Begging form and growth pattern of nestlings correlate with parental food-allocation patterns in the Horned Lark (Eremophilaalpestris)

Abstract

Life-history theory assumes that selection favors parents that can maximize their reproductive success via behavioral strategies. As brood size determines the reproductive value of each nestling, parents may adjust their food-allocation patterns according to brood size. We test this assumption in the Horned Lark (Eremophila alpestris (L., 1758)). Our findings revealed that nestling begging forms varied with brood size, by gaping in one-chick broods and postural activity in two-and three-chick broods. Accordingly, parental food-allocation patterns differed in different-sized broods. In one-chick broods, parents increased feeding rates with the gaping duration of nestling. In two-chick broods, parents did not change food-allocation patterns according to nestlings' begging. In three-chick broods, however, they fed later-hatched nestlings more even when early-hatched nestlings begged more intensely. Horned Larks exhibited obvious sexual differences in parenting style and ability, which resulted in nestlings from two-and three-chick broods changing their begging intensity according to the sex of the provisioning adult. Furthermore, nestling growth pattern diverged with brood sizes, with body mass growing faster in one-chick broods than in two-and three-chick broods. Growth rate of beak gape and tarsus length did not differ significantly among brood sizes, but beak gape was larger and tarsus length was shorter in one-chick broods than in larger broods at fledging. Our results thus support the idea that parents may use food allocation to regulate sibling rivalry, which in turn cause nestlings to beg food in different forms and grow in different patterns so that their reproductive success can be enhanced.Résumé : La théorie du cycle biologique repose sur l'hypothèse voulant que la sélection favorise les parents qui peuvent maximiser leur succès de reproduction par des stratégies comportementales. Comme la taille de la couvée détermine la valeur de reproduction de chaque oisillon, les parents pourraient ajuster leurs habitudes d'attribution de nourriture selon la taille de la couvée. Nous avons vérifié cette hypothèse chez l'alouette hausse-col (Eremophila alpestris (L., 1758)). Nos constatations révèlent que les formes de demande des oisillons varient selon la taille de la couvée, allant du bâillement pour les couvées d'un oisillon à une activité posturale dans les couvées à deux ou trois oisillons. Par conséquent, les habitudes d'attribution de nourriture par les parents varient selon la taille de la couvée. Dans les couvées à un oisillon, plus la durée du bâillement de l'oisillon est grande, plus le taux d'approvisionnement par les parents est élevé. Dans les couvées à deux oisillons, les parents ne modifient pas leurs habitudes d'attribution de nourriture selon la demande des oisillons. Dans les couvées à trois oisillons, cependant, ils nourrissent plus les oisillons éclos plus tard, et ce, même quand les demandes des oisillons plus précoces sont plus intenses. Les alouettes hausse-col présentent des différences sexue...

Seasonal variation in food availability influences the breeding strategy of White‐collared Blackbirds Turdus albocinctus on the Tibetan Plateau

“…Generally, the female contributes more to incubation and nest attendance, whereas the male contributes more to nest defence and brood provisioning (Gochfeld , Du et al . ). This sexual division can lead to energy conservation for the female in brood provisioning, as she has invested much energy and time in egg‐laying and incubation.…”

“…Based on these data, we calculated (1) individual provisioning rate as the number of food‐delivery visits per hour performed by either sex, (2) the total amount of food delivered by male and female in the same time by adding together the food delivered in each feeding visit by either sex, (3) parental feeding efficiency as the proportion of nestlings in the brood that were fed and (4) nestling begging intensity by averaging the scores of head‐raising, height of neck‐stretching and distance to the provisioner (Du et al . ).…”

Breeding Behavior, Nestling Growth, and Begging Behavior in the Plain Laughingthrush (Garrulax davidi): Implications for Parent–Offspring Conflict

“…In small-sized passerine birds, postural activities are the major form of nestling begging for food [43,51]. In broods with intense sibling rivalry, where competition for food is high, nestlings that receive more food or are fed first by provisioners usually show higher intensity of postural activities [29,30,38,51].…”

“…The nest is divided into four quadrants, along with a central location, creating five distinct areas. The specific feeding position is determined based on the location of the parental beak during the act of food delivery [43]. (iii) Insect size: the size of the insects provided as food is categorized based on the relative length compared to the beak gape.…”

“…These were normalized based on the brood's size. For two-chick nests, the average score was divided by two; for three-chick nests, it was divided by three; and for four-chick nests, it was divided by four [43].…”