Article by Dr Wim Peters
Article Published 12 June 2008

The Sun, Giver of Life

Without the sun there would be no life on earth. Not as we know it and see it anyway. Without light and warmth who would want to live on this planet anyway? So we owe much – in fact our whole existence - to that celestial body. To enumerate all the individual reactions and processes that require the sun’s rays, would fill a book. That is to say, if we could know and list them all because there are millions. But all the effects are not beneficial. By now we have learnt to stay out of fierce sunlight for too long as we know what damage uncontrolled exposure to ultraviolet can do to our bodies. We have adapted and learnt to conserve water for times when the sun beats down relentlessly on a baked earth. We know what happens to heat-sensitive items that are exposed to direct sun – they melt or shrivel up. But this is not an article about what the sun means and does to us as humans. Suffice to say that, on balance, it is our ultimate benefactor.

But what role does the sun fulfil in pigeon racing? For many years fanciers have experienced devastating and inexplicable results on some fair weather days. On days when all should have been plain sailing with ‘good pigeon weather’, the races occasionally end up as disasters. (‘Good pigeon weather’ is a blue sky day with few clouds about, maximum temperatures at about 20 C and with no wing or a slight breeze ‘on the nose’.) Fanciers in the know usually ascribe these days to changes occurring on the sun, where magnetic storms - observable as high sunspot activity and solar flares - take place. These solar winds cause massive radiation storms in space which result in bombardment of the earth with atomic nuclei. Fortunately for us most of these atomic bombardments are caught up in the Van Allen belts and only a small portion are able to penetrate the atmosphere and reach earth. The solar atomic particles disturb the normal magnetic field surrounding the earth – the effect of which can be seen as the spectacular northern and southern polar lights (Aurora Borealis and Aurora Australis) – and which, many believe, confuse the magnetic homing systems of pigeons. To what extent it plays a role in the homing ability of racing pigeons, has yet to be adequately and scientifically established and is often hotly debated.

But pigeon racing is influenced in another major way by the sun. The direct warming effect of the sun’s rays can play havoc with racing. This has to do with overheating - dubbed ‘heat stroke’ in human medicine - and dehydration. Let us examine the development of these two conditions a little closer and determine whether anything can be done regarding their prevention and what to do in respect of treatment.

Heat Stroke.

When any object or body is exposed to the direct rays of the sun it absorbs heat. The rise in the body’s temperature is dependent on the strength of the sun’s rays at the time, time-length of exposure, environmental heat dispelling phenomena like the wind and the body’s own heat-dissipating strategies like panting, sweating and so on. What is critical is that most warm-blooded creatures have a thermoneutral zone (TNZ), that is, a range of body temperature during which normal activities can be performed. That range lies between the upper (UCL) and lower critical level (LCL) temperatures and is peculiar to each species. Furthermore there are individual differences within a species depending on protective hair cover, amount of body fat, fitness, health of the body systems etc. In addition, in humans there are exceptional feats of physiological body control so much so that the normal critical levels are exceeded. Feats which seem to defy logical explanations. One thinks of fire-walking, swimming at the North pole (by the human polar bear Howard Pugh), exceptional feats of staying underwater, conquering Mt Everest without oxygen tanks and so on. They remind one that the human mind can control the physiology of the body to such an extent that many seemingly impossible natural physical limits can be exceeded.

But let us concentrate on pigeons. Which is not to say that similar feats are impossible for our feathered friends. We have witnessed pigeons that persist in flying until they float to earth, dead on landing. We know that some racers when returning home will persevere till practically their last breath but whether this is comparable to the human achievements, is difficult to say. Probably not and perhaps disease plays a role.

But pigeons, like other animals, do have a thermoneutral zone (TNZ), during which normal activities are possible and where activities exceeding the limits of the TNZ can be fatal. And it is usually when a few factors occur together that the limits of the upper critical temperature (UCL) are exceeded. Most important is the day’s ambient temperature. It has been found that when the temperature of the day reaches or exceeds 30 C then the UCL is quickly reached. The second important factor is the amount of exercise performed by the pigeon. Here the wind on the day plays a huge role, as flying against the wind has two negative effects. As a natural outflow of seeking the area where there is less wind, the pigeon flies very low above the ground. This is also where the temperature is highest, mainly as result of reflected heat from the earth’s surface. So, working against the wind, which creates more energy per distance covered and flying within a zone of increased temperature, leads a rapid increase in body temperature. We thus have a double heat-producing activity.

High humidity levels create unfavourable circumstances for heat loss as respiratory water loss and cutaneous water evaporation both rely on evaporation of water to bring about heat loss. And we know how difficult it can be to cool down on hot humid days. Evaporation is reduced and with it an important strategy for heat dissipation.

What can we do to prevent the birds from overheating when they are still some distance from the loft? Besides making sure that we only ship fit and well-trained athletes, there is nothing really that could be done. In this situation the pigeons must perforce look after themselves. Which underlines again the importance of adequate training and careful selection of candidates. It is essential that the pigeons’ core temperature reduces immediately when they exceed the TNZ. This usually entails that all exercise is restricted or stopped. For racing pigeons, flying must cease. Water if nearby, can assist tremendously. First by drinking, as these birds are invariably dehydrated to some degree and secondly by bathing or walking in the water. Flying cannot be continued with until the core temperature falls once again within the limits of the TNZ.

