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Distress call playbacks are used as deterrents to keep birds out of areas where they are causing problems. However, the calls often are ineffective, owing to birds' rapid habitation to them. Recent studies on the functional significance of distress calls indicate that adult passerines only distress call when physically constrained and that the calls are designed to startle the predator holding the caller into releasing it. Further, distress calls attract other birds, which approach the caller to acquire information about the predator. These findings suggest that distress calls would be more effective if their broadcast is paired with a predator model that appears to be grasping the caller. Such a pairing should reinforce a bird's fear of the predator model and delay its habituation to the distress call.
University of Nebraska - Lincoln
DigitalCommons@University of Nebraska - Lincoln
Proceedings of the Sixteenth Vertebrate Pest
Conference (1994) Vertebrate Pest Conference Proceedings collection
Michael R. Conover
Berryman Institute and Wildlife Damage Management Program, Department of Fisheries and Wildlife, Utah State University,
Logan, Utah
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CALL PLAYBACKS" (1994). Proceedings of the Sixteenth Vertebrate Pest Conference (1994). Paper 12.
MICHAEL R. CONOVER, Berryman Institute and Wildlife Damage Management Program, Department of Fisheries
and Wildlife, Utah State University, Logan, Utah 84322-5210.
ABSTRACT: Distress call playbacks are used as deterrents to keep birds out of areas where they are causing problems.
However, the calls often are ineffective, owing to birds' rapid habitation to them. Recent studies on the functional
significance of distress calls indicate that adult passerines only distress call when physically constrained and that the calls
are designed to startle the predator holding the caller into releasing it. Further, distress calls attract other birds, which
approach the caller to acquire information about the predator. These findings suggest that distress calls would be more
effective if their broadcast is paired with a predator model that appears to be grasping the caller. Such a pairing should
reinforce a bird's fear of the predator model and delay its habituation to the distress call.
Proc. 16th Vertebr. Pest Conf. (W.S. Halverson& A.C. Crabb,
Eds.) Published at Univ. of Calif., Davis. 1994.
Distress call playbacks have been used for decades to
keep birds out of areas where they are causing problems
(Frings and Jumber 1954, Frings et al. 1955). Their
ability to repel birds has been evaluated in agricultural
fields (Boudreau 1975, Naef-Daenzer 1983, Summers
1985), airports (Blokpoel 1976), fish ponds (Spanier
1980), and roosts (Pearson et al 1967, Brough 1969).
Usually, distress call playbacks effectively deter birds for
only a few days or weeks before habituation sets in.
Hence, distress call playbacks are most effective for
short-term problems such as protecting a ripening field
that will be harvested in a few days or in dispersing a
group of birds that are migrating through an area.
Before distress call playbacks can live up to their
potential of alleviating longer-term problems, we need to
know why birds habituate rapidly to them and what can
be done to delay this process. In this regard, we must
understand why birds distress call and how other birds,
who hear a distress call, interpret it and what they expect
to find when they approach the caller.
Distress calls are emitted by adult birds which are
physically constrained by a predator (Schmidt and Johnson
1984) and are distinctive from alarm calls (Thompson et
al. 1968; Stefanski and Falls 1972a, 1972b; Starkey and
Starkey 1973). Two major hypotheses have been
proposed to explain why an adult bird facing imminent
predation should distress call. The startle-the-predator
hypothesis states that a bird distress calls to startle the
predator into releasing it (Driver and Humphries 1969),
The other hypothesis is that distress calls are designed to
attract attention to the caller (attract-attention
hypothesis). There actually are four subcategories of this
hypothesis that differ in whose attention the caller is
trying to attract and what the intended recipient is suppose
to do when it arrives. The request-aid hypothesis states
that a bird distress calls to solicit the aid of kin or other
birds (reciprocal altruists) to help it escape.
The warn-kin hypothesis assumes that distress calls
are designed to warn kin about the dangerous predator
that has captured the caller and hence to increase the kin's
probability of surviving. This hypothesis argues that
distress calling does not increase the caller's chances of
surviving the predator attack but does enhance the caller's
inclusive fitness by increasing the probability of its kin
avoiding a similar fate.
