Basics of droppings
All birds produce droppings, which comprise undigested and waste material, mixed with urine (usually as a white paste). Droppings can occur at random, but also on, under and around well used perches, for instance roost sites or hunting sites or nest sites. So, although different types may not be species specific they may still be useful in tracking nests or roost sites etc. There are several types of dropping, which often relate to the diet of the bird in question. Seedeaters usually produce small, well formed droppings with obvious seeds and perhaps some fruit flesh within. Some may be confused with regurgitated pellets. Plant eaters often produce cylindrical pellet like fibrous droppings, which in some cases have a white urine cap (eg Red Grouse, below left). Other plant eaters, especially those with a less fibrous diet, produce semi-liquid masses. Insect-eaters may make cylindrical droppings with insect hard parts encased in white urine (classically Green Woodpeckers do this, below centre) or smaller, more globular droppings such as those of House Martins. Finally, many carnivorous and fish-eating birds (eg Grey Heron, below right) regurgitate most of the undigested hard parts (bones, fur, feathers etc) as pellets, and their droppings consist of white liquid, often jetted out to form ‘white wash’.