Using a Two-Species Individual-Based Model to Examine the Effectiveness of Barred Owl
Removals in the Pacific Northwest
Kat Perlman, M.S. Geography Candidate
May 22, 2017
Presentation Outline
1) Motivations for research
2) Model development
3) Model application
4) Preliminary results
5) Discussion
Historical Context of Research
• Northern spotted owl (NSO) listed as “Threatened” in 1990
• Initially- habitat loss identified primary factor population declines
• 2011 Revised Recovery Plan 1) Need for demographic model and habitat
suitability map
2) Barred owls as additional threat to recovery goals
Historical Context: Mapping Habitat
MaxEnt Habitat Map
HexSim Spatial Data
Spatial Extent of Model
Study Species
Oregonlive.com Onondagaaudubon.com
Northern Spotted Owl(Strix occidentalis caurina)
Barred Owl (Strix varia)
darwin.bio.uci.edu
Barred Owl Removals
• Pilot removal study: 2009, 20 barred owls removed
• USFWS removals: 2010-2012, 70 barred owls removed
• 2013: Final Environmental Impact Statement
• 2015-2019: removal experiment in demographic study areas
Research Questions
1) Are barred owl removals an effective mechanism for promoting recovery of northern spotted owl populations?
2) What time frames and removal intensities are necessary for barred owl removals to promote viable recovery of northern spotted owl populations?
Model Development: Creating the Barred Owl Population
• Range information• Dispersal distances
• Reproduction rates
• Age classes
• Resource use
• Population Density• Age class distribution• Survival
Model Development: Competitive Interactions
Primary mechanisms1) Resource sharing2) Habitat competition and territory abandonment3) Life cycle sequence
Model Application: Simulating Removals
Removal location(field)
Size (km2) Size (hexagons)
Cle Elum (WA) 607 705
Coast Range (OR) 775 895
Klamath (OR) 765 883
Hoopa Reservation (CA) 348 402
Cle Elum
Coast Range
Klamath
Hoopa ReservationHigh quality
Low quality
Removal location (modeled)
Size (km2) Size (hexagons)
Cle Elum 701 812
Coast Range 657 764
Klamath 878 1,021
Hoopa Reservation 389 452
Modeling Application: Recovery Rates
No removals
25% removals
50% removals
75% removals
100% removals
Range-wide
Removal areas only
Proportionally compare range-wide recovery rates to removal area-only recovery rates
Discussion: Next Steps
• Removal rate comparisons for all removal intensities, both range-wide and in removal patches only• Proportional effectiveness vs. theoretical recovery
• Number of territory holders vs. non-territory holders
• Examination of habitat quality in relation to population response
Acknowledgements
Advisor: Dr. Mary Santelmann, OSUDr. Robert Kennedy, OSUDr. Nathan Schumaker, EPADr. Dave Weins, USGS
Thank You!