10.7298/6by1-j636, https://doi.org/10.7298/m8yz-1r93, and https://doi.org/10.7298/hyyc-ws65.This study was funded in part by the Morris Animal Foundation D18ZO-103, in part by the New York State Department of Environmental Conservation, and in part by the Federal Aid in Wildlife Restoration Grant W-178-R Wildlife Health. The views expressed do not necessarily reflect the views of the Morris Animal Foundation or the New York State Department of Environmental Conservation, their officers, directors, affiliates, agents, nor staff
Research Interests:
Research Interests:
An adult male red fox (Vulpes vulpes) was hit by an automobile and presented in respiratory distress. Radiographs and a physical examination indicated that both bronchi had been avulsed from the lungs and euthanasia was elected. This is... more
An adult male red fox (Vulpes vulpes) was hit by an automobile and presented in respiratory distress. Radiographs and a physical examination indicated that both bronchi had been avulsed from the lungs and euthanasia was elected. This is the first report of a bilateral bronchial avulsion, as well as the first report of large airway avulsion in a canid, as a result of blunt thoracic trauma. Tracheal avulsion is a sporadically reported sequel to blunt trauma in domestic cats. Preliminary diagnosis can be made from history, clinical signs, and radiographs. Bronchoscopy yields a definitive diagnosis. Treatment is most often surgical resection of traumatized ends of airway and anastamosis. Depending on the location and extent of injury, other surgical techniques may be considered. An index of suspicion for this injury must be maintained in any patient suffering blunt trauma, as patients with this severe injury may present with mild signs and initially respond to conservative therapy. Thor...
Research Interests:
Steatitis was diagnosed at necropsy in a debilitated, adult female common loon (Gavia immer), constituting the first known case of the disease in loons. Steatitis has been described most commonly in a variety of domestic and captive... more
Steatitis was diagnosed at necropsy in a debilitated, adult female common loon (Gavia immer), constituting the first known case of the disease in loons. Steatitis has been described most commonly in a variety of domestic and captive species. In these cases, the cause of steatitis is most often vitamin E deficiency in a diet comprised mainly of fish. Until roughly 20 years ago, the occurrence of steatitis in wildlife was relatively rare. However, the condition is being seen increasingly in herons in Japan and both coasts of the US. While several environmental factors have been correlated with the outbreaks, the causes remain unclear and may be multifactorial. Rehabilitators are in a unique position to recognize and report the event of steatitis in wild birds such as loons, allowing researchers to better understand the extent and cause of steatitis in wild birds.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Bald eagles (Haliaeetus leucocephalus) are considered a recovery success in the United States after rebounding from near extirpation due to widespread use of the insecticide dichlorodiphenyltrichloroethane (DDT) in the twentieth century.... more
Bald eagles (Haliaeetus leucocephalus) are considered a recovery success in the United States after rebounding from near extirpation due to widespread use of the insecticide dichlorodiphenyltrichloroethane (DDT) in the twentieth century. Although abundances of bald eagles have increased since DDT was banned, other contaminants have remained in the environment with unknown influence on eagle population trends. Ingestion of spent lead (Pb) ammunition, the source of Pb most available to eagles and other scavengers in the United States, is known to kill individual eagles, but the influence of the contaminant on overall population dynamics remains unclear, resulting in longstanding controversy over the continued legality of the use of Pb in terrestrial hunting ammunition. We hypothesized that mortalities from the ingestion of Pb reduced the long‐term growth rate and resiliency of bald eagles in the northeast United States over the last 3 decades. We used Holling's definition of resil...
Research Interests:
Common loons (Gavia immer) are diving waterbirds that are particularly challenging to keep in captivity due to their specific behavioral and physiologic needs, special housing requirements, and susceptibility to stress‐related disease. We... more
Common loons (Gavia immer) are diving waterbirds that are particularly challenging to keep in captivity due to their specific behavioral and physiologic needs, special housing requirements, and susceptibility to stress‐related disease. We report a novel method for housing and captive rearing common loon chicks that was developed as part of the first‐ever loon translocation effort in southeast Massachusetts, from 2015 to 2017. Thirteen loon chicks were reared in aquatic pens in a natural lake environment, utilizing noninvasive feeding and monitoring techniques that avoided human habituation. Chicks were reared in aquatic pens for 16–28 days before being released onto the lake. All chicks remained clinically normal and were monitored on the lake for up to 4 months following release. At least four of the chicks were subsequently confirmed to have survived to adulthood when they returned to the area in breeding plumage two to 3 years following release. Two of these confirmed adults disp...
