(Capture) mark – release – recapture
<ul><li>Step 1. </li></ul><ul><li>Capture a sample of organisms. </li></ul><ul><li>Note: ensure the technique for trapping...
 
 
 
 
<ul><li>Step 2. </li></ul><ul><li>Mark the animals in some way. </li></ul><ul><li>Note: ensure the technique matches the o...
Step 3. Release the animals. (Capture) mark – release – recapture
Step 4. Recapture a second sample and count the number of marked individuals. Note: ensure the animals had time to mix wit...
Step 6. Estimate population size using the formula. (Capture) mark – release – recapture
<ul><li>Assumptions. </li></ul><ul><li>The # of organisms in the population does not change between samples. </li></ul><ul...
<ul><li>Objective Estimates </li></ul><ul><ul><li>Absolute estimates - numbers/unit area </li></ul></ul><ul><ul><ul><li>te...
<ul><li>Mark-Recapture Study </li></ul><ul><ul><li>Capture, mark and release 64 monarch butterflies  </li></ul></ul><ul><u...
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BiologyExchange.co.uk Shared Resource

  1. 1. (Capture) mark – release – recapture
  2. 2. <ul><li>Step 1. </li></ul><ul><li>Capture a sample of organisms. </li></ul><ul><li>Note: ensure the technique for trapping them matches the organisms being studied e.g. </li></ul><ul><li>Pitfall trap for crawling insects </li></ul><ul><li>Longworth trap for small mammals </li></ul>http://www.liverpoolmuseums.org.uk/wml/naturalworld/bughouse/shed.asp (Capture) mark – release – recapture
  3. 7. <ul><li>Step 2. </li></ul><ul><li>Mark the animals in some way. </li></ul><ul><li>Note: ensure the technique matches the organisms being studied e.g. </li></ul><ul><li>Nail varnish blobs on the back of beetles </li></ul><ul><li>Tags in small mammals ears </li></ul><ul><li>Rings for birds </li></ul>(Capture) mark – release – recapture
  4. 8. Step 3. Release the animals. (Capture) mark – release – recapture
  5. 9. Step 4. Recapture a second sample and count the number of marked individuals. Note: ensure the animals had time to mix with the rest of the population before capturing again. (Capture) mark – release – recapture
  6. 10. Step 6. Estimate population size using the formula. (Capture) mark – release – recapture
  7. 11. <ul><li>Assumptions. </li></ul><ul><li>The # of organisms in the population does not change between samples. </li></ul><ul><li>Marked animals mix randomly with the rest of the population. </li></ul><ul><li>Trapping and marking do not affect the animals in any way. </li></ul>(Capture) mark – release – recapture
  8. 12. <ul><li>Objective Estimates </li></ul><ul><ul><li>Absolute estimates - numbers/unit area </li></ul></ul><ul><ul><ul><li>techniques </li></ul></ul></ul><ul><ul><ul><ul><li>capture – recapture (mark-release-recapture) </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>capture animals, mark, release, recapture; determine proportion of marked and from this make total population estimate </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>major assumptions: </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>(i) marking doesn't affect animals (behaviorally, physiologically, or ecologically) </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>(ii) marked animals are completely mixed in population </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>(iii) probability of capturing a marked animal is the same as capturing an unmarked animal (closed population) </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>(iv) marked animals don't lose their marks </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>(v) marked mix naturally with unmarked </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>(vi) some other assumptions </li></ul></ul></ul></ul></ul>
  9. 13. <ul><li>Mark-Recapture Study </li></ul><ul><ul><li>Capture, mark and release 64 monarch butterflies </li></ul></ul><ul><ul><li>Capture monarchs at a later date. The number captured was 98 of which 22 were marked </li></ul></ul><ul><ul><li>The population size is estimated to be 285 butterflies </li></ul></ul>
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