The forest-dwelling Henderson reed-warbler feeds primarily on a wide variety of insects, including moths, caterpillars, ants, large wasps, flies, beetles, cockroaches and land snails, but seeds and fruit may also be eaten (2). It forages for this food at all levels of the forest, plucking its prey from foliage, twigs, branches, bark crevices and from the ground, often moving about in family groups (2).
The breeding season of the Henderson reed-warbler extends from late August to early January. The majority of nesting groups comprise one male and one female, but around one-third of nesting groups are made up of three adults. These trios, of two males and one female, or one male and two females, are unrelated, but co-operate to incubate and feed the young, whether or not they are the parents of the chicks. This remarkable teamwork may be due to young birds being more likely to secure a sought-after nesting territory when belonging to a trio rather than a pair (5). The pair or trio construct a bulky deep cup nest of dry leaves, coconut, rootlets and other plant fibres, into which they lay a clutch of two to three eggs. The eggs are incubated for 15 days and the chicks continue to receive some of their food from the adults for at least six weeks after fledging (2) (5).