

Yes, done at 800mm. However, there’s other reasons it’s reasonably sharp, some technical, some to do with Kites.
Technically, that’s cropped down a bit , taken in good light at a good angle from the sun (so 1/1250, ISO250 and that worked, other than messing with the luminance curve), and the bird was indeed slowing down to land - earlier in its flight the photos were a little softer.
But the crucial difference is that Red Kites are urban birds - though they apparently do hunt, they are seen as scavengers and carrion eaters. As such, they are much less fussed by humans than most birds of prey, and while they don’t interract with humans in Prospect Park itself, there are some who feed them, and there are tales of picnic thefts, conversely there’s no persecution of them in towns (it would be illegal, and unpopular). So a lazy speed at not much higher than head height perhaps as close as 30 yards is not that uncommon. It’s also more uncommon for me not to see a Kite somewhere on my walk than not (if usually because its soaring high up so very visible): I feel so happy about their successful reintroduction.
Which of course, given they are good looking birds, make them a joy to photo.
Until that time, do still practice on them higher up - with a 600mm lens you should get something, and the practice will get you ready for the good days. In particular:
And practice panning with pigeons, crows or anything else in view