Letter from Peter Hollander to the 5th Earl of Cranbrook requesting for heads of Collocalia esculenta

Letter from Philip Chapman to the 5th Earl of Cranbrook enclosing a photo taken from a colour slide, of a guano-encrusted bird nest from deep inside Cobra Cave

Letter from Philip Chapman to the 5th Earl of Cranbrook enclosing his revised draft of his Mulu report on cave-frequenting vertebrates in the Gunung Mulu National Park, Sarawak. He also answered the Earl's two questions

Letter from Prof Andrew J. Berger to the 5th Earl of Cranbrook informing him that he had nearly finished a revision of "Hawaiian Birdlife". He also asked for advice on the scientific name for the Guam swiftlet

Letter from Prof Andrew J. Berger to the 5th Earl of Cranbrook saying that the swiftlets in Hawaii were descendents of the ones released by Woodside

Letter from Prof D. G. Tucker to the 5th Earl of Cranbrook concerning sonograph analyses of tape recordings [see also "Type B sonagram of group of birds in cave" and "Brochure for portable transistor magnetic tape recorder"]

Letter from Prof David Norman to the 5th Earl of Cranbrook on X-ray scattering of swiftlet nest material

Letter from Prof E. W. Jameson, to the 5th Earl of Cranbrook on the breeding cycles of Collocalia esculenta. Attached: Periods when fifty percent of more of the nests of swiftlets (collocalia esculenta) have fresh eggs (data from Lord Medway, 1962)

Letter from Prof J. David Pye to the 5th Earl of Cranbrook concerning changes he made to a paper on swiftlets that he co-authored with the Earl

Letter from Prof J. David Pye to the 5th Earl of Cranbrook concerning his letter to Mrs J. F. M. Horne