Parental Care In Horned Larks Eremophila Alpestris On Qinghai-Tibetan Plateau

Parental care is beneficial for the growth and survival of offspring in the reproductive process, whereas it is costly for the parents because it demands time and energy and may limit the opportunities for finding a new mate. Parents face a trade-off between current and future offspring. In adddition, parents also must reconcile sexual conflict, parent-offspring conflict and parent care. However, parental care in many animals has not been elucidated. Social monogamy and biparental care of offspring is the predominant mode of parenting among birds, and it provides an opportunity for us to investigate parental care. Here, we explored parental care strategies, sexual conflict and parent-offspring communication of a monogamous species, the Horned Lark (Eremophila alpestris) in natural environment on Qinghai-Tibetan Plateau. We first examined the life history traits in the field, and then monitored parental care behaviors of the two parents for all nestling ages during the entire incubation and nestling period using video-recording systems, and finally we studied how the parent-offspring communication pattern changes with nestling development using immunohistochemical and acoustic approaches.We first examined the life history traits of Horned Larks on Qinghai-Tibetan Plateau, and compared life history variations among different subspecies and local populations of the Horned Lark around their holarctic distribution. We found the Horned Lark here had the lowest nest success and the highest altitude distribution. Nest predation was the main cause of nest failure, and the Horned Lark employed the breeding strategies with the maximum breeding attempts and the smallest clutch size. Then, we monitored parental care behaviors of the two parents for each nestling age during the entire incubation and nestling period, and found that male Horned Larks generally invested less in parental care, but had a larger body size than females. The incubation process of the Horned Lark involved only the female. The incubators of successfully hatched nests had significantly lower nest-visitation rates, which reduced the detection probability by predators; longer on-bout but shorter off-bout duration, which provided a better thermal environment for the development of embryos than the incubators of predated nests. During nestling period, nestling demands varied continuously and we found the two parents had sex-specific parental care strategies via nestling age. The female continuously adjusted care behaviors to follow the dynamics of nestling demands as nestling age increased. However, low mating opportunities drove males to act as assistants for females, and correspondingly caused males to pay less attention to nestling demands than females. Finally, we studied how the parent-offspring communication pattern changes with nestling development using neurobiological and acoustic approaches. Food calls are used to stimulate nestling begging, but parents called less at late nestling stage. The nestlings are dumb and their eyes are closed at hatching. However, at late nestling stage, the eyes are completely open and nestlings used begging calls to solicit food. Furthermore, the sizes of cerebrum and midbrain of nestlings increased significantly with nestling age, and the song control nuclei robust nucleus in the arcopallium (RA), which comprise the vocal motor pathway, increased with nestling age. Accordingly, the parents seldom give food calls when nestling’s visual and vocal system were well developed.In conclusion, the two parents of Horned Larks on Qinghai-Tibetan Plateau used sex-specific parental care strategies to resolve the sexual conflict. In addition, the parent-offspring communication pattern changed continuously with nestling development. This doctoral thesis studied the reproductive biology and behavioral ecology of Horned Larks, and provide field data to explain the variation mechanisms in parent-offspring communication from an angle of developmental neuroscience, and offered some references other family studies about parent-offspring conflict, parent-offspring communication and other parental care behaviors.