We found the diving behaviour of middle-aged birds differed from young and old birds.
In 80 0% depth, old birds pursued prey more often than young (z = 3.6, P<0.01) and middle-aged birds (z = 2.9, P<0.05); there was no difference between young and middle-aged birds (z = 0.94, P = 0.61).
In greater flamingos this theory has been supported by a curvilinear relationship with middle-aged birds showing a greater resistance to oxidative stress than young and old ones [48].
In 80 80% depth, young birds pursued prey less often than middle-aged birds (z = 3.2, P<0.01) and there was no difference between young and old birds (z = 2.1, P = 0.08) or between middle age and old birds (z = −0.73, P = 0.74).
The dive duration of middle age females was shorter than that of young and old birds while their dive effort (measure for dive and post-dive duration relation) was lower than that of young ones, suggesting middle-aged birds were in better physical condition than other ones.
We then treated age as categorical variable by grouping them in three age classes following [25]: class 1 for young birds (3 and 4 years, n = 7), class 2 for middle-aged birds (5 to 10 years, n = 7) and class 3 for old birds (11 to 14 years, n = 5).
The middle-aged bird buffs are still here but the RSPB has made strenuous efforts to welcome newcomers and provide engaging activities for children.
But the treetops hold fewer feathered gems each spring, to the point that a typical middle-aged bird-watcher now feels triumphant upon seeing a single bay-breasted or Canada warbler, two of the dozens of disappearing species common in our youth.
He is middle aged, in good health.
All men, mostly middle aged.
Ahhh the pleasures of middle aged dating!
