Example 8.5.1 of the textbook presents a simple model of a right whale population. A slight extension of this model has been used to inform the conservation practice of right whales. Fujiwara and Caswell (2001) modeled right whales by considering four different life stages: (1) newborn calves, (2) immature females, (3) mature females, and (4) mature females caring for newborns. The figure below shows the matrix diagram for their model.
They considered only the female portion of the population because females are the sex that limits population growth. The numbers next to the arrows are the estimated values for North Atlantic right whales. Notice that, unlike our model in Example 8.5.1, there are two classes of females that produce newborn calves: immature females and mature females. We have not labeled these arrows with numbers because the study by Fuijwara and Caswell explored different possibilities for these quantities.
References
Fuijwara, M. and H. Caswell. 2001. Demography of the endangered North Atlantic right whale. Nature 414:537-541