4.2.3 sampling animals

Question 1

techniques to catch invertebrates

Answer 1

• sweep nets
• pooter
• tree beating
• pitfall trap
• tullgren funnel
• light trap

Question 2

how are sweep nets/pooters used to catch invertebrates

Answer 2

sweep net
- walk through habitat with stout net
- sweep net through vegetation in wide arcs
- small animals (eg. insects) caught in net
- empty contents onto white sheet

pooter
- many animals may crawl/fly away
- use pooter to collect them before fly away

–> suitable for low vegetation which isn’t too woody

Question 3

how is tree beating used to catch invertebrates

Answer 3

• spread white sheet under branch
• knock branch with stout stick
• animals dislodged & drop onto sheet
• count quickly/identify before fly/crawl away

Question 4

how are pitfall traps used to catch invertebrates

Answer 4

• set in soil to catch small animals
• small container buried in soil with rim below surface
• contain little water/debris to stop animals crawling out
• should be sheltered if raining

Question 5

how are tullgren funnels used to catch invertebrates

Answer 5

• collects small animals from leaf litter
• place leaf litter in funnel
• light above litter drives animals downwards as litter dries/warms up
• animals fall through mesh screen into jar beneath

Question 6

how are light traps used to catch invertebrates

Answer 6

• collect flying insects at night
• consists of UV light which attracts insects
• under light = collecting vessel containing alcohol

Question 7

why do we catch small animals

Answer 7

estimate population size

Question 8

how do you know which technique to use to catch invertebrates

Answer 8

depends on habitat & which animals you wish to catch

Question 9

how can small mammals be trapped

Answer 9

= longworth trap
- doesn’t harm animal
- monitored regularly to release any animals
- enables population size to be calculated by mark-and-recapture technique

Question 10

steps of mark-and-recapture technique

Answer 10

1. capture sample of animals
2. mark each individual (no harm) = C1
3. release marked animals & leave traps for another period of time
4. number captured on second occasion = C2 & number of already marked animals captured = C3
5. calculate total population with formula

Question 11

formula for total population size

Answer 11

(C1 x C2) DIVIDED BY C3

Question 12

how can the total pop. estimation be affected

Answer 12

• some animals learn trap is harmless & contains food
• some animals don’t like the experience & avoid it after 1st capture

Question 13

what can also be estimated using mark-and-recapture

Answer 13

size of some insect populations

Question 14

how can populations of birds be estimated

Answer 14

ringing technique to identify individuals

Question 15

how can populations of larger animals be estimated

Answer 15

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