Neither is the label ''vertebrate pest" defin- 
able in any satisfactory way. Homo sapiens 
(a biological agent) emerges as the single out- 
standing pressure impinging for better or for 
worse upon the ecological niches and popula- 
tions of vertebrate animals, Manis responsible 
either directly or indirectly for altering the 
conditions that permit or prevent the continued 
existence of vertebrate populations. Whether 
an animal or population of animals constitutes 
a "pest'' is purely a biological judgment onthe 
part of man incriminating himself for creating 
or imagining the biological problem. There- 
fore, all pest control is biology versus biology 
via biology. The struggle is not so much man 
against nature as it is a struggle of humans 
against human nature, 
The ruby-throated hummingbird (Ar- 
chilochus colubris) that cross-pollinates 
flowers is a pest of horticulture. A pestis only 
a pest at a given time, place, and situation, At 
any other time, place, or situation the pest may 
be a blessing--nor is a pestless world either 
attainable or desirable. I suggest, therefore, as 
a preamble to this discussion that the best 
biological means of vertebrate pest control is 
the adoption of a charitable and philosophical 
approach to those animals that we ourselves 
cause to be called pests. May we learnto con- 
trol our own biological numbers, activities, 
value systems, and tolerances. Daniel B. 
Luten's (1963) essay, ''How Dense Can People 
Be" is worth the reading. 
In the meantime, how might we resolve 
crises in managing overpopulations of verte- 
brates by pitting biology against biology? There 
are two general choices of approach: (1) Ma- 
nipulate the ecological niche to decimate the 
organisms, i.e., Biotic Control, or (2) ma- 
nipulate the organism to decimate itself in 
its ecological niche, i.e., Biogenetic Control. 
This paper will consider both of these ap- 
proaches as they apply to nuisance fish, 
mammals, and birds. Most of the examples 
will be drawn from birds, as most of my work 
has been done with that class, 
From examining the various means of bio- 
logical control there evolves an appreciation 
of a hierachy of values attached to the selection 
of one means over another, These values re- 
volve around effectiveness, selectivity, sub- 
tleness, timing, humaneness, self-containment, 
economy, reversability, practicality, etc. Bio- 


103 
logical control can be grossly crude or finely 
sophisticated. 
Laboratory physiologists on the one hand 
and armchair zoologists on the other fre- 
quently come up with materials or theories 
that would seem to be of extraordinary effec- 
tiveness, but in practice they default because 
of the trump action of some one of the just- 
mentioned hierarchy of values. Wildlife bio- 
logists have learned to buy with caution, for 
the proving ground of a biological control agent 
is on the actual ecological niche of the target 
wild population. 
MANIPULATION OF ECOLOGICAL 
NICHE TO DECIMATE ORGANISMS, 
i.e., BIOTIC CONTROL 
With this approach we again have two 
choices: (1) To capitalize on the organisms' 
ecological requirements or (2) to capitalize 
on the organisms' ecological intolerances. 
Biotic requirements pertain to positive fea- 
tures in the environment: Food, water, pro- 
tective cover, breeding sites, releaser stimuli, 
etc. Biotic intolerances pertain to negative 
features in the environment: Predators, dis- 
eases, parasites, poisons, disturbance, com- 
petition, etc. 
The ecological niches of animals are not 
simply circles or smooth spheres. Each spe- 
cies has a niche that can be represented 
symbolically as a snowflake--complex and 
unique. The projections of the snowflake con- 
figuration may be said to represent the ani- 
mals' requirements; the indentations of the 
configuration are its intolerances, Usually 
some projections or indentations are more 
conspicuous than the others and are more 
vulnerable. Wildlife technicians call these 
the limiting factors; zooiogists call these the 
isolating characters or evolutionary special- 
izations. Every species has them-~but the anal- 
ogy between snow crystals and ecological niches 
stops here, or rather can be extended to 
Gestalten. Niches are more like Gestalten of 
the psychologists: Formed patterns of sensa- 
tions and reflexes integrated and functioning 
in interrelationship, The totality of your aware- 
ness at this particular instant is your Gestalt. 
The niche, or Gestalt, is multidimensional and 
dynamic. The niche is different in July from 
