Poisoning

In the last few decades, the consumption of poisoned or infected with dangerous substances food is the biggest threat for the survival of vulture species worldwide. Bulgarian species – Egyptian, Bearded, Cinereous (or Black) and Griffon vultures are widely distributed in the Old World. Unfortunately, almost everywhere in their habitats, vulture populations are decreasing or even tend to go locally extinct. For certain, the death cases, caused by poisoning, are the main reason for the visible decrease in their populations. In our modern, industrial world the Egyptian Vulture as species that has the skills to choose from a variety of food sources and shows high “ecological flexibility”, is the most endangered by different sorts of poisons and harmful substances in their food. Scroll down to read more about the various types of poisoning that threaten the survival of Egyptian Vultures. For the last 18 years at least 10 Egyptian Vultures in Bulgaria have died from different kinds of poisoning.

One of the most productive females in Bulgaria, died from poisoning and found below its nest 
in Eastern Rhodopes

Poisonous predator baits
Traditionally, in the last few centuries in the “advanced” world, predators have been considered “pest”. The 50s and 60s of the 20th century were the hardest period for the survival of Egyptian Vultures in Bulgaria. In the fight against the then-considered “pest” predators (mainly wolves) people started using strychnine – a substance, that was widely distributed everywhere and oficially set by the Forestry Services. Despite the fact that vultures have been officially protected in Bulgaria since the end of the 19th century, during these years they often became innocent victims of the poisonous baits, intentionally set for wolves and other predators. Marked in history are cases of the deaths of tens, even hundreds of vultures. The record-breaking case in Bulgaria is one from the 50s of the 20th century when in the Rila mountain 86 Griffon Vultures had died after consuming the dead body of a donkey, powdered with strychnine with the only aim to destroy wolf populations in the Rila mountain. In the middle years of the last century accidents like that had probably been so common that they caused the almost simultaneous and very fast extinction of the Griffon, Bearded and Black vultures from Bulgaria, even though they had been a common sight in  the landscape. During that time, Egyptian vultures probably suffered the least, because poisons were set mainly in winter, when Egyptians, as the only migratory vulture species, had been in Africa. Despite that, even though there are small amounts of data, saved since those days, their populations were also completely destroyed by poisons in many areas (e.g. the areas north of the town of Kotel, the Romanian part of Dobrudja, parts of the Eastern Rhodopes, etc.). Nowadays, the setting of any kind of poisonous predator baits is strictly forbidden, according to the Penal code of Bulgaria.

Wolf feeding on the remains of naturally died domestic animal

Poisons on rubbish dumps
While searching for food, many Egyptian vulture pairs tend to visit rural or town landfill areas every day. All the harmful substances these places are teeming with are threatening their survival. Different types of chemicals from the rubbish of our everyday lifestyle are reaching the rubbish dumps. This includes the poisoned bodies of cats, dogs and rodents, which can be a huge risk for birds' health. Another danger is the fact that sometimes companies are hired by local municipalities to execute “poisoning” (called deratization) on landfills, but no matter how precise the execution is (it's forbidden by law to try to poison rats with spreading poison on the surface) any actions of this kind are particularly risky for the survival of Egyptian vultures. 19 years ago, in 1992, ornithologists in Macedonia accidentally came across another case of poisoning. After a campaign of rat poisoning on a landfill, they found the death bodies of 65 Egyptian vultures, which is equal to half of the population of the species in the country. In this particular case, the vultures were attracted at the rubbish dump by slaughterhouse offal thrown on the rubbish dump, which coincided with the rat poisoning. The vultures congregated at the landfill to collect body mass before their long trip to Africa later in the autumn.

Dogs probably shot and thrown in ditch              Flock of over 30 Egyptian Vultures circling
on the rubbish dump of Krumovgrad above rubbish dump in Turkey

The rubbish dump of Varna city

Chemicals, used in agriculture
The use of pesticides in agriculture (mainly insecticides and rodenticides) causes the death of insects, rats and reptiles, which are a part of the Egyptian vultures menu. As typical natural “cleaners”, vultures make use of animal remains, but if the concentration of harmful substances inside is high, birds can develop lack of coordination and body weakness, which can possibly lead to other dangers, concerning their health (making them more vulnerable to predators, car crashes and electrocution, etc.). If the amount of these chemicals is too big, it can even lead to the death of the bird. What is particularly dangerous is the poisoning of mice in and around agriculture fields in summer. This is usually done by huge groups of people and the poisoned rodents become preferred food sources for vultures.

Spraying with pesticides in monoculture field        Sign marking field sprayed with pesticides

Antibiotics, used in factory farming
The growth of factory farming is always connected to the use of huge amounts of antibiotics as a preventive measure against different diseases. Poultry, pigs and cattle, raised in factory farms, are often medically treated with antibiotics. These animals, who don't make it despite the treatment, are often thrown on places, where vultures have total access to them and that can possibly make them engulf big amounts of antibiotics, which actually weakens their immune system and makes them extremely vulnerable to usually safe for them pathogens and viruses.

Lead poisoning
The lead poisoning in birds of prey is still not very well-examined threat that endangers the welfare of vulture species. The poisoning itself occurs when the birds consume animals that had died as a result of hunting activities, so their bodies contain lead shots. In an environment that's high on acidity, like the stomach of Egyptian vultures, these lead shots can be partially dissolved, so the amount of heavy metals inside the body of the bird grows bigger and bigger. Even a few shots, in case they're not regurgitated in the form of undigested food remains (pellets), can lead the vulture to the brink of death or can even have a lethal effect. Nowadays, lead poisoning is the biggest threat for another, even more endangered bird species that has higher stomach acidity – the California Condor.

Veterinary medicines
In India, where cows are sacred animals and their treatment is very similar to that of humans, in the last few decades for relieving the pain these animals are feeling (like, when they have arthritis), people have used medicine, called diclofenac (non-steroidal anti-inflammatory drug). Only after a few years of research, in 2003 an international team of scientists found out that the consumption of animals, previously treated with this medicine can be lethal for at least 3 vulture species, inhabiting South and Sotheastern Asia. This finding revealed the mystery around the catastrophic extinction of vultures in India, Pakistan and other countries, where some species have collabsed in numbers – from populations of tens of millions to just a few thousands.