The controlled harvest of surplus renewable 
natural resources is sound biology, good 
economics, and the core principle of conserva- 
tion, The militancy that once rescued wildlife 
species from extinction is slow to relax how- 
ever. It seems to be ingrained in American 
culture that to eat eggs of wild birds is not only 
illegal but also morally oblique. In 1912, my 
late esteemed cousin, Henry Wetherbee 
Henshaw, Chief of the U.S. Bureau of Biological 
Survey, wrote, 'Itis strongly recommended... 
in localities where [house] sparrows are too 
numerous they be trapped for table use, thus 
utilizing for food a bird which in many places 
has come to be both a public and a private 
nuisance,'' Soliocentrism, in 1965, as in 1912, 
is still poised to snip off noses of those who 
advocate blackbird pie or gull omelet. 
Much too little is known about the diseases 
of wildlife for deliberate use of this kind of 
biological control at this time. There is need 
for a great amount of research on the subject. 
Similarly with the introduction of competitive 
vertebrate species, we can never know enough 
about the biology of an exotic species to predict 
in what direction its biological course will run 
once it is liberated. The deliberate introduction 
of the house sparrow (Passer domesticus) and 
the starling (Sturnus vulgaris) into North 
America, in part, at least for control of in- 
sects, and their competition with several native 
species for the essentials of life should be 
regarded as an outmoded concept of mongoosoid 
biological control. 
The shortage of negative biotic tools has 
understandably led to the preeminence of pest 
control by chemical means, Dr. Walter Dykstra 
in this symposium has already developed this 
subject. 
MANIPULATION OF ORGANISM TO 
DECIMATE ITSELF IN ITS 
ECOLOGICAL NICHE, i.e., 
BIOGENETIC CONTROL 
Biogenesis, the dependence of racial survival 
upon individuals begetting replacement indi- 
viduals, can be thwarted physiologically in 
wildlife species just as it can and should be 
in the human species, Manipulation of the rate 
of reproduction results in higher or lower 
levels of population. Theoretically the presence 
of a number of sterile individuals in a popula- 
tion should exert extraordinary reductional 
pressures upon that population, much greater 
than if the same number were killed, for those 
sterile individuals that are allowed to remain 
not only fail to contribute biogenetically to the 
next generation but meanwhile compete for 
biotic space, food, and social order. 
Birth control should not be viewed as the 
panacea for pests however. By definition 
vertebrate pests are weeds--organisms with 
high tolerances, low requirements, and quanti- 
tative resilience. The vertebrates that we 
classify as pests have very steep population 
growth curves. Populations of many of the 
vertebrate pest species are probably at or 
near the leveled-off top of the classical 
sigmoid growth curve. To artificially push 
them off the plateau, by biogenetic control or 
any other means, onto the precipitous slope 
of the sigmoid growth curve is of no avail un- 
less the biogenetic control effort be unrelenting 
or unless it be accompanied by a concurrent 
control of the biotic requirements that nurture 
the growth curve and survival rate. A half- 
sterilized bacterial culture doesn't remain 
sterile for long, neither does a reproductively 
inhibited population of dump-fed rats. Bio- 
genetic control then should be viewed as an 
artificial means. As most pest thrive in the 
filth that separates us from Eden, it would be 
a pity to remove the pests and preserve the 
filth, whether it be physical or a cultural sys- 
tem of biologically false values. 
The chain of reproduction has many links, 
any one of which may be broken to result in 
biogenetic failure. A search for link-breakers 
has been pursued at the Bureau's wildlife re- 
search unit at the University of Massachusetts 
(Wetherbee, progress reports, 1959-64). David 
E. Davis (1961), following the lead of Knipling 
(1960) in insect control, first elucidated the 
principle of gametocidal population controlfor 
vertebrate pests, 
The following discussion will consider the 
recent findings in biogenetic failure via three 
routes of attack: Male gametes, female gam- 
etes, and embryos. 
Antifecundity in the Male 
Wentworth (1962) and Crawford (1962) atthe 
Massachusetts unit reviewed the physiological 
105 
