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 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

5 Count Raven Numbers 300% Increase, Sauer et al 2007 n = 1,226 P < Year Sauer et al William Boarman, USGS

6 Unnatural Nest Substrate

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%

8 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

9 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:

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

12 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

13 Impacts on 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%

14 Sage-Grouse nest survival declines with increased raven numbers

15 Threshold of raven abundance ~0.4 ravens / km 2 Coates 2007 Ravens per transect

16 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:

17 Important Interaction

18 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)

19 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

20 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)

21 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 = ~32 Surveys = >15,000 Survey with ravens = >11,000

22 Preliminary Information Subject to Revision. Not for Citation or Distribution Example 1. Course-scale site selection for targeted management actions Preliminary State-wide Raven Occurrence Map Elevation Vegetation (NDVI) Developed % Herbaceous 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

23 Example 1. Course-scale site selection for targeted management actions Preliminary State-wide and Great Basin Raven Occurrence Map DRAFT Preliminary Information Subject to Revision. Not for Citation or Distribution

24 Example 1. Course-scale site selection for targeted management actions Preliminary State-wide and Great Basin Raven Occurrence Map DRAFT Preliminary Information Subject to Revision. Not for Citation or Distribution

25 Example 1. Course-scale site selection for targeted management actions Preliminary State-wide and Great Basin Raven Density Map DRAFT Preliminary Information Subject to Revision. Not for Citation or Distribution

26 Example 1. Course-scale site selection for targeted management actions Index: Raven occurrence x density Preliminary State-wide Impact Map DRAFT Sage-grouse Nesting Habitat (Coates et al. 2016) DRAFT Preliminary Information Subject to Revision. Not for Citation or Distribution

27 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

28 Example 2. Local-scale surveys at selected sites for density estimates DRAFT Preliminary Information Subject to Revision. Not for Citation or Distribution

29 Example 2. Local-scale surveys at selected sites for density estimates DRAFT EXAMPLE ~0.53 ravens per km 2 Developing models and user-friendly interface for agencies to estimate density with confidence intervals Preliminary Information Subject to Revision. Not for Citation or Distribution

30 Example 2. Local-scale surveys at selected sites for density estimates DRAFT DRAFT Examples of time-series estimates Preliminary Information Subject to Revision. Not for Citation or Distribution

31 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

32 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

33 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

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

35 Example 3. Three-tiered management action approach Preliminary Information Subject to Revision. Not for Citation or Distribution DRAFT EXAMPLE ~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

36 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

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 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

39 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 action DRAFT Pre-management Post-management DRAFT DRAFT Pre Post

40 4. Conduct post management monitoring Example Measuring Effectiveness of Actions Preliminary Information Subject to Revision. Not for Citation or Distribution

41 Preliminary Information Subject to Revision. Not for Citation or Distribution Preliminary Abundance Estimates of Ravens Number of Ravens in sagebrush cover types across Great Basin ~145,000 Number in Nevada sage-grouse habitat ~40,000 Number across state Sage-grouse spring habitat ~110,000

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