Bird droppings are unique among animals as they combine their faeces and urine for excretion, giving it a generic look. Although this allows you to tell it is from a bird, it is harder to know which species the dropping is from.
There are three main categories of bird droppings: Droppings from birds that eat invertebrates, droppings from birds that eat vertebrates, and from birds that eat plants. It is easier to tell from the contents, rather than the size, colour or shape, which category it falls into. However, identify the bird also relies on the habitat, tracks, and location of the dropping.
Although it is difficult, let’s look at some ways to help you identify which bird droppings you are looking at.
Identifying is difficult
Analysing the shape, content, and colour of the dropping will help classify a broad category of birds, and there are three main categories. Without some other knowledge, however, it is challenging to tell which bird has left the clue.
The surrounding habitat, location of the dropping, and any tracks close by can help you identify the bird.
Unfortunately, analysing bird droppings is difficult as there can be differences in the shape, colour, texture, and size due to seasonal variation, changes in diet, and how much water they have taken in.
Bird droppings can also give a great indication of where to look for birds. If particular rocks or trees are stained white, this will indicate that these are popular perches for birds. The uric acid in the droppings will stain these white, and rocks marked by a significant presence of white can allow you to set up for a nice view of the bird when it comes back.
Birds will drop their waste anywhere, unlike most animals that use latrines around their territory to mark their area. Large amounts of droppings can indicate nesting or roosting sites, taking the form of scattered pellets or a large splash on trees, rocks, or other surrounding areas.
Looking at the habitat and environment you are in can give you an idea of which bird it was. If you can see many parrots, for example, in the area, then the chance is that it will have come from one of them.
Looking at the tracks left by birds can also indicate what birds are in the area, and if you can match this up to the category of dropping, then this gives you a better indication of which birds are in the area.
Droppings are just one way of identifying birds, and although they help, you need to use all the methods at your disposal.
Splitting up bird droppings into different categories is the easiest way to tell the difference. This should be based on their content rather than their shape, as it is standard in most.
Because birds change their diet depending on the time of year and what food is available, the categories are guidelines only.
Droppings with invertebrate remains
Droppings from a bird that has fed on invertebrates tend to be very dry and are hard to the touch. They have a granular consistency which indicates the indigestible fragments of the invertebrates exoskeleton. They are sausage-shaped and, due to the lack of water, are not usually spiralled. They will crumble, showing the indigestible remains.
Many birds feed on invertebrates, can be made by many passerines and waterbirds such as herons, storks and egrets.
These droppings are usually made from birds that don’t regurgitate pellets of the parts of the animal that are indigestible. These are typically small birds that pulp their food before swallowing.
These droppings are dark in colour, sometimes even black, but often with a reddish tinge depending on the food source. They are usually shiny from the intake of chitin from the exoskeleton.
Droppings with vertebrate remains
Droppings from birds that feed on invertebrates contain a lot of liquid and are usually semi-liquid and smooth. They include a high amount of water content from the blood and body fluids of their prey.
They are generally white, and large amounts are known as whitewash. This is caused by uric acid, which flushes the salts from the body liquids of their prey. Bleaching of the dropping is caused by the amount of calcium in the digested skeleton. The bleach can also be caused by guanine found in the scales of fish. The increased amount of calcium and guanine shows that the bird has eaten their prey whole.
Bone, teeth, keratin, claws, bills, feathers, and scales are not usually found in the droppings but are instead regurgitated into small pellets called castings.
It can be pretty tricky to tell which birds droppings you are looking at as many eat both invertebrates and vertebrates. This can be especially difficult in birds such as storks and herons. The ostrich, which doesn’t feed on vertebrates, also produces similar droppings, although this is down to their diet. Ostriches feed on the skeletons of small animals and shells of invertebrates to ensure they get enough calcium.
Droppings with plant remains
Droppings from birds that eat plants without seeds look similar to those from birds that eat invertebrates. They are sausage-shaped and can have the same dark colour. In winter, they are hard, but in summer, they are softer and darker due to the increased chlorophyll and water content found in plants.
They may be coiled in summer due to the high water content and contain fruit seeds or pips. If only the flesh has been eaten, it can be soft and pasty, with the colour almost matching the fruit that has been eaten.
Pigeons and parrots, along with waterbirds such as ducks and geese are examples of animals that eat fruit without seeds.
If the bird has eaten plants, including the seeds, then the droppings are more solid. In winter, they are harder as the seeds are drier, while in summer, they have a higher moisture content with a spiral appearance.
In summer, the colour is greenish with a smooth consistency. As the seeds are not as hard, they are able to be digested more easily, leading to a pulp, but in winter, the seeds leave a granular consistency full of seed husks and are greyish-yellow.
These seeds are essential for the environment as they germinate more quickly once they have passed through the bird’s digestive tract.
As with other droppings, it is difficult to tell which birds have left them as ducks and geese also eat seeds, along with waxbills, finches, and doves.