AMER. ZOOL., 25:695-705 (1985)
Ethology, Zoosemiotic and Sociobiology1
JACK P. HAILMAN
Department of Zoology, University of Wisconsin,
Madison, Wisconsin 53706
SYNOPSIS. Current research reveals that the somewhat separate subdisciplines ethology,
zoosemiotic and sociobiology function together in clarifying animal behavior. Ethology is
taken as the study of individual behavioral patterns, zoosemiotic as the study of animal
communication, and sociobiology as the study of social organization. The explosive progress in all research areas cannot be summarized briefly but examples are drawn to provide
the flavor of each subdiscipline and their interactions. Among the illustrative topics selected
are behavioral development, animal orientation, signal structure, the context of communication, language, mating systems and cooperative breeding. At junctures some possible paths toward future study are identified, but the concluding examples point to the
principal theme and prediction: the integrated study of behavior combining historically
distinct approaches—which promises to help clarify not only the lives of our fellow earthly
inhabitants but our own lives as well.
than the sum of its parts. When our survey
era
opened, classical ethology and com"The study of animal behavior . . . is
really a new science, although we reckon parative psychology represented the major
its beginning with the work of Charles Dar- split in behavioral studies, but that distincwin" (Klopfer and Hailman, 1967, p. ix). tion is hardly visible today. In the interim
It is a sobering realization that the litera- sociobiology solidified, with zoosemiotic
ture of ethology's first century—from Dar- occupying a sort of middle ground, spawnwin's (1859) Origin to the founding of Amer- ing predictions of nearly total separation
ican Zoologist in 1961—is tiny compared between ethology and sociobiology (e.g., the
with that of the last quarter century, which delightful cartoon in Wilson, 1975, p. 5).
is our survey period here. What has been At root, however, the three subdisciplines
happening? What is the state of the art? ask after the same fundamental causes and
origins: the control, development, perpetWhere are behavioral studies headed?
uation and phylogeny of behavior (Hailman,
1982). To borrow, admittedly irreOne stupendous whole
a phrase from Alexander Pope,
ligiously,
The study of animal behavior, like Caeare
but parts of one stupendous
"All
sar's Gaul, is divided into three parts, which
I shall call ethology, zoosemiotic and socio- whole."
biology. ("Zoosemiotic" is the form parallel with "logic"; some authors prefer The plan
"zoosemiotics.") Bear with HumptyIt is impossible even to list recent
Dumpty and me: "When I use a word, it advances much less give due credit. A tesmeans just what I choose it to mean—nei- timony to explosive growth is the prolifther more nor less." Theoretical conno- eration of textbooks, which document the
tations aside, ethology is at heart the study development of ideas and provide an entry
of individual behavioral patterns, zoose- into the vast primary literature (e.g., Manmiotic is the study of animal communica- ning, 1967; Marler and Hamilton, 1966;
tion, and sociobiology is the study of ani- Hinde, 1966, 1982; Klopfer and Hailman,
mal social systems.
1967; Eibl-Eibesfeldt, 1970; Alcock, 1975;
Dewsbury,
1978; Marler and VandenThe whole of behavioral studies is more
bergh, 1979; Wallace, 1979; Immelmann,
1980; Broom, 1981; Barnett, 1981; Hunt1
Plenary Lecture for the Division of Animal Behav- ingford, 1984; Drickamer and Vessey,
ior presented at the Annual Meeting of the American
1982; Gould, 1982; Grier, 1984; along with
Society of Zoologists, 27-30 December 1984, at Den- revisions and a host of other volumes). I
ver, Colorado.
INTRODUCTION
695
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JACK P. HAILMAN
perforce select ruthlessly a few issues to
impart a flavor of what is happening. I show
unabashed aviocentric choice of examples
because birds have probably contributed
the most to behavioral studies and because
birds remain my first love despite my work
with amphibians, mammals, fishes and
insects. My avian bias is, however, ironic
in view of the salutory expansion of investigations to almost every major taxon of
living animals (e.g., Matthews and Matthews, 1978). First I consider each part in
turn—ethology, zoosemiotic and sociobiology—and then put the parts together
with selected examples.
