The paper “The Shelf Life of Bird Eggs: Testing Egg Viability Using a Tropical Climate Gradient”

(Ecology [2005]: 2164–2175) investigated the effect of altitude and length of exposure on the hatch rate of thrasher eggs. Data consistent with the estimated probabilities of hatching after a number of days of exposure given in the paper are shown here.

Probability of Hatching Exposure (days) 1 2 3 4 5 6 7 8 Proportion (lowland) 0.09 0.06 0.07

a. Plot the data for the low- and mid-elevation experimental treatments versus exposure. Are the plots generally the shape you would expect from “logistic”

plots?

b. Using the techniques introduced in this section, calculate yr 5 lna p 1 2 p b for each of the exposure times in the cloud forest and fit the line yr 5 a 1 b(Days). What is the sig nifi cance of a negative slope to this line?

c. Using your best-fit line from Part (b), what would you estimate the proportion of eggs that would, on average, hatch if they were exposed to cloud forest conditions for 3 days? 5 days?

d. At what point in time does the estimated proportion of hatching for cloud forest conditions seem to cross from greater than