Sunday, 23 November 2014

Don't let kindness land up killing your garden birds.

Greenfinch - often seems vulnerable to disease
It has been such a mild autumn with an incredible abundance of food, (especially a colossal beech mast year) that I have only just started to think about ordering some bird seed to begin feeding my garden birds.

I am quite often asked if one should feed birds all the year round, or just during the lean winter and spring months. Personally, I prefer to see birds collecting “natural” food to raise their young, so once there is an ample supply of food – usually towards the end of April or early May, I pack up the feeders and put them away for the summer.

You should always concentrate on the hygiene aspect of putting out food and water, regardless of what time of year you feed birds, although perhaps if you do feed birds all the year round and also offer them water, it becomes even more vital to make sure that you keep feeders and bird “baths” clean due to the constant use.  
There are a number of diseases that garden birds can pick up if you do not keep feeding sites well managed.

Trichomoniasis (or ‘Canker’ as the disease is also known), has been known in Poultry and Game for some time, however for some unknown reason the parasite then jumped from its usual host group to the wild finch population. The parasite survives in moist conditions, needing water to survive, so that in hot dry conditions it will be killed by desiccation.

Greenfinches are most frequently affected by this disease and birds that become infected with the Protozoal parasite (called Trichomonas gallinae ) will not usually survive. The disease was first recorded in April 2005, but then exploded in 2006 and 2007 as infection spread across the country.

Birds take on a fluffed up, lethargic appearance and in some areas up to 35% of Greenfinches and 21% Chaffinches have died. The disease lives in the upper digestive tract and therefore the most likely way that it is spread between birds is via saliva-contaminated water and food.

Salmonella organisms also invade the digestive tract of wild birds and bacteria are present in large numbers in infected droppings, which are the source of contamination for uninfected birds. 

Avian Pox is also a relatively new disease in the UK, which seems to be increasingly identified in garden birds. The disease is caused by a virus which stimulates excessive skin growth and nodular warty lesions, often around the face of the bird.

Great tits seem to be particularly prone to Avian Pox infection, but I have also seen lesions on Blue tits and I know that other birds can get this pox too. Most birds build up immunity to the infection and survive, however, it seems that Great tits can develop big wart like growths which in the worst case scenario can prove fatal, especially if the growth impedes the everyday functions of the bird in any way.

Because it is a relatively resistant virus it can survive on contaminated perches and feeding stations for a considerable time, infecting a number of birds in the local area.

Finally, there is a disease that is specific to Chaffinch, called “Chaffinch Viral Papilloma” (CVP). CVP is thought to affect around 1% of the Chaffinch population at any given time. Cases usually occur in clusters and quite high proportions of local populations may be affected in outbreaks.

This disease causes wart-like growths on the feet and usually, but not always, only one leg is affected. The growths vary from small nodules to large irregular shaped and deeply-fissured masses which almost engulf the entire lower leg and foot and which can distort the toes. Affected birds usually seem in otherwise good health but some may show signs of lameness and hop mainly on the unaffected foot.

The fact that cases occur in clusters suggests that the presence of affected birds presents a risk to others that are susceptible. The mode of transmission is not known but it seems likely that the virus may be spread via surfaces the birds stand or perch upon or by direct contact.

The most effective method to avoid cross-transmission of all these problems is to follow good, regular hygiene practice at your feeders and take steps to minimise crowding at perching or feeding sites. So, you should try to ensure that you clean and disinfect feeders on a regular basis and the same applies to bird baths.

Try to only put out enough food on the ground for each day, so that it does not become contaminated with droppings or start to rot in mild, wet weather. It is also a really good idea to move feeding stations around the garden and maybe have a number of sites rather than just one main one, if the size of garden allows.

One final thought. I often see pheasant feeders that have obviously been situated in the same place for some time, as the ground is completely bare underneath them. Remember, all of the above is also relevant to game birds and the small birds that regularly feed alongside them at these hoppers.

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