Ornithology, Evolution, and Philosophy 123

CuratorofOrnithologyattheAmericanMuseumofNaturalHistory 129
cause a deviation from the ideal 50:50 ratio in adults. A high mortality of females
during the breeding season occurs probably in all those species in which the
female carries the whole burden of incubation, particularly in ground nesting birds.
Females outnumber males in polygynous species like the weaver birds (Ploceidae).
Unequal sex ratios favoring the male or the female sex have been found to be
correlated with peculiarities in the life histories of these birds; however, caution
must be observed in the use of sex ratio data gathered by field observers.
In one of the few papers coauthored by Ernst and Gretel Mayr (1954g) they
demonstrated that the smaller species of owls (wing less than 210 mm) usually
molt their tail feathers simultaneous. The small species may require the tail less in
flight than the larger ones. In these species (wing more than 230 mm) the tail molt
proceeds usually from the outer rectrices inward.
The Sanford Hall of “The Biology of Birds,” opened on May 25, 1948, was the
first one at the AMNH dedicated to the biology of any group of animals. Mayr
was chairman of the planning committee. The hall demonstrated the diversity of
species including examples of extinct birds, the constructions of nests; it explained
the principles underlying flight, peculiarities of feathers and body (airsacs) as well
as migration and evolution (Mayr 1948b). The basic rule was that not a single
exhibit should be placed in the hall that did not illustrate some biological principle
or generalization. These concepts for the layout were derived from those developed
by Bernhard Rensch in Berlin (p. 44). After the opening ceremonies of the Sanford
Hall Mayr had serious physical problems like irregular heart beat, from which he
suffered for more than 5 years. The cause may or may not have been the pressure
to finish the job in time and to stay within tight budget limits see (p. 302).
Once again Mayr planned to write a comprehensive book, Natural History of
Birds for which he signed a contract in July 1940. 9 The manuscript was to be
submitted in 1942. However, this project was laid out too exhaustive and never
completed because of other more pressing tasks. He confessed to his colleague
Wilhelm Meise in Berlin on 4 January 1950, almost 10 years after signing the
contract:
“Concerning my own book on the biology of birds, the trouble is that I always
seem to have so many other jobs to perform. This spring I shall give courses at
Columbia University and will have little time for my own research and writing.
However, for your information, I will send you an outline of the book as far as
I have planned it, also part of the more detailed outline concerning the egg, the
care of the eggs, and the care of the young. None of this is, of course, final. It always
9 At that time, L.C. Dunn (Columbia University, New York) finalized the program of the
Jesup Lectures on “Systematics and the Origin of Species” (see p. 190–193) and Mayr
wrote to him on June 21, 1940 in a vain attempt to postpone these lectures: “I have had
an offer from Oxford University Press to prepare a textbook on ornithology. This means
so much to me and to my future that I can ill afford to turn it down in favor of the
systematics’ project. Maybe I can accept your kind invitation to lecture at Columbia by
changing the subject. I could possibly use the notes assembled for the preparation of my
textbook on ornithology, to give a really serious course of ornithology. I might be ready
for this in the winter of 1941 to 1942.” However, preparations for the systematics lectures
to be held in March 1941 were too far advanced for any changes to be considered.