They discovered that whereas the birds on Corsica bred at the time when caterpillars 
(They; discovered; that; T:whereas the birds on Corsica bred at the time when caterpillars) (the birds on Corsica; bred; T:at the time; when caterpillars)
They the birds on Corsica
discovered bred
that T:whereas the birds on Corsica bred at the time when caterpillars
T:at the time when caterpillars