Wigganson Matandiko (student no: -02031904
Biol 525 – 001 Research Methods
Potential Interaction between predation risk, food limitation and
disease
Wigganson Matandiko, Montana State University
Supervisor: Dr. Scott Creel, Senior Lecturer, Department of Ecology
Co-Supervisor:
Project Duration: September 2013- December 2015;
Budget:
Wigganson Matandiko (student no: -02031904
Biol 525 – 001 Research Methods
Potential Interaction between predation risk, food limitation and
disease
Project Summary…..
Again, the first sentence must indicate in general what the study is about, and the conclusion of
the first paragraph should indicate more specifically what the study will focus on with some
additional particulars such as what species, or what location, or what measurement method.
Introduction
Recent studies and publication have shown that predation risks can play significantly
negative impact on prey species such as elk in the Greater Yellowstone Park. A
conservative view has been that predators limit prey through direct killing. Research
finding has however shown that it is not the only factor at play, but those anti-predator
responses mounted by prey have costs such as lowered survival, growth and
reproduction. The author in the publication entitled “Toward a predictive theory of risk
effects: Hypothesis for prey attributes and compensatory mortality” advocates that
stronger tests of these hypotheses will require continued development of methods to
identify and quantify the fitness costs of anti-predator responses in wild animals1. In this
study we seek to explore alternative approaches to testing the hypothesis by taking into
consideration the potential interaction between predation risk, food limitation and
disease affecting both predator and prey. The study will focus on lions (panthera leo),
hyenas (crocuta crocuta) and African wild dogs (lycaon pictus) of three National Parks
in eastern, central and western Zambia. The measurements of interest are number of
prey species successfully hunted within carnivore home ranges, prey density (with
estimates of age structure), fecal glucocorticoid metabolites2, fecal chlorophyll trends3,
alteration in foraging patterns and other causes of mortalities within and in the vicinity of
carnivore home ranges.
Wigganson Matandiko (student no: -02031904
Biol 525 – 001 Research Methods
Then describe the broad theory or scientific question or management question (you may be working on a
small piece, but how does that fit into the larger picture?) and develop from there. Typical development
sequence would be:
1.
2.
3.
4.
5.
begin with the scientific big question and/or the pressing management question
place the question in a big-picture scientific context, and then drill down, pointing out what is known,
what is questionable, and what is not known, along the way
restate your own research plans in slightly more detail than in the summary, emphasizing what is
unique, or distinctive, or at least more promising about your approach
restate overall goals, objectives, and expected results
explain how your results will be useable to guide management decisions or answer a central scientific
question
Identified mounted responses to predation risk by the same author include:i).change of group size in order to dilute direct predation risk. He affirms “the risk that at
least one herd member will be killed, increases as herd size increases and that
individual risk, decreases as herd size increases”. However it is also important to note
that the risk factor for communicable disease transmission also increases as animals
congregate. As the adage says, “birds of the same farther flock together”. The animals
will tend to share common grazing ranges and watering point. So while combating risks
of predation, a subtle spread of disease may be enhanced. This is one level where
disease can interact with predation risk. At the same time, if this is happening in the dry
season when forage is scarce, the herd usually depletes the immediate available
resource and then move on in search for better pastures. This often leads them further
away from watering points. It is often the case that the very young and old succumb to
exhaustion and lack of water. Such effects resulting in mortalities are often reported in
the drier months of the year.
ii).The degree of forage specialization as a strategy against predation can be seen in
some bulk grazers that target the grass plains to improve their visual acuity in detecting
predators but others do the opposite by going in the underbrush and forested area
where they cannot easily be noticed. The strategy is least effective in the dry season
when most deciduous trees shed their foliage.
Wigganson Matandiko (student no: -02031904
Biol 525 – 001 Research Methods
iii). Increased serum glucocorticoid that can subsequently be detected in fecal matter as
indicator of stress (Fecal glucocorticoid [fGC]). This however was found with limitation
due to progesterone (pregnancy hormone) that equally yield metabolites resembling
fGC and extruded in fecal droppings. If GC concentrations increase due to stress, it
must follow that any stressor outside risk of predation may increase the serum level.
The question of interest is whether the changes in concentration are comparable to
animals with relatively low stress. To elucidate this fact, a carefully selected control
group of the same species in fenced game ranches with relatively low stress levels will
have to be tested for fGC and compare statistically the difference.
iv). Vigilance and fitness is also recognized in anti-predator response. The earlier is said
to be affected by age, sex, body condition position within the group and local
environmental conditions1.
