Falcon Study

Roland · July 31, 2011

In answer to Diclofenac Gordon Chalmbers replied on the Alberta Classic site fings regards Colourand elimination if possible.

Some may fing it a bit long....

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Diclofenac is the operative ingredient in Voltaren, a drug used to treat rheumatoid arthritis in humans. It doesn't affect humans the same as it affects vultures in which severe kidney damage leads to death. Gord.

A research study a few years ago showed that one type of plumage known as the wild variant, described by the researchers as blue-gray, has a white (not pale gray) rump patch between the base of the tail and the lower back, and that all other types of plumage lack this white patch. This study was designed to determine whether the wild variant with the white patch might provide an advantage compared with other types of plumage during the spectacular high-speed attacks by peregrine falcons. The study was conducted during a seven-year period on flocks of feral pigeons during which 1,485 attacks by five adult peregrines, plus 309 attacks when three of these falcons were juveniles, were recorded. To determine the natural distribution of the various types of plumage in the population of feral pigeons in the study area, the researchers first trapped and banded 5,235 of these birds. About 22-23% were the wild variant type (described as gray [standard blue bar?] with a white rump patch), 20% were blue bar (described as gray without a white rump patch), 32-33% were blue check, 10% were red, just under 10% were splash and about 2-3% were white. The study showed that mature falcons selected and attacked pigeons with types of plumage in the same relative proportion that they occurred naturally - except for pigeons of the wild variant type with the white rump patch. Adult falcons captured more pigeons without the white rump patch and many fewer pigeons with this patch. Adult falcons captured more pigeons without the white rump patch and many fewer pigeons with this patch. However, young falcons attacked all plumage types in proportion to their occurrence in the population.

To confirm the survival advantage of the white rump patch, the researchers captured 756 wild type and blue barred pigeons and switched the feathers on their rump patches. These birds were later released, and predation on the group by three adult peregrines was monitored. The results showed that the wild variant with no white rump patch now suffered predation at the same rate as normal blue bars. As expected, the blue bars with the newly attached white rump patch now had rates of predation as low as those of normal wild variant pigeons.

This experiment showed clearly that the white rump patch conferred greater survivability for feral pigeons during attacks by peregrines. It seems that all feral pigeons perform the same evasive roll during an attack by falcons. During an attack, feral pigeons begin this avoidance behaviour by dipping one wing, rotating rapidly and rolling out of the line of attack. The researchers commented that the white patch might have a protective function by disguising the beginning of the evasive roll by the contrasting white patch and gray wings and body. The suggestion is that the brain of a falcon that is focused on an obvious target centered on the roll might not detect the dodging behaviour begun by the gray wings that blend with the landscape as the predator closes in from behind. In short, falcons are primed to concentrate on the obvious feature-- the white patch -- and fail to notice the pigeon starting to roll away and escape. As an anti-predator strategy, the use of contrasting patterns of body surfaces is widespread in nature. For example, fish and shore birds that are attacked by predators also alternately display their dark upper and lighter lower surfaces to confuse predators.

For fanciers for whom predation by falcons is a major problem, a concerted effort to attempt the selection of racing pigeons with the white rump patch â€“ not the very light gray patch seen in many blue bars - would seem to be a practical but long-term approach to reduce by quite a margin, but not completely eliminate, the chances of predation by lightning swift falcons. Gord.

A realistic answer too I believe in how colour breeding wouldn't be of much use in our lifetime.

But at least we can treat our birds with Diclofenac and know that won't have to die needlessly ....

July 31, 2011

I read a similar study a few years ago about pigeons with a white patch on their rump. One of the conclusions of that study was that pigeon fanciers should breed pigeons with white rumps. Apart from me not knowing how to do that - they didn't say whether it is a recessive or dominant trait - white rumps don't help us as it doesn't stop the birds being attacked, and as that attack starts from well above it won't make a blind bit of difference whether the bird has a white rump or not cos the peregrine can't see that until the pigeon starts ducking & diving, by which time the batch is scattered to every point of the compass and the real damage is already done.