OSME Rarity form

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Advice on completing a rarities form

A rarities description should be seen as scientific information that will be stored long-term in the OSME archives. Recorders and rarities committees do not make the rules, they just put into practice the principles of factual knowledge and proof upon which all science is based. It is only by testing claims of fact beyond all reasonable doubt, by means of an accurate and thorough description, that recorders can save the science of ornithology from inaccurate or vague information.

The aim of this short note is to help you with note-taking and to do it in a logical and thorough manner. Bird identification usually depends on knowing what to look for - the 'field marks' - but a thorough rarities description should include the entire bird as far as is possible in the time available.

Occasionally after taxonomic changes (e.g. the separation of Basra Reed Warbler from Clamorous and Great Reed Warbler) it is necessary decades later to re-assign a bird to a different species. So it is of great importance to give as thorough a description as possible, backed up (but not replaced by) photos.

Note-taking

A notebook is as vital a piece of equipment as a pair of binoculars. The human brain makes mistakes and a few quick notes made at the time of observation can be invaluable later when you are trying to make an identification. Without a notebook, an observer is relying on memory; as a result, vital field marks may be missed, overlooked or imagined.

The normal method is to use the following series of information points, so as to get a comprehensive description. But if there is one particularly important part of the plumage, it is reasonable to describe that in detail first.

• General impression of bird(s) + its activities (jizz)
• Size
• Shape
• Plumage (head, upperparts, wings, underparts, tail)
• Bare parts (bill, legs)
• Voice (song / call)
• Which characteristics do you consider exclude similar species?

Regular comparisons (of size, shape, jizz etc) with more familiar species improve a description.

The OSME rarities form is available here as a PDF

Please send in your rarity records either by mail to:
OSME, c/o RSPB, The Lodge, Sandy, Bedfordshire, SG19 2DL United Kingdom
or by email to: rarities@osme.org