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Birds and people

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Birds and people

There was an item on the news today that dinosaurs started losing the battle for survival fifty million years before the asteroid strike that finally wiped them out. It is surmised that splitting up of continents and climatic change brought down the curtain on their existence and sealed their fate. Amazingly, their surviving descendants are still very much with us. We see and hear them daily and few of us realise that we are engaging in virtual time travel to the past whenever we look at a bird! From the pterodactyl through the archaeopterix to the modern birds there is a linkage which scientists assert confirm that birds are descended from dinosaurs. It is to my eternal regret that having grown up in a country with over 1000 species of birds, some of which are endemic to Uganda and among the most colourful of all birds, I did not pay too much attention to them in my younger days. It lends credence to that well worn aphorism that ‘familiarity breeds contempt’. 

 

For a few years now we have had a ‘Tweet of the day’ which precedes the main BBC current affairs programme. It is only a couple of mintues long and consists of birdsong with a brief description of the bird. Living in an area where birds are rarely heard it is a welcome start to the day. They seem to all go about their daily activities in silence for much of the time except in the morning when there is a ‘dawn chorus’ in the warmer months. This is in complete contrast to the daylong birdsong  in Uganda. There was a mango tree in our garden that was home to doves that would regularly engage in their unique song.  I often wondered where they were

singing about.

 

There is nothing quite like the sound of various birds all ‘twittering’ away to assert their territorial boundaries or advertising themselves on the ornithological equivalent of dating ‘nest’ sites. One  wonders how many species  have survived the past five decades.

 

One of the joys of visiting home is listening to bird song instead of the constant thrum of traffic. One  reads in dismay  that  numbers of unique birds such as the ‘national bird’, the crested crane, are rapidly dwindling. The  destruction of their habitats is responsible. Some are on the brink of extinction. The shoebill stork has only 300 individuals left in Uganda.

 

As a young boy, I witnessed something that disturbed me at the time and was seared into my memory. Me and a cousin were walking past a neighbour’s garden where a chicken with its chicks was pecking away at some grubs.

 

Suddenly a huge eagle appeared from nowhere at great speed, swooped down and picked up one of the tiny chicks in its talons. It then rapidly ascended and settled on one of the branches of a nearby tree. Before it could peck at its dinner, there emerged from the house a man with a large shotgun who then aimed and blasted away in the direction of the eagle which instantly plummeted to the ground in a flurry of feathers. The  mindless violence  visited upon a majestic creature that was merely following its instincts seemed  disproprtionate. That brief sequence of events was the first demonstration of the destructive power that an armed man could wield  acting as ‘judge’, jury and ‘executioner’.

 

Move forward 50 years from that episode and the population of eagles and vultures is set to crash by as much as 80% by some estimates due to the continued use of a powerful poison (Carbofuran) originally used as a pesticide that continues to be available in East Africa. It has been banned in North America for many years. Poachers use it to poison water holes where water fowl feed. These die en masse and are gathered  in their hundreds to be sold on to unsuspecting customers.

 

Fishermen too use the same poison to catch fish with minimal effort. This  results in far more fish dying than can be gathered by the fishermen. The eagles and other scavengers such as vultures then pick up the dead flotsam and ingest the poisoned fish. The  bonanza soon proves lethal to them and their offspring.

 

Pastoralists too are decimating peregrine birds in their hundreds. These have moved with their herds into areas previously designated as game parks and they soon find that their encroachment comes at a price. Large predators attack cattle herds as a source of easy pickings.

 

Man then hits back by the cunning method of using carcasses laced with  poisons such as carbofuran. It is an effortless way to  kill the lions, leopards and other top predators. As soon as  they drop dead, they are spotted in less than half an hour by circling vultures which descend sometimes in their hundreds to clean up the dead animals. However they too soon succumb to the poison and drop dead.

 

Poachers have used this technique to prevent game rangers from spotting where a poisoned or shot elephant has fallen. It takes  poachers over an hour to hack off two large tusks. Game rangers may spot where a large dead animal lies by looking up at circling vultures and then following this lead to locate a carcass. By eliminating the ‘Great Peregrine Spotters’ the game wardens lose a valuable  ally which gives poachers extra time to carry out their nefarious activities.

 

In a Namibian game park recently, there was an instance where 600 vultures were eliminated at one go after feeding on a poisoned elephant carcass. Normally if lions kill a wildebeest, the pride feeds on the carcass and afterwards amble away to find a spot to doze  off and digest their large meal.

