I've noticed large numbers of pigeons with abnormalities of the toes
and feet in every urban area I've visited. The life of an urban bird
is not an easy one; pigeons can acquire deformed feet in several ways.
The main causes are diseases ("pigeon pox" or "bumble-foot") and
injury from entanglement in synthetic threads such as fishing line.
I often see pigeons with extremely distorted feet and this seems to be
true of city-dwelling pigeons throughout the world. It is not as
common among other creatures (including other birds) in urban
environments. Can anyone tell me what causes these deformities?
Heather McDougal, London
The deformities on pigeons' feet are caused by infection with
Staphylococcus. The common name for the condition is bumble-foot. The
bacteria, which are present on the skin and in the pigeons' droppings,
get into the foot through cracks in the skin and eventually cause
tendinitis, arthritis and joint abscesses. The condition in feral
pigeons is incurable."
New Scientist: Questions & answers on everyday scientific phenomena
"There are several causes of deformity in pigeons. 'Pigeon pox' is a
disease that causes growths and deformities of the feet. Vitamin B
deficiency can cause paralysis.
Overgrown beaks are fairly common; the excess growth will often break
off by itself and the birds can usually still feed. Synthetic threads
caught on their toes or feet can cause the loss of toes, whole feet,
or unpleasant wounds."
Eastbourne Borough Council: Feral Pigeons
"Deformities of the feet are caused mainly by disease and injury and
are most noticeable among ground feeding species, especially in urban
Cuts to the feet can allow infection to occur which may result in
swelling and lameness... Avian pox can cause wart-like growths on the
feet of house sparrows, starlings and pigeons...
A common disability among urban birds is the loss of all or part of a
foot due to a discarded thread or wire, while discarded fishing line
can have a similar effect in the countryside. Many birds can survive
an amputation but any resulting infection will usually prove fatal.
Congenital deformities involving extra or missing toes are rare and
gross abnormalities, such as an extra leg, do not survive."
Royal Society for the Protection of Birds: Bird deformities
Regarding the matter of whether this sort of handicap will affect the
pigeon's ability to survive, this is likely to be determined by the
competitiveness of the environment. If food is plentiful and predators
are few, an injured pigeon may do quite well. Several years ago I
worked in a downtown office. A regular fixture of the sidewalk outside
the building was a pigeon that my co-workers named "Pete." Pete was a
one-legged bird, which meant that he could neither walk nor fly
normally. However, he was resourceful enough to scavenge enough food
to stay fit and active for more than five years. Pete was finally
brought down not by starvation, but by an automobile that failed to
yield to him as he was crossing the street.
Google search strategy:
Google Web Search: "pigeons" + "feet" + "toes"
Google Web Search: "deformity OR deformities" + "pigeons" + "feet"
I hope this information is helpful. If anything is unclear, please
request clarification; I'll be glad to offer further assistance before
you rate my answer.