Since the late 1950s mist nets have been the mainstay of many ornithological studies, allowing large numbers of birds to be caught for ringing and other investigations. Mist nets are made of fine mesh that, under ideal circumstances, is difficult for birds to see. They are efficient but extracting birds requires skill to ensure that the birds are extracted with minimum stress. The ease of extraction varies with the species: some birds are easy to extract but others, such as wrens, tits and starlings, can be much more difficult. To ensure safety for the birds, access to nets is tightly controlled and ornithologists wishing to use them have to undergo prolonged training under a British Trust for Ornithology (www.bto.org) scheme.
Infrequently, one or more birds manage to get into premises where food products are handled, e.g. supermarket warehouses or even the shops themselves. Under the Food and Environment Protection Act such premises should be proofed against animal incursion but inadequate proofing, its poor maintenance, staff carelessness and other eventualities can allow birds to enter. As a last resort, mist nets may be used inside such premises in an attempt to catch the birds, which must then be released at least four miles away. This is to protect public health and safety. The scheme that allows this is managed by Natural England (https://www.gov.uk/government/organisations/natural-england), who can issue licences to premises owners to allow them to employ suitably trained people (“accredited agents”) to undertake the exercise. Prior to erecting mist nets within the buildings a sufficiently intensive survey must be carried out to identify flight lines used by the bird(s) in order to maximise the chances of catching it (or them). The licence (https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/514190/CL03__take_birds_trapped_food_premises.pdf) allows the use of mist nets to remove nine species (Blackbird, Blue Tit, Dunnock, Great Tit, House Sparrow, Pied Wagtail, Robin, Song Thrush and Starling).
WildWings Bird Management has run courses for staff of some pest control companies to enable them to undertake this work. The course covers legislation, site surveying, bird identification, erection, taking down and safe storage of mist nets, extraction and safe handling of caught birds and their release, and practical experience in the use of mist nets. Courses are not run during the breeding season or in cold weather, so the windows for holding such courses are limited. For information contact email@example.com. By no means all people have the aptitude, patience and dexterity to extract birds from mist nets and so participation in a course does not automatically qualify a participant to become an “accredited agent”.