Siskins / Erlenzeisig

The bird's appearance shows sexual dimorphism. The male has a greyish green back; yellow rump; the sides of the tail are yellow and the end is black; the wings are black with a distinctive yellow wing stripe; its breast is yellowish becoming whiter and striped towards the cloaca. The plumage of the female is more olive-colored than the male.
This bird has two calls, both powerful but conflicting, one is descending and the other is ascending, their onomatopoeic sounds can be represented as "tilu" and "tluih".
On occasions they also issue a harsh rattling chirrup.