Pheasants' heads cool rapidly as they prepare to fight - then heat up afterwards, new research shows.
Scientists from the University of Plymouth and Exeter used thermal cameras to watch juvenile pheasants, and see how their temperature changed during aggressive interactions that establish the pecking order.
They found that pheasants - both the instigator and the recipient of the aggression - grew more cool-headed before a fight, due to a stress response in which blood rushes to the body's core. Their heads became hotter again after the confrontation, as normal blood flow was restored.
Published in the journal Philosophical Transactions of the Royal Society B, the new study was funded by the European Research Council and the Association for the Study of Animal Behaviour.
While male and female pheasants followed a similar pattern of cooling and heating before and after a fight, females were cooler on average. Changes in blood flow are an important part of the stress response in multiple animal species, in a variety of different situations.
The pheasants in the study were six or seven weeks old. They were captive at the time, but were later released into the wild.
The paper comes 100 years after Norwegian zoologist Thorleif Schjelderup-Ebbe coined the term "pecking order" in his PhD thesis about chickens.
- The full study - Knoch et al: Hot-headed peckers: thermographic changes during aggression among juvenile pheasants (Phasianus colchicus) - is published in Philosophical Transactions of the Royal Society B.
