Environmental Research Unit, PO Box 434, Stanley, Falkland Islands
Grass WrenCistothorus platensis falklandicus
Local Name: Short-billed Marsh Wren
Breeding Range: Falkland Islands
Falklands Population: ~2,000 breeding pairs
World Population: as above (subspecies restricted to Falklands)
One of two species of wren living in the Falklands, the Grass Wren is fairly widespread but nowhere abundant. The subspecies Cistothorus platensis falklandicus is only found in the Falkland Islands. Favoured habitat is tall marshland, grassland, reed beds and tussac grass. Hollow ball-shaped nests woven from grass, often with an entrance tunnel, are constructed well above the ground in tall grass or reeds. Between 5 and 7 eggs are laid during October or November. A wide variety of invertebrates are taken as food, including moths, flies, beetles, caterpillars and grubs. By nesting above ground Grass Wrens do have some defence against introduced rodents. Nevertheless Grass Wrens are found at higher densities on islands which are still rat-free, showing that the introduction of rats has been detrimental. Sexes are similar.