Failure to cool down may lead to organ shutdown and death.

Dehydration.

Dehydration occurs to any body that loses moisture and fails to replace it. Moisture can be lost in a variety of ways. Loss of water can be a pathologic process as through diarrhoea or through a traumatic accident like severe burning, but usually it is a normal physysiological response in order to maintain the TNZ, such as when sweating occurs. As soon as the UCL is reached or exceeded, the pigeon’s body goes into a defence mode. The pigeons must lose heat which is accomplished mainly by evaporation of water from various surfaces and radiation from the featherless parts. As pigeons do not sweat, they developed a unique and interesting strategy, which was only recently discovered by scientists. It was found that desert-living doves and pigeons developed a system of ‘cutaneous water evaporation’ or CWE. It is a process whereby the skin cells part allowing small openings in the skin through which water can escape and evaporate. In this process no electrolytes are lost – as happens in sweating; just pure water escapes from the body. The scientists also found that CWE was more effective than RWE (respiratory water evaporation – from the lungs and throat) at cooling the bird, both in the maximum degree of cooling and the relative amount of water lost per degree of cooling.

What all this has to do with racing? Well, it has been found that the exercise performed by our pigeons when flying home creates as much as 13 times the amount of heat as compared with non-flying birds. And furthermore the scientists determined that pigeons stop flying when their body temperature reaches the UCL at 44.5 C. Which, though only 3 C higher than their normal resting temperature, has dramatic effects on racing in hot climates (like the SCMDPR). In turn, this makes effective heat-losing mechanisms, absolute essential. In pigeons these are evaporation, radiation and convection. During the processes of radiation and convection no moisture is lost so we’ll turn our attention to evaporation.

It has been calculated that a 4% loss of body mass due to loss of water – dehydration therefore – forces pigeons to stop flying. (Biesel & Nachtigall 1987). Looking at these figures would suggest that they are incorrect as our pigeons on long races lose much more body mass than 4%. However it must be borne in mind that the total mass loss during these races includes the loss of water, fat, metabolites and muscle tissue.

Electrolytes.

As this article was prompted by the unsolved debate about whether or not to supply electrolytes to pigeons before or after they return from races, we need to discuss that issue. My view, with few exceptions, has always been that these products need not be supplied to pigeons at any time. The reason being that there does not appear to be a greater loss of electrolytes during a race than in the course of a normal day.

As a matter of fact, I believe that the administration of electrolytes could be harmful, particularly to the dehydrated pigeon returning home from a long race on a hot day. At the least, one would suggest that their usage is contra-indicated.

Imagine this scenario; it’s a hot day and the race is from 800 km (500 miles) with a slight head wind. The bird makes it back just before dark. “What has happened to it during the day?” Flying requires muscular activity which rapidly builds up heat, particularly with high external temperatures. The bird must dispose of this heat otherwise it will be unable to continue. Too much body heat would kill it! A great deal of heat is lost by means of CWE from the outstretched, moving wings, via respiration (RWE) from the lungs and via radiation from the legs and skin – where no water is lost. CWE from the skin and RWE from the mouth and respiratory system, cause water loss. Note well; water only, no salts. Increased heat causes increased water loss. The pigeon battles on, no water is available and it becomes dehydrated from water loss but still manages to reach home. We now have a flown out, dehydrated pigeon and wish to restore its physiological equilibrium as quickly as possible. Water only was lost from the system (blood and body tissues) and as a result salts (electrolytes) remaining are more concentrated . Giving more electrolytes now would worsen the condition. What is needed is plain water – as soon as possible – to counteract the haemoconcentration (concentrated blood). By all means warm up the water but do not add electrolytes. Furthermore the pigeon needs easily digestible feed with fats, carbohydrates, proteins and REST. The usual feed or special seeds can be given. But I prefer pellets, as they are semi-cooked, turn into mash after intake which means that they do not first have to be ground to pulp, have a large surface area exposed to the digestive enzymes and are pretty much balanced with respect to their content of proteins, carbohydrates, fats, vitamins and minerals. All this means they provide a rapid supply of essential food stuffs with which to build up the pigeon as quickly as possible. The electrolytes that the pigeon did lose via its kidneys and bowels are easily replaced by the salts normally contained in a balanced diet.

So, adding electrolytes to concentrated blood increases the concentration even more and is the incorrect thing to do. That ………. is the theory.

But what happens in practice? I am not deaf or blind to the results of successful fanciers who do give electrolytes. Many fanciers use them upon return from races and their birds do not seem to suffer any setbacks. Amongst these are some of the internationally well-known champions. From Australia , Holland , Belgium , USA , South Africa – around the globe fanciers administer post-race electrolytes. ‘But how can one reconcile these opposing viewpoints?’ I believe that the answer lies in quantity and time given. The electrolytes (salts) are usually given for just one day which time is insufficient for serious problems to develop.

