Interesting. That's odd, since it implies that they must have had some sort of very long-term biological clock, such as they would realise that, for example, "72 months ago it was (according to day length) mid-summer, but now it appears to be mid-winter"! AFAIAA, most living things (plants as well as animals) usually adapt pretty rapidly to migration between hemispheres.I used to have a friend who bred various birds of Antipodean origin, and apparently they bred more successfully if kept on "Australian time". It surprised me too. We built a timed dimmer circuit so the light brightened gradually to simulate the dawn, and faded out to simulate dusk.
Kind Regards, John