Birds

Birds

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Plover Hide and Seek

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A snowy plover chick’s cryptic coloring helps it hide from predators. (Photo: Rachel Smith, SDZG at Marine Corps Base Camp Pendleton)

Well it’s finally here, SUMMER! As a born-and-raised San Diegan, I know that one thing is for certain this time of year: the beaches become a popular place to visit for some fun in the sun. Besides having to share the sometimes-crowded beaches with other humans, we need to remember that there are other animals that also live on the beach. I am fortunate to have the opportunity to work with two of those wonderful animals, the threatened western snowy plover and the endangered California least tern.

The snowy plover can be seen year round in San Diego, but the California least tern only comes to our shores during the breeding season, which is April through August. I’m sure if you’ve been anywhere near the tern breeding colonies, you will have seen these small white birds flying around like fighter pilots chasing one another and sounding like storm trooper ray guns. The plovers are small, sandy brown shorebirds with gray legs that hang out in the wrack line of kelp, eating as many bugs as they can get in their bills.

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Can you spot the snowy plover chick hiding in this vegetation? Click on the image to enlarge it. (Photo: Rachel Smith, SDZG at Marine Corps Base Camp Pendleton)

During the summer at Marine Corps Base Camp Pendleton, the beaches are full of plovers and terns nesting and raising their chicks. For both terns and plovers, it takes about four weeks for chicks to be able to fly. Thus, they have to rely on camouflage to evade the eyes of predators; as biologists and monitors, this camouflage can make it challenging for us to locate them. Plover chicks are particularly good at hiding. First off, for lack of a better description, they are adorable. They look like freckled gray cotton balls with legs. Those legs come in handy when evading land predators, especially as the chicks get closer and closer to fledging (meaning they can fly). Their first defense is hiding, especially when they are young, and these little guys are experts at hide and seek.

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There it is! Click on the image for a better look. (Photo: Rachel Smith, SDZG at Marine Corps Base Camp Pendleton)

We are always keeping an eye out for them, looking for clues based on the behavior of the adult plovers (especially adult males) but we don’t always find them. It’s amazing how well the chicks blend into the sand and vegetation. They practically disappear and you often have to be right over them to see them. Often, our best chance of seeing the chicks when we are out monitoring is using our truck as a makeshift blind to watch for them out foraging around in the dunes and along the water’s edge. Amazingly, the birds do not perceive the truck as a threat and we can get much closer when we are inside the truck than outside of it.

Another technique we use is to blend in by staying a long distance away and using a spotting scope or binoculars to watch the behavior of the adult male (who does the rearing of the chicks) to find out where the chicks are hanging out. Watching these chicks grow up to become fledglings is a real treat, especially when I see them trying out their wings and getting a little air for the first time. It just puts a smile on my face knowing they have made it and are pretty much all grown up.

So, while I’m out with my fellow biologists doing our part to help protect these amazing animals, you as beach goers can do your part by respecting closed beach areas even when it is crowded, and keeping the beaches clean not only for each other but for all the animals that live there too. By doing this you can be a hero for wildlife and go home happy knowing that you are giving plovers and terns a safe place to grow up for future generations to enjoy.

Rachel Smith is a senior research associate at the San Diego Zoo Institute for Conservation Research.

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Breeding Strategies: Secretive Plovers & Gregarious Terns

Presenting food to a mate potential  mate is part of the least tern's courtship ritual.

Presenting food to a mate potential mate is part of the least tern’s courtship ritual. (Photo: Rachel Smith, SDZG on MCB Camp Pendleton)

Both least terns and snowy plovers are ground-nesting birds that nest on barren to sparsely vegetated beaches, but they employ quite different breeding strategies. Over the past couple of months, I have been able to observe and compare these strategies while searching for and monitoring their nests.

