The role of helpers in feeding chicks in cooperatively breeding green (red-billed) woodhoopoes

Abstract

Observations were made of ten green (redbilled) woodhoopoe Phoeniculus purpureus flocks during the breeding season in order to quantify the relationship between flock size and the amount of food delivered to chicks. The study period was kept short specifically to minimize the effects of environmental stochasticity. Neither woodhoopoe feeding visit rates nor the total amount of food brought to chicks increased with flock size. Although nonbreeders did not increase the net rate of food provisioning to chicks, they reduced parental input in chick rearing, and hence energy expenditure by the breeding pair. However, over an 8-year study period, which includes data for 144 flock years, this did not result in increased breeding frequency or enhanced survival of breeders. There is thus no evidence that helpers' feeding contributions to young per se influence the indirect fitness of helpers.

Voice Breaking in Males Results in Sexual Dimorphism of Green Woodhoopoe Calls

“…Each group consisted of between two and eight individuals (mean ± SE: 3.5 ± 0.3) that defended an all-purpose territory throughout the year. Green woodhoopoes in this area inhabit riverine forest, which forms belts along river valleys (du Plessis, 1989). Valleys are separated by open grassland, which is not used by the birds.…”

“…The green (or red-billed) woodhoopoe (Phoeniculus purpureus) is a highly vocal species found in cooperatively breeding groups of 2-12 individuals in South Africa (du Plessis, 1991). Woodhoopoes of both sexes produce a variety of calls, including a cackle that forms the basis of inter-group territorial displays (Ligon & Ligon, 1978;Radford, 2003), a movementinitiation call (Radford, 2004), an anti-predator alarm call (Fry et al, 1988), and a 'kek' call that may function to maintain contact between dispersed group members and/or serve to mediate spacing between foraging competitors (Radford, in press).…”

Age‐Related Changes in Nestling Diet of the Cooperatively Breeding Green Woodhoopoe

“…The green woodhoopoe ( Phoeniculus purpureus ) provides an ideal opportunity to examine potential diet changes with increasing nestling age in a cooperatively breeding species. First, all adult group members (in South Africa, that is a breeding pair and up to six male and female helpers) provision young throughout the nestling period (du Plessis 1991), allowing a comparison of individuals of different sex and reproductive status. Second, because groups in South Africa only breed once a year (Radford 2004a), all individuals focus their helping behaviour at the nest; there are no fledglings from previous breeding attempts requiring care.…”

First evidence for heritable variation in cooperative breeding behaviour

“…Phylogenetic studies suggest a role for genetics in helping behaviour, since related species that are ecologically distinct often show similar cooperative behaviour (Cockburn 1996; but see Nicholls et al 2000;Ekman & Ericson 2006). The so-called 'phylogenetic inertia' hypothesis (Edwards & Naeem 1993), in which cooperative breeding persists in lineages even when there are no selective forces favouring it, could explain the apparent lack of fitness benefits for helpers that has been found in several species (Sappington 1977;Du Plessis 1991;Dickinson 2004b). Surprisingly, little attention has been paid to whether cooperative breeding behaviour displays any heritable variation or is genetically correlated with other traits (Komdeur 2006).…”