Staff at the specialist animal rescue charity believe their parents had flown away, leaving the two birds stranded and vulnerable.
The cygnets were unable to follow as their wing feathers have not developed yet.
A vigilant member of the public found them and safely delivered them to Secret World for their own safety, where they were assessed by animal carer Marie Dentson.
Ms Dentson said: “Both birds were found to be in good health but were too young to be left alone.
“Baby birds left to fend for themselves are vulnerable, so the pair were found just in time.
“They are flourishing in one of our outside paddocks and will stay onsite until they are stronger and able to fly.
“When the birds are strong enough, we’ll find a suitable release site for them, near other swans and then release them back into the wild.”
Secret World Wildlife Rescue was founded by Pauline Kidner in 1992. Now in its 26th–year, the charity cares for more than 5,000 sick, injured and orphaned animals each year.
Some 10-days ago, staff were alerted to three baby sparrows whose nest had been damaged by heavy rainfall. The tiny birds were found by a member of the public who called the charity’s helpline.
Along with the birds, Secret World staff also found a cracked egg which fell out of the nest. The three birds and the cracked egg were taken to the charity’s hospital room and immediately put in an incubator. Although animal carers believed the birds wouldn’t survive, the trio are still alive, and the damaged egg has begun to hatch.
Mrs Kidner said: “The sparrows will continue to receive round-the-clock care and hourly feeds.
“At this time of year, our hospital rooms are full of tiny birds. Most are casualties to the weather.
“Last year, we rescued 1,194 garden birds and we expect that figure is to be even greater this year.”