Identifying and Handling
Contaminant-related Wildlife
Mortality/Morbidity
Steve Sheffield, Joe Sullivan, and Woody Hill
Introduction
► Wildlife
biologists can encounter mortality
and/or morbidity incidents in the field
► Mortality
– incidence of death
► Morbidity
► Wildlife
– incidence of sickness/ill health
mortality/morbidity incidents can be
natural, accidental, or result from disease or
exposure to environmental contaminants
Environmental Contaminants
► Environmental contaminants include:






pesticides
metals/metalloids
organic chemicals
inorganic chemicals
pharmaceutical drugs
natural plant/animal toxins
Contaminant Impacts
► Understanding contaminant impacts
involves
examination of many parameters:








species (or higher taxa) involved
trophic level of the species involved
chemical(s) involved
route(s) of exposure
signs of intoxication
fate and transport through the environment
environmental compartment (media) involved
environmental persistence
Species Specific Hazards
► Not
all contaminants pose the same hazard to all
taxonomic groups of animals
► Factors involved include:
 evolutionary status (detoxifying enzyme systems
more advanced in mammals)
 physical /chemical properties of the chemical (e.g.,
lipid solubility, volatility, etc.)
 differing toxicities of chemicals
 routes(s) of exposure
 trophic level of the animal
Trophic Level Effects
► Possible
effects of trophic level:
 Bioaccumulation – chemicals accumulate in
an animals faster than they can be metabolized
and excreted
 Biomagnification – results from
bioaccumulation and biotransfer where tissue
concentrations of a chemical moves up the
food chain through two or more trophic levels
Factors to Consider
►
Three factors to consider with discovery of a field
mortality/morbidity incident suspected to be caused by
environmental contaminants:
(1)
Time is of the essence! Generally, there is little time to
plan/conduct a research study of the incident
(2)
Time available for collecting evidence such as tissue samples
and/or other environmental media (plants, soil, water, sediment,
air) may be hours to a few days
(3)
Chemicals decompose, tissues decay/dessicate, and carcasses
are readily scavenged, all of which greatly affect time available
for sampling
Chapter Objective
► Provide
guidelines for wildlife biologists in the
field to assess wildlife mortality/ morbidity
incidents and sampling techniques useful in
detection and documentation of environmental
contaminants impacting wildlife
Environmental Contaminants
► Human
activities have resulted in the pervasive and
dynamic nature of contaminants in the environment
► Many
different industries contribute to this contaminant
load, including chemical, agriculture, mining, energy,
electronics, pharmaceutical, pest control, and others
► Greatest
number of wildlife mortality/ morbidity
incidents have been reported for 2 specific categories of
contaminants:
 Anticholinesterase (anti-ChE) insecticides
 Anticoagulant rodenticides
Routes of Exposure to
Environmental Contaminants
► Oral
 Primary consumption of contaminant
 Secondary poisoning from consumption of poisoned
prey item
► Dermal
► Inhalation
► Placental/Egg yolk
Possible Effects of
Environmental Contaminants
► Lethal
effects – death of the animal
effects – serve to debilitate an exposed
animal; reduced survival, growth, and
reproductive rates can occur from impacts on
one or more bodily systems
► Sublethal
Lethal Effects of
Environmental Contaminants
► The
full extent of wildlife mortality from
contaminants is difficult to assess – wildlife
species often are secretive, camouflaged, mobile,
live in dense habitat
► Typical
field studies often reveal low estimates
of mortality because carcasses disappear rapidly
Difficulties in Conducting
Field Studies
► Most
animal carcasses disappear within 24-48 hours;
scavenging rate very high
► Exposed
animals that become sick may move from area
or otherwise disappear
► Exposed
animals may not always demonstrate visible
signs of morbidity
► Exposed
animals may become more vulnerable to
predation or other mortality factor as a result of
exposure
Classes of Contaminants
► Metals/Metalloids
► Organic
Chemicals
► Inorganic
Chemicals
► Pharmaceuticals
► Pesticides
► Natural
Plant/Animal Toxins
Metals
► Metals