I wish to quantify to some degree the effect of such responses (either directly or
indirectly) by looking at mortalities of both predator and prey in a specific home range
delineated by the predators. Two main goals involving fixed transect counts in predator
range versus non predator range and investigation of the causes of mortality due to
disease, predator and food limitation. It is suspected that predation risk is capable of
triggering a cascade that can lead to disease and food limitation. It holds that food
limitation can also trigger disease and predation risk leading to the weaker being hunted
first.
Absence of predators may have a desirable effect in a short to medium terms in that
prey population may become incremental. However, over a long period this tends to
have deleterious effect as a result of unchecked increase of prey density that results in
over foraging (or over grazing – food limitation). This in itself is a recipe for disease
outbreaks.
The designated areas for legal hunting and harvest are game management zones
acting as buffer around the National Parks. As rule, no hunting is supposed to be
carried out within the Parks. The research findings will help management decision in
Wigganson Matandiko (student no: -02031904
Biol 525 – 001 Research Methods
dealing with disease, over stocking and food limitation. This will also be the basis for
animal translocation and reintroduction in depleted National Parks. And even though
from a conservation point of view, feed supplementation is not advocated, reduction of
animal habitat range may demand that some areas of the Parks be supplemented.
Failure to this, advocacy for range expansion through land reclamation is to be engaged
followed by prevention of further encroachments to National Parks.
Approach:
(Some formats will subsume design and methods into approach; other formats will treat those as
subsections or sections.)
Begin by restating the question.
If the question is not directly about some observable(s), you must expand the question into a set
of hypotheses, where each hypothesis leads to observable consequences which can discriminate
among the hypotheses. The set of hypotheses should be exhaustive. The hypotheses should be
mutually exclusive.
Can predator risk lead to prey anti-predator response resulting in interaction involving
food limitation and disease? If so in what way can we quantify the response to predation
either directly or indirectly? To address these questions the research is designed to take
inventory of wildlife numbers in perceived large carnivore ranges by taking transects
from previous animal census counts. This is in a bid to establish abundance or absence
of prey species. Upon confirmation of their presence, home ranges for three carnivore
species (Lion, hyena and African wild dog) will be determined by satellite collars fixed
on representatives of two lion prides, two wild dog parks and three hyena clans. We will
take advantage of the collaring exercise by Collection of serum samples, whole blood,
hair, and dung samples that will be stored for baseline survey for disease, carbon
isotope and genetic identification.
The second aspect of the research study is to assess the response to predation by the
frequency with which prey is found within the home ranges of the selected carnivores.
Predation response by observing fecal glucocorticoid metabolites in some studies have
not yielded results to warrant stress levels due to predation 2. Moreover it has been
Wigganson Matandiko (student no: -02031904
Biol 525 – 001 Research Methods
noted by the same authors that pregnant females tend to have high yields of the
metabolite due to progesterone whose metabolites resemble that of glucocorticoids and
have an affinity for serum binding globulins. None the less the metabolites will still be
investigated after careful consideration of the likely calving seasons and avoid fecal
sample collection in the months of suspected pregnancy. Reproducing the findings
reported by other researchers in a different environmental setting will augment the
results of other researchers. The difference here is that the control group will come from
the equivalent species found in game ranches where there is notably no risk to
predation and low external stressors.
The third aspect of this research will look at changes in the diet of both wild carnivores
and their prey to be investigated through assessment of fecal and grass chlorophyll
concentration using the technique applied by Christainsen et al (2009). The question of
interest is whether food limitation is having an effect on both carnivore and prey. The
study will take a spatial scale in that the browse and grass ranges of the landscape will
be assessed to note the months of scarcity in contrast to the months of abundance. The
landscapes in Zambia have a typical three season phase delineated as the rain season,
the dry and the cold seasons. By experience, we know the months when browse and
grazing grass is scarce. In such months prey tend to travel longer distances in search of
forage. However, a pattern of movement between feed grounds and watering points is
easily noticeable. In the rain season the weather is favorable to an abundance of plant
regrowth and hence acts to limit the long distance movements between feed grounds
and water (natural water catchment areas tend to be full in the rain season). The
analysis of isotopes of stable carbon (12C,
13C, 14C)
will be investigated to trace back
shifts in diet on the short and long term as described by the method of Robert H. Tykot
(2006) and posting on the Wikipedia website (2010). Of interest also is the ‘elasticity’ of
the carnivore home range in response to availability of food resource, does it remain
static or is there periodic oscillation between expansion and shrinkage? What does it
mean when there is expansion; can it be interpreted in terms of expanding carnivore
population or a sign of food scarcity such that carnivores have to spread in search of
prey? What is the effect on such survival instincts on both predator and prey? In the
Wigganson Matandiko (student no: -02031904
Biol 525 – 001 Research Methods
unlikely hood of shrinkage of home ranges, what would the carnivores be subsisting on?
This might lead to a theory of survival on the die offs due to disease or starvation.