ETHOLOGY
Heinroth (1910) established "Ethologie" in its modern sense although the term
had been used differently in the previous
century by philosopher John Stuart Mill
and the French biologists Geoffrey and
Alfred Giard Saint-Hilaire. Notwithstanding the reaction of American psychologists
to "instinct" concepts of European ethology (e.g., Tinbergen, 1951), "ethology"
today may usefully represent the study of
individual behavioral patterns. As both
"ethology" and "animal behavior" often
refer to behavioral studies as a whole the
general texts cited above include advances
in the study of individual behavior.
Perhaps the most striking overall development in ethology, sensu stricto, is a revolution in approach: a move away from
intuitive explanatory concepts based on
qualitative observations gathered in an
unplanned manner toward operational
models based on quantitative measurements gathered through systematic sampling and controlled experimentation.
Testaments to this shift are the frequent
citations to J. Altmann's (1974) paper on
sampling methods and an entire handbook
on methodology (Lehner, 1979). Although
authors have long used the term "operational" as window-dressing, many now recognize Percy Bridgman's (1927, 1938) concept as intended: denned by measuring
operations. As a result—perhaps even to
the extent of discarding potentially useful
ideas—many once-popular terms are
hardly used today: instinct, motivation,
fixed action pattern, appetitive behavior,
consumatory act, releaser, innate releasing
mechanism, drive, sign stimulus, reaction
specific energy, and so on. Ethology has
turned "mechanistic," incorporating operational concepts such as cybernetic feedback to explain behavioral control (e.g.,
McFarland, 1971). There has even been
an attempt to devise an explicitly operational framework to embrace all of control
and ontogeny (Hailman, 1982).
From many specific areas that could be
used to illustrate ethological progress I
choose but two: orientation and ontogeny.
Were space not limiting my other choices
would have been to discuss fascinating
advances in neuroethology—an interdisciplinary subject in its own right—and the
incredible progress made in understanding
hormonal bases of behavior.
Migration, orientation and homing
The question of where North temperate
birds go in winter fascinated Aristotle and
was answered in modern times, but how
they find their way on migration was nearly
a complete puzzle 25 years ago. Emlen
(1967) found a species that was fooled by
the night sky on a planetarium dome, and
showed that indigo buntings navigated by
that portion of the sky near the pole star.
He also showed that the same species must
possess a magnetic compass (Emlen et al.,
1976). The most detailed knowledge about
animal orientation continued to come from
homing pigeons (e.g., Keeton, 1974;
Kreithen and Keeton, 1974; Walcott and
Green, 1974). It was already known that
homing pigeons possessed a "sun-compass," which combined assessment of the
sun's position with an accurate internal
chronometer. But without a map, a compass is of limited use. Intensive research
using diverse methods produced an amazing array of findings. Homing pigeons not
only have a sun-compass but they learn
landmarks, can see ultraviolet rays invisible
to the human eye, possess an uncanny magnetic sense, can see polarization patterns
in the blue sky, can hear infrasound (such
as the wind blowing through the Rocky
Mountains from thousands of miles away),
and may even be able to orient by odors
in their environment. Put simply, birds have
ETHOLOGY, ZOOSEMIOTIC AND SOCIOBIOLOGY
"backup" guidance systems in abundance,
making use of sensory abilities that few
workers even imagined a couple of decades
ago.
Ontogeny
The early notion that behavior was neatly
divisible into instinctive and learned patterns was under strong attack even before
our survey era (e.g., Lehrman, 1953). Rhetoric aside, empirical analyses of typical
"instincts" such as the begging response of
young gull chicks (Tinbergen and Perdeck,
1950) revealed that experience was critical
to development (Hailman, 1967). The
chick's responsiveness to irrelevant items
such as grass-blades habituates, but begging increases by operant conditioning
toward the parent, which delivers food
reward in response to the begging. The
chick also learns to recognize its parent's
total gestalt through a "perceptual sharpening" process akin to classical conditioning. Even the motor response improves
through the simple experience of standing
upright in a dark incubator, suggesting that
the once-touted "deprivation" studies are
of limited usefulness. Another salutory
advance came with the investigation of
avian embryonic behavior (e.g., Gottlieb,
1968). Precocial birds while still in the egg
can receive stimuli and communicate with
their mother and other embryos of the
clutch. The phenomenon of imprinting,
whereby newly hatched precocial birds
rapidly learn the characteristics of their
mothers, was extended to mammals (e.g.,
Klopfer and Klopfer, 1968) and intensively
studied in birds (e.g., Gottlieb, 1971; Hess,
1973). The pervasive role of experience in
development stimulated much interesting
research in learned traditions (reviewed by
Bonner, 1980).
