Behaviour of spruce grouse broods in the field
Behaviour of juvenile spruce grouse (Dendragapus canadensis), from hatching to brood breakup, was observed in 30 radio-tracked broods inhabiting lodgepole pine (Pinus contorta) forests of southwestern Alberta. The immediate posthatch period (first 20 days) was characterized by a close spatial relationship between the chicks and hen, with brooding being the dominant behaviour. Hens with broods appeared to respond immediately, both vocally and through movement toward their chicks, whenever the latter uttered the following calls: sreep, sury, seer, and purring. Brooding sessions decreased in frequency but not duration (median of 11 min) until they disappeared from the behavioural repertoire of the chicks at about 50 days of age. Hen–chick and intersibling distances increased as the chicks grew older. The breakup of broods appeared to result when the cohesiveness of the brood decreased to a point at which calls of the chicks no longer elicited a response from the brood hen. There was no evidence that agonism contributed to this decline in brood cohesion.