Jj. Negro et al., EFFECTS OF FOOD-DEPRIVATION AND HANDLING STRESS ON FAULT-BAR FORMATION IN NESTLING AMERICAN KESTRELS FALCO-SPARVERIUS, Ardea, 82(2), 1994, pp. 263-267
We document the extent of fault-bar formation in the wing and tail fea
thers of 45 hand-reared and 18 parentally reared American Kestrels Fal
co sparverius raised in captivity on temporarily interrupted (30 birds
) and uninterrupted (15 birds) ad libitum diets. Hand-reared birds wer
e handled extensively throughout the experiment, parentally reared bir
ds were not. Hand-reared nestlings developed an average of 2.8, 8.0 an
d 4.3 and parentally reared nestlings an average of 0.6, 1.4 and 0.4 f
ault bars on their rectrices, primaries and secondaries, respectively.
All hand-reared birds, including the group whose diet was not interru
pted, had significantly more fault bars on their rectrices, primaries
and secondaries, than did parentally reared birds. Fault-bar formation
in birds whose ad libitum diets were interrupted did not increase at
times of food deprivation and handreared birds from which ad libitum f
ood had been withheld for 24 to 48 hours did not have more fault bars
than hand-reared birds whose diets had not been interrupted. Our resul
ts suggest that excessive fault-bar formation in captive birds is most
likely due to handling stress, rather than to food deprivation.