ZOOSEMIOTIC
The American philosopher Charles
Sanders Peirce used "semiotic" to denote
the analysis of communication processes.
As the study of animal communication was
a subdiscipline without a name, Sebeok
(1965) apparently coined the compound
"zoosemiotic." The growth of zoosemiotic
in the last quarter century has been explo-
697
sive. Sebeok (1968, 1977) has edited two
compendia, other books have appeared
(e.g., W. J. Smith, 1977; Hailman, 1977;
Kroodsma and Miller, 1982), and all the
general texts cited at the outset contain
significant material on communication. I
choose three themes as representative: signal structure, context and language.
Signal structure
Just prior to the founding of American
Zoologist, Marler (1955) argued that avian
calls possessed physical characteristics
especially suited to their uses. Calls given
when detecting a hawk overhead, for
example, had a gradual onset and offset,
and consisted of relatively pure tones lacking frequency modulation. Such calls are
difficult to localize and hence suited as
"alarm calls" that would not betray the
caller's position. Territorial song, "contact
notes" and other vocalizations used to signal the caller's position were entirely different: they had abrupt beginnings and
ends, a broad frequency spectrum, frequency or amplitude modulations, and were
broken up into a series of short parts. Marler's paper sparked interest in the physics
of stimuli, sensory physiology and physical
properties of the environment that might
structure communication signals.
Mother Nature has yielded her secrets
slowly, however. Optical signals reveal the
complexities of the task (Hailman, 1977).
Light is so rich in variables and interactions with the medium—wavelength/frequency, amplitude, coherency, polarization, refraction, reflection, diffraction,
interference, scattering, shadows, etc.—
that a given signal can carry immense
amounts of information about a huge variety of different subjects. Physical measurement of environmental light on the one
hand and of animal and background colors
on the other is in its infancy (partially
reviewed in Hailman, 1977; Burtt, 1979).
Seliger et al. (1982) showed that the bioluminescent spectrum of fireflies varies
predictably among species according to the
ambient background light at the time of
night that they signal, and Burtt (1979;
Hailman, 1977, p. 242) showed that the
flash patterns of wood warblers contrast
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JACK P. HAILMAN
highly with background leaves when plotted on a three-dimensional color space.
A larger relevant literature exists on
acoustical communication, but a synthesis
has also developed slowly. Birds possess
acoustical conduit between the two ears
(Dooling, 1982), which means that differences in sound amplitude and arrival-time
at the two ears are smaller than once supposed, requiring revision of predictions
about call-structure to enhance or diminish
localizability. A growing literature on
sound propagation has revealed many
complexities (Wiley and Richards, 1978,
1982). Effects of temperature, humidity,
wind and such factors, for example, suggest that the period around dawn may be
optimal for acoustic communication, perhaps explaining the well-documented dawn
chorus of songbirds.
Bossert and Wilson (1963) provided the
first real theory of how chemical signals
should be constructed in terms of diffusion
rate and degradation for alarm warnings,
chemical trails and sex-attractants. Even the
role of interspecific crowding of communication channels has been explored, as
when a flycatcher and vireo singing in the
same environment avoid overlapping their
songs (R. W. Ficken et al, 1974). Still,
research on the physics, physiology and
ecology of animal communication is merely
beginning, and we can look forward to
many future developments including interesting surprises.
Context and information
Another important advance in zoosemiotic was the notion of of context (W. J.
