Monty returns every Spring after wintering in Africa
Mystery surrounds the reason why a pair of nesting ospreys have failed to produce offspring at a Mid Wales nature reserve over the past two years.
A male osprey - known as Monty - and his female companion have returned from Africa to nest at Cors Dyfi near Machynlleth in 2009 and 2010.
But the lack of romance between the non-love birds has led to fears that they may be brother and sister.
About 30,000 people visited the site of The Dyfi Osprey Project this year.
Emyr Evans of Montgomeryshire Wildlife Trust (MWT), which manages the reserve, said if they were brother and sister they would not mate.
He added: "Another possibility is that they are both too young to breed because ospreys don't start to produce until they are four or five years old.
"Because these birds were not ringed in the nest it is impossible to tell their age without catching them and conducting tests."
A pair of ospreys which nest at the Aberglaslyn site near Porthmadog, are thought to be Wales' only breeding pair.
But Mr Evans believes there may be at least one other pair of ospreys breeding in Wales.
Monty may have been born in Welshpool in 2004
"There was a pair breeding in Welshpool in 2004 that produced one chick, which could be Monty," he said.
"Alternatively he could be the offspring of a breeding pair that we don't know about.
"Ospreys tend to return to breed in the same region that they were born which explains why there are 200 breeding pairs in Scotland.
"Because Monty and the female osprey have returned to Cors Dyfi for the last two years I suspect that they were born in this area, which could mean they are brother and sister."
MWT runs the Dyfi Osprey Project as a community initiative with a group of more than 40 local volunteers to deliver the project both through the medium of Welsh and English.
A camera system is placed on a dead ash tree 10m away from the nest
Mr Evans said: "We couldn't have survived without the goodwill and hard work of volunteers such as a local electrician who does work for us without charge."
A man-made nest 50ft (15.2m) up on top of a telegraph pole and dotted with white paint to resemble bird droppings was built to encourage the ospreys to breed.
The nest is near the Aberystwyth to Machynlleth railway line.
"Network Rail have also been supportive by running a cable from a sub-station to the nest so that the birds can be filmed which otherwise would have cost us £50,000," said Mr Evans.