Endemic Small Mammals of Southeastern Alaska: Evolutionary Diversity, Ecology, & Conservation

1. Endemic Small Mammals of Southeastern Alaska: Evolutionary Diversity, Ecology, & Conservation Winston P. Smith USDA Forest Service, PNW Research Station Forestry Sciences Laboratory Juneau, AK 99801-8545 USA

2. Acknowledgments: ____________________________________________________________________ WRANGELL, THORNE BAY and CRAIG Ranger Districts, Tongass National Forest. UAM: Joe Cook, Steve MacDonald, Chris Conroy, John Demboski, Karen Stone, and Amy Runck. SPECIAL THANKS: Jeff Nichols, field crew leader and analytical support; Scott Gende,analytical support and comments on presentation and completion reports. Lillian Petershoare and JFSL Library.

3. Background – Setting: • _________________________________________________________________ • Unique attributes - dynamic recent geological history - naturally fragmented and isolated habitat - largest NF and largest remaining temperate rainforest - spatial and temporal heterogeneity • Limited information on natural history • Depauperate small mammal fauna • High potential for endemism

4. Background – Planning: • _________________________________________________________________ • Extensive clearcut logging since 1954: - 50% of most productive forest on some islands – 40+% of some watersheds - >300 yrs to develop old forest features • TLMP - endemic small mammals ranked as highest risk of extinction; • Conservation strategy - metapopulation framework- lacks empirical foundation

5. Land Mammal Fauna • _________________________________________________________________ • 87 islands + 24 mainland localities • 45 land mammal species - 65 small (<10kg) mammal taxa:15 endemic 11 confined 36 widely distributed, 3 unknown; • Mammal fauna – nestedstructure with varying genetic divergence: - colonization rather than extinction; - significant relationship between isolation and species richness; - competition influenced similar species (e.g., bears, shrews);

6. Land Mammal Fauna • _________________________________________________________________ - neo-endemics (flying squirrel) and paleo- endemics (marten); - number of endemics on outer islands suggests glacial refugia; - some taxa have affinities with eastern NA forms (e.g., flying squirrel, marten); • Most species – Upper Lynn Canal; • Most endemics – Mainland Subregion; • Ermine show highest degree of endemism with 5 subspecies representing 3 clades. (map)

7. Mustela erminea Distribution in SE Alaska MacDonald and Cook 1996 M. e. arctica Juneau * M. e. salva CANADA N M. e. alascensis M. e. celenda M. e. seclusa .

8. Peromyscus keeni1 Distribution in SE Alaska MacDonald and Cook 1996 *Island Endemics P. k. algidus *P. k. sitkensis P. k. macrorhinus * Juneau CANADA N *P. k. hylaeus . *P. k. oceanicus 1Hogan et al. 1993

9. Island Biogeography Processes: colonization & extinction Variables: island size, distance from mainland, vagility island island immigration island island Continent immigration island island island island

10. Community Dynamics and Structure S = 4 S = 7 island island Continent S = 9 S = 3 island Species Richness(S) island S = 12 S = 14 equilibrium Colonization island island Extinction S = 3 S = 5 island Island area island

11. Faunal Extinctions island island N Refugia island island Glacial Advance Continent island island island island

12. Regional Colonization island island N Refugia Glacial Retreat island island Continent island island island island

13. Southern red-backed vole Photo by P. Myers

14. Natural History:Red-backed vole __________________________________________________________ • Nearctic Distribution-in SE Alaska, southern mainland and nearshore islands; • Mesic forest habitat specialist; • Omnivorous, but primarily eats fungi (mycophagous) in the Pacific Northwest; • Sensitive to overstory removal and fire in western coniferous forests; • Influenced by landscape context, but little evidence of edge effects. (map)

15. Clethrionomys gapperi Distribution in SE Alaska MacDonald and Cook 1996 *Island Endemics Juneau * CANADA N C. g. stikinensis *C. g. wrangeli *C. g. solus C. g. phaeus C. g. saturatus

16. Prince of Wales Flying Squirrel • Markedly different from PNW populations • Nocturnal, active year- round • 1 litter (2-4 young)/year • Reputed old-growth habitat specialist • Mycophagist in PNW • Vulnerable to isolation in managed landscapes (map)

17. Glaucomys sabrinus Distribution in SE Alaska MacDonald and Cook 1996 G. s. zaphaeus G. s. alpinus • Juneau * CANADA N G. s. griseifrons .

18. Research Objectives: ___________________________________ • Estimate density of red-backed voles and flying squirrels among habitats; • Contrast seasonal abundance, age and sex composition, body condition, survival, and reproductive condition of voles and squirrels among habitats; • Examine habitat use and density relative to microsite and stand-level vegetative and structural features.

19. Study Area (voles): ________________________________________________ • Wrangell Island • 4 habitats: - 3 unmanaged habitats in largely unmanaged landscapes; - thinned young growth stands within watershed with ~40% POG clearcut .

20. Gap-Phase Old-Growth Forest Structurally heterogeneous, vertically and horizontally - large (>150 cm), old (>800 yr) trees. Northerly exposure <500 m elevation Fine scale disturbance Sitka spruce/ western hemlock

21. Multi-Cohort Old-Growth Forest Southerly exposure; Catastrophic disturbance per 100-200 yr; Heterogeneous stands of even-aged patches ; Uniform diameter, dense canopy forest: 100-102ha.

22. Unmanaged Peatland-scrub/ Mixed-conifer Forest Structurally complex, biologically diverse communities. Spatially heterogeneous: from open muskeg to forest over a scale of 101 – 102 m. 2 replicates in 1 watershed.

