Chapter 54.2, Problem 3R

Summary Introduction

To review:

The type of survivorship curve obtained from the plot of the number of birds surviving with age from the data given in the table.

Given:

The number of female birds surviving to a particular age for a cohort is given in Table 1 below.

Table 1: Number of female birds surviving to a particular age for a cohort.

Year	Age (x)	Number of female birds (Nx)	Survivorship (lx)
2012	0	100	1
2013	1	50	0.5
2014	2	40	0.4
2015	3	30	0.3

Introduction:

There are three types of survivorship curves. Type I survivorship curves are concave and these species have a high survivorship through their adulthood and a steep decline in old age. Species with a type II survivorship curve face a constant risk of death throughout their life. Type III survivorship curves are convex and such species have a high mortality rate early in their life and become stable on reaching maturity.