I can highly recommend this book to give insight into how people like Kelson sourced their rare specimens.Interestingly it would appear that one of the reasons Kelson travelled to Paris was that the 'Plume Trade' was outlawed in London during his time and supplies probably started to dry up.
For those interested ..a fascinating article on the defence offered by the feather trade..https://archive.org/stream/feathersfactsrep00royarich/feathersfactsrep00royarich_djvu.txt
Even the Queen got involved..The Queen's Letter. In 1906, at the Annual Meeting of the Society for the Protection of Birds (which had been incorporated under Royal Charter in 1904), a letter was read from Queen Alexandra, stating that Her Majesty " never wears Egret plumes herself, and will certainly do all in her power to discourage the cruelty practised on these beautiful birds " ; and further, giving the President of the Society (the Duchess of Portland) full permission to use her name " in any way you think best to conduce to the protection of birds."
THE TRADE IN BIRDS' FEATHERS. In 1876 Professor Newton wrote to the " Times " (January 28th) : " Like others of my brother naturalists, I have been long aware by report of the enormous sales of birds' feathers which are being constantly held in London ; but the particulars of them do not, except by accident, come before us. Chance has thrown in my way a catalogue, or portion of a catalogue, of one of these auctions, and its contents are such as to horrify me, for I had no conception of the amount of destruction to which exotic birds are condemned by fashion — an amount which cannot fail speedily to extirpate some of the fairest members of creation,
During the “plume Boom”, between 1880 and 1914, the business of killing birds for the millinery trade was practiced on a global scale.
It involved the deaths of hundreds of millions of birds in many parts of the world. Birds of all kinds were used for both their feather and bodily appearance.
Colourful and exotic birds like the Hummingbird, Parrot and Bird-of-paradise were enormously popular, but common fowl, such as pigeon, turkey and goose, were also used.
London was the centre of the trade in exotic feathers, and in the periodic monthly, bi-monthly and quarterly feather sales, traders and feather merchants were able to bid for the “skins”, “plumes” and “quills” of the most beautiful and most interesting unprotected birds of the world.
A single 1892 order of feathers by a London dealer included 6,000 birds of paradise, 40,000 hummingbirds and 360,000 "various" East Indian bird feathers.