Least terns are colonial nesters, using a “safety in numbers” approach, whereas snowy plovers use a strategy of nesting separately and being physically cryptic and secretive in behavior. Unlike the least terns, which have bright yellow bills and prominent black caps on their heads, snowy plovers have pale brown upper parts and blend in far better to their sandy surroundings making their nests less conspicuous and less likely to be discovered by predators. This also makes it much harder for us to find snowy plover nests!

If they didn't occur in such concentrations, least tern nests would be a challenge to find.

If they didn’t occur in such concentrations, the least tern’s well-camouflaged nests could be a challenge for us to find. (Photo courtesy Marine Corps Base Camp Pendleton)

On a good day my crew members and I might find about a dozen snowy plover nests, whereas during the peak of least tern nesting we can—and have—easily found over 200 least tern nests in one day! On a particularly busy day this season, we could hardly walk more than 20 feet without discovering a new least tern nest. Calling out the nest count sounded a bit like we were bidding at an auction; sometimes several nests were found almost simultaneously with one crew member exclaiming “I’ve got nest 500!” only to be quickly followed by “501!” and a few seconds later by “502!”

Because least terns nest in large colonies of up to several hundred individuals, their nests are much more obvious, but there is a lower probability of a particular individual’s nest becoming the victim of a predator. Being in a colony also offers the additional protection of having many adults present that can mob predators. Having walked through an active least tern nesting colony, I can personally attest to the protective nature of the adults. They have threatened me with their harsh “zwreep” alarm calls, flown inches from the top of my head while dive-bombing me, and even defecated on me and my data sheets in an attempt to drive me away from their nests!

Monica Stupaczuk is a research associate with the San Diego Zoo Institute for Conservation Research. You can learn more about this project by reading A Day in the Life of a Beach Biologist.

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Saving Kauai’s Honeycreepers

Akikiki eggs

To start a captive breeding flock to help save the critically endangered akikiki, we collected two eggs each from a number of  nests.

Since it began in 1993, the San Diego Zoo Global’s Hawaii Endangered Bird Conservation Program (HEBCP) has worked with over a dozen native bird species found only on the Hawaiian Islands. The conservation status of these birds ranges from non-endangered surrogate species to critically endangered species that are on the brink of extinction.

The past decade has seen a precipitous decline in two species of Hawaii honeycreepers, the akikiki and akeke‘e. These two small species of forest birds are found only in a remote area on the island of Kauai and the wild population has been monitored for years. Due to the declines of both species in the wild, bird experts determined these two species should be raised in captivity as a safeguard against extinction. Based on that decision and with funding from the US Fish and Wildlife Service, as well as a grant from the Mohamed Bin Zayed Species Conservation Fund, our HEBCP team began planning the techniques and protocols to safely and successfully add these two new species to our facilities on both the Big Island and Maui.

Whenever possible, the best scenario for bringing a species into captivity is to collect eggs from nests out in the wild. There are many reasons why this is the preferred method. By collecting eggs, you eliminate the chance of bringing in a disease that an adult bird might have into the captive flock. It can also be very difficult to teach an adult bird from the wild to eat from a food pan and acclimate it to a captive diet. Another reason we didn’t want to start our captive flock by collecting adult birds out of the wild is that there are so few akikiki and akeke‘e left in Kauai’s forests and we didn’t want to negatively affect the wild population. When you collect a wild female’s eggs she almost always builds a new nest and lays a second clutch. Thus, you can build a captive flock without reducing the number of wild chicks produced.

One of the first decisions made by our team was to setup an egg house on Kauai instead of trying to transport eggs from there to our facilities on Maui or the Big Island. Akikiki and akeke‘e eggs are incredibly tiny, weighing between 1.2 and 2.5 grams. As a comparison, two plain M&Ms weigh 1.8 grams! These eggs are so delicate that they could become damaged during transport if they were flown to another island. With generous help from Jesse Fukushima from Kauai Realty, Inc. as well as Bryan and Tanya Tanaka, we rented a house on Kauai and shipped over all the equipment and tools we would need to care for the eggs and chicks we hoped to obtain. This included everything from incubators and brooders for the eggs and chicks to the food items that we would eventually be feeding.

