Science to Inform Adaptive Management for Ravens

Transcription

1 Science to Inform Adaptive Management for Ravens U.S. Geological Survey, Western Ecological Research Center Partners: Nevada Department of Wildlife, Idaho State University, Oregon State University

2 Breeding Bird Survey Data (BBS; Sauer and Link) Detected ravens at ~40% of surveys

3 Breeding Bird Survey Data (BBS; Sauer and Link) Detected ravens at ~80% of surveys Increased number of observations per detection

4 Surveys in the late 1960s and early 1970s Nearly all areas consisted of <10 ravens/survey Highest raven count predictions Great Basin (>5) Northern Rockies (>5) Southern Rockies/ Colorado Plateu (<5) (BBS; Sauer and Link)

5 Raven Population Growth within Great Basin BCR ~230% increase Raven Counts Currently: Great Basin to >15 Sonoran and Mojave to >10 Coastal CA to >15 Southern Rockies/Colorado Plateau to >20 No Decreases

6 Secondary Roads Primary Roads 2 -tracks Powerlines

7 Findings 1-km increase in distance to power line decreased selection by 31% 100-m increase in distance from edge decreased selections by 20%

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9 Included non-resident (non-breeding) ravens selected at larger spatial scales Effect of transmission line greatest within 2.2 km (4.5 km corridor) Additive effects of energy infrastructure and altered land cover types Increased land cover edges, non-native vegetation, and patchiness

10 Odds of raven occurrence increased 45.8% in areas where livestock were present

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12 Bill Boarman, USGS, 2003

13 Juvenile survival (%) ANTHROPOGENIC RESOURCES INCREASE SURVIVAL TO DISPERSAL (CA) 80 (χ 2 = 16.8, P < 0.001) Nest distance to nearest anthropogenic resource (km) Webb et al Condor 106:

14 Anthropogenic Factors Indirectly Affect Prey Anthropogenic Subsidies (e.g., food sources, nest substrate) Habitats of Prey Raven Populations Prey Behavior Prey Population Vital Rate

15 Indirect Effect Nest Predation DRAFT Common Name Raven Impact # Sources Likely or Potential Raven Impact USESA (Year Listed) U.S. States Desert Tortoise Numerous High T (1980) T (CA, UT); S2 (AZ) Piping Plover Limited Low E / T* (1985) E (DE, MD, ME, NC, ND, NH, NJ), S2B (MT); T (CO, FL, GA, KS, MA, NE, NM, VA; CT, SD, TX); SP (AL) Greater Sage-Grouse Numerous High NL T (WA); S2 (ID); S3 (NV); SC (CO, UT) Roseate Tern Limited Low E/T^ (1987) Ex (MD); E (MA, ME, NC, NH, NJ, NY, CT); T (FL) Marbled Murrelet Numerous High T^^ (1992) E (CA); T (OR, WA) San Clemente Loggerhead Shrike Limited Unknown E (1977) NL California Condor Limited High E/T*** (1967) E (CA) Gunnison Sage-Grouse Limited High T (2014) SC (CO); T (UT) Greater Sandhill Crane Numerous High NL E (WA); T (CA); S3B (ID); SC (CO) California Least Tern Numerous High E (1970) E (CA, OR) Western Snowy Plover Numerous High T^^^ (1993) T (OR); SC (CO) Preliminary Information Subject to Revision. Not for Citation or Distribution

16 Ravens are most frequent predator of Sage-Grouse (9 years of video data) Long-Tailed Weasel 5% Literature: Coates et al JFO 79: Lockyer et al JFWM 4: Casazza, USGS, unpublished Bobcat 3% Coyote 14% American Badger 25% Common Raven 53%

17 Sage-Grouse nest survival declines with increased raven numbers

18 Nests fail in areas of high raven abundance ~0.4 ravens / km 2 Ravens per transect Coates Dissertation. Idaho State University.

19 Threshold of raven abundance ~0.9 ravens / km 2 Coates 2007 Ravens per transect

20 Ravens predation increases with less shrub cover 95% CI Resp. Covariate Estimate lower upper Raven raven * shrub cover * grass forb understory shrub height % decrease in shrub cover increased the odds of raven predation by 7.5% 20 30% sagebrush cover and >40% total shrub cover Coates et al JWM 74:

21 Important Interaction

22 Indirect Effect Nest Predation Population Growth

23 Example of Science-based Adaptive Management Strategy Tier 1 Maintain or improve habitat conditions that reduce predation Tier 2 Reduce access to anthropogenic subsidies (concurrent with Tier 1 actions) Tier 3 Lethal raven removal (concurrent with Tier 1 and 2 actions)

24 Example of Science-based Adaptive Management Strategy 1. Course-scale site selection for targeted management actions 2. Local-scale surveys at selected sites for density estimates 3. Three-tiered management action approach 4. Conduct post management monitoring

25 Example 1. Course-scale site selection for targeted management actions Informing management: Which areas of the state would benefit from raven management actions? Information Products: State-wide map (course-scale) of raven occurrence map State-wide map (course-scale) of raven density Impact state-wide maps (prey distribution, raven density, and raven occurrence)

26 Preliminary Information Subject to Revision. Not for Citation or Distribution 1. Course-scale site selection for targeted management actions Example Preliminary State-wide Raven Occurrence Map Surveyed sites = 15 Surveys = 12,420 Survey with ravens = 3,482 Ravens detected = 5115

