Feeding performance, kinematics and skills change with age in a granivorous songbird

Changes in neuromuscular performance due to maturation and ageing affect a
wide range of motor behaviours in birds and mammals. The consequences may
be especially pronounced during forceful and complex movements, such as
feeding on seeds in songbirds, which require well-developed jaw muscles
and fast, strongly coordinated beak and tongue movements. We investigated
how feeding performance changes with age by filming juvenile and adult
domestic canaries repeatedly over a span of two years with high-speed
video. We extracted metrics of feeding performance, beak kinematics and
seed handling skills of individuals during feeding on seeds with different
characteristics. Age significantly affected several feeding metrics on the
more challenging hemp seed, but not on the smaller and softer canary seed.
Beak-opening frequency displayed a parabolic pattern, increasing early in
life and slightly declining at old age, with no sex differences. Seed
handling skills improved linearly with age and more strongly in males. The
success rate of hemp seed husking also followed a parabolic pattern,
improving in juveniles and declining in old age. Our results suggest that
while learning and experience enhance feeding efficiency in early life,
age-related declines may stem from reduced bite force or sensorimotor
control deterioration.