Examination of nocturnal activity and behaviour in resident white-crowned sparrows (Zonotrichia leucophrys nuttalli)

Abstract

Abstract Observations of nocturnal activity in resident species held in captivity are often attributed to migratory restlessness (MR). Previous publications investigating migratory white-crowned sparrows ( Zonotrichia leucophrys gambelii ) provided a distinct set of traits characteristic of MR, which we used to test the expression of activity and behaviour in the resident subspecies ( Z. l. nuttalli ). Under a winter photocycle, the 24-h activity profile of Z. l. nuttalli closely resembled that of migrant relatives. Following photostimulation, most birds expressed some activity during the dark phase; however, the diel pattern differed greatly from that of migrants. Unlike Z. l. gambelii , peak activity levels during the light phase remained greater than those expressed during the dark phase. Furthermore, birds did not express a quiescent phase prior to the initiation of the dark phase, nor did photostimulation result in increases in body mass or fat deposits. However, two birds did exhibit migration-specific behaviours (beak-up and beak-up flight) coupled with intense dark phase locomotor activity, which is consistent with MR expression. The suite of contrasts between conspecifics however, may suggest a different context of nocturnal behaviour, perhaps representing an underlying ancestral migratory phenotype that may now be associated with territorial or reproductive activities.