Extinct New Zealand birds. Refer to the Evolutionary Ecology Research (July 2003) study of the patterns of extinction in the New Zealand bird population, presented in Exercise 2.24 (p. 70). Recall that the NZBIRDS file contains qualitative data on flight capability (volant or flightless), habitat

(aquatic, ground terrestrial, or aerial terrestrial), nesting site (ground, cavity within ground, tree, or cavity above ground), nest density (high or low), diet (fish, vertebrates, vegetables, or invertebrates), and extinct status (extinct, absent from island, present), and quantitative data on body mass (grams) and egg length (millimeters) for 132 bird species at the time of the Maori colonization of New Zealand.

a. Write a model for mean body mass as a function of flight capability.

b. Write a model for mean body mass as a function of diet.

c. Write a model for mean egg length as a function of nesting site.

d. Fit the model you wrote in part a to the data and interpret the estimates of the b’s.

e. Conduct a test to determine whether the model from part a is statistically useful (at a = .01) for estimating mean body mass.

f. Fit the model you wrote in part b to the data and interpret the estimates of the b’s.

g. Conduct a test to determine whether the model from part b is statistically useful (at a = .01) for estimating mean body mass.

h. Fit the model you wrote in part c to the data and interpret the estimates of the b’s.

i. Conduct a test to determine whether the model from part c is statistically useful (at a = .01) for estimating mean egg length.