Natures wonders: bird migration diural time switch (Introduction)

by David Turell , Tuesday, October 18, 2016, 18:42 (2956 days ago) @ David Turell

Birds with a diurnal activity pattern switch abruptly at migration time:

http://phys.org/news/2016-10-blackbirds-abruptly-fly-by-night-behaviour-migration.html

"Each year, billions of songbirds set out on autumn evenings to fly to their wintering grounds, necessitating a change of daily rhythm for the usually diurnal animals. Scientists had always assumed that the birds gradually adjusted their rhythm, but new technology has now enabled researchers at the Max Planck Institute for Ornithology in Radolfzell, with international partners, to observe free-living blackbirds at the onset of migration. They discovered that the birds change abruptly from diurnal to nocturnal activity immediately before departure.

"Setting out on a journey in the dead of night is something most people find difficult. When diurnal songbirds like the European blackbird (Turdus merula) set off on autumn nights on the long journey to warmer climes, they too must spring into action at an unaccustomed time. They take to the air on starry nights between dusk and midnight, requiring a change from daytime to night-time activity.

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"The miniaturisation of radio-telemetry solved this problem for the ornithologists, who attached the two-gramme devices to the birds' backs, like a kind of rucksack. Some of these birds would migrate and others would remain at the same location through the winter. Measurements revealed that the daytime and night-time activities of a partially migratory blackbird population were no different between migrants and residents in the days before departure. Furthermore, the free-living blackbirds did not display any pre-migratory agitation before their autumn departure. On the contrary, they switched abruptly to a nocturnal rhythm at the time of departure. "The blackbirds get off to a flying start, going from zero to a hundred just like that. It's suddenly time for them to head off at night and travel through the following nights - although they're actually diurnal birds", says Jesko Partecke."

Comment: This abrupt switch in diurnal activity patter has got to be under strict genetic control and is instinctual. Since birds follow warmer weather, did they learn this pattern and epigenetically altered their genome, or was this a directed change by God.