Domestication effects on foraging strategy, social behaviour and different fear responses: a comparison between the red junglefowl ( Gallus gallus) and a modern layer strain

Abstract

According to the resource allocation theory, behaviours that have high energetic costs should decrease in frequency in breeds that are selected to invest a higher proportion of energy into production traits. We studied differences between red junglefowl, ancestor of domesticated breeds, and a modern White Leghorn laying strain with respect to foraging strategy, social behaviour and different fear responses. The behaviour of each breed was observed in four test situations: (1) a foraging-social maze of four arms where two arms contained easily obtainable familiar food and two contained hidden novel food, so the birds had to work to obtain it. One arm with each food type had a mirror, which provided a simulated social stimulus. (2) A hawk model test, where a hawk model was briefly presented while the birds had access to food. (3) A tonic immobility test, measuring passive fear responses. (4) A restraint test whereby the birds were restrained with a rope around one tarsus, measuring active fear responses. In the maze test, junglefowl spent more time feeding from the novel food site and next to a mirror, whereas the Leghorn spent more time in the arm with the easily obtainable familiar food and mirror. Both breeds responded on the simulated predator attack with an immediate decrease in foraging behaviour and an increase in “walking alert”. After the model presentation, junglefowl walked alert and vocalised significantly more than the Leghorn, whereas Leghorn was standing alert more compared to junglefowl. It was easier to induce tonic immobility in the Leghorn than in junglefowl and Leghorn also had a less active response in the restraint test compared to junglefowl. Females in general tended to respond more active than males. The results on social behaviour were not clear. In conclusion, Leghorn used a more energy-conserving foraging strategy and was less active in the fear tests, compared to junglefowl. These results may be interpreted as correlated responses to selection for increased production, allowing modern strains to allocate more resources to reproduction and growth.