Wildlife TV

Learn interesting and funny plant and animal facts with videos and photos

Why do people think that ostriches bury their heads in the sand?

You may have found yourself in an argument with someone who is refusing to see sense and listen to you. You may have found yourself saying that they have buried their head in the sand.

It is a common metaphor that is a part of our cultural vocabulary; we use when people are being ignorant of facts, refusing to acknowledge advice or in denial about their situation. It has been commonly used in this way for centuries, since Roman times. But what is the origin of the phrase? It comes from the ancient observations of the behaviour of animals, namely, ostriches. So, why do ostriches bury their heads in the sand? Well the answer is that they don’t.

It has long been believed that ostriches will bury their heads in the sand to avoid predators; that they are so stupid as to believe that by concealing their heads they become invisible to predators. However, the truth is that this is a myth; there has never been any observation of an ostrich burying its head and yet for centuries the idea has stuck with us. There are, however, many behaviours which ostriches perform that might have given rise to this curious myth.

Ostrich Head and Neck (Struthio camelus)

Ostriches (Struthio camelus) are strange and fascinating birds; is it really true that they bury their heads in sand? If not, why do so many people think so? Photo Credits.

The common ostrich (Struthio camelus) is the world’s largest bird (currently alive). It is found across large swathes of sub-Saharan Africa and, historically, North Africa and Arabia. The first recorded occurrence of a belief that they bury their heads comes from Gaius Plinius Secundus, also known as Pliny The Elder (AD 23 – AD 79) a Roman scholar who invented the idea of the encyclopedia. Pliny spent most of his time observing and recording natural phenomena, including the behaviour or wild animals. He was a great author and philosopher who wrote volumes of information about the natural world, however, not all of it turned out to be entirely accurate. So from where did he get his ideas about ostriches? There are several potential explanations.

Gaius Plinius Secundus (aka Pliny the Elder)

Gaius Plinius Secundus (aka Pliny the Elder) was a Roman scholar who wrote about ostriches hiding their heads to evade detection. He was a great naturalist and even invented encyclopedias, but he was wrong on this one issue. Photo Credits.

Ostriches are extremely fast runners. They have long powerful legs that can accelerate them to up to 70 kilometres per hour; clearing 4 or 5 meters in a single bound. Quite rightly, they use their tremendous speed as their first resort when faced with a threat, however, sometimes, they might be trapped or injured or otherwise unable to escape. When they are not able to run, ostriches will lie down as flat as possible, stretching their necks out flat against the ground. Their necks and heads, incidentally, are often the colour of their habitat’s terrain (sandy brown/grey) and so at a casual glance, only their bodies would be visible, perhaps leading to the assumption that they have buried the rest.

Ostriches are omnivorous, eating a wide variety of things, however, they mostly feed on low level vegetable matter such as roots and fallen seeds, as well as invertebrates such as crickets. They also practice geophagia; picking up stones and pebbles from the ground and swallowing them, keeping them in their gizzards to help grind up and digest food. As a result of this diet, ostriches have their heads down at ground level for large amounts of time. Perhaps this has been misinterpreted and has helped propagate the idea of burying their heads.

Male Ostrich (Struthio camelus) Feeding

Ostriches (Struthio camelus) find most of their food on the ground and so have their heads down often. This may have given rise to the idea that they even bury their heads. Photo Credits.

It has also been suggested that ostriches will lower their heads to ground level in order to scan the horizon for threats. They may simply also lower their heads to ground level to be less obvious to prowling predators when they feel nervous. But the idea that they believe that they can conceal themselves completely by hiding their head is unfounded. Pliny the Elder suggested that they also stuck their heads into bushes to achieve the same effect. This notion is born from the idea that ostriches are ‘stupid‘ animals because they have such tiny brains: Ostriches have brains smaller than their own eyeballs (although they do have the largest eyes of any land animal)! In reality, animal cognition is not as simple as saying that a small brain equals a stupid animal. However, their small heads may have contributed to the myth; when their heads are down at ground level, they are so small that they can be difficult to see, this optical illusion may have led people to believe the animals’ heads were in fact buried.

Ostrich Chick (Struthio camelus)

Adult ostriches (Struthio camelus) grow to be the largest birds on the planet, but the start life as very cute chicks! Photo Credits.

Ultimately we have seen that an ancient misconception has turned into a common metaphor for human behaviour and it has been hard to separate the popular myth from the scientific truth ever since. There are many reasons that might explain why Pliny the Elder first wrote about the idea, but ultimately, we may never know where it came from originally.

Much love,

-Nick

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Hematophagia: Vampires are Real!

Animals eat all sorts of things. The diversity of species in the animal kingdom is matched by the diversity of diets. In previous posts we’ve seen how some animals will eat bones (osteophagia), rocks or soil (geophagia), and even faeces (coprophagia). The next ‘phagia‘ we’re going to look at is hematophagia; feeding on blood.

