Sentence:  Many of these classic methods are still used, with some modern improvements. For example, with the aid of special microphones and automated sound detection software, ornithologists recently reported [...] that pine siskins ("Spinus pinus") undergo an irregular, nomadic type of nocturnal <WSD>migration</WSD>. 
Meaning of the word marked with <WSD> tags:  Seasonal moving for animals, as birds or fishes, to breed or find a new home.