1853Blackbird-catching [see sense 3a]. 1864 J. C. Hotten (new ed.) Blackbird-catching,..slang for the slave-trade.
1902 A. Lang xi. 303 ‘He was never in the Labour trade.’ ‘Blackbird catching?.. No.’
1948 H. Wolhuter 71 He presently settled down to what, in those days, was called ‘blackbird-catching’—recruiting natives for the mines without a licence.