When we think of feeding on blood, the animals that come to mind are blood sucking leeches and pesky mosquitoes but in reality, it is a widespread feeding behaviour utilised by a broad range of species. There are two categories of animal that feed on blood, obligatory and optional; some animals exclusively feed on blood (they are obliged) and some just supplement blood into their regular diet (it is an option). We call animals that feed on blood ‘sanguivores

So why does blood make a good meal? Blood carries vital chemicals around the bodies of many animals and as is loaded with nutrients, proteins, salts and fats; it is a nutritious and high energy food source. Most predators, such as big cats, will gain the nutrients found in blood because they eat all of an animal’s tissues, but hematophagy is used to describe when animals specialise in feeding on this valuable food resource.

Common Vampire Bat (Desmodus Rotundus)

There is nothing supernatural about vampire bats, they are simply an animal adapted to a specific diet. Photo Credits.

Blood is, of course, kept inside animals’ bodies, so in order to drink it, a certain amount of ‘surgery‘ is required. The process of accessing blood is called phlebotomy, it involves cutting into flesh and revealing veins, arteries or capillaries. The tools used by hematophagic animals are almost always their mouth-parts but there are many different anatomical approaches.

The first part of phlebotomy is cutting the flesh; mosquitoes (family: Culicidae), ticks (superfamily: Ixodoidea) and other blood sucking invertebrates have sharp mouth-parts that pierce the skin and dig down to find a source of blood, they then suck up the liquid or let the victim’s blood pressure force the blood into the diner’s mouth. Vampire bats (subfamily: Desmodontinae), found in Central and South America, have a slightly more crude and messier method, they simply use their teeth to slice open their victim’s skin and then lap up the pool of blood that comes out of the wound with their tongue. Interestingly, vampire bats will also use their teeth to trim fur away from the site where they intend to feed.

Anopheles stephensi

This mosquito (Anopheles stephensi) is feeding on human blood by piercing her mouth-parts through the host’s skin. She is digesting the rich nutrients and expelling the excess liquid. Photo Credits.

So vampires are real, but they aren’t supernatural beings, they are animals looking for a good meal, and there are many different species.

Vampire bats are a special group of bats that have become specialist blood drinkers, hence their name. They do not rely on echolocation like many other bats but instead they have specialised senses for finding sleeping mammals on which they can feed. They sniff out carbon dioxide (CO2) and chemicals found in sweat, and have special thermoreceptors on their noses which allow them to detect heat; this also allows them to find warm spots on an animal’s body where blood is closest to the surface.

Vampire Bats (Desmondus rotundus)

These common vampire bats (Desmodus rotundus) are being given a free meal of fresh blood, but in the wild they specialise in stealing blood from sleeping mammals. Photo Credits.

Mosquitoes are perhaps the most famous blood suckers, however, in reality they are not exclusively hematophagic. Not all species of mosquito feed on blood, and for those that do, it is only the females. This family of flies has evolved to feed on nectar and fruit juices but the females of some species have adapted their mouth parts and specialise in drinking blood from the bodies of mammals or birds. But why only the females? The reason for that is related to the nutritiousness of blood as a food source; they use the extra nutrients to help in egg production and development.

Sanguivorous animals are generally parasites; they take blood from their hosts and give nothing back in return (except maybe for a nasty disease). There is one animal that until very recently was thought to be beneficial to it’s hosts, but the relationship is not what it seems. Oxpeckers (genus: Buphagus) are Southern African birds that spend their time riding large grazing animals around, feeding (mostly) on ectoparasites such as ticks. A large animal like a giraffe (Giraffa camelopardalis) has a lot of surface area and a lot of blood and as such attracts a lot of parasites. Oxpeckers have found that riding along on a giraffe is a great way to find all the food they need. It used to be assumed that oxpeckers provided a wonderful service to the large mammals of Africa but recent studies have shown this might not be the case. Although oxpeckers are very fond of ticks (which are already full of blood), they also practice hematophagia and will regularly drink fresh blood from wounds on their host mammal’s body. Oxpeckers will even open up wounds and prevent them from healing so that they have a regular source of blood, this can be painful for the animal as well as putting them at risk of infections.

Yellow-billed Oxpecker (Buphagus africanus)

The yellow-billed oxpecker (Buphagus africanus) is one of the two species of African bird that feed on mammals’ parasites. Recent studies have shown they might cause more harm than good by keeping wounds open to drink blood. Photo Credits.

Hematophagy in practice can be a risky business; anyone who has been bitten by mosquito knows that their first response is usually of aggression and the same is true for other animals. Feeding on an animal’s blood requires physical contact and if caught, there is a possibility of being attacked or even killed. However, blood is such a valuable food resource that many animals are willing to take on these risks in order to obtain it, and many of them have a few tricks that help them get away with it.

