Soaring With Condors (Part I): Shell Game

By Sandy Masuo

Did you know that the Los Angeles Zoo has been an integral part of California condor conservation efforts since the inception of the California Condor Recovery Program (CCRP) in 1982? Were you aware that the Zoo has housed this iconic species since 1967, when the legendary Topatopa (who went on to sire more than 20 chicks) was brought to the Zoo as a malnourished fledgling?

Though the Zoo does not exhibit California condors to the public—unless you are fortunate enough to be here on a day when Dolly, the first outreach ambassador for her species, is making an appearance—condor care at the Zoo takes place every day, 365 days a year. Seasonally, L.A. Zoo staff collaborate with other agencies in the CCRP to share data and provide veterinary care for the birds, as well as check on the health of eggs, chicks, and adult condors in the wild.

This blog takes you behind the scenes and out into the field to see the amazing work that the Los Angeles Zoo staff pursue as part of the California Condor Recovery Program.

Shell Game

In an old nursery rhyme, Humpty Dumpty is a great egg sitting on a wall. One day he takes a great fall and all the king’s horses and all the king’s men could not put him together again.

Condors Big Sur - May 2007 (Photo by DJ Smetana)

A California condor pair sit on a wall in Big Sur. (Photo by DJ Smetana)

It could almost be a metaphor for the California condor, which once ranged throughout much of the Southwest, from the great inland valley to the coast. With westward expansion during the mid-nineteenth century, increasing human activity began to take its toll on the birds. People poisoned them (intentionally and unintentionally), took their eggs, and significantly reduced the numbers of large game animals. As scavengers, condors do not quarry and kill their own food but rely on large predators (largely extirpated from condor range) to leave the remains of carcasses on which they feed. By the 1980s, the California condor population had crashed to just 22 individuals.

Fortunately, biologists from the USFWS were cleverer than the king’s horses and men and enlisted the aid of zoos, aviculturists, and other agencies to bring the species back from the precipice. Now, some 30 years after the last wild bird was brought in from the wild, the population has grown to more than 400 birds in California, Oregon, Arizona, and Mexico. A vital part of that success revolves around eggs and egg management.

California condors are a species that optimally would hatch and rear a chick only every two years. Fortunately, if you take away the egg from a nesting pair, they will produce a new one. So, caretakers can pull eggs for artificial incubation, prompting the parents to lay replacement eggs—thus doubling the number of offspring produced.

L.A. Zoo Condor Keeper Debbie Ciani marks condor egg (Photo by Jamie Pham)

L.A. Zoo Condor Keeper Debbie Ciani candles a developing California condor egg. (Photo by Jamie Pham)

The California Condor Recovery Plan is a multi-agency effort and includes management of wild birds and nests as well as the birds that live at the participating institutions. Because it’s important to maintain genetic diversity, at any given point the Zoo’s condor staff may be incubating eggs from in-house birds, wild nests, or breeding pairs at other zoos. Between 85 and 90 percent of the fertile eggs laid in a season develop into chicks. The bad eggs (whether in wild or captive settings) are pulled and substituted with dummy eggs until a genetically appropriate good egg can be sent to replace the original egg.

The Los Angeles Zoo condor facilities can accommodate up to eleven pairs of birds (right now eight pairs and a lone female are in residence). The individuals are matched up based on genetic information and population management criteria, and new pairs do not always breed. It can take a season or more for them to accept one another and form a bond. Once breeding season begins, the birds are encouraged to produce as many eggs as possible—usually two, though some pairs can produce three in a season.

Condor Egg Candling (Photo by Jamie Pham)

As the chick inside grows, the egg becomes more opaque and the visible blood vessels expand. (Photo by Jamie Pham)

In her 20 years as part of the Zoo’s California condor team, Animal Keeper Debbie Ciani has seen many of the 166-plus California condor eggs that have been hatched at the L.A. Zoo. During breeding season, keepers weigh condor eggs daily, and candle them once or twice weekly. Candling is a method of monitoring egg development that involves shining a bright light behind the egg in a dark room so that the caretaker can see how the embryo inside is changing. If an egg is not developing, it’s usually apparent within the first week. From day 51 of incubation until hatch, eggs are checked and candled several times a day.

“Eggs vary in size, shape, texture, and color among all the females,” Ciani explains, “but each individual seems to have consistently formed eggs from year to year. We used to joke that you could show us any egg from one of our females and we could tell you who laid it. Some are smaller, some are bigger, some are rounder (like a baseball), and some are more torpedo-shaped. They come in different shades of blue and can be smooth or pebbly, shiny or more matte. The average condor egg is about 280 grams although we have had females lay very small eggs, sometimes as small as 225 grams.” By comparison, the average softball weighs about 200 grams.

Condor eggs at the L.A. Zoo (Photo by Jamie Pham)

Three California condor eggs laid by three different females show how variable egg appearance can be. (Photo by Jamie Pham)

A female named Itaxmay (SB 141) has laid very big, very round eggs from the beginning. Her record is a 334-gram egg a few years ago, and in January 2015, she and her mate, AC6 (SB 5)—one of the original wild birds— produced an egg that weighed about 316 grams when it was first laid. Despite the size of Itaxmay’s eggs, they do not require any extra care either during incubation or after hatch. Chick weight at hatch is a percentage of original egg weight, so a larger than average egg means a larger than average chick will hatch from it. However, this does not mean the chick will grow into a larger bird. (As with humans, weight at birth does not correlate with adult weight.)
EGG UPDATE:
On February 4 and February 8, the first two eggs of the 2016 season arrived. The chicks from these eggs were due to hatch around April 2. At 4:15 a.m. on March 30, Condor Keeper Jenny Schmidt loaded pipped egg LA116 into a portable incubator and drove up to Filmore, California where she met USFWS biologists and handed off the egg. The biologists drove another 1.5 hours into Hopper Mountain National Wildlife Refuge where they began the long hike to the condor nest of condor male #247 and female #156. The early nest-check about 30 days prior found that the egg was no good. A dummy egg was left for the pair to incubate for the time being. The chick is expected to hatch on day 57 which would be Friday, April 1. Another switch much like this one will happen shortly with the second condor egg, LA216. This is just one example how the Los Angeles Zoo staff and USFWS biologists coordinate and work as a single unit to pursue California condor conservation work.

Weighing a condor egg at the L.A. Zoo (Photo by Jamie Pham)

In addition to charting changes inside the egg, each condor egg is weighed. (Photo by Jamie Pham)

Older condor egg incubator (Photo by Jamie Pham)

Old condor egg incubator (Photo by Jamie Pham)

Newer condor egg incubator at the L.A. Zoo (Photo by Jamie Pham)

According to Condor Keeper Chandra David, “the large older Petersimes are our tried and true incubators. They maintain their temperature very well and most parts are easy to come by when repairs are needed. The downside is that there is a possibility of making a mistake when setting eggs into the trays that could ultimately damage an egg. The new incubators are easier to use, with less room for keeper error—though they are a German product, so keepers have to get used to converting temperatures from Celsius to Fahrenheit.”