Distribution, habitat, and management of ferruginous pygmy-owls in the Altar Valley and beyond Aaron D. Flesch School of Renewable Natural Resources University of Arizona Overview • Determine • distribution • abundance • important habitat elements • Discuss influence of land-use • Consider implications for management and recovery • Questions Data Altar Valley – 1999 • Surveys and habitat research Sonora, Mexico – 2000-’03 • Quantified distribution, abundance, and habitat Altar Valley - Study Area Excluded • North of MP 31 • Los Encinos •Elkhorn Design – Altar Valley • Surveyed best areas • Size estimates of 4 home ranges • Habitat selection within 3 home ranges Sonora - Study Area Arizona Excluded • Above 1,200 m • Gran Desierto de Altar • Chihuahuan desert • Urban centers 100 km • Agricultural areas Sinaloa Design - Sonora Stratified Random Sample Two Strata: • Major Vegetation Community • Topographic Formation Vegetation Communities Arizona Upland Lower Colorado River Valley Central Gulf Coast Plains of Sonora Semidesert Grassland Sinaloan Thornscrub Sinaloan Deciduous Forest Topographic Formations & Site Selection Canyons Lower Upper Valley Bajadas Bottoms Bajadas Owl Surveys - Sonora and Altar Valley Tape Playback Surveys • Conspecific territorial calls • 8 min – Sonora • 10 min – Altar Valley Nest Searches Sonora - Explanatory Variables Physiography • Slope • Drainage width and density Vegetation • Formation type and riparian width • Canopy height and vegetation volume • Species composition Cavity Substrates • Abundance of large cacti and trees Land Use • Intensity of grazing, woodcutting, and agriculture Sonora - Frequency of Occurrence 100 80 60 Frequency % 40 20 0 AZ Upland (69) Colorado Valley (20) Gulf Coast (21) Plains (65) Grassland (56) Thornscrub (140) Decid. Forest (21) Sonora (392) Relative Abundance Varied with Latitude 1.0 0.5 No. males/station 0.0 South North F376 = 21.50, P<0.0001 DistributionDistribution && abundanceabundance ofof ferruginousferruginous pygmy-owlspygmy-owls in in Sonora, Sonora, Mex. Mx. 2000-01.2000-01. Sonora - Important Factors PP=<0.0001 0.0075 P = 0.0003 40 OddsOdds == 1.91.02 40 Odds = 3.4 30 30 20 20 10 10 % Stations occupied 0 0 0 1030507090 0 1030507090 Riparian woodland (%) Riparian mesquite (%) Sonora - Important Factors: Riparian Vegetation 0.6 0.4 No. males/station 0.2 0 200 400 600 800 Width of riparian vegetation (m) Sonora - Important Factors: Vegetation Volume Semidesert Sinaloan 0.6 Grassland Thornscrub 0.4 No. males/station 0.2 10 20 30 40 50 23 29 35 41 47 53 Riparian volume 1-3 m (%) Upland volume 1-3 m (%) Sonora - Important Factors: Cavity Substrates Substrate 40 Absent Present 30 20 10 % Stations occupied 0 Cacti: P <0.0001 Odds = 21.5 cacti trees Trees: P <0.0001 Odds = 1.9 Sonora - Large Cacti: One vs. Many 30 20 10 % Stations occupied 0 0255075100 % Quarters present Sonoran Desert: Upland Vegetation Mesquite Ironwood Paloverde 50 40 30 20 10 % Stations occupied Stations % 0 0 10305070 0103050 0 10305070 Dominance in uplands (%) Land Use: Woodcutting 40 30 20 10 % Stations occupied 0 None Low Mod. High Woodcutting intensity Land Use: Grazing I Statewide 70 50 30 10 % Transects occupied P = 0.018 Low Mod. High Odds = 0.21 Grazing Intensity Land Use: Grazing II Valley Bottoms Upper Bajadas Low 60 Moderate 0.7 High 40 0.5 20 0.3 No. males/station % Transects occupied 0 0.1 <350 >700 Low Mod. High Elevation (m) Grazing Intensity Land Use: Grazing III Semidesert Grasslands 30 Grazing intensity Low Moderate 20 High 10 % Stations occupied 0 Upper Lower Valley Bajada Bajada Bottom Land Use: Agriculture Statewide Valley bottoms 0.5 0.3 No. males/station 0.1 01020 Agriculture dominance (%) Altar Valley • 2 small areas occupied by numerous individuals • 5 areas occupied by pairs Altar Valley – Habitat Use • Habitat • Mesquite woodlands with ≥1 saguaro • Riparian woodlands with large broadleaf trees • Habitat selection within home ranges •Select • woodlands with adjacent desertscrub • larger, taller trees Altar Valley – Spatial Use • Spatial Use • 4 home ranges 9.9 to 47.3 ha Conclusions • Well distributed throughout Sonora • Rare in Altar Valley • Habitat limitations? N. Smith • Importance of Altar Valley to recovery? • Is recovery compatible with existing land uses? Connections with Arizona Tohono O’odham Nation Occupied site Limiting Factors and Management • Altar Valley: Cavities • Promote substrate regeneration • Limit threats in areas suitable for saguaros •Fire • High grazing intensity Augmentation in the Altar Valley • Add Cavities • Nest Boxes • Saguaro Translocation Sasabe G. Proudfoot Management in Altar Valley Conflicts or compatibility Use and Management • Livestock grazing • Woodcutting • Prescribed fire Pygmy-owl Habitat • Cavities • Woodlands Management in Altar Valley II Acknowledgements U.S. Fish and Wildlife Service: Frank Baucom, Charles Sanchez, and Wayne Shifflett, AZESFO, Region II, BANWR Mexico Coordinator: Eduardo Lopez Saavedra, IMADES Field Assistants: Gabriel Valencia Ortega, Elliott Swarthout, Shawn Lowrey, Greg Greene, Sky Jacobs, Rob Hunt, Andres Villarreal, Alexis Bachrach My Advisor: Bob Steidl Special Thanks: People and Landowners of Sonora and the Altar Valley, Arizona.