Scavenging may be a function of inability to hunt in some predators due to a variety of
reasons one of which is lack of readily available prey for hunting. The implication of
scavenging on carcasses whose cause of death is unknown is in itself a risk that might
lead to the demise of carnivores.
Finally, reports of mortalities will be collated with accompanying GPS coordinates from
wildlife police officers, tour operators, and the hunting fraternity. The concept is to
construct mortality maps of preyed species that will be comparable to the carnivore
home ranges and with the prevailing vegetation. This is for ascertaining prey utilization
by carnivores in the three categorized seasons. By analyzing the numbers preyed and
other non- preyed mortalities we will may come to seek logical explanation to the
following pertinent questions:
i) When prey is most abundant within the carnivore home range and why
ii) The frequency with which they are preyed upon in the three seasons and
carnivore home range.
iii) Why prey have to balance between risk of predation and survival (food and water
availability).
iv) How and why some disease outbreak is possibly precipitated by predation risk.
v) Synchrony variation in carnivore home range size with the seasonal change.
vi) Why there might be need for translocation and reintroduction of some species in
some National Parks.
vii) Evaluation of fGC as stress indicator in high predation risk versus the low risk.
Wigganson Matandiko (student no: -02031904
Biol 525 – 001 Research Methods
Describe the type of design for the study (before/after, treatment/control, case/control, dose
response, “monitoring,”…). Explain the logical mapping between the design type and the
hypotheses.
Two sources of retrospective data will be sort to arrive at species density estimates. The
anti-poaching patrol teams keep records of animals encountered and mortalities seen in
the area of patrol. This will be useful information pertaining to the area where research
is to be conducted. Other sources through interview and questionnaire surveys will be
tour operators, non-governmental organizations and from hunting safari operators.
Secondly records from aerial surveys and hunting quotas will be used to guide in
determining prey species abundance in assumed carnivore home ranges. Random
transect counts, (preferably by aero plane financial resources allowing) will be
undertaken in the areas to see how the figures correlate with aerial surveys on record.
This will be followed by selection of an area (transect most consistent with aerial
surveys) in the park where two to three predator (lion, hyena and wild dogs) species are
frequently located in proximity to the prey species from the aerial survey records. This
will be followed by collaring representative predator species with satellite collars that will
be used to monitor movement and subsequent home range size. It is anticipated that at
least two lions per pride will be collared (minimum of two prides to be monitored), two
hyenas per clan (minimum of three clans) and three wild dogs per park (minimum of two
parks). The chance mechanism in selection will depend on which predator shows up
first after playing calls. The predator that appears first will be targeted for collaring at
that particular time. Chemical immobilization will be done by use of Dan inject darting
gun. A cocktail immobilizing drug of MZT (Medetomidine hydrochloride – 8mg [Zalopine]
and Zolazepam-Tiletamine – 125mg [Zoletil]) is here proposed for use because of the
advantage of reversal with antidote (Atipamezole [antisedan 5mg/ml]). This will
minimize mortality risk due to anesthesia by reducing wake up time.
After all the three species are successfully collared, a deliberate effort will be made to
carry out one random transect per quarter in the area to assess prey density
consistence. As home ranges of the predators become more and more pronounced,
the quarterly transects will narrow down to the home ranges. This will give a good
comparison of the transect densities within predator home range versus outside. A foot
and vehicle patrol team will undertake quarterly visits to assess vegetation biomass,
mortality and frequency of prey presence / absence in the predator ranges. Prior
information of any recorded mortalities in the area will also be used as baseline data for
investigating pathogen presence.
Selection of game ranches to be used as control will be subjected to random sampling
after looking at those ranches with most representative prey species. It is targeted to at
least have a minimum of three – four game ranches where fecal and vegetation
biomass will be obtained to tally with samples from the National Parks.
Inventory the data that will be collected. Explain how the data will discriminate among the
hypotheses.
Wigganson Matandiko (student no: -02031904
Biol 525 – 001 Research Methods
Data to be collected
i.
ii.
iii.
iv.
v.
vi.
Predator density.
Predator area home range and fluctuation over time.
Prey density.
Prey species hunted by carnivores.
Prey fecal Glucocorticoides.
Prey fecal glucocorticoids from game ranch species where predation risk is
absent.
vii. Fecal and grass chlorophyll trends in the parks and game ranches where the
control groups will be selected.
viii. Alteration in foraging pattern.
ix. Mortality record and possible causes
Describe the sampling design for the data collection: how many observations,
when, where (in relation to the study design), sampling basis (systematic,
random, cluster, …). Provide the rationale for the design: representativeness
(absence of bias), efficiency (getting the narrowest possible confidence limits for
a given investment in data collection).