| The endangered Kirtland's warbler (Dendroicia kirtlandii) primarily nests in large stands (>32 ha) of young (5--25 years old) jack pine (Pinus banksiana) which grow on Grayling sand soil. Although the Kirtland's warbler's affinity for this habitat is poorly understood, one theory suggests that higher prey abundance in young jack pine may play a role. This study explored the validity of this theory. Two-hundred and two Kirtland's warbler fecal samples, collected from June--September 1995--1997, were analyzed to determine diet and examine the relationship of diet to warbler age, sex, and jack pine stand characteristics. Jack pine stands were characterized by size [small (<100 ha), large (>100 ha)], age [young (6--10 years), old (11--15 years)], location within the breeding range (core, periphery) and regeneration method (plantation, wildfire). The most important food items were Homoptera (spittlebugs), Hymenoptera (ants), Blueberry, Coleoptera (beetles), and Lepidoptera (moth larvae) which occurred in 61, 45, 42, 25, and 22% of fecal samples, respectively. Warbler age or sex did not affect diet; percent occurrence of arthropod taxa and Blueberry was similar between warblers of different age and sex. Also, jack pine characteristics of age, regeneration method, size, and location did not appear to influence Kirtland's warbler diet. The similarity in diet between warbler age and sex and stand characteristics suggests that prey abundance may not drive Kirtland's warblers affinity for young aged jack pine. |
