Landscape dynamics of bird and small mammal communities in sagebrush-dominated mountain meadows

1. Landscape dynamics of bird and small mammal communities in sagebrush-dominated mountain meadows Tammy L. Wilson MS candidate USGS Utah Cooperative Fish and Wildlife Research Unit Department of Forest, Range, and Wildlife Sciences Utah State University Committee: John A. Bissonette Thomas C. Edwards Jr. James A. MacMahon

2. Overview • Status of sagebrush-steppe ecosystems • Species that use sagebrush habitats • Project goals and organization • Methodology • L+1 level analysis • Pattern and process • What is a landscape? • Thinking outside of the box • Choosing the right scale • Vector analysis • Brief summary

3. Status of Sagebrush-steppe ecosystems in the Western United States excluding Arizona and New Mexico Knick et al. 2003. Teetering on the edge or too late? Conservation and research issues for avifauna of sagebrush habitats. The Condor. 105:611-634

4. Sagebrush Obligates of Management Concern (SO) • Species that require sagebrush for some portion of their life history • Sage Sparrow • Brewer’s Sparrow* • Sage Thrasher • Greater Sage-grouse • Pygmy Rabbit • Sagebrush Vole * • Least Chipmunk* * Species Observed Greater Sage-grouse USFWS- Mountain and Prairie Region http://mountain-prairie.fws.gov/species/birds/sagegrouse/

5. Sagebrush Near-Obligates (SNO) • Species that commonly use sagebrush but do not require it • 33 species of birds • 19 species of small mammals

6. Project Goal • Determine the contribution of high elevation sagebrush steppe to bird and small mammal species diversity patterns • Determine whether or not high elevation sagebrush provides a refuge for sagebrush obligate species Tammy Wilson Jason Robinson, and Joel Ulmer cleaning mammal traps Beth Johnson, Ruth Kikkert, and Ron Daigle trapping small mammals

7. Hierarchy Theory Two Masters Thesis projects will be divided using a conceptual hierarchy based on the triadic approach

8. The conceptual hierarchy • L Project focal level is the animal community within a sagebrush meadow • L+1 Tammy Wilson is focusing on the influence of meadow arrangement on bird and small mammal diversity and density • L-1 Beth Johnson is examining the relationship between meadow characteristics and bird and small mammal diversity and density

9. Objectives • Assess the influence of meadow arrangement on bird and small mammal diversity and density of selected species (supplementation and complementation processes) Tammy Wilson collecting Vegetation data

10. Study Area Wasatch-Cache National Forest in Northern Utah

11. Methods First Tier Randomization • Designed to reduce pseudoreplication at both levels of observation • 50 Random points generated within the study area using a dispersion interval of 2500m

12. Methods • Meadows in an area around the points were digitized using DOQQs • The meadow closest to the randomly selected point was chosen as the focal meadow of interest

13. Methods • Meadows were sampled if they met the following criteria • on public land • contain at least some sagebrush • within 5km for birds or 1km for mammals of a road • contained within a forested matrix (evaluated using a 6 km2 buffer) • mostly less than 50% slope • 36 Meadows were sampled for birds and 11 for mammals in the summers of 2003 and 2004 • Each meadow was sampled only once

14. Methods Second Tier Randomization • 2-10 sub-sample points were placed in each focal meadow • 100 or so Sub-sample points were randomly placed within the meadow • Points were evaluated in order until no more points fit in the meadow or 10 points were selected • 250m apart • occur on a slope less than 50% • not in water • not in a group of trees • excess points were deleted

15. Methods • Birds and Vegetation were measured at each sub-sample point • Mammals and soil characteristics were measured at the first 2 sub-sample points in selected meadows • The bird and mammal data became the response variable for both L+1 and L-1 level analyses

16. Mammals • Mammals were trapped using a 50m radius trap web with 8 arms • Sherman live traps and Victor snap traps were placed at the center, 5m, 10m, 20m, 30m, 40m, and 50m points along each arm of the web

17. 11 12 22 36 53 55 178 722 Mammals Trapped 1128 Total observations 16 Species observed 1 SO observed 4 SNOs observed

