Guanaco and grassland distribution in northern Patagonia, Argentina

AAG 2012

February 28,2012

Paul J. Haverkamp, Martin E. Zamero, Jonathan A. Greenberg,

Ricardo Baldi, Susan L. Ustin

Study Objectives

Hypothesis: Guanacos will select for areas with the highest grass cover since grasses are their primary food source.

• Objectives:

– Objective 1: develop a grass cover map of Somuncurá Reserve using Landsat ETM+ imagery.

– Objective 2: determine which levels of grass cover guanacos select in Somuncurá Reserve.

Guanaco and Vegetation

• Grasses

– Preferred vegetation of guanacos (~65% of diet in spring, ~45% of diet in summer)

– Tend to be sparse and interspersed with large proportions of soil and shrubs

• Shrubs

– Less preferred in spring (~17% of diet), but greater use in summer (~37% of diet)

– Varying densities of shrubs

• Forbes

– Varying preference

Baldi 1999. Ph.D. Dissertation.

Vegetation Transect Analysis

• Identified species (except grasses) and

grouped transects by percent of grasses,

shrubs, forbes, and soil/rock.

• Added GPS points to ArcGIS and added

transect cover values.

December 25, 2009

Color Infrared (CIR) of Study Site

Vegetation Transects

Random Forest Results

• Combination of EVI

and MSI gave the

best correlation.

• Pearson’s r = 0.776

– Test data comparing

actual to predicted

grass cover

• Grass cover percent

map

Study Objectives

Hypothesis: Guanacos will select for areas with the highest grass cover since grasses are their primary food source.

• Objectives:

– Objective 1: develop a grass cover map of Somuncurá Reserve using Landsat ETM+ imagery.

– Objective 2: determine which levels of grass cover guanacos select in Somuncurá Reserve.

Guanaco Field Study Methods

• 10 wildlife and domestic animal censuses:

• 95 transects along road system totaling

over 327 km.

– Split based on fences, intersections,

topography changes, length.

– 500m buffer on each side of split.

— Oct. 2007

— Nov. 2007

— Jan. 2008

— Mar. 2008

— Jun. 2008

— Dec. 2008

— Aug. 2009

— Oct. 2009

— Dec. 2009

— Feb. 2010

Census Issues

• Not consistent in space or time.

• Censuses done when funding available.

• Measured in different parts of year.

• North and south parts of Somuncurá.

Animal Transects

Animal Transects

Guanaco Selection

Manly et al. 2002.

Census Analysis

• For each census :

– Guanaco observations per transect.

– Used Distance program to get effective strip

width (ESW) for each transect.

– ESW as buffer to find suitable guanaco

observations per transect, per census.

Thomas et al. 2010. Journ. Appl. Ecol. 5-14.

Census Analysis

• Buffered guanaco locations 75m for a 150m

diameter area used resource unit.

• Overlaid onto grass cover map and calculated

mean grass cover of the guanaco resource unit.

– Used resources of four grass cover classes.

• Overlaid ESW buffered survey transects on

grass cover map and retrieved pixel values.

– Available resources of four grass cover classes.

Selection Results

• Pearson’s Chi-square goodness of fit.

• Significant selection (using, observed

more or less use, based on available area

of grasses, expected)– Nov. 2007 – XP

2 = 14.249, p = 0.003

– Jan. 2008 – XP2 = 9.714, p = 0.021

– Dec. 2008 – XP2 = 19.322, p = < 0.0005

– Aug. 2009 – XP2 = 14.050, p = 0.003

– Oct. 2009 – XP2 = 39.282, p = < 0.0001

– Dec. 2009 – XP2 = 17.762, p = < 0.0005

Selection Ratios

Guanacos Selecting

• Selecting 20-<30% significantly more than

expected in each significant census except

January 2008.

• Selecting 10-<20% significantly less than

expected in Jan. 2008, Dec. 2008, and Dec.

2009.

• Aug. 2009 selected 40-<53% significantly less

than expected.

• Oct. 2009 selected 30-<40% and 40-<53%

significantly less than expected.

Spring Grass Cover Selection, Bi

0.065

0.210

0.395

0.330

October 2007

0.304

0.350

0.182

0.165

November 2007

0.105

0.3490.300

0.245

December 2008

0.191

0.4200.189

0.201

October 2009

0.127

0.3390.292

0.242

December 2009

10-<20%

20-<30%

30-<40%

40-<53%

Summer Grass Cover Selection, Bi

0.119

0.305

0.295

0.281

January 2008

0.144

0.294

0.287

0.275

March 2008

0.187

0.274

0.268

0.272

February 2010

10-<20%

20-<30%

30-<40%

40-<53%

Fall Grass Cover Selection, Bi

10-<20%

20-<30%

30-<40%

40-<53%

0.292

0.342

0.201

0.165

June 2008

Winter Grass Cover Selection, Bi

10-<20%

20-<30%

30-<40%

40-<53%

0.170

0.516

0.268

0.046August 2009

Interesting Observation

Interesting Observation

Interesting Observation

Acknowledgements

• CSTARS – UC Davis

• CONICET – Consejo Nacional de Investigaciones Científicas y

Técnicas CENPAT - Centro Nacional Patagónico

• Geography Graduate Group – UC Davis

• California Space Grant Consortium

• CODEMA – Consejo Provincial de Ecología y Medio Ambiente,

Provincia de Río Negro

• Wildlife Conservation Society

• Hemispheric Institute of the Americas – UC Davis

• Henry A. Jastro Shields Research Scholarship – UC Davis

• Pablo Raposo – Fieldwork

• Ana María Beeskow – Plant identification