Abstract
In many taxa, breeding success depends heavily on reliable vocal recognition between parents and offspring. Although the acoustic basis of this recognition has been explored in several species, few studies have examined the evolution of acoustic cues to identity across development. Here, in a captive breeding program, we investigated for the first time the acoustic signals produced by North African houbara bustard Chlamydotis undulata undulata chicks. Two call types (contact and distress) were recorded from 15 chicks in 4 age classes. Acoustic analyses showed that the acoustic parameters of the calls varied systematically with age in both contact and distress calls. However, both call types remained highly stereotyped and individualized between chicks at every tested age, indicating that calls encode reliable information about individual identity throughout development, thus potentially enabling the mother to distinguish her own chicks through their development up to fledging. Playback experiments are now needed to verify such parent-chick recognition in houbara bustards and its efficiency across chick ontogeny.
Highlights
Individual recognition between parents and offspring is crucial for maintaining parent−young bonds, for selective feeding and for avoiding misdirected expensive parental care, preventing fitness costs and increasing breeding success (Beecher 1981)
For all acoustic parameters of the contact calls (CC), interindividual CVs were significantly higher than intraindividual CVs at every age, and 9 temporal and frequency parameters had potential individual coding (PIC) values higher than 2 for at least one age (Table 2, Fig. S3), indicating a high probability for individual coding in call structure
The highest PIC values were measured for temporal parameters in the 2 first age categories (Age 1 and Age 2), whereas the highest PIC values were measured for frequency parameters in the last 2 age categories (Age 3 and Age 4)
Summary
Individual recognition between parents and offspring is crucial for maintaining parent−young bonds, for selective feeding and for avoiding misdirected expensive parental care, preventing fitness costs and increasing breeding success (Beecher 1981). Parent−offspring recognition has been documented in many taxa, including mammals (Bohn et al 2007, Charrier et al 2009, Pitcher et al 2010, Knörnschild et al 2013, Sibiryakova et al 2015), reptiles (Main & Bull 1996, Bull et al 1999) and birds (passerines: Leonard et al 1997, Draganoiu et al 2006, Levréro et al 2009; non-passerines: Lefevre et al 1998, Charrier et al 2001, Clark et al 2006) This ability is relevant for most bird species where chicks are wholly dependent on adults for food, warmth and protection against predators.
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