Our next task was to decide what incubation, hatching, and rearing methods to use for these two new-to-us species. We had to think of everything from what temperature we would use to incubate the eggs to what food items we would feed the chicks. Fortunately for us, the akikiki and akeke‘e are insectivores (meaning most of their diet comes from insects) which are very similar to two other honeycreeper species that we have already worked with, the Hawaii creeper and the Hawaii akepa. Thus, with some small adjustments, we adopted successful protocols we had used with the Hawaii creeper and Hawaii akepa to use with our new species.

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Out on a limb: Akikiki nest on terminal branches, so accessing the nests requires scaling great heights!

We had the house, we had the supplies, we had the protocols…the only thing left to do was to collect the eggs! Unfortunately, this was much easier said than done. Akikiki and akeke‘e nest in the remote Alakai Swamp on Kauai. There are no roads into this habitat, it can only be reached by a long, arduous seven-hour hike through the rainforest. Yet, getting to the birds’ territory is the easy part. Akikiki and akeke‘e build their nests at the ends of branches, sometimes 40 feet up in the air! The big question was: how would we reach the nests to harvest eggs? The State of Hawaii’s Kauai Forest Bird Recovery Project (KFBRP) team identified a technique where a 40-foot ladder is raised to almost vertical and, instead of leaning against something, is then tied off onto anchors behind the ladder. This setup would allow our HEBCP staff to gain access to the nests that were previously too remote to collect from.

On March 26, 2015, after spending the previous day practicing the ladder techniques and transporting the ladder to the nest site, we set the ladder up and, with assistance from the KFBRP team, collected two eggs from an akikiki nest. The eggs were placed in a thermos and lowered from the nest by rope before being transferred into a battery-powered incubator. The ladder was then moved to a second akikiki nest and two more eggs were harvested and placed into the portable incubator, then carried back to camp on foot. A helicopter that was on standby was notified of our successful harvest and began flying to the landing zone near the camp. We carefully brought the eggs to the waiting helicopter and flew out of the swamp. The strenous hike into the location translates into a 20-minute helicopter ride to a landing zone just a few miles from the egg house. At the house, the eggs were weighed and candled. Candling the eggs is a process in which a bright light is shone through each egg to see which ones are fertile and how far along they are in development. With bated breath we candled our first egg. Inside, we saw active blood vessels and an embryo moving around—it was fertile! We candled the other three eggs and discovered the same thing. All four akikiki eggs were fertile and looked to be a few days away from hatching. We carefully put the eggs back into the incubator and let out a sigh of relief. We had successfully collected four fertile eggs from a brand new species of endangered Hawaiian honeycreeper, and if all goes well we should have four chicks in a few days time!

Check back regularly for more blogs to complete the story!

Jeremy Hodges is a senior hospital keeper at the San Diego Zoo and seasonally participates as a research coordinator with the Hawaii Endangered Bird Conservation Program.

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California Condor Chick: 30 to 45 Days of Age

A Condor Cam screen capture of the fluffy, growing chick.

This Condor Cam screen capture shows the California condor chick to be developing nicely.

At approximately one month of age, our California condor chick should weigh around 4 pounds (2 kilograms). The parents, Sisquoc and Shatash, may start leaving the chick alone overnight, sleeping near the nest instead of in it. If the weather is still cool or it’s raining, the parents may continue to brood overnight until the weather improves. Even though the parents are increasing their time away from the chick, they remain VERY vigilant and protective of their nest and especially their chick. Some field biologists have even seen wild condor parents chasing black bears away from the nest area!

Up until now, the chick has been scooting around the nest on its tarsal joints. We refer to that as a “tarsal crawl.” It’s not uncommon, at this age, to see the chick standing all the way up on its feet, teetering around the nest, holding its wings out for balance. As its legs get sturdier, the chick may even approach the parent, begging for food. The “wing-begging” behavior we’ve been seeing will get more pronounced: lots of wing flapping, head bobbing, and trying to position itself in front of the parent.

