Surveys and Monitoring

Question 1

Methods involved

Answer 1

1. Territory mapping
2. Mark and recapture/re-sighting
3. Transects and point counts
4. Botanical surveys

Question 2

Territory mapping

Answer 2

Multiple visits - record locations and activity of all sightings (movement etc.)
Can overlap on maps and define specific clusters - i.e. territories
Time sensitive - needs lots o repeats
No good for colonial species; poly-territorial spp or territories that can’t be detected

Question 3

Mark and recapture/re-sighting

Answer 3

Estimate pop size from % marked individuals recaptured/resighted in a subsequent sample - need unique marks
Labour intensive but best for elusive spp
Can use camera traps if nocturnal - need big animals to set it off though
Pit fall traps for reptiles, small mammals etc.

Question 4

Mark and recapture assumptions

Answer 4

1. No movement of populations between 2 periods
2. Requires closed population (no immigration or emigration)
3. Influenced by mortality and recruitment (birth)
   Method for open population - Jolly-Jeber method instead assumes…
4. Marks last in sampling period
5. Capture probabilities are constant across individuals ‘trap-happy’ = more likely to be captured
6. Emigration loses have to be permanent

Question 5

Types of marks

Answer 5

Natural - on cetaceans injury scars are unique, similar to spot patterns on cheetahs
Artificial - fur/toe clipping - will last a few months
Permanent marks - pit tags under skin will be individual and good in long-term studies

Question 6

Transects and point counts

Answer 6

Count all individuals in an area
Transects move along
Point - certain place for certain time
Point counts preferred when - habitats are fragmented, or difficulties moving on route etc. 
Otherwise - transects better.

Question 7

Transect and point assumptions

Answer 7

1. Precise detection and all individuals will be detected
2. Individuals don’t move before detection, no double counts
3. Individuals detected independently and distances measured accurately

Question 8

Using transect and point data

Answer 8

If looking at population trends you can just use the counts
-not useful for comparisons across species and habitats
-not useful for population size either
Have to apply distance sampling - detectability declines with distances from transects and it varies with species (elusive or not) and habitats (dense)
-allows detection of individuals not found, can calculate density

Question 9

Botanical survey

Answer 9

None previously mentioned are really relevant to plants - this one is
Use distance sampling still - size needs to be considered (cacti etc.)
Quadrats are common - optimum size trade-off with time taken and sample size
Difficult to determine what is 1 individual (multiple stems), so often use % cover