Alistair McKillop of Renfield Recruitment, a one-office firm in central Glasgow dealing with only white-collar staff, reckons there are 70 direct competitors in the local Yellow Pages.
Although he cannot definitely rule out a direct effect by the pollution on the birds' metabolism of the yellow pigment, or its incorporation into their feathers, the correlation between a shortage of caterpillars and faded plumage is strong evidence of a link between pollution, diet and bird colour.
The network did manage to coax 59 percent of former Nextel customers to stay tied up with Big Yellow, which may account for it selling nearly 1.2 million Direct Connect devices.