Playback experiments were undertaken to determine whether the species that drongos steal food from respond to drongo-specific alarm calls, and whether they distinguish between drongo-specific true and false alarms. Click here to receive our stories and photo galleries via email. A few weeks too early / late or a few kilometers off course and you could miss the greatest show on Earth. And wouldn’t that be a pity? Perhaps the best evidence of a function for vocal mimicry indicates that it is used deceptively by cuckoos whose chicks mimic the begging calls of host species, thus allowing them to evade rejection by host parents [7]. Photo credits: T. Flower, M. Boerner. (c) Pied babblers (n = 20) responded for longer to playback of true and false chink alarm calls than to non-alarm calls, but did not differ in their response to the true or false chink alarm calls (LMM: χ22 = 41.25, p < 0.001 (see electronic supplementary material S2, table S2)). Drongos used two strategies to kleptoparasitize food: (i) attack, the drongo flew directly at a target that was handling a food item and chased or attacked it; and (ii) call from perch, the drongo called from a perch while watching a target that was handling a food item, in response to which the target commonly fled to cover abandoning the food. Therefore, to determine what factors affect the response time of meerkats and pied babblers to calls and whether or not a target individual abandoned a food item, linear mixed models (LMMs) and generalized linear mixed models (GLMMs) were undertaken, respectively (see electronic supplementary material, S1 for further details). He’ll rapidly get back to his natural behaviour, hawking flies or following meerkats and babblers to steal their food, allowing me to tag along and watch what happens.”. The Department of Environment and Conservation for Northern Province, SA provided authorization for my work (FAUNA 270/2008) and the Percy Fitzpatrick Institute, University of Cape Town provided ethical permission (2010/V20/TF). One novel possibility is that false mimicked alarm calls may be used deceptively as part of a repertoire of alarm calls to scare and then steal food from (or kleptoparasitize) other species. If the address matches an existing account you will receive an email with instructions to reset your password. The study population consisted of 50 drongos habituated to close observation (less than 5 m), that had been captured and given individually unique colour rings. We publish inspiring and thought-provoking stories and photo galleries about African wildlife and safaris for our sophisticated international community. Factors affecting pup growth and survival in co-operatively breeding meerkats. Details of the habitat and climate have been published elsewhere [20]. In the drongo-specific alarm call playback experiment, the response time of meerkats and pied babblers to true or false alarm calls did not significantly differ, but were significantly longer than to non-alarm calls (figure 2a,c); further statistics for analyses of playback experiments are located in figures 1 and 2, and see electronic supplementary material, S2. The four calls were played at 20 min intervals to a meerkat or pied babbler that had been provisioned with a food item and the duration of alarm response and whether the food item was abandoned were recorded. Photo Galleries, Photographer of the Year. Further investigation of drongo call use could therefore provide valuable insights into the strategies employed by signallers in deceptive communication. False alarm calls were unlikely to be accidental alarm calls given coincidentally when target species found food, since drongos gave more alarms when following target species than when they foraged alone (paired t-test: T24 = −10.16, p < 0.001, n = 25 drongos). The drongos then make fake alarm calls that mimic other species and cause the meerkats to run for cover, allowing the drongos to swoop in. These results provide the first conclusive evidence that false alarm calls are deceptive and demonstrate a novel function for vocal mimicry. Drongos were also observed interacting with 18 other bird species. The drongo-specific and mimicked calls made in false alarms were structurally indistinguishable from calls made during true alarms at predators by drongos and other species. Publisher Juvenile drongos commonly accompanied adults that were stealing food using false alarms and subsequently made false alarms themselves. Pied babblers were presented with three mealworms impaled on a thorn to increase handling time since the babbler had to remove them before eating. A minimum of six focals were collected per drongo (mean total observation time per drongo: 10.47 h, range: 4.02–20.10) between March 2008 and July 2008. Furthermore, meerkats and pied babblers did not differ in the likelihood they abandoned food in response to the true glossy starling and false drongo-mimic alarm calls, but were more likely to do so in response to these calls than to non-alarm calls (figure 3b,d). Animals commonly eavesdrop on the alarm calls of other species in their environment [6,24,25] and drongos appear to exploit this behaviour by using deceptive alarm calls to steal food from target species [16]. Of these, six were considered drongo-specific alarm calls since they were recorded from at least 20 of 25 focal drongos, were the call types most likely to be made in both true and false alarms, and were never recorded from other species. Drongo species, including fork-tailed drongos, are renowned vocal mimics and the racket-tailed drongo is known to mimic alarm calls [18,19], a behaviour which has also been anecdotally reported for the fork-tailed drongo [18]. (a) Meerkats (n = 20) responded for longer and (b) were more likely to abandon food, in response to playback of false (drongo-mimicked) and true glossy starling alarm calls than to non-alarm calls of these species, but did not differ in their response to the false (drongo-mimicked) and true glossy starling alarm calls (LMM response time: χ23 = 50.44, p < 0.001; GLMM abandon food: χ23 = 11.72, p = 0.008 (see electronic supplementary material S2, table S3)). (a) Meerkats (n = 22) responded for longer and (b) were more likely to abandon food in response to playback of true and false chink alarm calls than to non-alarm calls, but did not differ in their response to the true or false chink alarm calls (LMM response time: χ22=48.29, p < 0.001; GLMM abandon food: χ22 = 6.25, p = 0.044 (see electronic supplementary material S2, table S1)). Drongos made a wide variety of alarm call types during both true and false alarms [22]. To conclusively demonstrate that false alarm calls (both species-specific and mimicked) are deceptive, it must be shown that: (i) false alarms are specific to deceptive contexts and are rarely if ever made in direct physical attacks on targets; (ii) the type of calls made in true alarms at predators are the same as the types of calls made in false alarms to scare target species and steal their food; and (iii) that the target species react with a similar alarm response to playbacks of alarm calls originally recorded in a true or false context. These false alarms not only influenced the target, but also other group members, which also fled to cover in 110/183 (60%) cases where their response was recorded. Playbacks were undertaken only when group members were engaged in foraging, and at least 5 min after any natural alarm or group disturbance. However, they also follow other species, including pied babblers and meerkats, catching food that the species flush as they forage, and occasionally kleptoparasitize food directly from them [14,16]. Playback amplitude was standardized at 80.3 db at 3 m, which was the mean amplitude of alarm calls given in response to a hawk glider model (see electronic supplementary material, S1 for details).

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