Furthermore…………. Speaking to renowned pigeon racers from all over the world, they are nearly all in agreement about giving electrolytes to birds returning from races. They all claim that the pigeons recuperate faster. One fancier even gives the electrolytes before the race – on basketing day – and claims that the birds look better on return, recuperate faster, losses are smaller and results improve. So what does one do? I am a scientist, trusting in methodical experiments and rational thought but I am also aware that science has, through the years, made many blunders. In addition I am sensitive to the observations and experiences of non-scientific minds. I believe that these are

uncluttered and unbound by the rigid rules of science; their ideas and experiences are valuable and not to be ignored, or taken lightly. All the more so where years of man-in-the-street pigeon racing has developed certain strategies and customs. Strategies and customs that work ….. in practice and not just in theory. Streetwise pigeon racing, if you will.

Internet

So, to try and get to the truth I delved into the internet. Not into the advertorial articles of medicine merchants or accounts of how big name fanciers do their stuff but into scientifically controlled trials and studies. I only found one study where electrolyte levels were measured in pigeons and where the result of electrolyte administration was reported but I did find interesting reports on the administration of certain electrolytes to chickens. The researchers found that when young broiler chickens were subjected to heat stress, their appetites decreased, they showed decreased weight gain and increased food conversion rate. Further research showed that they had decreased serum Potassium (K) and Bicarbonate (HCO3) levels. It is known that heat stress in chickens causes loss of potassium through the urine. Increased respiration causes loss of serum CO2 and HCO3 resulting in acidosis and a nutritional requirement for HCO3. The researchers then replaced these low serum levels (of K and HCO3) with KCl and NaHCO3 (potassium chloride and sodium bicarbonate) at 1.5% and 0.5% respectively. Weight gain and food conversion returned to almost normal.

These experiments were conducted at temperatures ranging between 35 and 37 C. In trials in thermostressed turkeys and quail, it was shown that KCL supplementation also increased serum K levels. Perhaps the same occurs in pigeons? But are pigeons heat-stressed when racing? Considering the low velocities recorded on days when the ambient temperature reaches 30 C or higher, one can probably assume that heat stress does occur on these days. But what happens at temperatures of say 20 C? Does the pigeon’s body temperature rise high enough to cause heat stress? And if not, are we justified in claiming that K is lost?

Alternative Evidence?

In work done at the University of Ghent in Belgium it was found that the blood pH of pigeons returning from a race was not significantly altered and returned to pre-race levels within hours. The article from Germany referred to earlier reported on post race electrolyte levels in pigeons. Following races from 113 to 620 km, pigeons whose blood levels were tested, showed that, when compared to control birds;

1. The haematocrit decreased from 54.4 to 51 %, indicating minimal dehydration.

2. Plasma concentrations of glucose and lactate did not change, supporting the theory that carbohydrates are used as fuel in the initial phase of flight

3. Plasma free fatty acids were significantly increased during flight and triglyceride concentrations were gradually decreased with progressive flight duration. Which all support the view that lipids are the main energy source during flight.

4. Plasma uric acid concentrations were increased two- to fourfold. Urea levels increased to 400% while plasma protein concentration was reduced. These results suggest increased protein degradation during flight.

5. Plasma levels of Na, K, Ca, and Mg in the flown birds did not differ significantly from control values. These values suggest that severe dehydration did not occur during the flights. (The question now is; Was thermostress a factor during these races? If not, and the minimal dehydration referred to in 1. above seems to suggest that heat stress was not a factor, it could explain why the K levels did not decrease as in the trials with the chickens, as described earlier.)

What are we to make of it all? Obviously more research is needed. But in the absence of further trials determining the electrolyte levels in racing pigeons before and after races, we must make do with what is available. (If anyone is ready to tackle this task I would suggest that the races be split into distance categories and that some races are included where the pigeons are heat-stressed. The study of whether electrolyte levels alter after prolonged exercise and how quickly they can return to normal would be a valuable undertaking and put to an end the often-disputed question of electrolyte supplementation.)

In the absence of contrary evidence I will continue to hold the view that returning dehydrated pigeons, should not be given electrolytes initially. Once the dehydration has been corrected, which, in most cases should not be too long, electrolyte products can be given. If the dehydration is fairly severe, I would withhold electrolyte treatment for 24 hours. In mild cases the birds need only one drink of untreated water after which electrolytes may be added to the drinker.

Pigeon racing should be a relaxing pastime. The competition in most countries has, however, become so fierce and the lure of big money for important winners so enticing that every effort is made to ensure success. Commerce has spotted this hunger for winning and has responded by producing hundreds of remedies, pills and potions. To say that the huge array of preparations is confusing to the fancier, would be putting it mildly. The purchase of these products is not necessary for success and success is most definitely not guaranteed if these preparations are given. The right (read good!) pigeons, effective management, an efficient loft and lots of roadwork, as well tenaciously sticking to the guiding principle of KISS – Keep It Simple Sam – will see the desired results. I wish you luck.

wpeters@iafrica.com