Smith, 1963): the signal produced is merely
the "message" of the sender—the "meaning" taken by the receiver depends upon
the context ofsignaling.W.J. Smith (1965)
was also among the first to derive ideas
from human semiotic (ably summarized in
W.J. Smith, 1977). The notion of context
led to the belief that signals refer only to
motivational states of the sender, so that
signals and states bear a one-to-one correspondence. For example, a certain vocalization by a flycatcher signals merely "locomotory hesitancy," its meaning determined
by context, such as when given at a terri-
torial boundary or upon detecting a potential predator. Beer (1975, 1976) strongly
challenged the idea of one-to-one correspondence between internal states and signals, and others believe signals directly
refer to environmental loci or even specific
classes of objects (e.g., Seyfarthe<a/., 1980a,
b).
Information theory was introduced into
zoosemiotic by Haldane and Spurway
(1954). The mathematical theory of communication was developed by Wiener {e.g.,
1948) and Shannon (1949), and it is interesting that Weaver's (1949) essay appended
to Shannon's classic work tried to integrate
semiotical notions. Wilson (1962), using
methods by which Haldane and Spurway
measured the information transferred by
honey bee dances, made a parallel study of
chemical trails in fire ants, employing
information as the common currency for
comparing physically dissimilar systems. It
is likely that information theory leaves its
promise unfulfilled mainly because analyses of communication are not yet sufficiently advanced to characterize the systems as completely as required to employ
such techniques.
Language
No discussion of zoosemiotic is complete
without comment on "animal language."
Any communication, the dictionary says, is
language in a general sense, but the question is whether animals show linguistic abilities in the sense of human language. Recent
studies may be broken into three genre.
First there are studies drawing any sort
of parallel between animal communication
and language. For example, von Frisch's
{e.g., 1953) famous decoding of the honey
bee's waggle-dance led him repeatedly to
refer to the system as language. He was
impressed that rates of waggling correspond with the distance to the food source
and that the orientation of the dance corresponds with the direction to the food
source. Von Frisch felt that the apparent
arbitrariness of these correspondences was
the key property of language (Gould, 1982,
pp. 399-406). Quite a different tack focuses
on development; painstaking studies of
song-learning in birds {e.g., Marler and
ETHOLOGY, ZOOSEMIOTIC AND SOCIOBIOLOGY
Peters, 1982) suggest various parallels with
language-learning in children. A third
example relates to alarm calls, where prey
species appear to give a different call for
each general class of predator such as hawk
or snake (S. R. Robinson, 1980, 1981;
Owings and Virginia, 1978; Seyfarth et al.,
1980a, b). Some authors assert that such
calls have object-referents (different predators) and therefore are language-like,
although other interpretations are possible.
The second genre centers around teaching to an animal some human or humandevised language. Initial attempts with
chimpanzees came to grief simply because
chimps cannot produce many human-like
sounds (Hayes, 1952). The modern version
began with teaching a chimp the American
Sign Language used by the deaf (Gardner
and Gardner, 1969). Many derivative studies, using gestural signals or wholly contrived computer apparatus, have established that apes can learn to associate
arbitrary signs with referents such as objects
and actions (Premack, 1972; Fouts, 1973;
Rumbaugh, 1973; Rumbaugh and Gill,
1976; Savage-Rumbaugh et al, 1980).
Controversy remains concerning the extent
to which apes can concatenate signs into
meaningful combinations. Pepperberg
(1981, 1983) took the other tack of teaching spoken English to a parrot, whose vocal
abilities greatly exceed those of primates.
The bird has a large vocabulary and uses
words in meaningful combinations of its
own invention.
The third genre analyzes properties of
naturally occurring communication in
which there are recurring vocal elements.
Early reports by Moynihan (1966), S. T.
Smith (1972) and Beer (1976) showed
either the recurrence of elements within
long vocalizations or the sequencing of elements to form combined sounds. J. G. Robinson (1979) began formal analyses of such
systems in primates (see also Cleveland and
Snowdon, 1982; andj. G. Robinson, 1984).
The clearest-cut system reported so far is
the "chick-a-dee" calls of the black-capped
chickadee, which uses four note-types
recombinantly to create hundreds of different call-types in a system possessing many
699
formal similarities with language (Hailman
etal., 1985).
