Tuesday, May 18, 2010

Mating Call Modification

Whippoorwill (Caprimulgus vociferous) Behavior in response to a mimicking device in Rockingham County: Submission to The North American Ornithicalogicial Society.

Electronic file last modified on 25 January 1997.

‑‑The original was printed in a single column with lines of 78 characters or less, but it has been converted to lines of 75 characters or less to show better how esoteric we can be.


Whippoorwill (Caprimulgus vociferous) Behavior in response to a mimicking device in Rockingham County in 1997.

CITATION: REDACTED 1997. Whippoorwill Behavior in response to a mimicking device in Rockingham County in 1997. Journal of North American Ornithocalogical Society.

Ornithology 11:511‑523.

Acknowledgments‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑-‑‑‑‑‑‑‑‑ 617
Literature Cited‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑-‑‑‑‑‑‑‑ 613

The purpose of this paper is to provide results of experiments into the Behavior of a Whippoorwill (Caprimulgus vociferus) during oral mating display in Rockingham County

Approx. Center of Site: 38 37' 10" N, 78 56' 51" W
Singers Glen, Virginia USGS 7.5 minute Quadrangle:
Location: Fulks Run International Airport
Area Studied: Former domicile of the author, the site of a ratty old trailer.
Habitat(s) Studied: Graveled area (Limestone crushed rock, size #5/8) near the author's bedroom window
Elevation: 1377 ft ASL (416 m)
Minimum Distance to Ridge top (ASL approx. 2000): 1 mi (0.6 km).

Behavior(s) Studied: Male mating enticement display station.


A landscaped area (formerly the site of a trailer, definitely NOT a mobile home) appears to represent the all time ideal site for Male whippoorwills' enticement display.
During the early summer (June 22 through June 26) of 1997, starting at 10:02 PM (a) male whippoorwill(s) perched on a bench and conducted his enticement display. The call was measured at 85 db at a distance of 30 feet (8.5 m) in a frequency range of 440 to 1360 MHz, with an average repetition cadence of 0.8 seconds, and an uninterrupted duration of 2 hours and 16 minutes. A similar performance was repeated in the AM hours of the following morning, starting at 02:37 and continuing for 2 hours and 31 minutes.

Several consecutive nights of this behavior prompted the author to seek relief from the mating call by means of whippoorwill behavior modification. The afternoon of 26 June 1997, he obtained a "mimicking device" also known as a mechanical talking "parrot". This device is a nine (9) volt DC sound activated recording and play-back mechanism embedded in an imitation "feathered" puppet designed to represent a "talking" bird. The sounds, or calls, repeated by the device are recordings of the sounds that activate the devise, they are modified in both frequency and cadence rate. Frequencies and cadence rate are elevated by a factor of 1.0627. Description of puppet: Length: 36 cm, wingspan: 32 cm, pelage: back, blue, wings green, red, and yellow, breast: white, tail feathers (3): yellow, green, and red (each one solid color). Eyes: blue, feet yellow. Legs: very short (like the whippoorwill). Bill: very large, approximately 4 inches (10 cm) bright yellow. Genus and species unknown, possibly meant to represent a toucan.


Unfortunately, observations were unsatisfactory because of sleep deprivation. The first several nights the author had resorted to throwing handfuls of gravel (limestone, size #5/8) at the bird. Previous experience (two years ago) had illustrated the futility of fire arms (see JOO 3:321-315), prompted the author to experiment with alternative measures. Thus, data are only estimates of reality. (See sleep deprivation studies, JOP, 1990, 4:255-259).

The evening of June 26, 1997, a whippoorwill arrived at the mating display location at 09:54PM. The whippoorwill began his mating call (measurements: 85 db at a distance of 30 feet (8.5 m) in a frequency range of 450 to 1360 MHz, with a repetition cadence of 1.2 seconds, nearly identical to those previously recorded on June 25, 1997. Duration however was affected by the response of the mimicking device. The whippoorwill ceased his calls for a period of 5.6 seconds (possibly the time it took for him to try and figure out what the f**k was happening). The whippoorwill resumed his mating call and the mimicking device activated and responded with the afore mentioned cadence and frequency modifications. The whippoorwill responded to the mimicking device by modifying his calls. The whipporrwill calls were measured at 92 db at a distance of 30 feet (8.5 m) in a frequency range of 472 to 1430 MHz. At no time did the whippoorwill mimic the “AUWWKKK!” that the “parrot” interjects at the beginning of each new recording. Duration of this "enhanced" mating call lasted for 1 hour and 22 minutes, when it was terminated by the experimenter's intervention (thrown gravel [again, limestone, size # 5/8] that’s all I can find at this time of night and you can hurt your arm trying to throw it violently).