can be essential or non-essential; that is,
they may or may not have biological function
► Non-essential metals
are most hazardous to
wildlife species; they can enter body and replace
those which are essential
► Non-essential metals
Cd, Cr+6
of most concern: Hg, Pb,
Metalloids
► Metalloids
are transitory between metals and
non-metals
► Metalloids
can be essential or non-essential; that
is, they may or may not have biological function
► Non-essential metalloids
are most hazardous to
wildlife species; they can enter body and replace
those which are essential
► Non-essential metalloids
Se
of most concern: As,
Organic Chemicals
► Organic
chemicals are based on C-H pairs
ranging from single carbon chains to multiple
aromatic rings
► Organic
chemicals of most concern are: organic
solvents, ethylene glycol, petroleum products
(PAHs), and polyhalogenated compounds
(PCBs, PBDEs, PCDDs, PCDFs, PFOSs)
Inorganic Chemicals
► Inorganic
chemicals are a diverse group that do
not have carbon as their principal elements
► Includes
4 general groups: alkalis and chlorine,
industrial gases, inorganic pigments, and
industrial inorganic chemicals
► Two
inorganic chemicals pose a particular
hazard to wildlife species: cyanide and white
phosphorus
Pharmaceuticals
► There
is a wide diversity of pharmaceutical
drugs, hormones, and related organic wastewater
contaminants that pose a potential hazard to
wildlife species
► Most
of these prescription drugs have not been
tested for effects on wildlife
► Two
pharmaceutical drugs that have caused
numerous mortality/morbidity incidents are
sodium pentobarbital and diclofenac
Pesticides
– any substance or mixture of
substances intended for preventing, destroying,
repelling, or mitigating any pest
► Pesticide
contaminant category – intentionally
released into environment
► Unique
► Specific
classes of pesticides of major concern to
wildlife include insecticides, herbicides,
fungicides, fumigants, rodenticides, avicides
Pesticides (Insecticides)
are neurotoxicants – target insect nervous
system
► Most
► Four
distinct groups of insecticides include:
 chlorinated hydrocarbons (e.g., DDT)
 anti-cholinesterases (organophosphorus and
carbamate compounds)
 synthetic pyrethroids
 other botanicals (e.g, nicotine, rotenone)
Pesticides (Herbicides)
► Herbicides
are chemical compounds capable of
either killing or severely injuring plants
► There
are at least 65 different broad classes and
>22 different chemical groups of herbicides,
including: (germination inhibitors,
photosynthesis inhibitors, meristem inhibitors,
contact action, auxin growth regulators, and
foliar grass inhibitors
Pesticides (Fungicides)
► Fungicides
derived from a wide variety of
chemicals whose focus is to kill fungi
► There
are at least 36 different chemical groups
of fungicides – a direct result of the great
diversity of fungi
► There
are 3 general types of fungicides: foliar,
soil, and dressings
Pesticides (Fumigants)
► Fumigants are
used to kill insects, nematodes,
weed seeds, and fungi in soil as well as in stored
grains, fruit, vegetables, clothes, and other
products
► They
usually are used in enclosed spaces due to
the high volatility of the chemicals
► They
generally are nonselective, highly reactive,
and cytotoxic
Pesticides (Rodenticides)
► Rodenticides were
developed to control pest
small mammals (particularly rodents)
► They
cam be categorized into several groups:
 inorganic (metal-based) compounds (e.g., thallium
sulfate)
 insecticides (e.g., DDT)
 natural plant toxins (e.g., strychnine)
 anti-coagulants (warfarin, brodifacoum, etc.)
Pesticides (Avicides)
► Avicides
were developed to control avian pests,
particularly flocking species such as European
starlings, blackbirds, and pigeons
► Several
different insecticides and other
pesticides with avicidal properties have been
used for this purpose
Natural Plant/Animal Toxins
► Natural
plant and animal toxins are toxic
chemicals of biological origin
► Produced by
living organisms such as bacteria,
blue-green algae, fungi, marine invertebrates and
fishes, vascular plants, and poisonous aquatic
and terrestrial animal species
Natural Plant Toxins
plant toxins – secondary plant
compounds, some of which are used as the basis
for pesticides (e.g., nicotine, pyrethrum,
rotenone, etc.)
