Hmmm interesting...
What worries me tigger...if your having to ask things like "Whats so uncool about liking widllife between 14-19" then alarms bells ring that you really dont understand teenagers so your probably going to struggle with this idea...
The teenage life is a trecherous one.....trust me i was bullied for pretty much my whole school life....the slightest tinyest little thing is a good enough reason to be bullied...kids are and can be very nasty and cruel...
I had the lot...
No dad (parents divorced) which in my day was reason to be picked on(maybe not these days?)
I was shortest in my year (still short)
I had to have braces on my teeth
I got puppy fat
I have naturally very curly/afro hair
I was a late starter in terms of puberty
I am circumsised....yes...oh bullies LOVE that one!!
I liked birdwatching......OOPS....there it is!
With all i had going against me, i lived in fear of people knowing i did birdwatching or fed the garden birds...so i pretty much hid it away until very recently.
BUT....i could AWLAYS without any fear talk about birds of prey or falconry....talking about watching a kestrel....
or having pet sloworms....hunting for
Grass Snakes..
Birdwatching?....i would be punched kicked and spat on....bieng 'into eagles and stuff'....cool as hell!
I agree about the bird centre idea...get someone to bring in an eagle owl or a peregrine....or find a local reptile group to not only wow them with a 12 ft reticulated python but maybe show them our own 'POISONOUS'
Adder? or our our
Grass Snake etc
Your battle will be that probably 90% of the kids secretly love birds or would love to raise tadpoles but wont dare admit that for fear of being laughed out of the 'gang' etc....
The trick i believe is sadly to think like a bully....or the victim i guess, and think of ways of doing something in such a cool way that even the BULLY (or the coolest kid) will accept it?....If mr cool (who is usually your ring leader) gives something the 'cool' factor your 99% there.
Off the top of my head...stuff at night? adds a bit of danger/excitement...so maybe bat detectors?....moth trap?...glow worm hunt!! now that will win anyone over trust me...they will turn there noses up and thinks its 'lame' etc until they come across there first glowing little alien ufo thing in the grass
Avoid the stereotype of girl stuff and boy stuff as girls love danger just as much but maybe also offer rearing moths and butterfly's from eggs?...growing wildflower seeds...im not sure when they would have last gone with the school but maybe a trip to the natural history museum or something to get them back into the idea of nature which may have been lost on them since they discovered sex,drugs, drinking, smoking and that awful stuff they call dance music? ha ha...then you can look at projects...building a wildlife garden, sorting out the village pond...putting up OWL and KESTREL boxes (Birds of PREY )

....building a hybernaculum for snakes?...
What area are you in?....do some research and find out (like Kent) if you have many reports of BIG CATS wild in your area like we do?...they wont believe your even telling the truth until they go and read/google it...maybe a big cat watch/hunt?....
Good luck.