Any advice on selecting a decent telephoto lens for birding?

Just bought a K100 from ebay and with some help from you guys and John Riley can noe use my M series lenses the images are brilliant, and you won't belive this the remote from my Optio 550 works on the K100

Thanks for all your help

Regards Peter

I have my M series working on this camera but it is not saving the images to the card