Parental care in a sexually monomorphic, ground-nesting passerine, the Pink-billed Lark Spizocorys conirostris (Alaudidae)

Abstract

Within the family Alaudidae, most monomorphic species exhibit some degree of biparental care, but direct paternal care in most species is confined to food provisioning to offspring during the nestling period. Uniquely, the genus Spizocorys is the only sexually monomorphic lark genus in which the majority of species exhibit biparental care in all stages of the breeding cycle, including incubation. Video observations were used to determine parental nest attentiveness, incubation and brooding duty partitioning, and food provision through the breeding stages of Pink-billed Lark Spizocorys conirostris. In this study we found that Pink-billed Larks exhibit biparental care in all stages of breeding, although the parental contributions differed subtly. Incubation nest attentiveness was on the lower limit for passerines with biparental care. Both male and female nest attentiveness were also well below the reported averages for biparental care in birds. There was no significant difference between the male and female incubation attentiveness, although the males had significantly longer recess-bouts. The results suggest that females are primarily responsible for incubation and brooding, with males fulfilling a supplementary role. Males, however, share the responsibility for food delivery and preferentially deliver invertebrate prey rich in proteins and calories. There is also a change in diet from predominantly insectivorous to a greater emphasis on granivory with progression of the nestling period.