Indices for Relative Abundance
• An index of abundance is a measure that varies directly with the abundance of the population of interest.
• Based on:• Scats, pellets, pellet groups• Point or transect counts (Bird Songs)• Tracks• Signs • Etc.
Index of Deer abundance in Nova Scotia
• Based on counting pellet groups –Pellet Group Index PGI
• Pellet groups are counted along a 1 km
transect that are within 1 m on either side of the transect.
• Counting takes place in the spring
Deer Density
• Index can be converted to a density estimate
• Need to know how long a period the pellet groups have accumulated over
• Need to know how often deer defecate per day.
Catch-effort Methods
Assumptions:1 – The population is closed2 – Probability of each individual being
caught in a trap is constant throughout the experiment
3 – All individuals have the same probability of being caught in sample i
Cat
ch p
er u
nit e
ffor
t
Accumulated catch
Number
of in
divid
uals
Leslie plot of catch-effort data
Capture-Mark-Recapture Techniques
• For Closed Populations:
• Single marking, single recapture – Petersen Method
• Multiple markings and recaptures – Schnabel Method
• For Open populations:
• Multiple capture and recapture -
Jolly-Seber method
• How do we know that a population is decreasing and in need of protection?
Long-term monitoring! Increase or decrease?
Habitat
• habitat – physical condition where species live – defined specifically for individual species.
• source/sink
Movement
Movement (Dispersal) is central to population health!
- Density
- Genetics
What factors affect movement?
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