Seeds, fruits, insects and meats are the first things that generally jump into people’s minds when they think of what birds eat. This is generally the preferred diet and case with most birds, whether it be an eagle feeding on a kill or a waxbill jumping around feeding on grass seeds. Sometimes birds will go completely off of their preferred diet, taking advantage of a plentiful or nutritious food source, like doves picking up termites. Like most wild animals, birds have to take their chances when they present themselves.
Some bird species have taken this to the extreme, though, and learnt to feed on things that other birds have never used before. In some cases they have become so specialised that their food can even be found in their name. In this blog we are going to have a look at these birds and how they utilise these special food sources.
Not just scavengers
As most vultures are scavenging birds, they are associated with large carcasses. Most of our vulture species will feed solely on carrion, but there are four species that have added some variation to their diets. They will all, however, still scavenge if and when the opportunity presents itself. These variants are not things that the vultures would have hunted and killed.
The hooded vulture has the habit of following predators like lions and wild dogs, even after a kill. These vultures know that at some point the predator’s stomach is going to work, and that’s exactly what they are waiting for. The bacteria in their stomach are so strong that they allow these vultures to eat the faeces of the large predators.
Another one of the smaller vultures, the Egyptian vulture, has learnt to use tools. The birds found in East Africa have learnt that ostrich eggs are a great meal. It just isn’t easy getting to the contents through the thick shell, and these vultures have come up with a solution. They use rocks, either using the rock as a hammer, bashing at the shell with the rock in their beak or flying above the eggs and dropping stones onto them.
Bearded vultures are unlike the other vultures in the way that they can swallow bones whole. Bones that are under a foot long are generally swallowed whole, while larger bones will be carried up high and dropped onto rocks to break. Dropping the bones may take several attempts, but the birds’ aim is really good, and they eventually crack the bones. Feeding on the bones and the bone marrow is said to make their diet as much as 15% more nutritious than other birds of prey that only feed on flesh.
The last of the four vultures with a varied diet is probably the most unusual of the lot. These vultures are the birds of prey that feed the most on fruits. As the name suggests, palm-nut vultures feed on the fruits of the raffia palm. The bill of this vulture has even changed, being nice and broad with a sharp edge, allowing it to scrape off the rich, oily flesh of the fruit. The vultures are often found close to large bodies of water where the palms are found and will also feed on fish and crabs.
Storks with a different taste
Storks are usually quite large birds that feed on small invertebrates, usually insects, or quite a few species feed on aquatic life. The African Openbill has taken this to a new level and feeds on large aquatic snails and mussels. The bill itself has evolved into an odd shape with a large gap in the middle. This gap is large enough that it is visible from quite a distance when the bird turns its head to the side.
Marabou storks are one of the largest of the storks but also have one of the most varied diets. They are well known to scavenge with vultures at carcasses, walk around marshes picking up frogs and tadpoles and living around rubbish dumps. In some areas, though, some individuals have learnt that flamingo chicks can be very tasty. The marabous are large enough to chase off a defenceless adult and swallow the chicks whole.
Different insects
A whole host of birds will feed on insects, and even birds that don’t feed on insects as adults will feed insects to their chicks. Some insects have come up with ways of defending themselves against this, though, and now, some birds have come up with ways of combating this.
Bees can be picked off individually by certain birds like bee-eaters, as they have learnt how to deal with the sting of the insect. Very few birds will take on an entire beehive, though as the hive would have to many bees present at once. Honeyguides won’t go in alone either, but they know that certain people will and their old friends, the honeybadger will as well. It was believed that the birds would feed on bee grubs afterwards, but it has been found that they also feed on actual wax itself. They are the only species that is capable of doing this with the bacteria in their stomachs breaking down the wax.
Hairy caterpillars, as the name suggests, are covered in hairs that act as an irritation. Even just brushing up against one of these guys can cause a horrible rash, and so they are avoided by most. Cuckoos, on the other hand, see these guys as food and happily snap them up. These hairs seem to cause a thick layer around the lining of the stomachs of the birds but have no effect on them at all.
As usual, birds manage to surprise us and come up with something out of the ordinary. It is their adaptions like this, finding ways to evolve to things like different foods, that allow some of these birds to do so well. Just when you think you have come across something a bird won’t eat, one of them comes along and shows you just how wrong you are.