► Natural
► Chemical
groups which can be highly toxic
include alkaloids, tannins, phenols, lectins,
glycosides, and terpenes, among others
Natural Animals Toxins
► Three
groups of microbial organisms (bacteria,
algae, fungi) are capable of producing some of
the most deadly toxins known
► Examples
of this include: botulinum (bacteria),
harmful algal blooms (blue-green algae in fresh
and brackish waters, phytoplankton in marine
waters, mycotoxins (fungi)
Contaminant Diagnostics - Safety
► Personal
safety is a primary concern in a wildlife
mortality/morbidity incident
► Field
investigators should not handle carcasses,
collect environmental samples, or enter the area of
the incident until adequate safety precautions have
been taken
► If
contaminant is known, information can be found
regarding its toxicity; if contaminant is unknown,
only trained personnel should attempt to enter site
for samples
Contaminant Diagnostics – Safety 2
► Once
contaminant(s) identified, proper protective
clothing (including on feet and hands) for the
contaminant(s) should be worn
► When
retrieving carcasses or debilitated animals
from water, impermeable gloves and rubber boots
should be worn
► Depending
upon the contaminant(s) involved,
respirators and/or TYVEK suits may be required
Contaminant Diagnostics – Safety 3
► In
hot/humid weather, heavy protective wear can be
dangerous, so work periods should be shortened to
prevent heat stress
►A
clean, shaded area should be provided where
workers can remove protective wear, cool off, and
get rehydrated
► If
disease is suspected, the list of precautions not as
extensive as for contaminants because diseases
generally are more species-specific than
contaminants
Contaminant Diagnosis – Initial Site
Reconnaissance
► Three
rules govern initiation of any wildlife
mortality/morbidity investigation:
Protect yourself and other involved
(2) Obtain the best case history possible
(3) Collect the best specimens possible
(1)
► Handling
and collection of specimens in the field will
affect what the laboratory can (and cannot) do with
them
Contaminant Diagnosis – Initial Site
Reconnaissance 2
► When
possible, notify a wildlife veterinarian (or
other trained personnel) and wait for their arrival
prior to initiating the investigation
► It
is critical to presume that there will be legal
implications of the investigation and the cause
may be a highly toxic or contagious agent
► Field
notes and documentation that begin with
initial stages of investigation are important
Contaminant Diagnosis – Initial Site
Reconnaissance 3
► Initial
ID of chemical(s) causing the incident should
be attempted if it can be done safely
 Early ID of the contaminant can: dictate safety
precautions needed
 direct types of samples that should be collected
 How samples should be handled
► If
source and cause of incident are not obvious, field
investigator should err on side of safety, collecting
samples inclusively
Contaminant Diagnosis – Initial Site
Reconnaissance 4
► As
a starting point to decide whether the cause is
disease or contaminant-related, consider the species
affected
► If
a single species (or group of related species) is
affected, disease more than likely involved; if many
different taxa affected, contaminants more than
likely involved
► Upon
initial discovery of the wildlife
mortality/morbidity site, the nearest wildlife
contaminant expert should be contacted
Contaminant Diagnosis – Initial Site
Reconnaissance 5
incidents – personal safety of utmost
importance because if a contaminant is present
in concentrations high enough to kill or
debilitate wildlife, it may pose a health hazard to
the field biologist
► Mortality
► In
many cases, locating carcasses can be difficult
and exposure to contaminants is obvious
Contaminant Diagnosis – Initial Site
Reconnaissance 6
► Once
carcasses found, immediate goals are:
 to prevent further deaths
 identify the cause and source of contaminant involved
► The
risk of contaminants to wildlife is dependent
on:
 toxicity
 concentration
 route of exposure
Contaminant Diagnosis – Initial Site
Reconnaissance 7
– discovery of sick (morbid) animals
requires fast action to be taken
► Morbidity
► Morbid
animals may be able to fully recover if
treated in time
► Prior
to collecting morbid animals, destination must
be identified and appropriate transport containers
obtained
► Transportation
and treatment of wildlife species
usually require specific permits
Contaminant Diagnostics – The
Wildlife Contamination Investigation
► Investigations
of wildlife mortality/morbidity
incidents suspected to be caused by contaminants
should proceed as though the cause was unknown
► All