It is possible that the parents, who are offering larger quantities of food per feeding session, might be providing a small amount of fur/hair in the chick’s diet. (Part of the adults’ diet includes mammals, like rats and rabbits.) Condors can digest just about every part of the animals they eat, except for fur. This fur accumulates in the digestive tract and is eventually regurgitated as waste. We refer to this as “casting.” A condor’s cast is composed of predominantly fur, whereas a cast from an owl has fur and bones; owls can’t digest bones, but condors can. We have seen condor chicks cast hair pellets as young as three weeks of age. When the chick casts, it throws its head forward several times, mouth open, until the pellet is ejected from its mouth. It can look like the chick is in trouble, but it is perfectly normal, and good for the chick.

At 45 days of age, the chick will get its first health exam. We will obtain a blood sample for the lab to make sure it is healthy and send a portion of this sample to a lab in the Genetics Division of the San Diego Zoo Institute for Conservation Research, located adjacent to the San Diego Zoo Safari Park. From this blood sample, the geneticists can determine if the chick is male or female. Also, during the exam, we will weigh the chick—it should weigh between 7.75 to 8.75 pounds (3.5 – 4 kilograms)—and inject a transponder chip as a form of identification. It’s the same kind of chip you can get for your dog or cat at the veterinarian. Most importantly, this exam allows us to administer a vaccine for West Nile Virus. West Nile Virus is disease that originated in Africa and was accidently introduced to North America by humans. North American wildlife, including condors, usually doesn’t have a natural immune response to West Nile Virus, so we are trying to give the chicks as much of a head start as we can.

This exam will be the first time that the chick will see humans, so it will naturally be disturbing for it. We try to be as quick as we can be (9 to 10 minutes) to minimize the disturbance. Additionally, we will keep the chick covered with a towel to reduce its exposure to humans and to provide it a bit of security. Sisquoc and Shatash are usually away from the nest when we perform the procedure in order to keep them as calm as possible, as well. We have to keep in mind that we don’t want the chick to become accustomed to or feel reassured by our presence; we want it to be a wild condor, uninterested and wary of humans, so that it may someday fly free in California, Arizona, or Mexico.

The chick will look very large at this age compared to how big it was at hatch, but remember that it is still less than half of its adult weight. There is much more growth and fun to come!

Ron Webb is a senior keeper at the San Diego Zoo Safari Park. Read his previous blog, Guide to Condor-chick Watching: Ages 1 Week to 1 Month.

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Spot On!

Brightly colored mouth nodes help a Gouldian finch chick get spotted by its parents.

Brightly colored mouth nodes help a Gouldian finch chick get spotted by its parents.

It’s baby bird season! A lot of our collection birds are sitting on eggs, feeding tiny chicks, and teaching their young fledglings how to make that final leap and learn to fly. As a senior associate in the Wildlife Disease Labs, I examine a lot of different species of baby birds. Some have really cool adaptations to life as a tiny chick in a dark nest!

Gouldian finches win the prize for the most colorful chick beaks. This species nests in the hollows of trees, keeping their chicks safe in the darkness. Pearlescent white and blue nodes on the each side of the chick’s mouth shimmer in the low light of the nest, creating an easy marker for the parents to spot. Gouldian finch chicks tend not to make any noise; they simply open their mouth, turning their head gently side to side, and the glimmer attracts the parents’ attention. They may be tiny, less than an inch tall at hatch, but it’s easy to spot the Gouldian finch chick spots!

 

It would be hard for a coua parent to not spot this plea for food!

It would be hard for a coua parent to not spot this plea for food!

