Answers to Hone Your Problem-Solving Skills Questions

1. Based on the isotopic composition of the bear tissues and of their food sources, grizzly bears living in inland areas consume less meat than coastal grizzlies, with a high proportion of their diet consisting of terrestrial plants.

2.

a. If bears switched from a diet of primarily fish to plants, the composition of N isotopes in bone and hair samples would shift to less enriched in ¹⁵N and lower δ¹⁵N values. The composition of C would be less enriched in ¹³C and there would be a lower (more negative) δ ¹³C.

b. If bears switched from consuming mostly fish to mostly terrestrial mammals, the composition of C isotopes would be less enriched in ¹³C and there would be a lower δ ¹³C. N isotope composition would not change appreciably.