factors must be checked or eliminated unless
there is solid evidence to support specific
conclusions
► Initial
decision as to whether or not an incident is
contaminant-related is a process of elimination
Contaminant Diagnostics – The
Wildlife Contamination Investigation
► Document
the incident with detailed field notes and
photographs
► The
investigator’s interpretation of the wildlife
mortality/morbidity incident scene will affect the
type, number, and location of samples taken and the
analyses performed
► Wildlife
mortality/morbidity incidents may be a
result of illegal activities, thus has the potential to
become a legal case
Contaminant Diagnostics – The
Wildlife Contamination Investigation
► Important factors
in interpretation of the incident
scene include:








location
time and date of incident
species involved
# of dead and/or sick animals
rate of deaths
chance of continuing mortality/morbidity
clinical signs observed
climatic conditions
Field Procedures – Sample
Documentation and Transport
► It
is critical that samples collected in the field be
handled properly to ensure that useable
information can be obtained
► All
samples should be properly bagged and
labeled
► Label
should include what type of specimen,
location it was collected, sample date/time, name
of person collecting the sample
Field Procedures – Sample
Documentation and Transport
► Samples
should be placed on ice in the field as
some contaminants degrade quickly and
tissues/carcasses can degrade quickly at warm
temperatures
► Once
samples are taken from the field, they
should be hard frozen
► Samples
for contaminant analysis should be
transported frozen or on dry ice
Field Procedures – Sample
Documentation and Transport
– techniques for handling
field-collected samples can vary by contaminant
type
► Handling samples
► When
animal tissues are collected, great care
should be taken to avoid cross-contamination
► Tissues
can be placed into plastic bags or small,
sterile glass jars; larger samples can be placed in
zip-lock bags
Field Procedures – Record Keeping
►A
field log is useful to make entries regarding
each sample collected for analysis
► Entries





should include:
sample ID number
type of sample collected
name of site where collection occurred
date
name or initials of person collecting the sample
Field Procedures – Record Keeping
► Accurate
record keeping is critical to
documenting wildlife mortality/morbidity
incidents
► The
more detailed information provided on the
field data sheet, the better the chances the
investigator(s) of the incident will be able to
understand what happened
Field Procedures – Sample Collection
► In
addition to wildlife tissue samples, other
environmental samples also are critical
► Environmental
samples should be collected from the
immediate area of where dead or debilitated animals
are found
► Those
experienced with site and contaminant types
can provide advice on number of samples required
and how far samples should be collected from the
original site
Field Procedures – Sample Collection
► In
addition to animal tissues, samples can be
taken from other environmental media, such as:




Plant tissues
Soil
Water/sediment
Air
Laboratory Procedures – Residue
Analysis
► Conducting residue
analysis requires
consideration of many factors, such as:




cost (generally expensive)
detection limits
QA/QC (quality assurance/quality control)
how to read and interpret the chemical analysis
report
 how to interpret the toxicological data
Laboratory Procedures – Residue
Analysis
► Interpretation
of residue analysis data can be tricky
► Overall,
we know very little about how body residue
levels of contaminants correlate to corresponding
effects seen in wildlife species
► Correlating
contaminant levels in the body (exposure)
with an effect provides the most powerful use of
residue analysis data
SUMMARY
►A
wide variety and volume of chemical
contaminants are found in the environment, and
frequently have been shown to exert negative
impacts (mortality, morbidity) on wildlife species
► As
a result, wildlife mortality/morbidity incidents
will occur
► There
is a strong need for field biologists to be able
to adequately identify and handle these incidents
SUMMARY - 2
► Few
field biologists receive training in
environmental or wildlife toxicology, thus it is
important that field biologists have a source for
SOPs for successfully handling wildlife
mortality/morbidity incidents
► This
chapter provides field biologists with
guidance on understanding wildlife toxicology
and procedures that should be followed when
confronted with a wildlife mortality/morbidity
incident
“The dose makes the poison”
Paracelsus
THE END