Using Territory as the Primary Analysis Unit for Habitat Supply

1. Using Territory as the Primary Analysis Unit for Habitat Supply Todd Mahon Wildfor Consultants Ltd. University of Alberta

2. Outline • Why use territories? • Example for northern goshawks in the Morice LRMP • Appropriateness for other species • Questions and Feedback

3. Why use territories as analysis units? • Accounting for spatial distribution of habitat relative to species of interest

4. Why use territories as analysis units? • Provides a more tangible output for managers to evaluate

5. Why use territories as analysis units? • Forms a basis for linking habitat supply to population modelling. Habitat Suitability + Territory spacing (for applicable species) + Demographic information + Process (predators-prey, competition) Population modelling

6. Northern Goshawks in the Morice LRMP • Goshawks widely recognized as a mature forest species, sensitive to timber harvesting • May be a good indicator for other mature forest dependent species and ecosystem function

7. Habitat Suitability Model – Nest Area • Large sample of local nest areas (n=42) to develop and verify model. Key Variables: Tree species Canopy closure Stand age Stand height Distance from forest edge

8. Regular 4-6 km spacing between nest areas

9. Key Factor in the Nest Area Model • Small amount of suitable nesting habitat required relative to territory size • Distribution of suitable habitat more important than amount of habitat • Habitat supply analysis is required at the territory scale to appropriately account for that issue

10. Analysis Approach • Overlay TSA with theoretical territory analysis units • Develop criteria for potential territory occupancy probabilities • Summarize occupancy probabilities for each output period from the habitat supply model

11. Defining Occupancy Classes • Used 4 classes to define probability of territory occupancy • Exact threshold requirements are not known • Probability likely varies depending on factors other than habitat (e.g. prey, nest predators) • Allows other people to make a broader interpretation of the data based on their experience and risk tolerance

12. Rationale for goshawk territory occupancy thresholds

13. Habitat suitability map with theoretical territories showing occupancy probabilities

14. Habitat supply output using occupancy probabilities for theoretical territories

15. Occupancy Probabilities Year 0 Year 25 Year 100

16. Sensitivity of Territory Overlay to Location • Initially considered having several territory overlays spatially offset • Very low variance (range <5) • Decided replicated overlays not necessary

17. Appropriateness of Territory Approach • Strongly territorial species • Spotted Owl, Grizzly bear (females) • Not suitable for species with high spatial overlap • Ungulates • Especially important for species with strong requirements for relatively small habitat areas • Distribution can become more important with decreasing habitat amount

18. QuestionsandFeedback • Examples from other projects?