THE FODIES (PLOCEINAE) OF THE SEYCHELLES ISLANDS

Abstract

Summary1. The endemic Foudia sechellarum (the Toq Toq) and the introduced F. madagascariensis (the Cardinal) occur in the Seychelles. The Toq Toq is now restricted to three island refuges, Frigate, Cousin and Cousine, while the Cardinal is found throughout the archipelago.2. Comparative study of their breeding biology and behaviour, mainly on Frigate, revealed the following details:(a) The populations of the two species are dispersed differently in the environment.(b) A proportion of the Toq Toq population probably breeds throughout the year while the Cardinal breeds between September and March.(c) The Toq Toq is primarily insectivorous, the Cardinal primarily graminivorous.(d) Nests are similar, though the Toq Toq structure is more bulky. The Toq Toq nests are sited in bushy trees, while Cardinals' occur in Coconut palms often at a considerable height.(e) Toq Toq eggs are white, clutch‐size 1–2, the Cardinal's eggs pale blue, clutch‐size 3.(f) Incubation and fledging periods and growth curves from a limited number of nests are given for each species.(g) Survival of Cardinals in the nest is better than Toq Toqs due to the greater predation suffered by Toq Toqs.(h) The Toq Toq moves in small family parties or couples taking insects mainly from below the fronds of palms. Aggregations occur at localized food supplies, washing and roosting places. Cardinals move in flocks congregating particularly around patches of seeding grass. The Toq Toq is a “contact species”, the Cardinal has “distance” characteristics. In an aviary, Toq Toqs were dominant over Cardinals at food bowls and on perches.(i) Both species establish territories when breeding, the Toq Toq's being as much as twice the size of the Cardinal's. Territorial behaviour is described.(j) The Toq Toq pair bond is probably complete prior to nesting and they may pair for life. The female is associated with the male in nest defence and building and there is no nest invitation behaviour. The Cardinal female comes to the territory from the flock, which the male leaves earlier, and is repeatedly attacked. Courtship sequences and display posture components are more aggressive in the Cardinal than in the Toq Toq. The Cardinal has a “Glide Flight” nest invitation.(k) The aberrant length of time spent in nest‐building by many male Cardinals and the frequent cases of nest demolition by the owners is supposedly due to the frequent failure of females to accept nests offered to them, even when courtship has apparently been satisfactory. The Seychelles population may not yet be fully adapted to the palm tree nest site.3. The coexistence of the two species is due to divergent adaptation to differing environments of origin the Toq Toq to the endemic forests of the Seychelles and the Cardinal to the open country of Madagascar. Both have shown flexibility in adjusting to the present coconut‐dominated vegetation of the Seychelles. The differences between them result from the degeneration of colour and voice in the Toq Toq on its remote islands and the differing methods of exploitation of contrasting food supplies. Differences in social organization correlate with food exploitation and are largely responsible for contrasts in territorial and courtship behaviour.4. These studies are considered in relation to other endemic Foudia populations and the genus is listed in three Species‐groups.