BBC: Clapper Rail Chicks
Posted at 3:02 pm June 14, 2007 by Joy DiGentiPart 3 in a series about the Bird Breeding Complex (BBC) at the Wild Animal Park.
Read Part 2, BBC: Bird of Paradise and Kingfisher Chicks.
We participate in a local recovery program for the light-footed clapper rail Rallus longirostris levipes, an endangered bird native to San Diego that inhabits coastal wetlands. We have two pairs of wild clapper rails in the second string of the BBC, called “BBC B,” that have been here since September 2005. They are very shy and usually I can only get a good look at them after everyone has left for lunch. It is quiet then and they come out to catch fish in the pool.
In the early morning we play a CD with clapper rail calls from different locations around the complex to stimulate breeding. The “clappering” calls make it seem like there are other breeding pairs in neighboring territories and both pairs responded multiple times. They have made nests in reed huts that their keeper, Marcy, built for them, and the female of the first pair laid one egg each day from May 10 to 18, for a clutch total of eight eggs. We pulled those eggs for artificial incubation and replaced them in the nest with dummy eggs (Guam rail eggs look just like them!).
During the first week of June, we were fortunate to have six chicks hatch. They were taken to SeaWorld San Diego to be puppet raised for release into the wild. The dummy eggs in the nest were pulled when the chicks hatched and the female has already started to lay a second clutch. The second pair has also started to lay and both of these clutches will be left with the parents to incubate and hopefully raise the chicks. One more example how we use diverse management techniques to maximize survivability of endangered species!
Including the birds described in this BBC blog series, Marcy takes care of 100 birds representing over 30 different species, every day. There is one whole building (BBC C) in her area that I didn’t even get to mention! But next time I want to tell you a little about BBC II.
Joy DiGenti is an administrative assistant in the Wild Animal Park’s Bird Department. She is currently on loan as a keeper.
Here’s more information about the historic clapper rail hatchings.
Here’s video of the clapper rail chicks.
Windows Media version | Quicktime version
Here’s video of the clapper rail release.
Windows Media version | Quicktime version
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June 15th, 2007 at 10:30 am
Thanks, Joy, for a fascinating education in the hatching and care of Clapper Rail chicks. They are cute, and I love the extreme care showed by the keepers at WAP and SWSD when they were transferred to their new “home.” I like to watch the puppet feeding chicks. It is so great that they are accepting of the food, and that the impression that is made on their brains is of birds not human hands.
I was curious to see the eggs hatching in the incubator in a small box. In the movie Fly Home they showed how the impression on the chicks was of a human because that is the first thing they saw after they hatched in a drawer. Does the hatching in a box and transfer in a round container seem to have any affect on the development and homing instincts of the endangered wild birds hatched in captivity? Or is how they are subsequently fed more critical to their memories?
June 15th, 2007 at 3:45 pm
Thanks for the information Joy! I don’t know very much about artificial incubation, so this might be a dumb question…but how do the chicks learn to hunt/fly etc without mom’s help after they hatch?
June 21st, 2007 at 3:26 pm
Thank you for your comments and good questions! In looking into answers to your questions, I have discovered that imprinting is more complex than I thought! Early behavioral studies indicated that there is a critical period (about 36 hours after hatch) for filial imprinting of precocial birds (ground birds that are covered with down at hatch and ready to leave the nest when the down is dry, within 24 hours). In the last ten years or so, the “critical period” concept has been questioned, and further research may be necessary. In our experience, though, it is safe to handle chicks without them imprinting on humans, in the first few hours after hatch. We introduce a puppet as soon as possible when they are more alert and aware of their surroundings. On the video of the clapper rail chicks, you probably noticed that the keepers did not actually handle the chicks for very long and they were fed with the puppet. In their daily care, keepers do not talk in the brooder room and they cover up with a sheet so that chicks do not hear or see them and become habituated to humans.
Clapper rail chicks are semiprecocial, they are brooded by the parents for several days, and are cared for by the parents for 5-6 weeks. That might mean there is a longer period of time before imprinting occurs or that it is not as much of an issue, like altricial birds that require intensive parental care and have more time to develop a parent-chick bond (imprinting is necessary for birds that are on their own early, for speedy recognition of their parents).