23. Thinned Young Growth (25 yr-old) -pre-commercial thinning 2-3 yr prior to study initiation; -2 replicates within the same watershed. Dense understory of herbaceous and woody plants and slash.

24. Study Design: ______________________________________ • Two replicates each of 4 habitats; • Replicates within the same watershed but >800 m apart; • 1-ha grid (11 X 11) + 8 assessment lines per replicate with 2 traps per station (n = 242); • Live trap spring 1999-2000 and early autumn 1998-2000.

25. Study Area (squirrels): _________________________________________________ • North-Central Prince of Wales Island • 2 habitats: 1) POG (mostly gap-phase) and 2) peatland-scrub/mixed-conifer; • 1) two ends of a continuum of forest cover; 2) peatland-scrub/mixed-conifer - little commercial, but potential ecological value.

26. Study Design: ____________________________________________ • Three replicates each of 2 habitats in largely unmanaged landscapes; • Replicates in the same watershed but >1 km apart; • 13-ha grid (10 X 10 array of traps); • Live trap spring and early autumn 1998-2000.

27. RESULTS: Demography

28. Mean Effective Area Sampled: Wrangell Red-backed Voles • First estimates for red-backed voles, which precludes comparison of density with earlier studies; • Effective area sample was an order of magnitude larger than grid; • Effective area sampled was significantly greater in gap-phase old-growth than in other habitats – relative comparisons among habitats are therefore invalid.

29. Wrangell Red-backed Vole Density Spring1999 - 2000 • Density higher in 1999 than 2000 with significant differences in multi-cohort and gap-phase old-growth; • Density lower in peatland/mixed-conifer in both years but significant only in 1999.

30. Wrangell Red-backed Vole Density Autumn1998 - 2000 • Density higher in 1998 than 1999 or 2000 with significant differences in all habitats; • Peatland/mixed-conifer consistently had lowest densities of voles with significant differences in 1999 and 2000; • Some evidence that thinned YG may serve as a habitat sink.

31. Wrangell Red-backed Vole Population Attributes among Habitats • Age and sex ratios were similar among habitats; • Summer survival and percentage of reproductive females were significantly lower in YG than other habitats – winter survival also was lower but not statistically significant.

32. Prince of Wales Flying Squirrel Seasonal Movements • Mean maximum distance moved was similar between habitats and seasons, averaging about 110 yards; • Home ranges also were similar between seasons and and habitats and ranged from about 5.5 acres to about 9.5 acres.

33. POW Flying SquirrelDensity Spring1999 - 2000

34. POW Flying SquirrelDensity Autumn 1998 - 2000 Reproductive

35. POW Flying SquirrelSurvival and Productivity

36. Densities in the Pacific Northwest

37. Why? Hypotheses • Competitive release • Reduced predation pressure • Diet

38. RESULTS: Habitat Relations

39. Logistic Regression Model – Spring 1999-2000:Red-backed Voles • Deciduous shrub cover (+) within 1.5 meters of the forest floor was the most significant variable influencing vole microhabitat selection overall: - by a factor of 2 in multi-cohort OG and 3 in peatland/mixed-conifer. • Moss cover (-), density of stumps(+) and density of small snags and saplings (+) were correlates of microhabitat use in gap-phase, thinned YG, and peatland/mixed-conifer.

40. Logistic Regression Model - Autumn 1999-2000:Red-backed Voles • Deciduous cover again had the greatest influence on microhabitat selection overall: - cover between 0.3 – 1.5 m had 2-fold (-) in gap-phase; - cover < 0.3 m had 5-fold (+) in gap- phase and 5-fold (-) in peatland/mixed- conifer.

41. Discriminant Model- Spring 1999-2000:Red-backed Vole

42. Discriminant Model- Autumn 1999-2000:Red-backed Vole

43. Red-backed Vole Density &Decayed Downed Wood Explained about 90% of variation in density Vole density (ha) Decay IV (volume/ha)

44. Red-backed Vole Density & Conifer Seedling Cover Explained about 85% of variation in vole density Vole density (ha) Conifer cover (%) <30 cm

45. Spring 1999-2000 ________________________________ Decayed wood class IV (+) Soft snags 10-49 cm dbh (-) Coarse woody debris (+) Decayed wood class III (+) Conifer cover 0.3 –1.5 m (-) Conifer cover <0.3 m (-) Water ground cover (+) Moss ground cover (-) Trees 10-49 cm dbh (-) Autumn 1999-2000 ________________________________ Decayed wood class IV (+) Soft snags 10-49 cm dbh (-) Coarse woody debris (+) Decayed wood class III (+) Conifer cover 0.3 –1.5 m (-) Conifer cover <0.3 m (-) Trees 5-10 cm dbh (-) Habitat Correlates of Density: Red-backed Vole

46. Logistic Regression Model:Northern Flying Squirrel • Density of trees >74 cm dbh and cover of Vaccinium most influenced microhabitat use during spring and autumn: - in peatland/mixed-conifer large tree density increased capture probability by a factor of 3 during spring and 17 in autumn; • Most influential habitat feature in gap-phase OG was ground cover of water was inversely correlated with microhabitat use.

47. Discriminant Function Model:Northern Flying Squirrel

48. Glaucomys sabrinusDensity and Live Trees >74 cm DBH Explained about 65% of variation in squirrel density Squirrels/ha Trees >74 cm dbh/ha

49. Spring 1998-2000 _____________________________________________ Moss ground cover (+) Decayed wood class I (+) Decayed wood class I (+) Decayed wood class IV (+) Autumn 1998-2000 ______________________________________________________ Trees >74 cm dbh (+) Trees 5-10 cm dbh (-) Trees 10-49 cm dbh (-) Ecological Correlates of Density: Northern Flying Squirrel

50. CONCLUSIONS