The attract-an-audience hypothesis assumes that birds
can gain valuable information by witnessing a predator-
prey interaction and use that information to avoid
predation in the future (Conover 1987). This hypothesis
states that sometimes the predator's best interest is to
release a victim rather than attract the attention of too
many birds. This hypothesis is supported by the finding
that birds can acquire information from watching
predator-prey interactions (Kruuk 1976, Curio et al. 1978,
Conover and Perito 1981, Conover 1984, Shields 1984,
Conover 1987).
The attract-another-predator hypothesis argues that
distress calls are given to attract a second predator that
will threaten or disturb the predator which has seized the
caller, allowing the latter an opportunity to escape. This
hypothesis is supported by the observations that distress
calls sometimes attract predators (Perrone 1980, Hogstedt
1983, Koenig et al. 1991).
Recent experiments support the startle-the-predator
hypothesis. Some captive raccoons (Procyon lotor) and
opossums (Didelphis marsupialis) that were attacking a
caged starling (Sturnus vulgaris) were startled when a
distress call was first broadcast, and they released the bird
(Conover, in press). Prior to the call's onset, these
predators exhibited no such behavior.
Conover (in press) demonstrated that distress calls
usually consisted of a brief series of notes less than five
seconds in duration and that these were followed by
periods of silence before another distress call was
initiated. This pattern was consistent with the startle-the-
predator hypothesis, but the attract-attention hypothesis
predicted long and continuous calls to increase the
chances that the intended recipient would be able to hear
the caller and locate it.
Conover (in press) also showed that birds are more
likely to distress call when they have an opportunity to
escape from the predator's grasp, as expected with the
startle-the-predator hypothesis. For instance, birds
distress call more when held loosely or by their limbs
than when held securely by the body or neck. These data
support the startle hypothesis. In contrast if the only
function of a distress call were to attract attention, then a
bird should distress call more when held securely by the
body or head because its chances of escaping on its own
are diminished and its need for aid is increased.
Upon hearing a distress call, birds usually approach
the caller rather than flee or hide. They do not usually
attack the predator or engage in any behavior that would
aid the caller, but rather they observe the predator
(Conover, in press). Birds engage in this behavior to
acquire information about the predator and are able to use
this information to reduce their own chances of falling
prey in the future (Conover and Perito 1981, Conover
1987, Conover, in press).
Such findings indicate that birds, which approach the
sound source when they hear a distress call playback, are
expecting to see a bird being physically constrained by a
predator. However, wildlife damage managers rarely pair
distress call playbacks with predator models or other
visual stimuli. This lack of pairing may reduce the
effectiveness of distress calls and allow birds to habituate
to their playback more rapidly than would otherwise be
the case. If distress call playbacks are paired with a
predator model, especially one that appear to be grasping
the caller, birds that approach the sound source might
have their initial fears reinforced rather than alleviated.
Support for this hypothesis comes from the findings that
starlings and American crows (Corvus branchyrhynchos)
habituated less to plastic owl models when the models
appeared to be grasping a struggling bird in their talon
(Conover and Perito 1981, Conover 1984).
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BOUDREAU, G. W. 1975. How to win the war with
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BROUGH, T. 1969. The dispersal of starlings from
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CONOVER, M. R. 1984. Protecting vegetables from
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CONOVER, M. R. 1987. Acquisition of predator
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CONOVER, M. R., and J. J. PERITO 1981. Response
of starlings to distress calls and predator models
holdingconspecific prey. Z. Tierpsychol. 57:163-172.
CONOVER, M. R. In press. Stimuli eliciting distress
calls in adult passerines and response of predators and
birds to their broadcast. Behav.
CURIO, E., U. ERNST, and W. VIETH. 1978. The
adaptive significance of avian mobbing. II. Cultural
transmission of enemy recognition in blackbirds:
effectiveness and some constraints. Z. Tierpsychol.
DRiyER, P. M., and D. A. HUMPHRIES. 1969. The
significance of the high-intensity alarm call in
captured passerines. Ibis 111:243-244.
