A pair of red kites have been living in the Ingram and Powburn areas for two years but this summer it is believed they have bred young.
Rhianne Dixon, visitor and events officer for the Northern Kites initiative, said: "We can't be 100 per cent sure but there might be a breeding pair in this area.
"We have been getting reports since 2006 of a pair of red kites living in the Powburn area and now another two have been seen this summer which makes us wonder if there is a breeding pair.
"If that's the case it would be absolutely fantastic news because it's been 150 years or so since they were here."
The species was once common across Great Britain; indeed, historically the species was probably the country's most widespread bird of prey.
Three hundred years ago, it was a common sight over much of northern England and in medieval times, it fed in the streets of London (where it was given special protection for its useful role in cleansing the streets).
Between the 16th and 19th centuries red kites suffered severe persecution.
They died out, in part, because of a loss of food supply as human society became tidier but, in the main, their disappearance was brought about because of human persecution.
This took the form of both shooting and poisoning because they were deemed a threat to livestock, despite their main food source being carrion (dead animals), worms and beetles.
By the end of the 19th century, just a handful of birds remained in Wales and this remained the case until just a few years ago.
They had probably gone from north east England, as breeding birds, by the 1840s. Therefore, it is safe to say that they have not bred in the region for almost 170 years.
They have made a comeback in this area thanks to the Northern Kites initiative, which included a world first with their reintroduction into a semi-urban environment centred on Gateshead's Derwent Valley.
Northern Kites is managed by Natural England and the RSPB in partnership with Gateshead Council, Northumbrian Water, the National Trust and the Forestry Commission, with additional funding from the Heritage Lottery Fund and SITA Trust.
They released 94 kites in the lower Derwent Valley between 2004 and 2006 but is thought there are now about 150 and that two of them have migrated to north Northumberland.
"Some of the kites released in Gateshead have never left but others have been found all over the country, as far afield as the Dorset Chilterns, so it is no surprise some have made their way into Northumberland," explained Rhianne.
"We now want to raise awareness of them in Northumberland; first of all to let people know they have these magnificent birds in their area and, secondly, to educate people about them.
"Unfortunately, persecution is still a big issue so we have to do what we can to get the message across that these birds are scavengers and no threat to livestock or farming.
"Last, but not least, we want people to let us know if they see any so we can keep track of their movements," she added.
The red kite is recognisable by its distinctive forked tail; russet plumage and a wing span which measures more than five and a half feet.
To find out more about the kites and where to see them, visit the Ingram visitor centre or the Cheviot Centre, in Wooler, where there are information panels. Alternatively, visit www.northernkites.org.uk.
l A Red Kite ramble has been organised on Wednesday, October 29 from 10am to 12.30pm.
Meet at Ingram visitor centre.
Staff from the Northern Kites project will lead a guided walk looking for red kites and other wildlife. This is a free event but places are limited so booking is essential on 0191 4961555.