The expectant mothers' eggs were not fertilized — so none of them hatched.
Wildlife officials said they replaced the eggs with viable ones from Chilean flamingos — “their near-relatives” — so that both the mother and father birds could watch the chicks hatch and then go on to raise them.
However, officials said, the flamingo mothers were given only a few viable eggs “so as to encourage the other birds to lay more eggs, in the hope one might be fertile.”
Mark Roberts, aviculture manager at Slimbridge, said it's “enriching for the birds.”
“It’s a wonderful and welcome surprise that the Andeans have started laying again after nearly two decades,” he said in the statement. “We’ve been encouraging the flock by helping them to build nests but there’s no doubt that the recent heat has had the desired effect. Unfortunately none of the eggs were viable so with the Andeans in full parenting mode we gave them Chilean chicks to bring up as their own.”
According to Cornell University's Lab of Ornithology, these long yellow-legged birds with black-tipped beaks and characteristically pink feathers have been breeding at “consistently low” rates. It is estimated that only 38,000 to 39,000 of them are in existence today, it added, “making this the rarest species of flamingo.”
The IUCN Red List said the creature is listed as “vulnerable” because “it has undergone a rapid population decline over the past three generations, owing to exploitation and declines in habitat quality. Exploitation has now decreased and recent survey data suggest that the population is now stable; however, it remains much depleted compared with past numbers.”
The recent heat wave, it seems, was paramount in encouraging WWT's Andean flamingos to produce eggs.
Mark McCarthy, who manages the Met Office National Climate Information Center, said in a statement last month that the United Kingdom experienced record-breaking heat in May and had its second-hottest June. Then, the mean temperature in July hit nearly 63 degrees Fahrenheit, though on July 26, temperatures in Faversham, a market town in Kent, reached 95 degrees, according to the center.
“For a large part of July, it looked as if we might see another record-breaking month, but lower temperatures in the North and West and the storms at the end of the month meant that was not the case,” McCarthy said. “However, temperatures were well above average and rainfall much lower, particularly in parts of England, continuing the pattern of an unusually warm, dry summer overall.”