The comparison to birds is bizarre because they are a public phenomena that anyone can see and study, gender transitions aren't.
>our own experiences with birds
Which is none in the case of gender transitions, or very little for some people. But certainly nowhere near the experience of an average person with birds.
>information provided by people who study birds for a living
Which is not reliable in the case of gender transitions, because those who "study them for a living" have proven themselves to be unreliable and value-laden communicators who either has an ideology to push or are too timid to challenge those who do have an ideology to push. Don't forget the substantial material incentive for diagnosing people with gender dysphoria (months and possibly years of consultation and medical appointments, services and products), if ornithologists were similarly ideological and have reasons to benefit from denying that birds are drones, I would be skeptical of their claims too, until I see lots of birds and study them myself at any rate.
>provide me one documented case of a biological male being diagnosed with gender dysphoria
Diagnosis is medical data that is mostly non-public, so this is an impossible demand for rigor. And yet, here's[1] the next best thing, a celebrated psychologist with a long career in sex and gender research, editor for several journals, slandered and fired because activists are outraged he tries to encourage gender-non-conforming kids to be comfortable in their assigned gender instead of transitioning them immediately. So anybody who doesn't diagnose a barbie-playing boy with dysphoria and transition them is at risk of being slandered and fired no matter what their contribution or position is. I consider this pretty solid evidence for the original claim.
[1] https://www.thecut.com/2016/02/fight-over-trans-kids-got-a-r...