 

The next set of nature’s specialists arrives in the form of jackals, hyenas, vultures and eagles. Vultures are designed to carry out  the job of picking every last scrap of meat from the bones of large herbivores.  They can usually do this in a staggeringly short time of less than a quarter of an hour in case of an adult wildebeest and then  take to the skies to search for the next meal. Because there are now fewer of them this task is taking longer.

 

Soon there will be none left to clear up remains of dead animals. Their carcasses will instead rot and possibly contaminate valuable water sources. The spread of zoonoses could increase due to loss of the processing of infected flesh via vulture guts which have powerful acid and immune systems that neutralise some mammalian viruses and prevent further transmission.

 

The wholesale slaughter of vultures and eagles will have serious consequences. In the annual animal migration around the Serengeti, around 500,000 animals die. The waste management team that clears up the carcasses is of the airborne variety. Their loss will prove irreplaceable as they are notoriously slow breeders and are exquisitely sensitive to environmental pollution. Another toxic  chemical DDT was discovered to weaken the shells of bird eggs with long term implications for birds at the top of the food chain which accumulated the chemical. Similar stories have occurred elsewhere.

 

In India a decade or more ago there was a series of unforeseen consequences of giving an anti-inflammatory painkiller drug to bullocks that ultimately resulted in the decimation of birds of prey and carrion scavengers such as vultures. Their rapid decline was followed by a massive increase in the numbers of feral dogs and the connection did not seem obvious at first.

 

A little bit of background. In India the killing of bovine animals is anathema so when they died of natural causes, the clearance of the carcasses usually fell upon scavengers such as vultures. These master dissectors don't depart until they have picked the bones clean leaving little for dogs and foxes to salvage. They gorge themselves until the effort of lifting off seems to require use of  some kind of  catapult such as you get on aircraft carriers!

 

In the past two decades or so, some farmers used to treat their hard working bullocks’ arthritic joints with a drug called Diclofenac. This is a nonsteroidal anti-inflammatory drug (NSAID) which reduced the pain of the arthritis and allowed the animals to work despite their joint problems. Eventually they would succumb to either natural diseases or perhaps toxicity from these drugs which can damage kidneys or sometimes the liver.

 

In any case when they died, their flesh still contained the drug in sufficient quantities to poison the birds (e.g.vultures) whose kidneys were ultrasensitive to the toxic side effects of the NSAID. So they started dying off in their thousands despite plenty of food.

 

A scientist soon discovered that the drug caused  kidney damage.  Sadly the catastrophic decline in the vulture numbers resulted in a dead cow bonanza for the dogs and rats whose population exploded. As there was no anti-rabies program targeted at dogs most of which were feral, the incidence of rabies among dogs and the humans they bit  rose in tandem.  What had seemed a miracle therapy for bovine arthritis resulted in a massive health hazard for humans.

 

The chain of events highlighted the consequences of failing to appreciate the impact of an intervention. One is advised to carry out well designed pilot studies. The scientific  detective work to finally identify the real culprit in this chain of events was well documented and took decades. The message was that  use of  commonly used NSAIDs which are potentially toxic could be disastrous. The implications  for East African cattle herders were serious but in a different way.

 

There, the tale involved a different poison but the effect on the population of vultures and birds of prey have been exactly the same. It turns out that there had been a sustained effort on cattle herders to destroy predators such as lions and leopards or even cheetahs by targeting them with poisoned bait.

 

The large predators die leaving the cattle herders very happy. Unfortunately the scavengers like vultures and hyenas which come to feast on the free ‘Maasai Fried Lion’ end up also getting a dose of the poison.

 

So there is a temporary explosion of the herbivorous game lower down the food chain that the predators used to keep in check. The sick animals harbouring various transmissible diseases remain within the herds possibly spreading harmful viruses.

 

Those animals with various  genetic abnormalities may live long enough to pass on their genes; the grazing sites cannot sustain the huge increase in numbers and when in addition a natural event like a drought hits, there could be a crash in the population which has a knock on effect all along the food chain. All because the natural culling which normally keeps numbers in balance had been eliminated.

 

At some point in the future the annual spectacle of migrations such as that of the wildebeest could become a thing of the past, all because no one really thought through the consequences of their actions. All we will be left with will be the overgrown grasses of the savannah with not a herbivore to keep them in check.  One hopes that this will not come to pass.

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