The bird, which is named LM12, arrived on Thursday, the earliest reappearance of a resident bird there in almost 50 years.
Its mate LF15 is expected soon at the Scottish Wildlife Trust reserve near Dunkeld, which operates a live webcam of the nest. The pair fledged three chicks in both 2015 and 2016.
Charlotte Fleming, Perthshire ranger for the Scottish Wildlife Trust said: "One of our eagle eyed volunteers spotted LM12 just after 17:00. "He spent several hours in the nearby trees but didn't touch down on the nest until early this morning when he appeared carrying his breakfast.
"From the views we've had of his distinctive chest pattern and long wing tips we are as sure as we can be that it is LM12. "He has also made himself well and truly at home, bringing in sticks and preparing the nest, which is further proof that he is the resident male.
A breeding pair have also been seen in recent years fishing on Loch Earn so hopefully they will also be back in the area in the very near future.
For more information and to watch the live webcam visit the website at https://scottishwildlifetrust.org.uk