You will learn a lot more about Guatemala in particular and Tikal in general if you hire a local guide.
Some drivers are also guides, especially for general sightseeing.
If you wish to do bird watching, the best known birdwatching guide is Clarence Massiah. He has been guiding at Tikal for several decades. Clarence also guides at all the archaeological sites throughout the Peten. He has been guide for many famous and distinguished travelers over the years. He is well enough known that you can book his services through any major travel agency.