| Popis: |
Prolactin has been associated with incubation and brooding in passerine birds, but its possible association with other parental behaviors remains unclear. We measured plasma concentrations of prolactin (prl) in Dark-eyed Juncos (Bunco hyemalis), a species in which only females incubate and brood but both sexes feed nestlings. Breeding males and females were bled at the time their eggs hatched, and half the males were taken from their territories. Females and the remaining males were bled again when their young left the nest. Removed males were quickly replaced by new males, some of which we caught and bled. Replacement males courted the females but rarely fed their predecessors’ young. Removed males were held in an aviary and bled again in late summer. Prl concentrations were higher in females than males, both at hatching and at nest leaving. Female prl was higher at hatching than at nest leaving and did not vary seasonally. Male prl was higher at hatching than at nest leaving and higher earlier in the season than later. Rearing young alone had no detectable effect on prl in females. Prl of replacement males was lower than that of fathers at hatching but not at nest leaving. Prl in removed males in the aviary was lower than in fathers at hatching but not at nest leaving. These patterns of prl secretion resemble those in other species that raise more than one brood per season and in which females provide the bulk of parental care. In addition, prl may be associated with male parental behavior in juncos. |
