wildlife research design

what are the broad types of study designs

descriptive - survey or observational

manipulative experiment

What is the best way to start

define the problem/ask a question and review the literature

how should you start an experiment

identify the variables and link variable with a prediction

• predictor (independant)

• response (independant)

how should you start a descrptive/observational study

formulate predictions which can be tested using observations

Challenges of experiment in wildlife biology

endangered species

lots of variables

can’t control or manipulate some variables

effects may be seen over long time frames

natural or quazi-experiments often lack replication

can’t randomly allocate samples to treatments and controls

independant replication

experiment units are independant only when we randomly assign treatments/controls to each unit

descriptive field study

if the value of two successive observations are more similar than values for two observations drawn at random they are dependant

replication

principles of reapplication apply to both experiments and descriptive studies where information is gathered to compare various alternatives

replication comes from number of sample units or experimental units

what is a sampling unit

basic element in/on which measurements/observations are made

what are the design types

These are correctly randomized samples

• completely randomized

• randomized block

• systematic

These are incorreclty “randomized” samples

• simple segregation

• clumped segregation

• isolative segregation

• randomized but with interdependant replicates

• no replication

Detectability

the likelihood of detecting an animal when its present

why is detectability probelmatic

methods simply count/detect visible animals, some individuals may be alive but undetectable

why would detection be less than 100%

crypsis/camouflage

animals avoiding humans

animals are nocturnal

Live in hard to access, hard to see places (arboreal, live in tree hollows, underground, aquatic) 

Activity patterns differ over time (daily and seasonally) 

Activity patterns differ according to individual (sex, age, reproduction) •

The available population varies over time as animals move in and out of the study area (temporary emigration) 

Selection of inappropriate technique

solving detectability issues

standardize sampling methods so detection effort is equal and the measurements you make are consistent

• overtime

• between locations

• between observers

• between animals

when should detectability be taken into account

should be estimated and taken into account wherever possible, for both abundance and occupancy