Vocal learning has evolved in only a few groups of mammals and birds. The developmental and evolutionary origins of vocal learning remain unclear. The imitation of a memorized sound is a clear example of vocal learning, but is that when vocal learning starts? Here we use an ontogenetic approach to examine how vocal learning emerges in a songbird, the chipping sparrow. The first vocalizations of...

Theoretical models aimed at explaining the evolution of honest, informative begging signals employed by nestling birds to solicit food from their parents, require that dishonest signalers incur a net viability cost in order to prevent runaway escalation of signal intensity over evolutionary time. Previous attempts to determine such a cost empirically have identified two candidate physiological ...

Begging calls are signals of need used by young birds to elicit care from adults. Different theoretical frameworks have been proposed to understand this parent-offspring communication. But relationships between parental response and begging intensity, or between begging characteristics and proxies of a young's need remain puzzling. Few studies have considered the adjustment of nestling begging ...

The aim of this study is to identify the conditions which encourage some people start begging using a grounded theory approach. As such, 23 beggars in city called Mashhad were selected through theoretical sampling 2020. data collection techniques included participatory observation and in-depth interviews. Rejection by family weakening social networks main underlying resort individuals indicatin...

Food begging is common in nutritionally dependent young of many animals, but structurally homologous calls recur in adult signal repertoires of many species. We propose eight functional hypotheses for begging in adults; these stem from observations in birds but apply broadly to other taxa in which begging occurs. Adult cooperatively-breeding white-throated magpie-jays (Calocitta formosa) use lo...

Parent-offspring conflict theory predicts that begging behaviour could escalate continuously over evolutionary time if it is not prevented by costliness of begging displays. Three main potential physiological costs have been proposed: growth, immunological and metabolic costs. However, empirical evidence on this subject remains elusive because published results are often contradictory. In this ...

Begging by dependent avian offspring is known to correlate with hunger level, and parents use this as a signal of brood demand to adjust their chick feeding behavior. While there is information on how each chick adjusts its begging to its own condition, little is known of how chicks adjust to the state of their nest mates. In two experiments we manipulated the competitive environment of individ...

Begging behaviour of nestlings has been intensively studied for several decades as a key component of parent-offspring conflict. There are essentially two main theories to account for intensity of food solicitation among offspring: that intensity of begging is related to some form of scramble competition between nest mates or that it offers honest signalling of need to parents. The vast majorit...

Begging vocalization is thought to have evolved as a consequence of the parent-offspring conflict over parental investment (Mock and Parker, 1997). Under this conflict, parents are reluctant to provide all the resources requested by current offspring because they are saving resources for future broods (Trivers, 1974). In this scenario, begging has evolved as an honest signal of need with the mo...

When siblings differ markedly in their need for food, they may benefit from signalling to each other their willingness to contest the next indivisible food item delivered by the parents. This sib–sib communication system, referred to as ‘sibling negotiation’, may allow them to adjust optimally to investment in begging. Using barn owl (Tyto alba) broods, I assessed the role of within-brood age h...