calculated from models are shown.Download figureOpen in new tabDownload powerPoint. Furthermore, I demonstrate by playback experiments that two of these species, meerkats (Suricata suricatta) and pied babblers (Turdoides bicolor), are deceived by both drongo-specific and mimicked false alarm calls. 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]. Predicted mean values ± 1 s.e. During focal observations I recorded all calls made by the focal drongos, other ringed drongos associating with them, and the species that focal drongos were following, from a distance of 2–30 m using a Sennheiser ME67 shotgun microphone coupled to a Marantz PMD660 digital recorder (sampling rate of 44.1 kHz and 16 bit resolution). (d) Call type did not significantly affect the likelihood that pied babblers abandoned food (GLMM: χ22 = 3.34, p = 0.188 (see electronic supplementary material S2, table S2)). He said, “I’ve trained the drongos to come to a call. The 10 highest quality false mimicked alarm calls of glossy starlings made by different drongos were selected for comparison with 10 true alarm calls made by glossy starlings in response to raptor species. Sometimes drongos stole food by attacking targets (52 ± 8% of kleptoparasitisms). Playbacks were made to 22 meerkats in 11 groups, and 20 pied babblers in 10 groups (two individuals per group) and there was a two-week break between experimentation on the first and second individual at a group. Calls were displayed in spectrograms and measurements were taken from them for the same five parameters previously defined in the drongo-specific call analysis. To determine whether drongo-specific alarm calls were the same when made in true and false alarms, I compared structural components of one of the drongo-specific alarm calls, the ‘chink’ call, when made by the same drongo in true and false alarms (figure 1a–c). Drongos are able to steal food even if it is dropped only for an instant and directly next to the target individual (T. Flower 2008, personal observations), so these are conservative conditions that would enable them to steal a food item from a target. Figure 2. Est. Consequently, they were habituated to close observation (less than 2 m) and were individually recognizable by unique dye marks on their fur or unique colour rings, respectively. When they did so, I interpreted these calls as true alarms, and observed an approaching predator (raptors, owls, foxes and mongoose species) on 98/190 occasions. Target individuals fled to cover in response to false alarm calls in 211/258 (82%) cases, leaving their food behind on 140/258 (54%) occasions, enabling the drongo to fly down and steal it. This classification is used as the reference against which other classification results are … Drongo non-alarm calls were recorded in the same context as for the drongo-specific alarm call playbacks; glossy non-alarm calls were recorded from individual glossy starlings in the absence of predators as they foraged, at locations at least 800 m apart (see electronic supplementary material, S1 for sonograms of non-alarm calls). True and false chink calls were available for 12 individual drongos. He said “This kind of access to so many different animals is unrivalled anywhere in the world and was key to the observations and experiments that underpinned my findings.” Dr Flower is now following juvenile drongos during their development, to learn more about how they learn the mimicking behaviour. These results support the three criteria outlined in this study; firstly, drongo false alarm calls were specifically made in kleptoparasitism and rarely made in non-alarm contexts; secondly, the drongo-specific and mimicked calls made by drongos in false alarms were the same as those made in true alarms by drongos and other species; thirdly, target species alarmed in response to both true and false drongo-specific and mimicked alarm calls, which caused them to abandon their food. Although group members were less likely to respond to drongo false alarms than drongo true alarms (Fisher's test: p = 0.005), there are several probable explanations for this. It therefore appears that both meerkats and pied babblers are deceived by drongo-specific and mimicked false alarm calls. Meerkats were provisioned with a live scorpion (of genus Opistophthalamus) collected at the field site and handled with tongs; meerkats commonly eat scorpions. Safari company False alarm calls as a means of resource usurpation in the great tit, Monkeys crying wolf? Data were analysed in a paired MANOVA. Celebrate Africa and do good. Dr Flower said, “That means that I and other researchers can get right into the thick of the action. The drongo, an African bird, deceives other species, including meerkats, by mimicking their alarm calls in order to scare them away and steal their abandoned food, according to a new study published in the 2 May 2014 edition of the journal Science. However, deceptive signals typically become ineffective when made too frequently relative to their honest counterpart [8,27]. This could explain why pied babblers did not abandon their food in response to playbacks of drongo-specific chink alarms, one of the most frequently made false alarm calls. And wouldn’t that be a pity? 1991. This work also provides valuable insight into the benefits of deploying variable mimetic signals in deceptive communication. When and where to go in Africa, and with whom. Multifactorial analyses involved repeated sampling of individuals or exemplars. Measurements were made on five parameters: (i) duration (ms); (ii) call frequency range, calculated as the maximum peak frequency measurement from the entire call minus the minimum peak frequency measurement (Hz); (iii) peak frequency (Hz); (iv) Wiener entropy (at peak frequency), which is a measure of the randomness of sounds where 1 = random noise and 0 = pure tone; and (v) frequency change, calculated as peak frequency at the end of a call minus peak frequency at the start of the call (Hz). Food items were categorized by size relative to drongo bill length; the corresponding wet mass of items of these sizes has been previously established [21] which enabled the calculation of food mass intake per hour for each focal observation. Mimicry could be particularly advantageous in this system, since deceptive signals typically become ineffective when made too frequently relative to honest signals [8] and by changing their false alarm calls, a species could maintain deception. When following target species, drongos kleptoparasitized food items from them including insect larvae, reptiles, scorpions and crickets, contributing an average 22 ± 4% to biomass intake per focal drongo. Playback experiments were undertaken to determine whether the species targeted by drongos respond to false mimicked alarm calls made by drongos and whether they differentiate between the drongos' false mimicked alarm calls and the true alarm calls of the species mimicked. Drongos were also observed interacting with 18 other bird species. I created 11 exemplars each comprising three different calls made by the same drongo to avoid pseudoreplication of my playback stimulus [23]. 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