FRINGS, H., and J. JUMBER. 1954. Preliminary
studies on the use of a specific sound to repel
starlings (Sturnus vulgaris) form objectionable roosts.
Science 119:318.
1955. Recorded calls of herring gulls (Larus
argentatus) as repellents and attractants. Science
HOGSTEDT, G. 1983. Adaption unto death: function of
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KOENIG, W. D., M. T. STANBACK, and P. N.
HOOGE. 1991. Distress calls in the acorn
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KRUUK, H. 1976. The biological function of gulls
attraction towards predators. Anim. Behav. 24:146-
NAEF-DAENZER, L. 1983. Scaring of carrion crows
{Corvus corone corone) by species-specific distress
calls and suspended bodies of dead crows. Proc. Bird
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1967. Dispersal of urban roosts with records of
starling distress calls. J. Wildl. Manage. 31:502-506.
PERRONE, M. JR. 1980. Factors affecting the
incidence of distress calls in passerines. Wilson Bull.
SCHMIDT, R. H., and R. J. JOHNSON. 1984. Bird
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SHIELDS, W. M. 1984. Barn swallow mobbing: self
defense, collateral kin defense, group defense, or
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SPANIER, E. 1980. The use of distress calls to repel
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J. Appl. Ecol. 17:287-294.
STARKEY, E. E., and J. F. STARKEY. 1973.
Description of an aerial predator alarm call for
mallard (Anas platyrhynchos) ducklings. Condor
STEFANSKI, R. A., and J. B. FALLS. 1972a. A study
of distress calls of song, swamp, and white-throated
sparrows (Aves: Fringillidae). I. Intraspecific
responses and functions. Can. J. Zool. 50:1501-
STEFANSKI, R. A., and J. B. FALLS. 1972b. A study
of distress calls of song, swamp, and white-throated
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SUMMERS, R. W. 1985. The effect of scarers on the
presence of starlings (Sturnus vulgaris) in cherry
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and G. W. CORNER. 1968. Differential heart rate
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origin. J. Wildl. Manage. 32:888-893.
... It is believed that the rise in collision rates is largely due to the increasing number of roads (Unsworth et al. 1993;Debruijn 1994;Mace et al. 1996), and the upgrading of roads, which has resulted in increased vehicle speed (Jones 1994) and volume (Drews 1995;Fahrig et al. 1995;Bruinderink & Hazebroek 1996) on roadways. However, documentation of collisions is often sketchy and incomplete, suggesting that the rate of animal/vehicle collisions, damage to vehicles and injury to animals may all be greater than estimated (e.g., Romin & Bissonnette 1996;Committee 1997;Philcox et al. 1999). ...
... The mean annual number of humans killed or injured in collisions between ungulates and vehicles in Europe (excluding Russia) has been estimated at 507,000 (Bruinderink & Hazebroek 1996). In Australia, 3296 animal/vehicle collisions were reported to police between 1990 and 1994 because they fit police criteria, the vehicle either needed to be towed or humans were injured (Committee 1997). ...
... Driver experience and awareness can also have an effect on the likelihood of a collision. New drivers, or those unfamiliar with the country or roadways, are more likely to be involved in collisions with animals (Committee 1997). This is particularly true for tourists who may be unaware of 'hot-spots' where collisions occur frequently (Woodward 1994;Committee 1997). ...
... Anti-predatory behaviour in birds has been studied extensively in the field of behavioural ecology. Most of the 90 studies on this topic aim to understand the mental processes that cause learning to occur, and rarely deal with the 91 issue of crop protection (Conover, 1994;Conover and Perito, 1981;Griffin, 2009Griffin, , 2004. Nevertheless, these 92 studies provide valuable fundamental knowledge that can inform us of how a UAV can be converted into a novel 93 predator, which the birds can potentially learn to recognise and avoid in the long term. ...
