ORNITHOLOGICAL LITERATURE 
851 
refutation of density-dependent regulation and the 
Logistic Equation; in its place Murray forwards a 
new equation to account for a population 
fluctuating around a long-term mean population 
size. While highly valuable for ecological theory, 
itisornithologically perhaps less so. and I will not 
discuss this important chapter further. Chapter 8 is 
a discussion on whether to use the terms “mass' or 
weight’; Murray makes some insightful remarks, 
out this is a light-weight contribution (relative to 
the other chapters) and could have been omitted. 
Returning to those chapters more germane to 
ornithology. Chapter 3 is possibly the most 
important because it shows how to construct a 
life (history) table beginning from basics (i.e., a 
scries of population censuses). There are surprises 
here for those unfamiliar with Murray's methods, 
Gotably the rejection of the standard birth rate 
equation (and its replacement with an equation of 
Murray’s own devising) and the use of the 
fundamental Lotka Equation for populations 
without a stable age structure. Both these 
standpoints will be controversial. For the skepti¬ 
cal, working through the numbers will show 
whether Murray is correct or not. Aside from 
these points, this chapter contains important 
considerations relating to avian mating systems. 
By realizing that the average clutch size must be 
die same for both sexes but that demographic 
variables may differ between the sexes. Murray 
extended the Murray-Nolan Clutch-size Equation 
to incorporate these inter-sexual demographic 
differences with what he called the Life History 
Equation (Chapter 3, page 88 cl set/.). This is a 
significant equation. For the many ornithologists 
curious why, for example, prairie-chickens (Tym- 
punuchus spp.) arc lek-mating polygynists or 
phalaropes (Phalaropus spp.) arc sex-role-re- 
versed polyandrists, Murray s Life History Equa- 
lion is a brilliant (if unconventional) assault on 
these fundamental problems. I his is a strong 
claim, but before consulting the book I ask you to 
imagine the following circumstances: visualize a 
Population of birds where the males have worse 
survival than females; imagine, too. that tcniales 
have an earlier average age of first breeding, also 
consider that the empirical data show that males 
have a higher average annual reproductive success 
than females: finally imagine the primary sex ratio 
is at unity. Can you deduce what consequences 
'hese differing demographic parameters would 
have on this population, or better derive a single 
equation which unifies these demographic param¬ 
eters? Not an easy task! Fortunately, Murray has 
done the “hard thinking’ for us with his Life 
History Equation. Exactly what Murray finds with 
this equation I will leave to the curious reader to 
discover-lhe results in Chapter 3 are significantly 
different from anything in the turgid behavioral 
ecology literature. 
Chapter 4 is an investigation of the demographic 
characteristics of a small persisting population of 
Ivory-billed Woodpeckers (Campephilusprincipa¬ 
lis), assuming the Big Woods, Arkansas sightings 
had any validity, and an exploration of the 
dynamics of small, persisting populations. Because 
little is known about the woodpecker's demogra¬ 
phy, much is inferred in this chapter. Due to these 
uncertainties, the demographic deductions con¬ 
cerning the Ivory-billed Woodpecker appear less 
convincing than in other chapters. Nonetheless, 
there is much of substance here, especially 
Murray's Population Equation. The value of 
Murray's Population Equation is that if you know 
the number of eggs laid in a population and have 
good data on demographic attributes (particularly 
age-specific survival), then you can easily calculate 
the number of adults of breeding age as well as the 
total population. The versatility of this equation 
allows us to see, for example, that It a long-lived 
and short-lived population produce the same 
number of eggs (n„), the long-lived population 
attains a greater population size (this is intuitively 
obvious). However, more enigmatic is the discov¬ 
ery that while the population sizes are quite 
different, the numbers of breeding adults are 
almost identical. Other useful insights are con¬ 
tained in this chapter. 
Chapter 5 is on Clutch Size and Length oi 
Breeding Season, and shows that clutch size 
varies inversely with the length of the breeding 
season, a deduction from the Murray-Nolan 
Clutch-size Equation. Generally-speaking this 
relationship must hold, but as Murray observed 
(page 160) “|t]he relationship between length of 
breeding season, number of broods, and clutch 
size is not perfect because in natural populations 
other factors also affect clutch size in each 
species". Fortunately, these “other factors" are 
accounted for in the .Murray-Nolan Equation. It is 
strange to read the reviewers' negative but 
baseless comments (pages 169-183) on this 
admirable chapter; Murray's exasperation at this 
sort of treatment was understandable. Chapter 6 is 
another extremely important chapter showing the 
Mayfield Method for calculating nesting success 
