Down like feathers don't enable you to fly; ask the Wright Brothers. I await the science.
Evolutionist claims are preposterous. You are pretending like my computer -- which has a flawed operating system made by Microsoft -- just needs a little kick in the side, or power surge to move one of those little 0's to a 1's postion. Presto chango we have Excel birthed. The API use the same types of calls. There is the proof.
For our next trick we will expose the computer to sunlight. The radiation zaps those little ones and zeros over millions of years, and SHAZAM Word is birthed.
These mutations are on a roll. With the help of some Chimpanzees we will have the robot from "Lost in Space" in no time (only if the computer is restricted to an isolated environment like a junk yard where it can do the "Punk-Eek"). Danger Will Robinson!
It really, really happens
You must believe it's true
Smarties are lined up
To try and brainwash you
It all ties together
With a little glue
From the goo, the zoo, to you
Death is nothing new
Canis familiaris, the dog, speciated from Canis lupus, the wolf, but this was accelerated due to human involvement.
When you actually study biology, speciation is a little harder to define then you may think it is. It is not simply that there are significant physical differences: poodles and St. Bernards can still interbreed. There has to be enough chromosomal incompatibility that if two members of different species *do* mate, sexual meiosis does not occur, or, if it does, the offspring is sterile.
So what you are asking for is not a single instance, but thousands of instances repeated and accumulated over generations.
... and no, downlike feathers do not enable you to fly. Read the doscussion of protoarchaeopteryx to learn more about feathers' evolution: they did not first evolve soft like down. I only used the example of down to illustrate that feathers' complex structure retains heat. But the point is there once were feathered lizards that could not fly demonstrating both the existence of supposedly non-existant intermediate forms and answering what once was a favorite charge of creationists: that intermediate forms are often non-functional.
I did find several examples where we lucked out and have been able to witness speciation due to a fortunate location of a mutation, resulting in "instant" or exceptionally rapid speciation:
http://www.talkorigins.org/faqs/faq-speciation.html
Exactly what does flying have to do with whether something is a bird or not?