Wataridori is a pencil puzzle involving drawing paths to connect all circles in a rectangular grid into pairs, in order to satisfy several constraints. In this paper, we prove that deciding solvability of a given Wataridori puzzle is NP-complete via reduction from Numberlink, another pencil puzzle that has already been proved to be NP-complete.

翻译：渡り鳥是一种铅笔谜题，要求在矩形网格中绘制路径将所有圆圈两两连接，以满足若干约束条件。本文通过从Numberlink（另一种已被证明是NP完全的铅笔谜题）进行归约，证明了判定给定渡り鳥谜题可解性是NP完全的。