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Bird damage to commercial crops is a significant problem across the globe, especially for high value crops like wine grapes. Various bird control methods have been developed in the past to reduce bird damage. After a brief review of the current bird damage control strategies, we found the most effective methods, such as netting and hiring a human scarer, rely on intensive manual labour, as well as fragile and costly infrastructure. Whereas the cheaper methods, such as using alarm calls and predator models, are effective for no more than two weeks before the birds habituate to them. We are proposing a novel Unmanned Aerial Vehicle (UAV, more commonly referred to as drone) system incorporating bird psychology for efficient bird damage control. The UAV is equipped with a loud speaker broadcasting distress calls, as well as a crow taxidermy installed on the undercarriage that appears as captured prey. This special UAV configuration is designed to engage birds’ well-established abilities to learn to recognise and avoid novel predators, thus providing the benefit that a long-term fear response towards the UAV can be expected. The initial trials were carried out in vineyards around south-eastern Australia. Results indicated the UAV can deter large pest birds such as ravens and cockatoos in a 50-m radius centred on the UAV for an extended period of time. The UAV can also effectively deter small pest birds such as silvereyes for brief time periods after exposure to the UAV. It is also evident from the results that while one UAV is sufficient to protect vineyards smaller than 25 ha, multiple UAVs are needed to protect a large vineyard effectively.
... Playback vocalizations of the infrequently emitted 'cry' vocalization of Congo Peafowl Afropavo congensis have been highly effective in stimulating locomotor activity and vocalizations of this species [Kuiper, 1997]. It has been suggested that the playback of songs could be used as enrichment in conditioning and in stimulating breeding and territorial calls [Bird and Johnson, 2001], but care is needed when using playback calls as these may elicit stress responses from conspecifics and can have negative effects [Conover, 1994]. Finally, classical music has been reported to reduce fearfulness (measured by increased feeding time and decreased tonic immobility) in meat chickens [Cornetto and Estevez, 2001]. ...
With the increase of mixed species exhibits in zoos, targeting enrichment for individual species may be problematic. Often, mammals may be the primary targets of enrichment, yet other species that share their environment (such as birds) will unavoidably be exposed to the enrichment as well. The purpose of this study was to determine if (1) auditory stimuli designed for enrichment of primates influenced the behavior of captive birds in the zoo setting, and (2) if the specific type of auditory enrichment impacted bird behavior. Three different African bird species were observed at the Buffalo Zoo during exposure to natural sounds, classical music and rock music. The results revealed that the average frequency of flying in all three bird species increased with naturalistic sounds and decreased with rock music (F = 7.63, df = 3,6, P = 0.018); vocalizations for two of the three species (Superb Starlings and Mousebirds) increased (F = 18.61, df = 2,6, P = 0.0027) in response to all auditory stimuli, however one species (Lady Ross's Turacos) increased frequency of duetting only in response to rock music (X(2) = 18.5, df = 2, P < 0.0001). Auditory enrichment implemented for large mammals may influence behavior in non-target species as well, in this case leading to increased activity by birds. Zoo Biol. XX:XX-XX, 2016. © 2016 Wiley Periodicals, Inc.
... Video playbacks, if effective, could be used in association with acoustic stimuli (e.g. distress calls) currently used to frighten and relocate birds that create conflicts with human activities, such as starlings in urban roosts, which constitute a major problem worldwide (Feare, 1984;Conover, 1994). ...
Multilevel societies are formed when stable groups of individuals spatially overlap and associate preferentially with other groups, producing a hierarchical social structure.1 Once thought to be exclusive to humans and large mammals, these complex societies have recently been described in birds.2,3 However, it remains largely unclear what benefits individuals gain by forming multilevel societies.1 One hypothesis-based on food sharing in hunter-gatherers4-is that multilevel societies facilitate access to a range of cooperative relationships, with individual investment varying across the hierarchical levels of the society. We tested experimentally whether such graded cooperation occurs in the multilevel society of a songbird, the superb fairy-wren (Malurus cyaneus). Specifically, we measured whether responses to playbacks of distress calls-used to recruit help when in extreme danger-varied according to the social level at which the focal individual is connected with the caller. We predicted that anti-predator responses should be highest within breeding groups (the core social unit), intermediate between groups from the same community, and lowest across groups from different communities. Our results confirm that birds exhibit the predicted hierarchical pattern of helping and that, within breeding groups, this pattern is independent of kinship. This pattern of graded helping responses supports the hypothesis that multilevel social structures can sustain stratified cooperative relationships and reveals similarity in cooperation in qualitatively different behaviors-anti-predator behavior and food sharing-in the multilevel societies of songbirds and humans.