The Northern crested coua has white circles on the inside of its mouth that look like targets to help the parent birds find the chick in the nest. These distinctive marks alert the parents that the chick is hungry and begging for food. Other chicks, like the common waxbill and paradise whydah, have similar black swirls and spots on the inside of their mouths. It turns out paradise whydahs will often lay their eggs in a common waxbill nest (free babysitting!), and when the chicks hatch the waxbill parents are unable to tell the difference between waxbill and whydah chicks. Waxbills will feed all of the chicks in their nest, even if the waxbill female hasn’t laid an egg of its own!

What other spots have you spotted around the Zoo or Safari Park recently?

Rachael Keeler is a Senior Research Associate with the Wildlife Disease Labs at the Institute for Conservation Research. Read her previous blogs, Let’s Hear It for Honking Swans! and Finding a Cure for Scratchy Throats.

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Guide to Condor-chick Watching: Ages 1 Week to 1 Month

The condor chick is knows what it wants (food) and knows how to get it from Shatash!

Condor Cam screenshot: Now that the condor chick is a little bigger, it will be easier to get a glimpse of Shatash (seen here) and Sisquoc feeding it.

At approximately two to three weeks of age, the real fun of condor chick-viewing begins! The chick is getting bigger, weighing between 17 and 42 ounces (500 and 1200 grams), and can often be seen poking its head out from under the parents’ wings. The parents might be spending less time sitting on the chick, weather permitting, leaving it unattended for longer periods of time (possibly 30 minutes or so). Never fear—the parents are nearby, often just out of the camera’s view, approximately six to eight feet away.

It is usually easier to observe feeding behavior at this age, as well. The parents stand a little to the side of the chick while feeding now, so you may catch a glimpse of food actually being transferred from the parent to the chick. The chick’s crop—a bulge in the esophagus where food is stored—may be visible when it’s full. Look for a bald patch of skin between the size of a golf ball and a tennis ball. You will also witness a very common behavior called “wing-begging.” This is when the chick is begging for food, flapping one or both of its stubby little wings and bobbing its head excitedly. This behavior can persist until after the chick fledges, or leaves its nest, at four to five months.

The chick hatched wearing a fluffy coat of white down feathers. The main function of down is insulation—it can keep a bird cool or warm, whatever its body needs. At this stage, the chick’s white down is starting to transition to gray. Sometimes this can make the chick look dirty or scruffy, but it is still as healthy as it ever. Both the chick and its parents frequently groom the feathers to make sure they are working the way they should be. These dark feathers also help the chick blend in with the substrate and the nest cave walls, since the parents are not covering the chick as much as they were right after hatching.

Some viewers may notice what look like scabs or wounds on its head, neck, and torso, matting its down feathers. No need to worry—what you’re seeing is regurgitated food stuck to the chick’s face or body. Feeding can be quite exciting for the chick and some food doesn’t always end up in its mouth (sound familiar, parents?). The chick obviously can’t take a bath at this age, but the food dries up, gets crusty, and flakes off —a major benefit of having a bald head! Anyone that has seen the big condors eat on exhibit at Condor Ridge at the San Diego Zoo Safari Park or at the San Diego Zoo’s Elephant Odyssey can attest to the condors’ ability to keep clean after a messy meal.

Also, the presence of flies in the nest is nothing to worry about. Keep in mind that condors are carnivores, feed their chicks via regurgitation, and nest in cavities (caves, crevices, etc.) that are often sheltered from the wind. All of these components add up to a very comfortable environment for flies as well as condors. Never fear – condors have excellent immune systems and are only mildly annoyed by the flies!

At three weeks of age, 2 pounds, 10 ounces to 3 pounds, 4 ounces (1.2-1.5 kilograms), condor chicks can start to thermoregulate, or control their own body temperature. This is when the parents can start leaving the chicks on their own during the day. Depending on the ambient temperature, the chick may be seen shivering or panting in an effort to warm or cool itself. Also, on warm days, the chick may inflate the air sacs in its chin and neck to cool down. Air sac inflation can also occur after a particularly filling meal. Often, the parents may spend time in the nest with the chick, but they may not necessarily sit on the chick.