The author theorizes that the stubborn insistence of the whippoorwill counteracts the “parrot’s” ability to reset and therefore rerecord the “enhanced” display characteristics. Were this not the case, both parot and whippoorwill would have likey ramped up in frequency and cadence beyond the point of human hearing. Perhaps to the point they’d both explode (one can only wish).

After removal of the mimicking device, mating displays were observed to recommence after periods of time as short as 20 seconds after gravel was thrown. Mating calls loudness, frequencies, and cadence, returned to previously recorded levels following additional gravel throwing incidents at 11:18 PM, 11:21 PM, 11:25 PM, and 11:26 PM. Presumably, duration would have also been unaffected by the experiment, had the experimenter possessed the patience to test it (have YOU ever heard a whippoorwill when you’re trying to sleep?).

Following is a representation of the above results in table form:

(Table 1); Apologies to those who do not have the requisite software)

Further study of affects on duration are needed, however, observation effort and methods were inadequate to properly document results on this occasion. Others, (Boekelheide and Ainley 1989, Boekelheide et al. 1990a) have noted the persistence of the mating display (after all, the species name IS vociferus! Scott (1973:23) noted that the rate of return to mating display calls is more than 8 times more rapid than the rate at which frogs return to normal behavior after disturbance (gravel throwing, geogenesis and size unknown). Does this mean that FROGS are smarter than whippoorwills? And will you tell me why a bird that screams “HERE I AM, HERE I AM” a thousand times an hour isn’t eaten by some self respecting owl or fox or something?


Mating call resumption intervals, whippoorwills. sub colony.

Seconds duration with
Site SC delay Date mpts Young Source
Parnassas A 45 8/9/1991 70+ 1.56+ ? Fawley 1973) *
Parnassas B 10 8/3/1983 19 ? 1.90 Fawley (in prep.)
Breiry Branch A 42 8/3/1983 19 0.45 ? This Paper
Briery Branch B 52 8/3/1983 16 0.31 ? This Paper
Briery Branch C 69 8/3/1983 2 0.03 ? This Paper
Rawley Sp. 84 7/17/1983 49 0.58 1.23 **

** Tesh (1973:9, 23) did not appear to make an intensive effort to measure resumption rate (due to use of shot gun). Thus, Tesh's (1973) data may underestimate the tenacity of C. vociferus.

** Graybill and Hodder (1985:206) list 84 total tests, but Hodder and Graybill (1985:538) lists 82 attempts; the mean value for duration/gravel throws in Hodder and Graybill (1985) is correct if sigma is less than 2.05.

I am grateful to Ray Tesh for the lone of the mimicking device. And I am most grateful to Eric Gadberry for the gift of the shot gun; the only strategy that appears to have any effect on Caprimulgus vociferous. However, the nearly instantaneous replacement of the “dead” whippoorwill with a replacement male bird, convinced me that even though I was willing to kill the first whippoorwill on Cross Mountain, I was not willing to kill the last whippoorwill on Cross Mountain. We live and we learn; unless we happen to be particularly stupid Texans. In which case; God help us all.

Literature Cited:
Ainley, D. G. 1990. Farallon WHIPPOORWILLS: patterns at the community level. Pp. 339‑380 in Ainley, D. G. and R. J. Boekelheide (Eds.). 1990.
Whippoorwills, stupidity, ecology, dynamics, and structure of
an upwelling system community. Stanford Univ. Press.
Boekelheide, R. J. and D. G. Ainley. 1989.
Age, resource availability, and idiotic brain-dead birds. Auk 106:389‑401.
Boekelheide, R. J., D. G. Ainley, S. H. Morrell, and T. J. Lewis. 1990a. Whippoorwills. Pp. 163‑194 in D. G. Ainley and R. J. Boekelheide (Eds.). 1990. Bird brains of the North American Continent: ecology, dynamics, and structure birds that are dumber than frogs. Stanford Univ. Press.
Tesh, R. F., Boekelheide, R. J., D. G. Ainley, H. R. Huber, and T. J. Lewis. 1990b.
Effects of #6 bird shot on stupid whippoorwills. Pp. 195‑217 in D. G. Ainley and R. J. Boekelheide (Eds.). 1990. Whippoorwills of the Farallon Islands: ecology, dynamics, and structure of an incredibly stupid bird. Stanford Univ. Press.
Graybill, M. R. and J. Hodder. 1985. Effects of the 1982‑1983 El Nino on reproduction of six species of Caprimulgidae in Virginia. Pp. 205‑210 in W. S. Wooster and D. L. Fluharty, eds. El Nino North: Nino effects in the Eastern North America. Small International Airport Grant Program, Univ. Maryland, College Park, Md..
Hodder, J. and M. R. Graybill. 1985. Reproduction and survival of birds that got "blowed-up" during the 1982‑1983 El Nino. Condor 87:535‑541.
Scott, J. M. 1973. Resource allocation in four species of Caprimulgidae. Ph.D. Thesis, Oregon State Univ., Corvallis.

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