Egyptian Geese Alopochen aegyptiaca are distributed across most of Africa. Their calls dominate the soundscape of many urban areas, yet their acoustic behaviour is poorly documented or understood. Using acoustic recordings made across a range of behavioural contexts, groups sizes and compositions, we identified a repertoire of eight distinct call types (loud, honk, short honk, hiss, soft, short soft, flight and noisy). Call classification was well supported by a supervised random forest analysis conducted on six robust time-frequency explanatory factors. Our results support a sexually dimorphic call repertoire, where both sexes produce a long, intermediate and short call type with energy distributions and structure (diffuse vs strongly pulsed) varying between types. All call types were produced in bouts. Honk bouts were longer and contained more calls when simultaneous calling by conspecifics was present, in particular when honk matching occurred. When matching or distant calls were found, honk bouts were more likely to continue. Our results document hidden complexity in the acoustic signalling of Egyptian Geese and highlight avenues for future investigation into the behaviour of this urban adapted species
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Рассмотрены недостатки и преимущества биоакустических устройств отпугивания птиц для применения на муниципальных объектах. Выполнен анализ их технических характеристик, ценовой политики, особенностей использования.
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p>The complex of measures on safety, considerable importance is the monitoring system and integrated the fight to reduce the number of air flight hazard species of birds (rooks, crows, magpies, hawks, etc.). Experience has shown that even periodic shooting does not give the desired effect, ie. A. The bird population is very mobile and able to move quickly scattered and maneuvering that practically negates all efforts for their physical elimination. The use of poisoned baits is prohibited and is ineffective, t. To. Various species of birds have different food preferences. Our research is devoted to finding a solution to this problem. As the main operational measures for scaring birds we offer the use of bio-acoustic instrument with a sound recording, effectively acting on air flight hazard species of birds, including corvids and Black Kite, which are not optional in many similar devices. Application of bioacoustics devices does not require an additional set of fireworks scare, but also an integral character of the device significantly increases the efficiency of the impact on birds and allows for a few minutes to eliminate concentrations of birds in large areas. The study analyzed information on aircraft collisions with birds, considered the scheme of air traffic, as well as the general plan for the landfill site, the Civil Aviation documents ornithological flight operations, carried out the operational test site survey. OAO Ekokompleks operates only in Barnaul licensed landfills for disposal of solid waste, located at the address: Barnaul, Cosmonavtov Prospekt, 74. The total area of the polygon - 328,679.7 square meters, the amount of dumping per year - 1800 thousand cubic meters Coordinates: 53 ° 23'24 "N, 83 ° 37'54" E. Availability of the current municipal landfill waste at a distance of 6.3 km from the aerodrome reference point Barnaul, in violation of the requirements of Claim 59 of the Federal Rules of use of air space of the Russian Federation of 11.03.2010 number 138. The conditions of surrounding environment determine the composition and behavior of birds, attending a training ground and pose a potential hazard to aircraft operations. On landfill dumping is carried out various types of waste, including food, are used by some species of birds as food. According to a preliminary survey, the main species of birds that use the landfill as a forage habitat - black kite, corvids - gray, crow, rook, jackdaw and gulls - silver and black-headed gull. Based on many years of observations and data analysis of the circumstances and consequences of collisions of Russian aircraft with birds stand air flight hazard species of birds, creating the greatest threat to flight safety. To the list of air flight hazard species include the black vulture, hooded crow, rook, magpie, jackdaw.</p
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Copyright® 1983 by ASTM International. Used by permission.
