I have no idea but I incline not to agree with you on that for the following reasons:
a) the bird was probably renewing the feather as it persistently picked at its plumage while perching;
b) I got the shots taken in Lion Nature Education Centre;
c) Some of the passers-by said this shrike had been there for over a month;
d) This shrike was pretty skilled preying on insects, scavenging littered food and looking for earthworms;
e) It was not easily intimidated by passers-by in the park; and
f) I also saw the brown shrike frequenting LNEC last year around this time.
Pete