sampling animals Flashcards
(20 cards)
steps of capture recapture
1) traps laid throughout habitat and left for suitable period of time
2) animals caught are counted and marked then released
3) traps re-laid and second sample is counted and number of marked and unmarked individuals is recorded
4) estimate the population size using formula
capture recapture formula (GCSE)
marked initially/total population= second sample/marked in second sample
capture recapture formula (new one)
n.animals in sample1 x n.animals in sample2/ n.animals marked in sample2
advantage of beating
-useful for dense vegetation
-low cost and simple
-target specific habitats like hedgerows
disadvantage of beating
-non specific
-disruption to habitat
-may cause stress- ethical concerns
4 key assumptions in capture recapture
1) the number of animals in the population doesn’t change between first and second sample
2) there is thorough mixing between samples
3) organisms are evenly distributed in their habitat
4) marking doesn’t affect organisms normal behaviour/ increase chance of predation
whats a sweep net
-net which u sweep through vegetation in wide arcs
-any contents may be emptied onto a white sheet to identify
-need to take caution as animals may crawl away when released (can use pooter to stop this)
disadvantage of pooter
-risk of inhalation
-limited to small insects
-manual effort can become tiring
-potential hygiene concerns
advantage of pooter
-safely collected, no ethical issues
-can target specific insects
-portable and convenient
what’s a pit fall trap
-small container buried in soil so rim is below surface
-should contain a little water or scrunched paper to stop animals crawling back out
-should be sheltered from rain and predators view
advantage of pit fall trap
-sample for long periods of time
-minimal monitoring
-cost/effective to catch ground dwelling insects
disadvantage of pit fall trap
-non selective capture
-risk of predation
-weather sensitivity
-ethical concerns (don’t monitor caught animals)
what’s a tullgren funnel
-place leaf litter in funnel
-light above litter drives animals downwards due to warm up and dry out
-fall through mesh screen to be collected in jar underneath
advantage of tullgren funnel
-no direct handling of insects minimising damage
-requires minimal supervision
disadvantage of tullgren funnel
-limited to mobile organisms
-time consuming
-excessive heat can damage organisms
what’s a light trap
-collect flying insects at night
-under light is vessel containing alcohol that insects may fall into
advantage of a light trap
-effective for nocturnal insects
-wide coverage area
-non destructive
-cost effective
disadvantage of light trap
-non selective capture
-environmental sensitivity
-attract predators
-limited to phototactic species
advantage of Longworth trap
-humane design
-reusable and durable
-suitable for long term studies
disadvantage of Longworth trap
-cause animal stress
-non target capture
-expensive
-regular monitoring