27 Preliminary Information Subject to Revision. Not for Citation or Distribution 1. Course-scale site selection for targeted management actions Example Preliminary State-wide Raven Occurrence Map Land cover & vegetation % Sagebrush, herbaceous, grassland, nonsagebrush shrubland, annual grasses, shrub height, sagebrush height, pinyon-juniper, forested, riparian, NDVI, wet meadow Anthropogenic Impervious (developed), road density, transmission lines (low, medium, high), cell and radio towers, agriculture, land ownership, countylevel livestock density Elevation & Topography Elevation, topographic roughness, topographic radiation aspect index, heat load index, compound topographic index, topographic position index Habitat edges open vs. shrub habitat, agriculture vs. shrub habitat, forested & pj vs. shrub, forested & pj vs. open Disturbance Cumulative burned area (wildfire) Hydrology Streams, springs, water bodies, open water

28 Probability of Occurrence Example 1. Course-scale site selection for targeted management actions Preliminary State-wide Raven Occurrence Map Influential Effects % Agriculture (1450 m) + Topographic depressions (3590 m) + Greenness (3590 m) + Bare Ground (570 m) + Distance to Spring + Road Density (570 m) + Cum. Burned Area (3590 m) + Distance to Developed Area + DRAFT DRAFT % Agriculture Road Density % Agriculture Road Density Preliminary Information Subject to Revision. Not for Citation or Distribution

29 Example 1. Course-scale site selection for targeted management actions Preliminary State-wide Impact Map Raven Probability of Occurrence DRAFT Sage-grouse Nesting Habitat (Coates et al. 2016) DRAFT Preliminary Information Subject to Revision. Not for Citation or Distribution

30 Example 2. Local-scale surveys at selected sites for density estimates Informing management: How to prioritize actions among sites? What is rationale for actions? At specific sites, where to start? Information Product: Develop standardized raven survey protocol o o User-friendly interface to estimate densities annually across site and state-wide User-friendly interface to generate site-specific raven maps and prey potential impact maps

31 Example 2. Local-scale surveys at selected sites for density estimates Standardized Protocol for Estimating Raven Density DRAFT Developing models and user-friendly interface for agencies to estimate density with confidence intervals Preliminary Information Subject to Revision. Not for Citation or Distribution

32 Example 3. Three-tiered management action approach Informing management: What evidence of potential impacts exist to assign management action? Information Products: Predation thresholds for management use (inform tiers) o o Raven density effects Overlap between ravens and species of concern Scientific findings to inform specific actions o Movement, space use patterns, and demography

33 Example 3. Three-tiered management action approach Science to Inform Management Actions (Thresholds) Previous Finding: Effect on sagegrouse nesting in NE Nevada ~0.4 ravens / km 2 DRAFT Recent Populationlevel analysis: Sample sizes: 14 sites ~400 sagegrouse nests ~12,000 raven surveys 45 site/year nest survival and raven density estimates Preliminary Information Subject to Revision. Not for Citation or Distribution

34 3. Three-tiered management action approach Example Science to Inform Management Actions (Thresholds) DRAFT Low raven density = increased variation in sage-grouse nest survival Preliminary Information Subject to Revision. Not for Citation or Distribution

35 3. Three-tiered management action approach Example Science to Inform Management Actions (Thresholds) DRAFT Preliminary Information Subject to Revision. Not for Citation or Distribution

36 3. Three-tiered management action approach Example Density Thresholds DRAFT ~0.4 ravens / km 2 Informing Management Tiers (and site-specific actions) Based on: 1) empirical density estimate, confidence limit and intersection with effects threshold 2) intersection with species of concern maps Preliminary Information Subject to Revision. Not for Citation or Distribution

37 Example 3. Three-tiered management action approach Specific Areas to Target for Management Preliminary Information Subject to Revision. Not for Citation or Distribution Local Scale Analysis DRAFT DRAFT Developing model and user-friendly interface for agencies to develop spatially explicit maps for targeting areas for management actions

38 Example 3. Three-tiered management action approach Specific Areas to Target for Management Preliminary Information Subject to Revision. Not for Citation or Distribution Local Scale Analysis DRAFT DRAFT Developing model and user-friendly interface for agencies to develop spatially explicit maps for targeting areas for management actions

39 3. Three-tiered management action approach Example Movement and Space Use Information Preliminary Information Subject to Revision. Not for Citation or Distribution Breeding Period Non-Breeding Period Credit: Walter Wehtje Credit: Walter Wehtje GPS Marked Individuals = 10 (objective = 30); Locations = 9,350 Estimate seasonal utilization distributions for breeding and non-breeding seasons Relate space use to sage-grouse nesting areas and anthropogenic subsidies

40 Example 4. Conduct post management monitoring Measuring Effectiveness of Actions Preliminary Information Subject to Revision. Not for Citation or Distribution Density (ravens / km 2 ) Informing Management: Are management actions beneficial? Is there variation in their effectiveness? When to stop actions? Continue rapid survey assessment Modify management actions based outcomes Adjust plan to accommodate changes in raven numbers and use Graduate sites out of the plan DRAFT Pre-management Post-management DRAFT DRAFT Pre Post

41 4. Conduct post management monitoring Example State-wide Initial Density Estimates and Rate of Change Preliminary Information Subject to Revision. Not for Citation or Distribution Average raven density: ~ 0.39 ravens / km 2 Estimated raven abundance in sage-grouse habitat: ~ 40,000 Estimated raven abundance in Nevada: ~ 110,000 Sage-grouse spring habitat Coates et al *Likely low state-wide estimates based on sampling assumptions

42 Next Steps Continue to improve state-wide occurrence, density, and impact maps Develop user-friendly interface to generate local scale maps and density estimates with survey data Incorporate new information on relationships between ravens, habitat and sage-grouse populations Incorporate findings using GPS data to inform dispersal, movement patterns, and space use of ravens