Research Interests:
Research Interests:
Assessment of body condition is critical for examination of live and dead dolphins. Using live and dead stranded and dead bycaught short-beaked common dolphins (Delphinus delphis) from New England waters, a simple, practical body... more
Assessment of body condition is critical for examination of live and dead dolphins. Using live and dead stranded and dead bycaught short-beaked common dolphins (Delphinus delphis) from New England waters, a simple, practical body condition scoring (BCS) system was developed that has utility for all delphinid species. Using photographs, a non-invasive, 4-point visual scale was created based on anatomical landmarks which are indicative of body condition and emaciation. The consistency of using this BCS system was tested via a blind study with five trained and experienced stranding responders independently scoring a subset of D. delphis cases (n=30) using photo documentation only, and results showed a significant level of agreement among observers. Specific morphometric data relating to body condition were analyzed to determine parameters which, in association with the clinical evaluation of the animal, may be indicative of potential success after release during a live stranding event....
Research Interests:
Lead (Pb) toxicity from ammunition has been shown to be a threat to scavenging birds across the globe. Toxic levels of lead have recently been found in Australia's largest bird of prey, the wedge-tailed eagle (Aquila audax), through... more
Lead (Pb) toxicity from ammunition has been shown to be a threat to scavenging birds across the globe. Toxic levels of lead have recently been found in Australia's largest bird of prey, the wedge-tailed eagle (Aquila audax), through inductively coupled plasma mass spectrometry (ICP-MS) analysis of liver and bone samples. However, ICP-MS is consumptive (causing damage to archived specimens), time-consuming, and expensive. For these reasons, portable X-ray fluorescence (XRF) devices have been optimized to measure bone lead in North American avian species, humans, and other environmental samples. In this study, we assessed portable XRF for bone lead measurement in Australian raptors in two parts. First, we validated the method using tissues from wedge-tailed eagles from Tasmania (A. a. fleayi), analysing bone samples taken from sites on the femur immediately adjacent to sites for which we had ICP-MS data (n = 89). Second, we measured lead via portable XRF in the skulls of wedge-tailed eagles from south-eastern mainland Australia (A. a. audax) collected during a criminal prosecution (n = 92). Portable XRF bone lead measurement demonstrated an excellent correlation with ICP-MS results using root-transformed regression (R2 = 0.88). Calculated equivalent ICP-MS values revealed that greater than 50% of the eagles from mainland Australia had elevated lead levels (>10 mg/kg) and 13% had severe lead exposure (>20 mg/kg). Our results support previous studies of North American avian species and suggest that portable XRF could be a useful and inexpensive option for measurement of bone lead in Australian scavenger species.
Research Interests:
Abstract: There are no published plasma biochemistry reference intervals for any species within the order Gaviiformes, which includes the common loon (Gavia immer). Because of their unique classification and lack of close taxonomic... more
Abstract: There are no published plasma biochemistry reference intervals for any species within the order Gaviiformes, which includes the common loon (Gavia immer). Because of their unique classification and lack of close taxonomic relatives, species-specific values for clinical data in loons are needed. This study determined reference intervals for plasma biochemical values in adult common loons, and reference intervals for protein electrophoresis values in both adult and juvenile common loons. Healthy, wild adult (n = 148, age >3 yr) and juvenile (n = 31, age 4–12 wk) common loons were sampled on freshwater summer breeding territories at study sites across North America. Plasma biochemical analytes included glucose (Glu), total calcium, phosphorus, sodium, potassium, chloride, blood urea nitrogen (BUN), uric acid, cholesterol, triglycerides, creatine kinase, γ-glutamyl transferase, alkaline phosphatase (ALP), lactate dehydrogenase, aspartate aminotransferase, amylase, and bile acids. Protein electrophoresis data included albumin to globulin ratio (A: G), prealbumin, albumin, α1-globulin, α2-globulin, β-globulin, and γ-globulin. Adult females had significantly higher Glu, ALP, and BUN than adult males. Juvenile loons had higher β-globulins than adults, whereas adults had higher α1-globulins. Establishment of complete reference intervals will improve clinical assessment of captive loons, and allow researchers to better understand the health of wild loons in response to the multiple environmental stressors faced by these species.
