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SDM Observer Models

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SDM Observer Models

  1. 1. Hierarchical Models for Species Distributions Bob O'Hara BiK-F Frankfurt am Main, Germany
  2. 2. Stuff I'd like to talk about Dispersal Dynamics Processes
  3. 3. Sampling & Observation http://www.flickr.com/photos/slowloris/
  4. 4. Presence Only Models Pseudo-absences MaxEnt Dave Wharton : Both approximations to point processes
  5. 5. Problem: False Absences Some things are just not seen
  6. 6. We need to measure effort
  7. 7. Different ways of estimating effort lead to different sampling models
  8. 8. Estimating Sampling Effort Repeated visits: can use absences Use reports of other species as estimate of effort?
  9. 9. Data Database of UK butterfly records Year 2000 10km x 10km squares Covariates: proportion of habitat, latitude & longitude
  10. 10. The Model Process Model and Sampling Model http://pixdaus.com/single.php?id=235258
  11. 11. Process Model I i – presence of species s at site i X ij – proportion of habitat of type j at location i G ij – Latitude/longitude at location i
  12. 12. Observation Models Binomial Poisson Incidence Compare several: None
  13. 13. Binomial Observation Model Photo:USFWS r ~ Bin( N , p )
  14. 14. Poisson Observation Model Photo:USFWS r ~ Po( N l )
  15. 15. Bernoulli Observation Model Photo:USFWS At least 1 razorbill I ~ Bin( 1 , 1-e - N l )
  16. 16. No Observation Model
  17. 17. Adonis Blue (possibly) http://www.flickr.com/photos/markkilner/3867177467/
  18. 18. Predicted Ranges
  19. 19. Comparing Predictions
  20. 20. Gatekeeper http://www.flickr.com/photos/duncanh1/3859133643/
  21. 21. Predicted Ranges (presences slightly offset)
  22. 22. Comparing Predictions
  23. 23. So? We should include sampling models in our SDMs Might have to be imaginative about measuring effort There are several models we could use
  24. 24. For the Future Better process model http://services.niagaracollege.ca/unitedway/virtual%20break.htm Check which model is actually best

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