Distribution, habitat, and management of ferruginous pygmy-owls in the Altar Valley and beyond

Aaron D. Flesch

School of Renewable Natural Resources

University of 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, – 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 -

Study Area Arizona

Excluded • Above 1,200 m • • 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 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 ooa-Frequency ofOccurrence Sonora - % Frequency 100

AZ Uplan 20 40 60 80 0 C o lorado Val d (69)

ley (20 Gulf

Coast (21))

Pla i Grasslanns (65)

Thor d (56) n scru D e b cid. (140) F orest

(21)

So n ora (392) Relative AbundanceVariedwithLatitude F 376

= 21.50, No. males/station 0.0 0.5 1.0 P <0.0001 ot North South 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 % Stations 0 0255075100 % Quarters present Sonoran Desert: Upland Vegetation

Mesquite Ironwood Paloverde 50 40 30 20 10

% Stations occupied occupied Stations % 0 0 10305070 0103050 0 10305070 Dominance in uplands (%) Land Use: Woodcutting

40

30

20

10 % Stations occupied % Stations 0 None Low Mod. High

Woodcutting intensity Land Use:GrazingI

% Transects occupied 10 30 50 70 Statewide o o.High Mod. Low Grazing Intensity Odds = 0.21 P = 0.018 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 % Transects

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