Research Interests:
Research Interests: Business, Medicine, Multidisciplinary, Fishing, Wildlife, and 3 moreLead Poisoning, Fishery, and Ingestion
Research Interests:
ABSTRACTPoisoning from lead fishing tackle has been identified as the leading cause of mortality in adult common loons (Gavia immer). As a K‐selected species, adult survival is a critical component in the population demography of loons,... more
ABSTRACTPoisoning from lead fishing tackle has been identified as the leading cause of mortality in adult common loons (Gavia immer). As a K‐selected species, adult survival is a critical component in the population demography of loons, but the population‐level effects of mortality from ingested lead tackle on loons have not been quantified. We used a long‐term dataset (1989–2012) on common loon mortality in New Hampshire, USA, to describe the types of lead tackle ingested by loons, investigate methods of ingestion of lead tackle, document the number and rate of adult mortalities resulting from lead tackle, and test for a population‐level effect of lead tackle on the loon population in New Hampshire. Nearly half (48.6%) of collected adult mortalities resulted from lead toxicosis from ingested lead fishing tackle, representing an adjusted annual mortality rate of 1.7 ± 0.6% (SD) of the statewide population. Jigs accounted for 52.6% and sinkers for 38.8% of the archived lead tackle ob...
Research Interests:
Research Interests: Skeletal muscle biology, Biology, Malaria, Macrophages, Medicine, and 15 morePlasmodium, Spleen, Lakes, Brain, Kidney, Liver, Birds, Female, Animals, Lung, New Hampshire, Skeletal Muscle, Myocardium, Pericardium, and Fatal outcome
We investigated the relation between environmental mercury exposure and corticosterone concentrations in free-living adult common loons (Gavia immer). We determined blood and feather mercury concentrations and compared them to... more
We investigated the relation between environmental mercury exposure and corticosterone concentrations in free-living adult common loons (Gavia immer). We determined blood and feather mercury concentrations and compared them to testosterone, estradiol, and stress-induced plasma corticosterone concentrations. Although neither testosterone nor estradiol correlated with Hg levels, there was a robust positive relation between blood Hg and stress-induced corticosterone concentrations in males, but not in females. The lack of an effect in females may have been due to overall less contamination in females. There were no significant correlations between feather Hg and stress-induced corticosterone in either sex. To help determine whether Hg had a causal effect on corticosterone, we investigated the impact of experimental Hg intake on the corticosterone stress response in captive juvenile loons. Juveniles were subjected to three different feeding regimes: 0, 0.4 and 1.2μg Hg (as MeHgCL)/g wet...
Research Interests:
Research Interests: Biology, Health, Toxicity, Legislation, Wildlife, and 4 moreLead, Lead Poisoning, Waterfowl, and Environment
Research Interests:
Research Interests:
The Seabird Ecological Assessment Network (SEANET) is a collaborative project that investigates threats to marine and coastal birds in the northeastern United States, relying upon volunteer citizen scientists to monitor beaches... more
The Seabird Ecological Assessment Network (SEANET) is a collaborative project that investigates threats to marine and coastal birds in the northeastern United States, relying upon volunteer citizen scientists to monitor beaches regularly for beachcast birds. Before ...
Research Interests:
... Jan., a wildlife biologist, using radio telemetry from a fixed-wing aircraft, picked up the signal and visually located the bird along the lower Connecticut River at the mouth of the Salmon River in Haddam, Con-necticut, about 24.1 km... more
... Jan., a wildlife biologist, using radio telemetry from a fixed-wing aircraft, picked up the signal and visually located the bird along the lower Connecticut River at the mouth of the Salmon River in Haddam, Con-necticut, about 24.1 km from Long Island Sound. This eagle was not ...
Research Interests:
Research Interests:
A debilitated adult male common loon (Gavia immer) was taken to a veterinary practice in Liverpool, NY where it later died. Subsequently it was sent to Tufts Wildlife Clinic as part of a regional mortality study. During the necropsy,... more
A debilitated adult male common loon (Gavia immer) was taken to a veterinary practice in Liverpool, NY where it later died. Subsequently it was sent to Tufts Wildlife Clinic as part of a regional mortality study. During the necropsy, pathology involving most organ systems was noted. Microbiologic and histopathologic examination revealed an overwhelming infection by the fungus Cryptococcus spp.
