A TEST OF 3 MODELS OF KIRTLANDS WARBLER HABITAT SUITABILITY

We tested 3 models of Kirtland's warbler (Dendroica kirtlandii) habita t suitability during a period when we believe there was a surplus of g ood quality breeding habitat. A jack pine canopy-cover model was super ior to 2 jack pine stem-density models in predicting Kirtland's warble r habitat use and non-use. Estimated density of birds in high- and med ium-class habitat was higher for the canopy-cover model (4.4 birds/100 ha in high class, 2.9 birds/100 ha in medium class) than for either s tem-density model (2.2-2.5 birds/100 ha in high class, 1.2-1.7 birds/1 00 ha in medium class). Lower bird density was estimated in low- class habitat for the canopy-cover model (0.3 birds/100 ha) than for the st em-density models (0.7 birds/100 ha). Overall estimated density of mal e Kirtland's warblers on the Mack Lake wildfire area was 1.3-1.5 birds /100 ha. For all 3 models, Kirtland's warblers selected territories th at contained 16-27% low-, 23-49% medium-, and 32-50% high-class suitab ility habitat. There was no correlation between territory size and pro portion of territory in each habitat class. Even though many male Kirt land's warblers included low-class habitat in their territories, >97% of those birds also included medium- or high-class habitat. This study confirmed the importance of high stem density and high canopy cover t o Kirtland's warbler habitat occupancy of young jack pine habitat rege nerated from wildfire. However, low-class stem-density or low-class ca nopy-cover habitat also was included in territories, even though addit ional high- and medium-class habitat was available and apparently unoc cupied. Therefore, habitat managed for Kirtland's warblers should cont ain medium- and low- as well as high-class habitat patches in juxtapos ition.