Wildlife consultant Subaraj Rajathurai so loved nature that he and his wife named their two sons after species of birds - Serin, 24, and Saker, 19.

And in a nod to his passion, dozens from the nature community were clad in green for his funeral yesterday, bidding farewell to a giant of a man who died the way he lived - in peace.

The 56-year-old died of a heart attack during a nap on Tuesday afternoon.

"The community will have to band together. They know what Subaraj was fighting for, and they will continue to fight for him," his wife, Madam Shamla Subaraj, 54, said at the funeral.

She said that although her late husband had a history of heart problems and had stents placed in his heart, his death took the family by surprise.

He was discharged from hospital on Monday. On Tuesday afternoon, Madam Shamla was preparing lunch when she tried to rouse him, only to discover he was gone.

"Subaraj was the pioneer of nature outreach and conservation activism in Singapore. He has left a huge footprint here and he will be sorely missed," said Mr Tony O'Dempsey, a member of the Nature Society (Singapore), who was at Mr Subaraj's funeral.

With more than three decades of experience exploring Singapore's nature areas, Mr Subaraj was well known for his knowledge of nature, and for being an outspoken advocate for Singapore's native wildlife.

He helped secure the conservation of areas such as the Sungei Buloh Wetland Reserve, and was involved as a consultant in many developments, helping the authorities strike a balance between developing new infrastructure and the conservation of nature.

These include developments such as the Cross Island MRT line, which could potentially tunnel under the Central Catchment Nature Reserve, and the development of Tengah town, in which large swathes of secondary forests are to be cleared.

"He told me very early on that the three most important things to him were nature, God, and me, in that order," said Madam Shamla, a former nurse. "I had to accept it," she said.

She knew nothing about nature before marrying him, but now takes part in some consultations that developers have with the nature community.

Environmental group Herpetological Society of Singapore co-founder Sankar Ananthanarayanan said: "One thing I admire about him is that he spoke truth to power. He isn't afraid to stick to his principles, and that was something powerful to me."

Mr Subaraj had refused to sign a non-disclosure agreement with the developer of the Mandai nature precinct, following a spate of roadkill incidents in Mandai Lake Road after works started, so he could continue speaking out about the works. Said Mr Sankar: "What we can do is to learn from that, to keep that momentum going, and to fight for him."

Yesterday afternoon, family and friends gathered to pay their final respects to Mr Subaraj at the family's Tampines flat.

As they spoke, a brahminy kite - a bird-of-prey native to Singapore - was circling outside the window. It was as if it were paying homage to a friend.

Audrey Tan