Light-footed clapper rails are nonmigratory, so they probably do not have the same kind of homing instincts that migratory birds like geese use, and the box and container should not affect the rails’ ability to assimilate in the wild. When they are old enough to go outside (7-10 days), their surroundings will be similar to their habitat in the wild. The puppet-raised chicks will be housed with adult clapper rail mentors that will show them how to fly, forage, and stay hidden to avoid predators (and keepers).
June 25th, 2007 at 1:11 pm
Thanks for the further education about imprinting and feeding before going outside. It is fascinating and something that one doesn’t come across very often. I learn so much about wildlife from visiting these blogs, that people are constantly commenting to me that I should work in a zoo. I just find it all very educational and love to share it with whomever is willing to listen. The more we know about our fellow inhabitants of this globe, the better off we will all be in the future.
Kudos to all who care for the clapper rails and all the other new born and adult animals at the zoo and WAP.
July 1st, 2007 at 7:58 pm
Thanks for the information! I was wondering though, why do you use Guam Rail bird eggs in replacement dummy eggs [quote: “We pulled those eggs for artificial incubation and replaced them in the nest with dummy eggs (Guam rail eggs look just like them!).”]? I was recently at the zoo and saw the Guam rail, and on the information sign for the bird it stated that the Guam rail was extinct in the wild. If this is true, wouldn’t you want to preserve those eggs; not use them as just dummies?
July 27th, 2007 at 2:31 pm
The Guam rail was extinct in the wild and the small population on two islands (Rota and now a snake-controlled area of Guam) is maintained through a reintroduction program. We have been breeding Guam rails at BBC since 2000, as part of the Species Survival Plan (SSP) - some for release into the wild and some to maintain the genetic diversity of the captive population. In that time the Guam rails have laid many eggs, and hatched chicks, but not all of the eggs were fertile.
When infertile eggs, or the embryo has died in the early stages of development, do not hatch, we keep them and make them into dummy eggs. We can also determine if eggs are fertile by candling them when they are pulled for artificial incubation. A candler has a bright light that shines through the shell, illuminating the contents of the egg so that we can see the development of the embryo.
To make dummy eggs, we poke a small hole in the bottom of a real egg to drain the contents and then fill it with plaster of Paris to get it to the appropriate weight. When we don’t have dummy eggs for a certain species, like the Clapper rails, we select eggs that look the most similar so that they will accept them as their own. Fortunately, our small collection of Guam rail dummy eggs fit right in. And speaking of Clapper rails, our second pair hatched three chicks! Marcy said, “they are doing great, getting very tall and their feet are huge!” Unfortunately, the second clutch of eggs under the first pair did not hatch, but their chicks that went to Sea World have moved on to the Chula Vista Nature Center in preparation for release.
October 24th, 2007 at 4:17 pm
The article was most informative! I was wondering if it was a chick or one of the breeding pair that were lost to the recent fires. I was SO GLAD that only 2 of your precious animals were lost when the outcome could have been so much worse!
I have moved away from Southern California, but while I was there I enjoyed many wonderful days at the Park, and my son and his wife have their name on the sign for the California Condor donors! Needless to say it has a place forever in my heart.
Keep up the good work!
October 25th, 2007 at 9:22 am
I too appreciate the information. I am a California native living in Washington for the last 6 months and I cant tell you how happy we are to hear that most of the animals there out-weathered the firestorm. My son and I have spent so many wonderful days at the wild animal park. Truly a spectacular sanctuary . We miss it and we are so thankful it was spared. Our thoughts and prayers are with you!
November 5th, 2007 at 4:49 pm
Thank you for all of your thoughtful responses. The clapper rail that died after being evacuated from the fire was the breeding female from the first pair to lay eggs this year. She played an important part in the clapper rail reintroduction program and we are sad to lose her. Fortunately all of the chicks have already been released. The chicks from the first pair, that went to Sea World, were released in the San Diego River Preserve and the chicks from the second pair were released at Penasquitos Lagoon.