WFC 100 UC DAVIS Flashcards
monitoring
observing and describing patterns in abundance and distribution. Descriptive- what rather than why.
Research
answering specific biological questions of hypotheses about the mechanism and causes underlying an observed pattern. Answers why and how questions, and can be done through observation or experimentation.
observation
no manipulation of animals or their environment
experiment
manipulating animal behavior, abundance, or environmental conditions
Why sample?
-determine species occurrence
-determine population size/ abundance
-determine habitat use or requirements for a species
-monitor changes in population size and population dynamics
-monitor effect of habitat change, management, or perturbation on population size, behavior, species interactions
-other specific research questions
What is a sample?
a subset of an animal population, because you cannot study/track/monitor/count every individual!
How can you measure abundance/density?
- presence/absence
- index of abundance (track/ scat/ calls)
- relative abundance (proportion of samples from a species)
- total counts (absolute count)
- density (number per unit area)
How do you measure habitat use and movement?
- habitat use (what habitats are they in)
- habitat selection
- home ranges and territories
- migration routes, movement corridors
- movement behavior
- dispersal
- dispersion
How do you measure demography?
- Reproduction and fitness (fecundity, survival, age ratio)
- Survival (age-specific, seasonal, annual, perturbation)
- Immigration and emigration
How can you measure community metrics?
- Species composition (relative abundance/ proportion of each species)
- Diversity (richness- # of species, evenness- relative abundance, diversity index- index that combines richness and evenness)
How can you measure behavior?
- foraging, feeding, hunting
- mating
- rearing young
- movement and habitat use
- social interactions
- antipredator behavior
- thermal management
- communication
methods for estimation
- index
- direct count
- mark-recapture
- removal
- telemetry
Passive observation (non invasive)
-ideally no direct contact with animals
-passive monitoring using direct counts or indices
-can be less expensive and easier to implement
-challenging for cryptic and rare species
ex. birds point counts with binoculars, track plates, camera traps
experimental manipulation (non invasive)
intended influence on animals to study effect of treatment
capture (invasive)
-ideally no post-interaction differences
-may include marking animals for future identification or deploying tracking device on animal
-requires handling of animals
-capture with marking is common for all wildlife and allows for repeated measurement
ex. birds and bats: mist nets, Sherman traps, cages, culvert traps
Why census?
- basic inventory
- trend analysis
- monitor the effect of some change or perturbation
-answer a specific research or monitoring question
What to census?
- all species in a given area
- target groups
- single species
what do you measure while censusing?
- presence/absence
- total abundance
- relative abundance (number/unit effort)
- density (number/ unit area)
- spacing or habitat use
- demography (reproduction, survival, morphology or subspecies)
methods to census
- point counts
- transects
- area search
- spot mapping
- mist netting
- banding
Point counts
- observer goes to a fixed point
- stays for fixed period of time
- counts all birds seen or heard
- record number, sex, distance
- size of ‘plot’
assumptions of point counts
- all birds are detected
- distance is estimated correctly
- each bird is independent
- birds are not counted more than once
- observers have equal ability
- observers do not influence birds
what is the value of point counts?
- simple, objective, repeatable, cheap
-can use volunteers
-can census large #points quickly
-can get +/- relative abundance, density
Transects
- observer walks transects of fixed length
- count all bird seen or heard
- records number, sex, distance
- width of ‘transect’
transect assumptions
- same as for point counts
- observers keep constant pace in all areas
- observer movements do not influence birds