Research Interests:
Research Interests:
Research Interests:
ABSTP, ACT.--Packed cell volume (%), total solids (g/dl), white blood cell count (cells/tl), differential and absolute white blood cell counts, and prevalence of hemoparasites were determined for 85 healthy sharp- shinned hawks (Accipiter... more
ABSTP, ACT.--Packed cell volume (%), total solids (g/dl), white blood cell count (cells/tl), differential and absolute white blood cell counts, and prevalence of hemoparasites were determined for 85 healthy sharp- shinned hawks (Accipiter striatus) during the 1991 fall migration. The packed cell volume (47.6 + 6.73%), total solids (2.83 _+ 0.58 g/dl) and white blood cell count (12 900 +
Research Interests:
G(M1)-gangliosidosis is a rare progressive neurodegenerative disorder due to an autosomal recessively inherited deficiency of lysosomal β-galactosidase. We have identified seven American black bears (Ursus americanus) found in the... more
G(M1)-gangliosidosis is a rare progressive neurodegenerative disorder due to an autosomal recessively inherited deficiency of lysosomal β-galactosidase. We have identified seven American black bears (Ursus americanus) found in the Northeast United States suffering from G(M1)-gangliosidosis. This report describes the clinical features, brain MRI, and morphologic, biochemical and molecular genetic findings in the affected bears. Brain lipids were compared with those in the brain of a G(M1)-mouse. The bears presented at ages 10-14 months in poor clinical condition, lethargic, tremulous and ataxic. They continued to decline and were humanely euthanized. The T(2)-weighted MR images of the brain of one bear disclosed white matter hyperintensity. Morphological studies of the brain from five of the bears revealed enlarged neurons with foamy cytoplasm containing granules. Axonal spheroids were present in white matter. Electron microscopic examination revealed lamellated membrane structures within neurons. Cytoplasmic vacuoles were found in the liver, kidneys and chondrocytes and foamy macrophages within the lungs. Acid β-galactosidase activity in cultured skin fibroblasts was only 1-2% of control values. In the brain, ganglioside-bound sialic acid was increased more than 2-fold with G(M1)-ganglioside predominating. G(A1) content was also increased whereas cerebrosides and sulfatides were markedly decreased. The distribution of gangliosides was similar to that in the G(M1)-mouse brain, but the loss of myelin lipids was greater in the brain of the affected bear than in the brain of the G(M1) mouse. Isolated full-length cDNA of the black bear GLB1 gene revealed 86% homology to its human counterpart in nucleotide sequence and 82% in amino acid sequence. GLB1 cDNA from liver tissue of an affected bear contained a homozygous recessive T(1042) to C transition inducing a Tyr348 to His mutation (Y348H) within a highly conserved region of the GLB1 gene. The coincidence of several black bears with G(M1)-gangliosidosis in the same geographic area suggests increased frequency of a founder mutation in this animal population.
Research Interests: Magnetic Resonance Imaging, Humans, Cerebellum, Mice, United States, and 16 moreFemale, Animals, Retina, Genome, Clinical Sciences, Ursidae, Transfection, Base Sequence, Quntitative Thin Layer Chromatography, Human Fibroblasts, Gangliosides, Glycosyl Hydrolases, Gene Expression Regulation, Myelin Sheath, Molecular Sequence Data, and DNA mutational analysis
An 11-yr-old captive-raised male woodchuck (Marmota monax) presented with ataxia, poor balance, left-sided weakness, circling to the left and nystagmus with the fast-phase directed towards the left. The clinical signs were compatible with... more
An 11-yr-old captive-raised male woodchuck (Marmota monax) presented with ataxia, poor balance, left-sided weakness, circling to the left and nystagmus with the fast-phase directed towards the left. The clinical signs were compatible with a central vestibular deficit syndrome. Necropsy and histologic findings revealed a meningotheliomatous meningioma centered over the ventrolateral left pons and medulla along with acute bronchopneumonia, chronic glomerulopathy, interstitial nephritis, and phthisis bulbi.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
... Lead Isotopes Indicate Lead Shot Exposure in Alaska-Breeding Waterfowl Angela Matz and Paul Flint. ... Evidence for the Source of Lead Contamination within the California Condor JohnChesley, Peter Reinthal, Chris Parish, Kathy... more
... Lead Isotopes Indicate Lead Shot Exposure in Alaska-Breeding Waterfowl Angela Matz and Paul Flint. ... Evidence for the Source of Lead Contamination within the California Condor JohnChesley, Peter Reinthal, Chris Parish, Kathy Sullivan, and Ron Sieg. ...
Research Interests:
This article lists some basic guidelines for practitioners to use in treating wildlife patients. Major issues associated with wildlife practice are introduced. Important sources of equipment and major literature are contained in appendices.