SPECIES

Swynnerton's Robin Swynnertonia swynnertoni Scientific name definitions

Flemming P. Jensen
Version: 2.0 — Published February 4, 2022

Breeding

Introduction

Breeding habits have been studied in Zimbabwe. Swynnerton’s Robin is a monogamous, territorial, and solitary breeder. Young birds probably do not breed until 2 years old and the pairing appears to be for life. Breeding occurs during the rainy season, with the nest situated around 1 meter above the ground, in a tree or a shrub. Two eggs (occasionally 3) are incubated for 16 days and young remain in the nest for two weeks. Both parents feed chicks, but most food is provided by the female in the early morning, at midday, and in the evening. Normally one brood per year, occasionally two.

Phenology

In Zimbabwe breeding takes place from mid to late September or mid-October to mid-January or early February (15, 1, 3) and corresponds to the rainy season which last from October to April. In the Udzungwa Mountains (Tanzania), breeding is also correlated with the rainy season from November to April, with juveniles recorded in February (L. Hansen, in litt. in 17; FPJ). Birds on Mt. Mabu (Mozambique) were alarm-calling persistently in late October, suggesting that breeding had started (35).

Nest Site

In Chirinda Forest (Zimbabwe) nests are mainly built in Dracaena spp. (specifically in branch forks or at base of leaves), on stumps, or against tree-trunks, supported by vines (14, 36). In Bvumba Highlands (Zimbabwe) with no Dracaena, different species of trees and shrubs are used, including Macaranga mellifera, Rauvolfia caffra, Maytenus mossambicensis, Aphloia theiformis, and Erythroxylum emarginatum (1). In a study of 12 nests in Bvumba Highlands, 1 nest was in a natural cavity in a tree trunk, 3 were on stumps of trees, 3 were in forks of shrubs, and 5 were in indentations in trunks of large trees, usually where a branch had fallen off (1). Nests were generally well hidden by foliage above and around the nest-site, providing protection from direct rain and drips from the forest canopy; the mean height above ground was 1.02 m, with no nest above 2 m (1). In another study, mean nest height was 0.9 m (range 0.3–2, n = 57) (2).

Nest

The nest is an open cup with an external diameter of 80–140 mm, internal diameter of 50–60 mm, and cup depth of 30–40 mm (n = 52) (2). The nest is built mainly by the female (1). The bulk of the structure is formed by well-woven rootlets, dead and skeletonized small leaves, dried moss, and fine stems (14, 1). The outside mainly consists of green moss and the nest is lined by rather coarse dark-brown fibers from tree ferns (Cyantheaceae) (1).

Eggs

Clutch typically 2 eggs, occasionally 3 eggs. Eggs are pale blue-green or buffy in ground color and covered with numerous red-brown spots and freckles, usually denser at the thick end (14, 1). Mean size 20.9 × 14.9 mm (range 20–22 × 14–16, n = 19) (2). In Zimbabwe, 79% of clutches were laid in October–January (2). Eggs are laid early in the day and at about 30-hour intervals (1).

Incubation

Apparently starts with first egg as one nestling was larger and more active than other (n = 4) (1). Incubation period lasts 16 d and it appears that only the female incubates (1). During this period the male kept away from the vicinity of the nest and was not observed to feed the incubating female, but occasionally called nearby (1). Incubation stints (n = 44) lasted 5–23 min (mean 14) and absences (n = 41) lasted 5–23 min (mean 10) (1).

Young Birds

The nestlings have pink skin with dark gray down and bright yellow gape (1).

The young remain in the nest for 2 wk (2). When responding to the parent’s alarm call, chicks freeze at the bottom of the nest with eyes closed and while doing this the bright yellow gape remains hidden (1). Preening and wing stretching by the young is fairly frequent in the last 3 days before fledging, especially on the final day; chicks exhibit only a few feeble attempts at wing fluttering (1). At this stage the adults seem to encourage the young to leave the nest with a purring call and by flying around the nest after a feeding visit; sometimes young jump from the nest before reaching fledging age (1).

Parental Care

Brooding and Feeding

Chicks are brooded by the female alone for 7–9 days (mean 8) (1). The female regularly draws back into crouching position to inspect chicks (1). If the female is brooding when the male approaches with food, the male may pass food to the female and leave, with the female in turn feeding the chicks (1); but often the male would wait until the female leaves the nest before attempting to feed the chicks (1).

As the young grow, feeding becomes very rapid, and the frequency of visits increases (1). Often the adults arrive almost simultaneously, each feeding a single chick in about a second (1). Peak feeding times occur in the early morning, midday, and late afternoon (1). The bulk of the food is delivered by the female with the male becoming fully active only at peak feeding times (1). Feeding rate increases throughout the nesting period; e.g., at one nest, 57 feeding trips were recorded in first 3 days and 135 feeding trips were recorded in the last 3 days (1).

Nest Sanitation

No information.

Cooperative Breeding

No reports.

Brood Parasitism by Other Species

Occasional brood parasitism by Red-chested Cuckoo (Cuculus solitarius), with 3 of 63 nests (4.76%) parasitized in Zimbabwe (37).

Fledgling Stage

No information.

Immature Stage

No information.

Recommended Citation

Jensen, F. P. (2022). Swynnerton's Robin (Swynnertonia swynnertoni), version 2.0. In Birds of the World (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.swyrob1.02