Begging Calls Research Articles

Recognition of Parents' Voices by Young Cliff Swallows

Abstract Cliff Swallow (Hirundo pyrrhonota) chicks were played calls of parents and unrelated (control) adults at 9 and 18 days of age. Younger chicks showed no difference in the frequency of their antiphonal begging calls to parental vs. control calls. The older, near-fledging chicks, however, responded significantly more to parental calls than to control calls: 78% of their total antiphonal calls were in response to parental playback calls. In these older chicks, the degree of preference correlated with the measured acoustic differences between the parent and control calls. The results indicate that Cliff Swallow chicks are able to recognize their parents by voice before they leave the nest. Offspring recognition of parents is discussed as it relates to the evolution of parent-offspring recognition systems in general.

Parental Care of Fledged Young, Division of Labor, and the Development of Foraging Techniques in the Northern Wheatear (Oenanthe oenanthe L.)

Abstract The care of fledged young by parents and the interactions between parents and young were studied in seven broods of Northern Wheatears (Oenanthe oenanthe L.) in an agricultural area near Uppsala, central Sweden. Time budgets of young and the development of foraging skills were also quantified. Young of the same brood were observed out of the nestholes on the 15th or 16th day after hatching. The parents did not divide the brood until day 3 or 4, day 1 being the 16th day after hatching (assuming that all young fledged on the 15th day). Full stability of family units, with no transfers of responsibility for feeding specific young, was achieved on days 3-8. Both parents fed their respective groups of young at different sites, and young of the same family unit appeared to be aggregated in the territories. They perched nearer to each other on average than to young fed by the other parent. These results support the hypothesis that a division of labor in altricial birds has evolved to allow parents to locate their young more easily and to reduce travel distances between sites at which prey are captured and the locations of young. Young wheatears depended on their parents for 2 weeks after leaving the nest. During that time, they became more active and mobile, spent less time calling and waiting for the parents to feed them, chased their parents more intensively to obtain food, and spent more time foraging. The marked increase in the chasing frequency of young after the first week coincided with a marked decrease in parental feeding rates and in the responsiveness of the parents to the begging calls of the young. Young also greatly increased their foraging activity after day 10, when parental feeding rates dropped to very low levels. These data support the hypothesis that parental reluctance to feed the young determines the onset of fledgling independence. Rates at which young attempted to capture prey and the proportion of successful attacks increased with age. Foraging techniques that are more dependent on flight performance (aerial hawking, perch-to-ground sallying) appeared later and were used less by the young than was ground-gleaning. There was a negative relationship between the intensity of chasing by the young and their capture success rates during different hours, which suggests that they switched between chasing the parents and self-feeding, depending on which was the most profitable strategy at the moment.

Development and stability of single-parent family units in the song sparrow

Allocation of parental feedings to newly fledged young was observed in 34 song sparrow broods on the day of leaving the nest (day 0) and in five more broods the subsequent day (day 1). In the one case in which leaving the nest was observed, feedings were immediately divided between parents so that each young was fed by only one parent. Four-fifths of all young were fed by only a single parent on day 0 or day 1: the remaining fifth were fed by both parents during observation periods of about 90 min. Twenty-nine of the same broods were observed again during days 4–8, when only 1 of 82 young was fed by both parents. Slightly more young were fed by males than on days 0–1. The tendency for males to care for a higher proportion of older young occurred whether or not the pair began a further brood. Song sparrow fledglings gave individually distinct food begging calls. These may have assisted the formation or maintenance of specific parent–young feeding units. Brown-headed cowbird young in the brood were treated like song sparrows, except that they were fed more frequently.

Inter‐ and Intraspecific Variation in the Calls of Three Species of Grassfinches of the Subgenus Poephila (Gould) (Estrildidae)

AbstractTo investigate the nature of the microevolutionary and ontogenetic processes that modify the behaviour of grassfinches variation in the structure, function and frequency of call‐notes was studied in captive and free‐living birds. 94 wild‐caught birds and 149 aviary‐reared offspring of the Poephila subgenus were studied; they belonged to three species each of which consisted of two races which together exhibit a spectrum of evolving forms. The calls were analyzed on a sonagraph. The size of the repertoire differed between the species and within one of them. Variation in the contact calls correlated with variation in colours of beak and plumage. The adult calls developed from the juvenile begging calls.

Unusual Mobbing Behavior by Incubating Piñon Jays

Unusual Mobbing Behavior by Incubating Piñon Jays