SOCIOBIOLOGY
At least a decade before thejustly famous
book by Wilson (1975), "sociobiology" was
a coin of the realm. Our ASZ Division was
founded under the name "Animal Behavior and Sociobiology," university courses
were contemporarily offered under the
title, and S. Altmann (1965) used the term
in a title. "Sociobiology" carries many theoretical connotations best shed so that its
enduring questions rather than its ephemeral answers receive the emphasis. I chose
two aspects to represent the underlying salutory effects of this vigorous subdiscipline.
First, the study of social systems and social
organization requires individually recognizable animals. Individual marking has not
only made possible studies of demography
and social structure, but it has potentiated
results from ethology and zoosemiotic as
well. Furthermore, field observers have
learned to recognize individual animals
without marking them (e.g., Bateson, 1977).
The second aspect has been the explosive introduction of mathematical modeling into behavioral studies. During World
War II the mathematical resources of the
Allies were brought to bear on problems
of weaponry and organizational structure,
giving rise to a number of mathematical
approaches loosely called "operations
research." The notion of feedback, extensively developed by Wiener (e.g., 1948) and
applied to gunfire control systems, became
a pillar of cybernetics, as mentioned above
under ethology. The other pillar was information theory, developed by Wiener and
by Shannon (1949), as mentioned above in
connection with zoosemiotic. Besides an
immense improvement in statistical techniques, operations research also supplied
two specific approaches especially developed in sociobiology: linear programming
and the theory of zero-sum strategy games
(or simply "game theory")—logically interrelated foundations of an emerging body
of mathematics now called decision theory.
It is perhaps interesting to note that two
major techniques of operations research—
namely, network analysis (or PERT: the
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JACK P. HAILMAN
Program Evaluation and Review Technique) and queueing theory—have yet to
be applied strongly to behavioral studies.
I regrettably pass by the more ecological
aspects of sociobiology, such as the development of "optimal foraging theory" based
on linear programming, and must also skip
the remarkably useful notion of "evolutionarily stable strategies" developed by
Maynard Smith (e.g., 1974) from game theory. I even forego exciting advances in
dominance relations, including the application of game-theory to interactions (e.g.,
Maynard Smith and Price, 1973) and linear
programming to dominance hierarchies
(e.g., Chase, 1974, 1980). Instead I pick two
manifestly behavioral topics to provide the
flavor of advances in sociobiology: mating
systems and cooperative breeding.
Mating systems
A landmark in the analysis of mating systems was the concept of "polygynous
threshold" (Orians, 1969). Animal mating
systems vary bewilderingly, from monogamous pairs to nearly promiscuous mating.
The occurrence of multiple bonded mates
was not difficult to understand when, for
whatever demographic reason, there
occurred an evident imbalance in sex ratios.
What Orians showed for polygynous songbirds is that the territories held by males
varied in qualities relating to the successful
production of offspring. There must come
a point when a female realizes a higher
reproductive success by becoming a second
wife to a male defending a good territory
than by becoming the sole mate of a male
in peripheral habitat. The underlying reasoning was one of the first applications of
linear programming to behavior (although
not explicitly identified as such).
We have no comprehensive theory of
mating systems, but the investigations of
perhaps hundreds of systems bring continued surprises and clarifications. Very few
species exhibit polyandrous systems in
which one female is bonded simultaneously
to two or more males. Especially in birds,
where females are burdened with enormous eggs, polyandrous mating seems most
unlikely, yet several cases have been uncovered (e.g., Maynard Smith and Ridgpath,
1972; Jenni and Collier, 1972; Emlen and
Oring, 1977), even though the evolutionary conditions driving such systems remain
poorly understood (Jenni, 1974). Nor is
polygyny accounted for entirely by imbalanced sex ratios and environmental polygynous thresholds. Analyses continue to
produce little surprises. Bray et al. (1975)
vasectomized male redwing blackbirds and
found that some mates nevertheless laid
fertilized eggs, so it is a wise redwing who
knows his or her father. Most gulls have
three incubation patches and ordinarily lay
no more than three eggs, so the occurrence
of five-egg clutches (e.g., Segre etal., 1966)
should have signaled an interesting story,
although I was not smart enough to pursue
it. It took Hunt and Hunt (1977) to discover that such nests were attended by two
females and no male. The sex ratio in the
study colony was equal at hatching, but
when the birds returned to breed for the
first time after several years at sea the adults
were predominantly females. As gull nests
must be guarded against predation at all
times, single females cannot successfully
rear young even if inseminated by a male
mated to another female. Therefore,
unpaired females form homosexual bonds
for joint rearing of their two clutches in a
single nest.
