Summary: Mainwaring & Hartley (2013)

Individuals vary in behaviour. While the evolutionary and ecological consequences of this variation have been relatively well studied, the causes remain unknown. One of the primary influences of offspring behavioural development are the parents, which exert the majority of influence during the pre- and early post-natal periods. Female zebra finches Taeniopygia guttata, as for many other bird species, will hatch asynchronous clutches when females initiate incubation prior to completing laying. This drives differences in phenotypic expression between early and late-hatched young. Mainwaring & Hartley (2013) manipulated the hatching patterns of zebra finches and found that late-hatched birds from asynchronous clutches were bolder, exploring a novel environment more, than their earlier hatched or synchronous hatched siblings. They also noted sex differences in exploration of a novel object, with females being bolder than males, regardless of hatching regime. Mainwaring & Hartley's (2013) study provide support that variations in an offspring's early environment can have a significant influence on the expression of its behaviour and provides an insight into how parental investment plays a role in maintaining and generating behavioural variation.