Most blood drinking animals have special saliva that delivers a cocktail of chemicals into the bite site when they start to take blood. Their saliva can contain anaesthetics that prevent the host from feeling the bite and reacting to it, and also anticoagulants which prevent the blood from clotting so that it stays liquid and drinkable.

Animals have formed complex relationships with one another when it comes to feeding. When we think of animals feeding on other animals we tend to imagine large predators killing and devouring their prey, but in reality, some species have developed techniques for getting the sustenance they need without so much theatrics.

Much love,

-Nick

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Mating for Life Part 1: Monogamy in Birds

The animal kingdom is full of different mating strategies both of terms of the physical ‘deed’ and courting/attracting mates. Mating is when a male and female of the same species (or genus) come together to reproduce and create offspring. In reality, ‘mating for life‘ is quite rare in the animal kingdom, but several species practice monogamy; providing exclusive mating rights to a single partner for a given period of time.

  • Which animals mate for life?

Some animals are famous for their perceived monogamous behaviour: The European turtle dove (Streptopelia turtur) has been the subject of Shakespearean poetry for its dedication to its life partner. Turtle doves do indeed seem to pick a preferred mate, but they certainly aren’t as saintly as it first appears; females will commonly mate with passing males if they are deemed more desirable than their partner, this of course is done in secrecy when their partner is away feeding. Similarly, mute swans (Cygnus olor) are also almost a mascot for romance and love, especially in Western popular culture, and although they are very likely to stick with a single partner for most of their life, they are able to find new partners if their first partner dies.

A pair of Mute Swans

Mute swans (Cygnus olor) are famed for there life long partnerships. Cobs and pens (males and females) make a heart shape with their necks when courting.
Photo Credits.

  • Do all birds mate for life?

Well no, but around 90% of all bird species practice some variety of monogamy, however, there is a lot a variation within that. Emperor penguins (Aptenodytes forsteri) for example have a mating system called ‘serial monogamy‘. These penguins famously go to great lengths to work together as parents to raise a single chick in the hospitable ice fields of Antarctica but once that chick is grown, the couple part ways and might never meet again. Emperor penguins pick new mates every breeding season and although they are fiercely loyal to their partner during their relationship, their affair won’t last into the next year.

Some birds have social standards when it comes to being faithful to their partners; such as black vultures (Coragyps atratus) who form strong partner bonds but are never the less still tempted to cheat on their partners. If other members of a group black vultures catches an individual mating with someone other than their partner, then the group will attack them! Adultery is a punishable offence for these birds. Similarly, male blue-footed boobies (Sula nebouxii) will react dramatically to a cheating partner; males will roll eggs out of the nest if they doubt their paternity, prompting females to be more faithful or else they may lose their offspring.

Black Vultures

Groups of black vultures (Coragyps atratus) enforce monogamy by attacking any individual who is caught cheating on their partner.
Photo Credits.

Bald eagles (Haliaeetus leucocephalus) are noted for their dedication to a partner, often spending as long as 35 years living together. In order to form a bond, the eagles engage in spectacular flight displays and trust exercises, for example, they will soar high into the sky, inter-lock their talons (feet) and free-fall, only separating just above the ground. Once they find their ideal partners, a couple of bald eagles build a nest together and build upon it every year as they raise several chicks. A lifetime of building a home together can result in spectacular nests, the largest tree nests of any bird in fact; one nest in Florida, U.S.A. was 6 metres deep and weighed nearly 3 tons! However, even these birds don’t have perfect relationships; they will break up if they are unable to produce offspring after a few seasonal attempts.

A pair of Bald Eagles

Bald eagles (Haliaeetus leucocephalus) form strong partnership and build nests together throughout their lives, but if one or both of them cannot produce offspring, they will break up.
Photo Credits.

The outright champions of commitment to partners (other than humans of course) have to be albatrosses (family: Diomedeidae). We’ve mentioned these interesting sea birds before, but they are extremely fascinating when it comes to their monogamous mating behaviour. Like bald eagles, albatrosses engage in mating displays but there’s take place on the ground and involve elaborate dances with their prospective partners. Once a partner is selected they will spend the rest of their lives producing offspring exclusively with each other. As of yet, we don’t even know for how long an albatross can live, we haven’t been recording them for long enough, however, so far it has been observed that an albatross partnership can last for at least as long as 50 years, each year, the partners meet up at the same place to mate and raise their chicks. It takes an albatross many years to perfect the art of dancing, sometimes they won’t be able to secure a mate for 15 years, so this may explain why they are reluctant to split up, given the effort it took to form the relationship in the first place! Even when an albatross loses its mate, it may not seek out a new one for several years; perhaps they are mourning?

In the next post, we will look at some of the other animals that practice monogamy. Although birds are the most faithful to their mating partners, there are other animals that adopt similar practices.

Much love,

-Nick

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