Cooperative breeding
The naturalist Skutch (1935), reported
"helpers at the nest" in neotropical birds:
i.e., care of nestlings by more than two
adults. Why any animal would care for
young that are not its own was a question
long dodged by behavioral biologists until
the exemplary papers of Hamilton (1964)
opened the floodgates of kin selection.
Drawing on notions developed by the eminent population geneticists R. A. Fisher
and Sewall Wright, Hamilton reasoned that
animals had an evolutionary stake in the
success of all relatives because relatives
share genes as a result of common descent.
Full sibs, for example, share half their
genomes on the average, so that "altruistic" behavior toward brothers and sisters
should be promoted by evolution. Kin
selection has been invoked to explain a
variety of social circumstances, including
ETHOLOGY, ZOOSEMIOTIC AND SOCIOBIOLOGY
warning of conspecifics about predators
when doing so entails an obvious personal
risk. Nowhere, however, has the notion
been applied so vigorously as in cooperative breeding where individuals other than
the genetic parents cooperate in rearing of
young. This subject played a prominent
role in Wilson's (1975) treatise and Brown's
(1975) fine book covering much the same
ground.
Empirical studies generally support the
tendency for "helpers" to be genetically
related to offspring being reared. Nevertheless, the role of kin selection in cooperative breeding remains open as results
accumulate showing that both parents and
helpers realize direct gains. The diversity
of cooperative breeding systems uncovered suggests that no single set of factors
will explain all systems simply. Zahavi
(1974) showed that a babbler in Israel forms
tight-knit cooperative groups promoted by
a harsh, arid environment that mitigates
against successful reproduction by pairs.
Brown et al. (1982) removed helpers from
randomly selected groups, showing that
single pairs had lower reproductive success
than groups with helpers. Acorn woodpeckers in California store acorns in a central larder, so that common defense of the
food supply plays a role in promoting cooperative breeding {e.g., MacRoberts and
MacRoberts, 1976; Stacey, 1979; Koenig,
1981). Vehrencamp (1978) discovered that
in groove-billed anis various females of the
group lay eggs in a communal nest, with
the most dominant females laying last near
the top so that their eggs are most likely
to develop. A huge number of similarly
interesting systems have been found, and
new studies appear so rapidly that reviews
cannot keep pace.
One of the longest-term studies is of the
Florida scrub jay, begun in 1969 (Woolfenden and Fitzpatrick, 1984). The permanently monogamous pairs live on a territory in oak scrub, accompanied by zero
to about five adult helpers that participate
in territorial defense, anti-predatory
behavior and rearing of the young. In about
65% of the cases, the helper is helping its
genetic parents, and in another 26% is
helping a pair in which one of the two birds
701
is a (usually widowed and remated) genetic
parent. On those rare occasions that a
younger adult bird attempts to set up territory in a peripheral habitat, it is always
unsuccessful and usually disappears (probably by predation) within a matter of weeks.
Birds that ultimately breed must remain as
helpers on the territory of some breeding
pair, most commonly awaiting a jay of the
opposite sex on another territory to become
widowed. Breeding pairs directly benefit
from their helpers. Annual mortality of
breeders is only about 15% when they have
at least one helper, whereas the figure is
23% for birds without helpers, a difference
probably potentiated by increased effectiveness of anti-predator behavior. Furthermore, about 1.5 independent young
per year are produced with at least one
helper versus about 0.9 young without
helpers. Unlike avian systems in which
nestlings commonly die from starvation,
the helpers' bringing of food to the nest
cannot be relevant, for subsequent mortality is totally unrelated to fledging weight.
The difference in reproductive output is
largely attributable to predation: the ratio
of nestlings produced to eggs laid is 0.6
without helpers and nearly 0.7 with helpers, and the ratio of fledglings produced
from nestlings hatched is only about 0.54
without helpers but 0.68 with helpers—
both differences being highly significant.