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An animated model of a great horned owl Bubo virginianus grasping a model of an American crow Corvus brachyrhynchos significantly reduced crow damage compared to controls and to non-animated models. -P.J.Jarvis
In Switzerland, carrion crows can cause considerable damage to sprouting corn fields when feeding on the germinated corn. I tried to evaluate a method to prevent these damages. The use of species-specific distress calls, for the first time described by Frings and Jumber (1954), seemed to be the most promising method. Agronomes and biologists have applied it in field studies to several different bird species causing damage in agriculture and on airports (e.g., Gramet, 1962; Brough, 1968). However, the literature either describes single actions or several different scaring devices being used together. To be able to judge the method, quantitative information about reduction of damage, habituation, and some practical information about the construction of an effective apparatus was needed. Distress calls proved to be a very effective method to keep carrion crows from sprouting corn fields, while suspended bodies of dead crows had no scaring effect. With distress calls, the chosen intervals of 25 minutes with 20-30 seconds broadcasting proved to be appropriate. Among the factors influencing crow damage on corn fields, the most important was extreme wetness. Another factor of importance was the date of sprouting of the plants. A possible reason for this is that earlier in the year crows find less food, which causes them to search the ground and forage on all possible sources; open arable land is frequently visited as it offers much insect food.
In tests to assess the fright-producing ability of proposed auditory repellents for starlings (Sturnus vulgaris), 75 single starlings isolated in an acoustical chamber were subjected to 10-second broadcasts of one of five sounds (the human voice and four starling calls-distress, escape, drug-induced, and feeding) repeated every 5 minutes until the bird became habituated. Throughout the test each bird's heart rate (HR) was monitored and recorded via telemetry. There were clear differences in the HR response to four of the five stimuli. The distress call was a strong fright-producing agent, requiring an average of 8.1 applications before the birds became habituated and producing a significantly higher HR acceleration (P < 0.01) than any other stimulus. The human voice, escape call, and drug-induced call were intermediate; they required 2.5-2.9 applications before habituation, but the human voice produced significantly greater acceleration (P < 0.05) than the other two. The feeding call was hardly more than a neutral stimulus, requiring only 1.2 applications and producing a significantly lower acceleration (P < 0.01) than any other stimulus. The fact that such clear differences existed in HR response suggests that the distress, escape, and feeding calls, at least, transmitted specific, different information to the birds. Telemetered HR can thus be used to predict the effectiveness of auditory repellents in the field, and may provide a useful tool in other behavioral research.
A starling (Sturnus vulgaris) roost in Denver, Colorado, that contained 5,000 birds in October, 1964, and 1,500 in July, 1965, was dispersed both years in four evenings by starling distress calls on records played by 8 to 13 residents as birds arrived at the roost. A second roost that formed a few blocks away contained more than 10,000 starlings and a few common grackles (Quiscalus quiscula) when it was dispersed in three evenings in October, 1965, with starling distress calls played by 34 residents. If the starlings found later in outlying roosts were from this urban roost, more than 85 percent were moved to areas where they were not a nuisance. Participation by about half of the residents in an urban roost area appears to be sufficient for starling dispersal. Contrary to observations by previous workers, habituation to calls did not materialize, despite almost continuous playing by several residents in each roost area.
Among the various methods of dispersing troublesome roosts of the starling, Sturnus vulgaris, the bio-acoustic technique has great promise. Using a portable 12 W amplifier to broadcast recorded distress calls, sometimes assisted by other scaring measures, attempts have been made to disperse thirty-three roosts. The calls were played when the birds arrived to roost and clearances were usually effected in three evenings or less. Most sites were vacated for the rest of the season although new roosts were sometimes formed less than 2 miles away. The limitations of the technique are discussed.
Acorn Woodpeckers live in extremely stable kin groups. Nonetheless, only 59.9% of birds caught in roosting aggregations gave distress calls or fear screams. Distress calling was highly repeatable among individuals and apparently heritable. However, the incidence of distress calling did not vary seasonally or according to age, sex, or status. Also, with two marginally significant exceptions, distress calls did not vary consistently with group characteristics or with the composition of roosting aggregations. Screams did not attract conspecifics, but sometimes attracted large mammalian predators. These results fail to support Rohwer's (1975) "calling for help" hypothesis and instead are consistent with Högstedt's (1983) "predator attraction" hypothesis that distress calls function to attract secondary predators that will distract or dispute the original predator, thereby inadvertently allowing the caller to escape.