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!