WWT Washington Wetland Centre has sighted 16 adults and 21 young this year, in comparison to 23 adult birds last year.
They have nested by a lake and shingle island which expanded by the centre last autumn. Breeding at the site started in 2006.
Reserve manager John Gowland said it was a "real conservation success story".
"The high number of youngsters is a positive sign on the success of the improved shingle islands and emphasises the growing confidence of the nesting adults," he said.
The birds, which are a rare on Wearside, were once declared an extinct breeding species in the UK.
The avocet returned in the 1940s and is the emblem of the RSPB.
A wildfowl centre has recorded its highest number of rare avocet birds.