Assortative Pairing Based on Contact Call Similarity in Budgerigars, Melopsittacus undulatus

Abstract

A trait typical of parrots, but rare in other groups of birds, is the acquisition of new learned calls (acquired by copying conspecifics) throughout an individual's lifetime. The significance of this distinctive psittacid trait is not understood. In budgerigars, females preferentially affiliate with unfamiliar males whose contact calls resemble their own during brief dyadic choice trials; also, in forced‐pair situations, contact call similarity of members of pairs increases as a result of a male tendency to imitate his mate's call type. The functions of budgerigar call imitation and preference for pre‐pairing similarity are currently unknown. Moreover, as budgerigar pair formation occurs over a span of days or weeks, it is important to determine whether birds in breeding colonies assort and proceed to breed on the basis of pre‐pairing contact call similarity, and whether high levels of call similarity are maintained after pair formation is complete. To explore these questions, we recorded contact calls of male and female budgerigars before and after they were placed into an aviary equipped for breeding. As predicted, birds paired assortatively based on pre‐pairing call similarity. Once birds had paired, their calls converged further in acoustic structure, as previous work had led us to expect. However, after eggs were laid and the males began to feed their mates, the calls of mated birds diverged, suggesting that there might be some cost to maintenance of shared calls. Male care‐giving correlated with the degree to which his pre‐pairing calls resembled those of his mate, but not with the similarity achieved through convergence. These results suggest that female budgerigars may use a male's pre‐pairing call similarity as a predictor of paternal investment. The questions of why such similarity predicts male care‐giving, and why calls converge following initial pairing activities, require further work.

A test of multiple hypotheses for the function of call sharing in female budgerigars, Melopsittacus undulatus

“…Other hypotheses have been proposed for call sharing including the mate attraction and pair-bonding (Hile et al 2000; Moravec et al 2006; Keenan and Benkman 2008; Sewall 2009; Moravec and Striedter 2010) and group cohesion (Brown 1985; Bradbury et al 2001; Yurk et al 2002) hypotheses. The mate attraction and pair-bonding hypothesis is specific to mated pairs and suggests that the process of convergence or imitation can have two effects on pair bond formation: (1) it may help reinforce social bonds, and (2) it may enhance individual recognition of one's mate (Hile et al 2000; Moravec et al 2006; Keenan and Benkman 2008; Sewall 2009; Moravec and Striedter 2010).…”

“…In other species, shared vocalizations develop within groups through social learning of signals; such sharing has been observed in a number of taxa including cetaceans (Smolker and Pepper 1999; Janik 2000; Miller et al 2004; Watwood et al 2004), parrots (Farabaugh and Dooling 1996; Wanker et al 2005; Scarl and Bradbury 2009; Salinas–Melgoza and Wright 2012), songbirds (Mammen and Nowicki 1981; Farabaugh et al 1988; Brown and Farabaugh 1991; Sewall 2009), hummingbirds (Stiles 1979; Yang et al 2007), and bats (Boughman 1997). The sharing of vocal signals can occur at different levels, ranging from the small scale dyadic sharing between two individuals (Wanker et al 2005; Moravec et al 2006; Balsby and Scarl 2008) to large-scale geographic dialects (Baker and Cunningham 1985; Groth 1993; Myasato and Baker 1999; Wright et al 2008; Kershenbaum et al 2012). In addition, sharing can occur via imitation, in which one individual imitates another's call, or convergence, which we define as two or more birds developing new or intermediate vocalizations with aspects of each other's calls.…”

“…Call sharing in this species appears to exhibit different patterns depending on how groups are formed. In male–female pairs, males typically imitate female calls, and this process appears to contribute to pair bond formation and maintenance (Hile et al 2000; Hile et al 2005; Moravec et al 2006; Moravec and Striedter 2010). Imitation also occurs in all-male groups when immigrants are introduced to a new flock (Bartlett and Slater 1999; Young 2011).…”

Computational mate choice: Theory and empirical evidence

“…the proportion of time spent in proximity to a visual stimulus in fish, Cummings and Mollaghan, 2006;Walling et al, 2010, andbirds Hoi andGriggio, 2011; or to a chemical stimulus in mammals, CluttonBrock and McAuliffe, 2009), or the number of signals elicited (i.e. contact calls in birds, Moravec et al, 2006). Both recognition and comparative tests have several practical limitations, mainly due to the low accuracy and precision with which preferences are measured.…”

Factors shaping the ontogeny of vocal signals in a wild parrot

“…In most parrot species studied to date, contact calls have been shown to be individually specific (Saunders, 1983;Farabaugh et al, 1994;Cortopassi and Bradbury, 2006;Moravec et al, 2006;Buhrman-Deever et al, 2008;Berg et al, 2011). Whereas singing is usually a more sedentary occupation, contact calls are commonly used to coordinate movements of social companions between roosting, foraging and nest sites (Bradbury et al, 2001;Kondo and Watanabe, 2009) and can be given before, during or after wing-powered flights.…”