At this stage, too, the chick is more mobile, scooting around the nest on its haunches, or tarsal joints. We refer to this as a “tarsal crawl.” It’s not quite standing up on its feet, but it can move about, following the parents and investigating different parts of the nest. You may see the chick start to gather items (feather, scraps of old food) from around the nest and move them to one corner. The chick likes to sit or sleep on this pile and play with the different items. These feathers and old food scraps are often brought to the nest by the parents. Birds replace their feathers through a process called “molting,” similar to when mammals shed their hair or fur. We don’t know if the parents are bringing these items to the nest specifically for the chick or if it’s just happenstance, but the chick loves to investigate and play with them!

As the parents start leaving the chick alone for longer periods of time, it will be easier to watch the chick when it sleeps. Just like all growing youngsters, condor chicks sleep A LOT. With longer legs and gawky bodies, they often will be sprawled out, wings askew, in odd positions when they sleep. Do not worry! The chick is perfectly fine.

At approximately 1 month of age, the chick weighs around 3 pounds, 15 ounces (1.8 kilograms). The parents may start leaving the chick alone overnight, sleeping near the nest. If the weather is still cool or it is raining, the parents may continue to brood overnight until the weather improves. Even though the parents are increasing their time away from the chick, they remain VERY vigilant and protective of their nest and—especially their chick.
Happy viewing and thanks so much for your support!

Ron Webb is a senior keeper at the San Diego Zoo Safari Park. Read his previous post, A New Condor Chick on Condor Cam.

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Sweet, Juicy Papaya‚—for the Birds!

What's on the menu? Egg, commercial diet, and juicy, sweet papaya!

What’s on the menu? Scrambled egg, commercial diet, and juicy, sweet papaya!

As people recover from their holiday feasting, now is a nice time to reflect on feeding Hawaiian birds in a captive breeding program.

One of the biggest challenges of managing a captive propagation center for Hawaiian birds is providing a nutritionally balanced diet replicating foods the birds would eat in the wild. Ideally, a captive diet is composed of the exact same natural fruits, nectars, and animal and insect proteins birds forage on while wandering in native Hawaiian forests. But collecting the exact food items these birds eat in the wild is impossible!

Although wild diets cannot be perfectly recreated, we strive to fashion a representation offering the same nutritional components. Prior to working with any new bird species, Hawaii Endangered Bird Conservation Program (HEBCP) staff review data on a species’ nutritional requirements and foraging behavior in the wild, to create diets for the birds in captivity. For instance, wild alala historically consumed many native fruits, and supplemented their fruit-heavy diet with invertebrates as well as the occasional egg and nestling of other bird species.

For birds in managed care, we replicate what is contained in wild alala diets by providing apple, melon, mixed veggies, and papaya in place of native fruits. The alala also receive scrambled egg, mealworms, and bird pellets that offer a balance of carbohydrates, fats, amino acids, vitamins, and minerals. As you can see, these captive diets heavily feature food items available from commercial retailers.

Unfortunately, even commercially available foods can be difficult or expensive to obtain. This is where we benefit from close relationships with generous local supporters in our communities. For example, Kumu Farms in Wailuku, Maui, regularly donates organic, GMO-free papaya for the birds at the Maui Bird Conservation Center (MBCC). Although the MBCC is a relatively small facility, providing enough papaya for all almost 70 birds (representing 4 species) being bred in captivity is no small feat—but Kumu Farms donates papaya to help make this possible. And all the birds at MBCC eagerly devour Kumu Farm’s sweet, juicy gift!

Joshua Kramer is a research coordinator at the Maui Bird Conservation Center, operated by San Diego Zoo Global. Read his previous post, Maui Bird Conservation Center: Open House 2013.

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Nature’s Excellent Engineering Feat: The Egg

This kagu egg is just one example of nature's egg-cellent engineering feats.

