Hi David,
Surrounding walls are not likely to be places where birds will persist. You need to take measures to prevent access and roosting if appropriate. One such measure would be to install netting in loading/unloading areas.
BRCGS Guidance offer this:
The site (or its pest management contractor) should use a risk assessment approach to establish whether there is any potential for the ingress of birds, or for roosting and nesting at loading or unloading areas, and to assess the measures required to mitigate the risk.
The expectation here is not necessarily to rebuild or reconfigure facilities; instead, the intention is to recognise any potential problems and take steps to remove or mitigate these risks from birds roosting and nesting.
Your pest contractor should be looking at this for you and making recommendations if preventative measures are needed.
Kind regards,
Tony