INTERSECTIONS
Ethology, zoosemiotic and sociobiology
are sets of studies and approaches that cannot exist separately. Understanding of
behavior depends largely upon the intersections of these sets, so I close with two
examples of how the subdisciplines contribute jointly in solving problems.
The "all clear" signal
Most prey species are well equipped to
identify and detect predators (e.g., Curio,
1976), and if social, the detector may warn
companions of danger. Alarmed songbirds
typically flee to cover and there remain
motionless, but eventually sense that danger is past and so resume normal activities.
This resumption is often nearly simultaneous for all members of a special flock:
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JACK P. HAILMAN
how is resumption coordinated? A blackcapped chickadee detecting a hawk gives a
particular high-pitched call (M. S. Ficken
et al., 1978), which causes the flock members to scatter quickly to cover. Another
class of vocalizations, the "chick-a-dee" call.,
mentioned previously, communicate the
caller's locomotory tendencies (S. T. Smith,
1972; Hailman et al, 1985), although the
exact interpretation of the many different
call-types is not yet understood. Furthermore, dominance studies show that chickadees have a near-linear hierarchy. M. S.
Ficken and Witkin (1977) determined that
the first chickadee to move from hiding
was the flock's dominant male. Furthermore, he uttered "chick-a-dee" calls upon
his resumed locomotion, which in this context sent the "all clear" signal to other
members of the flock, which then also
resumed activity. Problems such as the "all
clear" signal are not the province of any
single subdiscipline. Predator-prey interaction is a typical subject of ethology; vocal
communication and the notion of context
are central to zoosemiotic; individual
marking and dominance hierarchies typify
sociobiology. The three sets of elements
work as a whole to explain "all clear" signaling.
Indirect effects of helpers
As mentioned, breeding Florida scrub
jays have higher reproductive output when
helper birds are present (Woolfenden and
Fitzpatrick, 1984), but the roles played by
helpers are not obvious. Two principal differences are in higher egg and nestling loses
in pairs without helpers. As a consequence
of feeding the young, helpers are often at
the nest and so might aid in detecting and
foiling any predation on the nestlings.
However, only the breeding female incubates eggs, and she often drives helpers
from the nest vicinity. Furthermore, of eggs
not lost to predation, the hatchability rate
is slightly higher in nests of pairs having
one or more helpers. How could this possibly be? A partial answer lies in increased
nest-attentiveness by breeding females that
have helpers (Hailman, Beattie, and Woolfenden, manuscript). Such females leave the
eggs less often and are never absent for the
long periods that characterize females
without helpers. Incubating females having helpers thus provide a more constant
incubation that could raise the hatchability
rate. Furthermore, because they are on the
eggs a greater fraction of the time and also
because they make fewer trips to and fro
that a predator could use to find the nest,
predation may be decreased. A key to
understanding indirect effects of helpers
lies in what the incubating female does
while off the nest. One thing she does is
forage. The female with helpers is fed on
the nest more often by her mate, and so
need not leave the eggs so often to forage
for herself. This result suggests that helpers potentiate foraging by the breeding
male, which they may do by taking turns
at sentinel duty, freeing the male to forage
more. Incubating females also participate
in territorial defense. Jays give a special call
and a characteristic bounding flight toward
an intruder, signals that the incubating
female can usually hear or see. Part of successful territorial defense depends upon the
relative numbers of contestants on the two
sides. In groups with helpers there may be
fewer territorial intrusions by neighboring
jays, or there may be sufficient defenders
that the incubating female need not leave
the eggs so often to participate. The example shows that the manifestly sociobiological phenomenon of helpers cannot be
studied in isolation. An understanding
requires typical ethological study of incubation, foraging, territorial and other individual behavioral patterns, as well as zoosemiotic analysis of communication signals.
CONCLUSIONS
Ours is the era of science. In the last
quarter century our world view has turned
over almost completely, based on a staggering accumulation of scientific findings.
From the discovery of subatomic particles
to radio-frequency probing of the cosmos,
science has revealed Nature's secrets in the
molecular bases of heredity, the functioning of cells, transposable genes, the earth's
history and its effects on the evolution of
life, the composition of our own solar system, and hundreds of other areas. The
temptation to become a sort of scientific
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