This kagu egg is just one example of nature’s egg-cellent engineering feats.

Have you ever wondered why eggs are shaped the way they are? Or why egg shape varies with the species? Most eggs have one tapered and one wider end to ensure they roll only in a circular pattern. This ensures that the eggs do not roll out of the nest when they are turned by the parents. Some species lay eggs with a more pronounced small end, which make them roll in a tight circle. For example, seabirds like murres nest strictly on rocky cliffs and use no nest material at all. The elongated shape of their egg makes it less likely to roll off the cliff edge. Birds that make deep cup-shaped nests typically have rounder eggs, because there is less risk that the eggs will roll out of the nest when turned. Nature’s exquisite engineering continues inside the egg, too!

The egg itself is a self-contained home, supplying all the nutrients and safety for the growing chick inside. The duration of incubation varies, but all chicks will grow until there is so little space inside that it is difficult to move. When it is time to hatch, the chick has to get into the proper position, with the head under the right wing and the beak pointed upwards toward the larger end of the egg (being in the wrong position can be fatal). The large end of the egg has an air-filled space called the air cell. The chick must use its beak to pierce the air cell membrane so it can start breathing the air inside. As CO2 builds up in the air cell, it triggers the yolk sac to retract into the chick’s abdominal cavity, getting the bird ready for life outside the egg. The next step is to break out of the shell.

The beak has a hard, sharp, triangular shaped structure, called an egg tooth, on the top of the beak that assists in breaking through the eggshell. The chick uses its legs to rotate as it pecks through the shell until a hole is large enough to break out of completely. Once outside the shell, the chick can rely on its yolk sac for energy and nutrients until it is getting enough food from its parents, or is feeding on its own.

With such a complicated process there are bound to be occasional problems with completing the incubation and hatching process. But when these problems arise, we can learn from them and provide helpful feedback for our animal care staff, enabling them to make management adjustments that will maximize the reproductive success of the many amazing species of birds we have in our care.

April Gorrow is a Senior Pathology Technician at the San Diego Zoo Institute for Conservation Research.

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California Condors: Little Things, Big Effects

Condors have excellent vision, but some threats are too small for even these birds to see.

Condors have excellent vision, but some threats are too small for even these birds to see.

In spring of 2011, I served as a summer research fellow at the San Diego Zoo Institute for Conservation Research. Here I learned that I could contribute to the conservation of endangered species in a way I never dreamed possible: on a molecular level! To say this was a stretch for me is an understatement. Freshman year of undergrad I distinctly remember the shock when I was handed back my first BIO 101 exam: it was the first “D” I ever received at any time as a student. I turned to my friend and proclaimed, “I will NEVER work with something I cannot see,” (referencing biological materials such as DNA, RNA, and proteins), conclusively announcing “All I want to do is work with animals.”

Despite my initial frustration, I stuck with the biology major, tagged on an animal science minor, and got a keeper internship at my local zoo. The internship turned into a part-time job working hands-on with exotic animals, a dream come true! While zookeeping was a very gratifying job, reproductive physiology had caught my attention not only in the classroom but through my experience at the zoo. I was amazed at how reproductive techniques such as semen collection, artificial insemination, and hormone monitoring could inform animal managers and scientists of a broader picture not always seen by the naked eye. My interest and enthusiasm landed me an internship in the Reproductive Physiology Division at the Institute and, eventually, a permanent position as a research technician. We work on traditional gamete preservation, hormone monitoring, and the exciting new field in the zoo world: environmental toxicology. This research combines molecular techniques and endocrinology to explore the effects of chemicals found in the environment on the development and reproduction of captive and wild animals.

I am now a graduate from the University of Missouri’s animal science master’s program with a thesis describing the molecular interactions of environmental chemicals and hormone receptors of a critically endangered species, the California condor. Needless to say, I have changed my stance on working with biological materials that are not visible to the naked eye!

