Breeding of the Seychelles Magpie Robin Copsychus sechellarum and implications for its conservation

Abstract

The total population of the Seychelles Magpie Robin Copsychus sechellarum declined from 38–41 birds in 12–13 territories in 1977–1978 to 17–21 birds in eight to nine territories in 1988–1990 and was entirely confined to Fregate Island (210 ha) in the Seychelles. After a successful cat eradication program in 1981–1982, recruitment improved, although the abandonment of agriculture had caused a reduction in the amount of feeding habitat and hence in the carrying capacity of the island. The population declined because of the failure of recruitment to compensate for the annual adult mortality. Foraging activity of the Magpie Robin was greater in high‐quality territories (measured by soil invertebrates available), leading to increased reproductive success. Through supplementary feeding, five times as many recruits were produced. Of the 11.5 potential annual breeding recruits, 5.3 are required to compensate for adult mortality, and the other 6.2 recruits can be regarded as “surplus” contributing to an increase. Magpie Robins prefer to breed in rotten trees, which are a scarce resource. The greater the distance between the nest site and feeding areas, the less time was spent in incubation and nest guarding, resulting in greater egg loss. Because of lack of suitable areas for establishing territories, many young Magpie Robins became “floaters”. Nest disturbance, both by these floaters and by the introduced Indian Mynah Acridotheres tristis, had adverse effects on the breeding success of robins. A recovery plan has been designed to save the Magpie Robin. Territories have been improved for feeding (by tree planting) and for breeding (by providing nestboxes and reducing nest disturbances). Given the vulnerability of one small island, the presence of surplus birds (supported mainly by supplementary food) and the suitability of neighbouring Aride Island (68 ha), successful translocations to this island took place in 1992 and 1994. Given the presence now of 47 individuals on two islands, it is hoped that the species will pull back from the brink of extinction.

Threats from introduced birds to native birds

“…In the Seychelles Archipelago, the critically endangered Seychelles Magpie-Robin is threatened by the clearing of all of the natural vegetation and numerous introduced species (Komdeur 1996). Its nesting success was reduced to zero in the presence of the Common Myna because the native species abandoned its nesting sites when the introduced species co-occupied its nesting trees (Komdeur 1996).…”

“…Its nesting success was reduced to zero in the presence of the Common Myna because the native species abandoned its nesting sites when the introduced species co-occupied its nesting trees (Komdeur 1996). Komdeur (1996) emphasised that the only self-sustaining Seychelles Magpie-Robin population was on an island never colonised by rats but colonised by the Common Myna. Nevertheless, interference competition from the Common Myna is a threat that needs to be addressed in the recovery of the species.…”

“…As demonstrated by many of the articles we reviewed, distinguishing among the effects of introduced birds, habitat loss and predation by rats is difficult (Gurevitch and Padilla 2004). For instance, the Seychelles Magpie-Robin had to contend with nest-trees being cleared for farming land, feeding habitat trampled by stock and nest predation from introduced rats (Komdeur 1996); interference competition with the Common Myna was in addition to these threats. Predation by introduced rats is also an issue for native birds in Tahiti (Meyer 2003), Lord Howe Island (NSW Scientific Committee 2011), Ascension Island (Hughes et al 2008), Norfolk Island (Garnett et al 2011), and the Hawaiian and other islands (Drake and Hunt 2009).…”

Restoration of a tropical island: Cousine Island, Seychelles

“…Throughout this time, plans were also being put in place to re-introduce certain highly threatened, Seychelles endemic land birds, primarily the Seychelles magpie robin (Copsychus sechellarum) (Komdeur 1996;LeMaitre 2002) and the Seychelles white-eye (Zosterops modestus) . Certain other endemic birds and indigenous organisms were also being considered for introduction, although these introductions have not been achieved to date.…”

“…Also, various scientists were encouraged to visit the island to undertake various studies of key species and processes, such as reptiles (Bourquin and Hitchins 1998), Seychelles giant millipede biology (Lawrence and Samways 2003), assessment of the invertebrates of the leaf litter and logs (Kelly and Samways 2003), spider assessments (Saaristo 1999), colonization by dragonflies (Samways 1998(Samways , 2003a, Seychelles warbler (Komdeur 1994(Komdeur , 1995 and Seychelles magpie robin biology (Komdeur 1996;LeMaitre 2002), turtle biometrics and nesting biology (Hitchins et al 2003a(Hitchins et al , b, 2004a(Hitchins et al , b, 2006, and marine assessments (Samways 2003a, b;Samways and Hatton 2001).…”