The mixture of urine and faeces voided through the cloaca (combination of anus and urinary plus genital openings) of varying degree of liquidity. In the nestlings of many passerine birds each dropping is enclosed in a gelatinous membrane so that it can be removed by the parent. The presence of insoluble salts in the urine is responsible for a white appearance, often in the form of a cap on the faecal matter. At sites where birds form colonies the material may accumulate and form thick layers of so-called 'guano' (also listed).

Alternative form for dropping : droppings.