HEK cells (seen here at 100 times their actual size) are used as concor receptor factories to study the effects of environmental contaminants on reproduction. Photo by Rachel Felton

HEK cells (seen here at 100 times their actual size) are used as condor receptor factories to study the effects of environmental contaminants on reproduction.

In the Lab
In my previous post DDT: Another Challenge for California Condor, I explained our first investigations of the effects of environmental chemicals on California condor reproduction. In the lab, we were able to develop an assay to screen condor estrogen receptors (ERs) with chemicals found circulating in the blood of condors living along California’s coast to detect activation of these hormone receptors. Determining which chemicals mimic (activate ERs) or block (deactivate ERs) signaling of the endogenous hormone estrogen will be an important step in better understanding the endocrine-disrupting potential of chemicals found in the condor’s coastal environment.

Chemical concentrations circulating in condor blood activated condor estrogen receptors in the lab. This discovery lead us to speculate that in the wild, coastal condors are being exposed to levels of chemicals that may cause developmental and/or reproductive harm. The chemical load in condors today is similar to that found in other birds of prey along the California coast such as the bald eagle and peregrine falcon. These species have experienced eggshell thinning in the past. Unfortunately, eggshell thinning is already compromising the coastal condor population.

Relocating California condors to coastline habitats reduces chances of lead poisoning but may pose other risks.

Relocating California condors to coastline habitats reduces chances of lead poisoning but may contain other, unseen threats.

In the Field
What does this mean for free-flying condors? The cliffs along the Southern California coast may not be the ideal escape from the threats of lead poisoning. If chronic exposure and the production of thin eggshells continue in the population, there is the potential for long-term effects since coastal condors are sensitive at the molecular level to contaminants found in their diets. In Oregon and Washington, condor reintroduction was put on hold due to elevated levels of chemicals in the blubber of marine mammals.

In Baja California, Mexico, the wild condor population may have to be moved to the coast of Mexico. Conservation managers are hoping to wean condors off expensive supplemental feedings and toward a diet composed of beached marine mammals. But before relocation of this population occurs, chemical compositions of beached marine mammals at the potential release sites will be evaluated in the lab for endocrine-disrupting capabilities. Our goal is to move condors away from lead and intensive management practices, but not into another health-compromising situation.

Rachel Felton is a senior research technician at the San Diego Zoo Institute for Conservation Research.

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Condors: Feeding Time Manners

Around the corner to the right is where the condors are fed.

The condors are fed around the corner to the right.

After fledging, a growing young condor starts to eat on its own, with the parents continuing to feed the youngster every once in a while. At the San Diego Zoo Safari Park, we do things a bit differently, as the fledged birds are moved to a remote socialization pen with other young release candidates and a mentor bird or two. We don’t move fledglings to the socialization pen until we’ve made sure they have been seen feeding themselves. The mentor birds do not feed anybody.

This year’s Condor Cam chick, Su’nan, who hatched on April 29, 2014, was starting to eat on her own when she was with her parents. When we saw that she was eating on her own, we were comfortable moving her to the socialization pen with the other young release candidates. We drop all of the food at the same time through a chute in the wall, hiding us from the young birds’ view. The most dominant members of the group (usually the biggest or the most experienced) eat first or displace other birds that may be in their way. The subordinate, younger birds usually wait until the dominant birds finish or let them come and eat with them.

Eventually, as the subordinate birds gain experience, they may move up in the social hierarchy. Currently, Su’nan is near the bottom of the pecking order, as expected, due to her size and age. She is doing just fine, though. Feeding is very competitive, just like it is in the wild. It may look rough and impolite to us, but we must remember that the condors are working under the rules that work best in their social system, not ours. This experience the youngsters are getting will better prepare them for a free-flying life in the wild.

Ron Webb is a senior keeper at the San Diego Zoo Safari Park. Read his previous post, Condors Saticoy and Cuyamaca Flying Free.