18. Birds • Fixed-radius point counts conducted for 8 minutes at each sub-sample point • The double observer method was used for each point count • All birds seen or heard were recorded • Distance and bearing was measured to each bird

19. 110 98 117 441 139 198 419 243 324 245 Birds Observed 3615 Total observations 82 Species Observed 1 SO observed 14 SNOs observed 10 Most common species Less common SNOs

20. Objectives • Assess the influence of meadow arrangement on bird and small mammal diversity and density of selected species Tammy Wilson collecting bird data

21. Linking Pattern and Process • Our study area contains sagebrush patches within a forested matrix • Habitat obligates can exist in patchy landscapes through complementation and/or supplementation of resources (Dunning et al. 1992) Dunning, J. B., B. J. Danielson, and H. R. Pulliam. 1992. Ecological processes that affect populations in complex landscapes. Oikos. 65:169-175

22. A B A B • Complementation • If non-substitutable resources are located in different patches, “the presence of resources in one patch is complemented by the close proximity of the resources in a second patch.” • Supplementation • If habitat patches are too small to support a population or individual, then necessary resources can be supplemented by using adjacent patches. Figures adapted from Dunning et al. 1992

23. Elements of complementation and supplementation • Proximity of adjacent meadows • Supplementary or complementary resources will have to be near enough for use by the individual or population • Size of focal meadow and adjacent meadows • The amount of resources contained within adjacent patches will be a function of their size

24. What is a Landscape? • Landscape metrics are typically calculated on a classified satellite imagery with a fixed grain, using an arbitrary extent • Organisms scale allometrically to their surroundings, so choice of right scale resolution and extent is important • We intend do detect many organisms, making it difficult to use any one species life history to define scale parameters • Without modification, these problems may limit our ability to detect important ecological phenomena

25. Effects of decreasing landscape extent • Large patches are truncated and edge effects are magnified • Rare classes are reduced or lost • Landscape metrics will change making them difficult to interpret

26. Thinking outside of the box • By eliminating the ‘landscape’ with a fixed grain and extent, we tend to eliminate the problems associated with the box and the image simultaneously • We already have a vector coverage of our digitized meadows • Patch size and distance to nearest, next, 3rd, 4th, 5th… nearest meadows can be measured directly with a vector analysis • Results are much easier to interpret, because scale-related problems are reduced

27. Vector analysis • Create centroids in each adjacent polygon • Measure distance to the adjacent polygons of interest • Create logistic regression relating presence/absence of selected SO or SNO species to distance and size of adjacent meadows • Extract amazing story about patch arrangement and ecological processes of supplementation and/or complementation 4 3 2 1

28. Thinking outside of the boxPart 2 • But we don’t get to ignore scale effects altogether because we still need to know how close a meadow needs to be in order to affect ecological process • J. Bowman related territory size and dispersal distance of birds and small mammals • Others, including C. S. Holling, related body size and territory size • C. S. Holling also noticed that body sizes tended to be clumped • Maybe there is a way to use this to get at the proper scale (extent) to use for our analysis

29. Choosing the right scale • Published data on our most commonly observed species can be analyzed using Bowman’s equations • The accuracy of these equations can be checked where we have both home range and dispersal data • The robustness of these equations can be tested by adding our species and re-running Bowman’s analysis • These relationships can be used to guide scale extent choices if there is a reasonable amount of overlap amongst species.

30. Summary • Preliminary observations • Only 2 or maybe 3 of 7 SOs and 18 of 52 SNOs were observed • Preliminary results suggest that small mammal diversity is lower (16 observed vs. 22 SO/SNO), and bird diversity higher (82 observed vs. 37 SO/SNO) in montane sagebrush patches than in contiguous low-elevation sagebrush • Future analyses • Linking patch arrangement to species diversity and habitat-specialist presence/absence • Analysis of published body mass, home range, and dispersal data to determine the scale important to detected species

31. Acknowledgements • Beth Johnson • Committee • John Bissonette • Tom Edwards • Jim MacMahon • Technicians • Ron Daigle • Ruth Kikkert • Jason Robinson • Joel Ulmer • Mark Johnson • Dave Johnson • Robert lloyd Morris • Funding • United States Forest Service • USGS Utah Cooperative Fish and Wildlife Research Unit

32. Questions…