No focus area can help you here. The three birds are not in the same plane of distance to the camera. With two birds, you would have a chance to put the camera in parallel with the two birds, but at 287mm focal length doing so will likely move both of them off-frame, so having both of them in focus does not buy you anything because you cannot see them.

What you can do is close down the aperture for a larger depth of field. At a shutter speed of 1/2000s, you can probably afford 4 stops (assuming you have image stabilization) to get 1/125s. 4 stops mean F22 which means diffraction will affect sharpness. You can counterbalance diffraction by use of RL deconvolution sharpening, but that amplifies noise, and at ISO6400 you cannot afford a lot of noise amplification. So perhaps just take 3 stops and F16. That will reduce the area of the blur circles by a factor of 8 which is already quite an improvement. While further increases of the depth of field by narrowing the aperture more are probably not helpful, you can still invest a bit of shutter time in return for lower ISO and get somewhat more defined results that way (and a bit more leeway for applying sharpening).

In this case, I'd probably have stuck with just having the front bird in focus. When you are photographing groups of people, you don't want to similarly designate some to be background elements, so it pays to pay attention to the depth of field.

Using A (instead of M) mode should make the camera pick a saner combination of ISO and shutter speed while letting you prescribe the aperture according to the depth of field you are aiming for.