This post first appeared on November 26, 2012
Although bay horses with the silver dilution look a lot like a bay horse with a flaxen mane and tail, not all bay horses that have lighter manes and tails are necessarily red silvers. There are other reasons a bay horse may have a lighter mane or tail.
The photo above is a comparison of a bay horse with a silver tail (to the far right) and two of the previously posted red silvers. Notice how the variegation is a bit different with the two types of tails. Silver dilute tails shift in tone in a way that reminds me of ombré textiles (and the current human hair trend of the same name), whereas the Gulastra Plume is more of a mixture of the two colors.
The silver tail in the picture is what Arabian breeders often call a Gulastra Plume. The trait takes its name from the Arabian stallion Gulastra. Gulastra himself was a chestnut with a self-colored tail, but flaxen tails were said it was common on his bay descendants. Like a lot of color variations named for specific horses, the “founder” is not necessarily the horse responsible for the original mutation. It is more accurate to say they brought attention to the trait. So not all horses with a Gulastra Plume are descendants of Gulastra. Some have no known Arabian blood at all, like the stout pony in this post.
In other breeds, it is sometimes called silvertail. Compared to an ordinary bay tail, the tail does look silver, but the lighter hairs often have a warm, flaxen tone rather than a cool, silvery one. Some silver-tailed bays – like this guy – have reduced black points on the legs, and flaxen hairs on the lower parts of the leg are not uncommon. This can make them even more likely to be mistaken for a bay silver, but the dark tones on the points are truly black and not a diluted chocolate. It is also possible to find silver tails on bays that have fully black points, though the reduced black seems to be more common.
Most horses with a Gulastra Plume do not have significantly lighter manes. This guy has a few white hairs interspersed in what is an otherwise fully black mane. From a distance, his mane looked black. Were he a silver (even an older silver), I would expect to see some hint of flaxen at least at the forelock.
Although the difference between the tails is very noticeable here, there may well be quite a bit of variation in the tails of horses with a Gulastra Plume. To my knowledge, it has not been formally studied, and as the posts over the next few days will show, the situation with flaxen and silver manes and tails on bays is not entirely clear. It is quite possible that there are multiple factors producing similar results. For that reason, it is often the color of the legs (chocolate rather than black) that is often more reliable when trying to identify bay silvers.