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The importance of scavengers

The photo above depicts members of a hyena clan scavenging on the carcass of a giraffe. Despite scavengers like hyenas and vultures often receiving a bad reputation and being viewed with disdain by many, they actually play a key role in ecosystems. By consuming carcasses, they prevent pathogens from spreading to human populations and contaminants from leaching into the environment.

What are scavengers?

A scavenger is an organism that primarily consumes decaying biomass, such as meat or rotting plant matter. There are many different types of scavengers; however, for the purposes of this article, we will focus on two of the most prominent and well-known scavengers: hyenas and vultures.

The spotted hyena, the most common type of hyena, is found in most of Sub-Saharan Africa. Although it is a very successful opportunistic hunter, it is also a prominent scavenger, specifically evolved to efficiently digest skin and bones found on carcasses.

Vultures, of which there are many different species, are perhaps the most well-adapted scavengers. Riding thermal winds to staggering heights, they scan the ground for carcasses, using their extraordinary eyesight. One Ruppell’s vulture was recorded at 37,000 feet, the same height as most commercial airlines.

Once a vulture finds a carcass, they usually gather in large numbers, using their curved and sharp beaks to consume almost all parts of the animal’s flesh. The stomachs of vultures contain an incredibly potent acid that destroys many of the harmful substances found in dead animals.

A bad reputation

If you have been fortunate enough to go on safari, you may have heard the ominous yowl of a hyena in the night or the eerie cackle of hyenas as they feed. Even vultures, when feeding, present a violent and seething mess of screeches, curved beaks, and feathers.

Having seen these creatures in the wild myself, it is hard to associate them with the positive connotations we often attribute to other predators, such as the regal nature of lions or the majestic flight of an eagle.

Hyenas, for local herdsmen, are considered a scourge, often preying on lambs and even fully grown cows, targeting the cattle’s backside and genitalia, leading to a slow and painful death. For the Maasai, being named a hyena, “Orkonoi” in Maa, is the same as being named greedy.

Vultures have suffered a similar damage to their reputation; for many cultures, they were seen as a bad omen. In Christianity, the vulture’s spiritual meaning in the Bible was an unclean animal linked to the kingdom of death.

The benefits of scavengers

When an animal dies, its carcass begins to decay due to a multitude of bacteria, fungi, and other microscopic organisms growing and consuming the body. Scavengers are part of the natural balance of the ecosystem; their role is that of a caretaker, quickly and efficiently removing the rotting carcasses left in the wild.

If large scavengers are removed from their natural ecosystems, bodies will begin to pile up, attracting flies and becoming hotbeds for microscopic growth, including the growth of pathogens that could potentially spread to other animals and humans.

Hyenas give humans health benefits

A study conducted in Mekelle, the capital of Northern Ethiopia’s Tigray region, found that annually, hyenas remove 207 tons of animal carcass waste from the city. The removal of the rotting carcasses had knock-on benefits to the local community, reducing an estimated five cases of anthrax and bovine tuberculosis for Mekelle residents and 140 cases for cattle, sheep, and goats. This natural disease control saves the city an estimated $52,000 annually in treatments and costs of livestock lost to diseases.

The death of vultures and the rise of rabies

Unfortunately, India has seen a rise in deadly diseases as a result of the loss of its most important scavenger, the vulture. Vultures are highly adept at cleaning up carcasses; they can eat almost 40% of their body weight in bulk, whereas other animals can only eat about 5%.

As a result of poisoning from the drug diclofenac, a painkiller administered to cattle, vultures began to die at an astonishing rate in South Asia. In fact the populations of three of India’s most common vulture species fell by more than 97% between 1992 and 2007.

The huge die-off of vultures allowed for the rise in feral dogs, feeding on the carrion that was once the vultures’ domain. Estimates suggest that the decline in vultures made way for an extra 5.5 million feral dogs, coinciding with a huge increase in cases of rabies.

Scientists reached the conclusion that the death of vultures and the consequential rise in rabies resulted in the death of 47,395 people. The indirect economic cost of this was estimated at $34 billion, equivalent to 3.6% of the India’s GDP.

This sheer enormity of the negative benefits caused by the loss of vultures in India is staggering, causing untold misery through the loss of life and a massive blow to the country’s economy through fighting the disease.

The case for Kenya

Sadly, Kenya has also lost 80-97% of its vultures over the past 50 years, largely as a result of mass poisonings. In the Maasai Mara, the death of vultures could well have contributed to an increase in feral dogs in the area, which, in turn, could have contributed to the death of many wild dogs that roamed the Maasai Mara.

A study conducted in 1990 on three wild dog packs in the Maasai Mara found that 21 of 23 members died suddenly within a six-week period, as a result of rabies.

African Wild Dog
African Wild Dogs in Tsavo Conservation Area 

This once again highlights the need to protect the fragile balance of ecosystems, from the plants at the start of the food chain to the scavengers at the end, regardless of the creatures’ reputation.

Thankfully, in recent years, we have begun to recognize the importance of our scavenger species, and many conservation programs have sprung up to protect them, especially our vultures.

To have a fully balanced and healthy ecosystem, we should aim to protect and nourish all creatures, as they all have a key role to play. From cackling clans of hyenas to the screeching vultures that unceremoniously dispose of carcasses, scavengers play a pivotal part in preventing pathogens and cycling nutrients through our dynamic and complex ecosystems.

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