The San Diego Zoo’s Flamingo Lagoon is home to 86 adult Caribbean flamingos, several species of waterfowl, and many free-loading mallards. In the middle of the exhibit is a very “active” island, as it is breeding season for our beloved flamingos. On that island are several mounds—the flamingos’ nests. These mounds are started every April by the keepers to help us track which bird is on which mound and when exactly eggs are laid so we can anticipate when they will hatch.
We build small starter nest mounds in rows and draw a map of the island, further aiding in record keeping. Bonded pairs compete for the mound they want, occupy it, build it up, and lay their egg. The mounds can reach a height of 2 feet (0 .6 meters)! The clutch size for flamingos is a single egg, and both parents share incubation duties. The egg hatches 27 to 31 days later.
From the time the egg is pipped, it can take up to 36 hours for the chick to hatch completely, resulting in one of the cutest and softest chicks I’ve had the pleasure of working with. They are covered with white to light gray down, with swollen pink legs and a straight pink bill. After about a week, those swollen legs turn a charcoal gray, and their bill starts to curve downward. When their feathers start to come in, they are a brownish gray color. They slowly turn pale pink and won’t reach their mature bright coloration for two to three years. Their legs take about the same amount of time to turn back to pink. Another transformation they undergo is their eye color: young flamingos have dark eyes that turn to a pale yellow as they mature.
We usually process each chick when it is three to five days old; this involves weighing it, giving it a microchip ID, and performing a quick visual exam before being returned to its eagerly awaiting parents. I find these days rewarding, as I get to hold the chicks and, as I mentioned, they are one of the softest chicks I’ve ever felt!
A total of 27 eggs have been laid so far this season. Some of these were pulled due to infertility, some were left unattended and therefore removed, and a few were broken by pairs trying to take over occupied mounds. As of today we have 10 chicks. The first chick hatched out on May 27, and the youngest chick hatched on June 11. Both Mom and Dad take turns brooding their chick (keeping it warm). They also share feeding responsibilities. Flamingo chicks are fed crop milk, which is very rich in fat and protein and is a blood red color. The chicks’ vocalizations stimulate the production of crop milk. If you listen closely, you’ll hear a distinct difference in their vocalization when they are standing under their parents, begging to be fed. It is a higher pitch and more rapid than their usual calls.
As the chicks get older, feedings may last several minutes. Some feedings last so long that I have gotten calls on the radio about concerns from guests that the birds’ beaks are stuck together. Fortunately, this is never the case. Sometimes the parents are sloppy feeders and spill some of the crop milk on their chicks; this makes it look like the chick is injured, but again, this is not the case. What’s interesting is that as the parents feed their chicks this crop milk, they are drained of their color—so much so that their plumage turns a pale pink or white! The parents gain this color back eventually as the chicks become independent and eat on their own. It may takes months, though, because some of our chicks like to be fed until they are 10 months old, even though they are perfectly capable of eating on their own.
We are hoping to hatch out two more chicks this year to make it a full dozen! Fingers crossed, but in the meantime the 10 chicks present are growing fast! Come by and see them as soon as you can. They are my reward for working hard all year, and I hope you all enjoy them as much as I do!
Athena Wilson is a senior keeper at the San Diego Zoo. Read her previous post, Crested Screamer Family Update.