Species-environment relationships of East African

birds along a body size gradient

K. Mertes Schwartz* and W. JetzDepartment of Ecology and Evolutionary Biology

Yale University

Spatial scale

Spatial scale or grain: breaking up our knowledge of the environment into units of a known, equal size

Spatial scale is important to mobile animal species

Home<10 km2

AcreageSecurity# bedrooms

SizeSecurityNearby resources

Home range<100 km2

Mix of required resources

Mix of required resources

Region<1000

km2

Food Critical resourcesFamily nearby

DispersalMate-searching

Seasonal resources

…but which environmental conditions are important at which scales?

Study species

Von der Decken’s hornbill

• 160-250g• omnivorous

(may consume more fruit)

• Forages on ground & in trees

Fork-tailed drongo • 40-50g• Pursues insects from

open perches• Highly vigilant

Kori bustard• 8-18kg• Consumes insects,

small animals (lizards, mammals), seeds, leaf material

Environmental data at different spatial scales

Predicted occurrence: Von der Decken’s hornbill

10m 100m 1000m

10m

Predicted occurrence: Drongo1000m100m

1 4km2

10m

Predicted occurrence: Kori bustard1000m100m

1 4km2

Summary

Large scales - Drongos: variable shrub density: minimal distance to roads- Von der Decken’s hornbills: restricted land cover classes- Kori bustards: restricted elevations and black cotton soils

Small scales- Drongos selected areas with low shrub density & variable elevation and distance to roads- Von der Decken’s hornbills selected areas with complex vegetation and dense shrubs- Kori bustards selected areas with variable shrub density and soil types

Species responses to environmental conditions were consistent with diet and body size

Take-home messages: Habitat managers make decisions at several spatial scales:

- land use planning issues at broad spatial scales- planning for stands, plots, and land cover types within

properties

Information on environmental patterns and species responses at multiple scales can be incorporated into land use planning to support the habitat requirements of multiple wildlife species.

With many thanks…Yale UniversityOs Schmitz, Karen Seto, David Vasseur, Anne Trainor, Larry Bonneau, Giuseppe Amatulli, Adam Wilson, Frank LaSorte, Jennie Miller, Kevin McLean

Max-Planck-Institut für Ornithologie, RadzolfellMartin Wikelski, Bruno Erne, Georg Heine

Mpala Research CentreMargaret Kinnaird, Korir Elkana, Hellen Koech, Morgan Pecora-Saipe, Stephanie Siller

Movebank Team

Questions?

Potential T. deckeni characteristic grains

RoadsWaterClouds &shadowBare soilsGrassShrubsHuman useRock

0162

0127

0170

119

347

345

0150 186

Study area: ecological zones

Black cotton, tall grass & shrubs

Black cotton, grass cover & trees

Red soil, few shrubs, high grass cover

Red soil, freq shrubs, high grass cover