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Why Rattle, Snake?

Nanci

Alien Lover
REALLY cool research!!http://www.jstor.org/stable/pdf/1564394.pdf?_=1469622835861


ABSTRACT.-A comparison of the acoustic characteristics (power spectra, intensity) of rattling sounds
made by 13 rattlesnakes representing 6 species revealed that rattling conforms to the same general pattern.
Although there was individual variation in lowest frequencies and bandwidths of the sounds, differences
between species were comparable to within-species variation. The rattlings of the snakes were medium-
intensity, broadband sounds (most energy from 2-20 kHz), with rapid onset and no structured changes in
frequency pattern over time. In all of these features they resembled the rattling of mechanical rattles such
as maracas. The rattling of snakes appears to be a signal designed to attract the attention of other animals
whose responses will reflect their hearing characteristics and previous experience.


Rattlesnakes occur in the New World and
represent a monophyletic group characterized
by rattles, which are epidermally-derived cau-
dal structures associated with specialized shak-
er muscles (Martin and Bagby, 1972, 1973;
Greene, 1988). In a recent review, Greene (1988)
concluded that the rattling was defensive and
not used in any other context such as intraspe-
cific communication. He noted that rattlesnakes
did not always rattle when threatened and that
rattling often was a second or third line of de-
fense against potential predators or large ani-
mals that might step on and injure the snake.
The rattling of a snake quickly attracts atten-
tion and has been identified as a "deimatic"
display, one designed to frighten the signal re-
ceiver (Edmunds, 1974), perhaps by startling it.
The rattling, however, could have different ef-
fects on naive and experienced animals. Fur-
thermore, the nature of the experience could
vary both with the setting of the encounter
(Loughry, 1987), and with the intent of the
threatening animal (Rowe and Owings, 1978).
Rattlesnakes occur in the New World and
represent a monophyletic group characterized
by rattles, which are epidermally-derived cau-
dal structures associated with specialized shak-
er muscles (Martin and Bagby, 1972, 1973;
Greene, 1988). In a recent review, Greene (1988)
concluded that the rattling was defensive and
not used in any other context such as intraspe-
cific communication. He noted that rattlesnakes
did not always rattle when threatened and that
rattling often was a second or third line of de-
fense against potential predators or large ani-
mals that might step on and injure the snake.
The rattling of a snake quickly attracts atten-
tion and has been identified as a "deimatic"
display, one designed to frighten the signal re-
ceiver (Edmunds, 1974), perhaps by startling it.
The rattling, however, could have different ef-
fects on naive and experienced animals. Fur-
thermore, the nature of the experience could
vary both with the setting of the encounter
(Loughry, 1987), and with the intent of the
threatening animal (Rowe and Owings, 1978).
Since biologists categorize an animal's defen-
sive display by an attacker's response (Endler,
1981; Schlenoff, 1985; Bates and Fenton, in press),
calling the rattling deimatic does not preclude
its also being aposematic.
Although several workers have described the
sounds of rattling snakes (e.g., Klauber, 1956;
Rowe and Owings, 1978), with the exception of
one abstract (Pylka et al., 1971), there are no
published comparisons of inter- and intraspe-
cific variation in these sounds. Similarities in
the pattern of development of the rattles of dif-
ferent species (Zimmerman and Pope, 1948) and
in their morphology (Klauber, 1956) suggest that
the sounds they produce also will be similar.
The purpose of this study was to examine the
sounds of rattlesnakes to test a series of predic-
tions about the nature of the sounds and how
they might affect the behavior of other animals.
While these predictions may conform to expec-
tations based on the unaided human ear, quan-
titative acoustic data are required to test them.
If the rattling of snakes is designed to attract
Since biologists categorize an animal's defen-
sive display by an attacker's response (Endler,
1981; Schlenoff, 1985; Bates and Fenton, in press),
calling the rattling deimatic does not preclude
its also being aposematic.
Although several workers have described the
sounds of rattling snakes (e.g., Klauber, 1956;
Rowe and Owings, 1978), with the exception of
one abstract (Pylka et al., 1971), there are no
published comparisons of inter- and intraspe-
cific variation in these sounds. Similarities in
the pattern of development of the rattles of dif-
ferent species (Zimmerman and Pope, 1948) and
in their morphology (Klauber, 1956) suggest that
the sounds they produce also will be similar.
The purpose of this study was to examine the
sounds of rattlesnakes to test a series of predic-
tions about the nature of the sounds and how
they might affect the behavior of other animals.
While these predictions may conform to expec-
tations based on the unaided human ear, quan-
titative acoustic data are required to test them.
If the rattling of snakes is designed to attract
general attention, we predicted that they will
be broadband, and if this function is the same
for different species of rattlesnakes, intra- and
interspecific variation in the sounds should be
comparable. If the rattling is designed to sur-
prise other animals and hold their attention,
the sounds should show rapid onset and little
change in acoustic features over their duration.
If the sounds are designed to protect the snake
from close approach by another animal, they
should be intense enough to cause discomfort
or even pain. Finally, if the rattling was in-
tended for communication with other rattle-
snakes, the acoustic properties of the sounds
should reflect the hearing capacity of the snakes
themselves.
 
Thanks Nanci! Keep the scholarly snake articles coming. I love them. I also believe knowing the facts is really important!
 
Thanks Nanci! Keep the scholarly snake articles coming. I love them. I also believe knowing the facts is really important!

Ditto! :cool:

It is amazing how many folks are opinionated and SWEAR that what they know supercedes any and all that have come before AND after them without ever citing ONE fact or credible theory which is supported by empirical research or data. In the field of human services & abnormal psych, of which I am a part of professionally since 1992 - and para-professionally on & off since 1980! - unless an article is considered a "classic," such as many of Freud's and similarly well-known authors who are considered groundbreakers or iconoclasts (i.e., Handelmann, Szaz, Foucalt, to name a few), articles which are written only within the past five years are considered as valuable sources or information. In herpetology, I'm not so sure. Therefore, I read all (or most) with an equally inquisitive nature and curiosity. :dunce:

Thanx for your valuable citations Nanci!! :crazy01:

BTW, for those who may have a hard or difficult time with some of the vocabulary used in these articles, don't feel bad if you have to read something over a few times to understand it or even have to look some of the terms up. There is NO WAY I knew what an anapsid was without looking it up! KNOWLEDGE DOES NOT SEEP INTO OUR BRAINS BY OZMOSIS OR BY PLACING A TEXTBOOK UNDER YOUR PILLOW AT NIGHT WHERE THE INFORMATION WILL PERMEATE YOUR GREY MATTER BY MORNING!!! (At least, it doesn't work that way in MY little corner of the world).

And remember that "the armature sprocket causes interference in the combustion line, which in turn causes an interruption within the flow in the dyna-flow!" - Ed Norton (The Honeymooners, circa 1957)
 
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