Pandas, Bears, and Pregnancy

Bai Yun’s ultrasounds have revealed a leg, spine, and heartbeat.

The giant panda diverged from the rest of the bear lineage some 20 million years ago, and they have developed some really unique traits not shared by other bears as a result. Dependence on bamboo for sustenance and the development of the pseudothumb to aid in bamboo acquisition are two examples of differences between pandas and other bears. However, when female pandas are pregnant (or pseudopregnant) they remind of us of just how bear-like they are. Although pandas do not experience the hibernation-like state of cold-weather bears most of the time, the females still couple hibernation-like behaviors with the changes in their pregnancy-related hormones.

Cold weather bears like polars, black and brown bears give birth while denned up in the winter. The females rear their young for the first few months in the quiet warmth of their den, before emerging in the spring. During the denning period, females generally forego food and are largely inactive, producing milk to sustain their young while they themselves conserve energy by resting. Winter is a good time for females to slow down and fast, because they wouldn’t find much food anyway during the frozen months of that season. Springtime is a good time to emerge hungry from the den because food abundance is on the uptick at that time of year, and the mothers leave the den with a long season of good eating ahead of them.

Panda mothers experience the same sluggishness and fasting behaviors, but their window for such behavior isn’t coupled with winter. This is probably because bamboo is not a seasonally available food source; it’s around them all year long.  Pandas tend to den up in the summer months instead. Those are some of the warmest months in the mountain ranges in China, and caring for tiny, fragile neonates during warm months affords the mother the opportunity to keep her cub sufficiently warm even when she needs to leave the den to feed a few weeks after birth, as panda mothers do.

Bai Yun’s hormones are in full pregnancy mode, declining from a peak a few weeks ago towards a presumptive birth window. To that end, we have kept monitoring her hormones, behavior, thermo imaging and ultrasound. What do our results show thus far?

Her behavior is interesting, showing a slight increase in denning activity over a week ago. She is building her nest. She is sluggish and still declining her bamboo, but has also become very finicky with respect to non-bamboo too. She has begun insisting that keepers peel her apple slices during husbandry sessions; no skins for Bai Yun! Her hormones continue to drop toward baseline. And her ultrasounds have revealed: a fetal heartbeat!

Yes, we are very excited to think Bai Yun is carrying what we hope will be her 6th cub. We are patiently waiting and crossing our fingers that she will carry this cub to term. I know you will be crossing your fingers with us!

Suzanne Hall is a senior research technician with the San Diego Zoo’s Institute for Conservation Research. Read her previous update, Panda Update: Seeking Seclusion.


The Secret Life of Eiders: Part 1

Mike releases a king eider back into the wild after it was rehabilitated in Alaska.

Most people have never heard of an eider before (pronounced EYE-der). This is a shame, as eiders are the most colorful and playful ducks I’ve ever worked with. Eiders are large sea ducks that are found along the coastline of Alaska, northern Canada, and even down into New England. The common eider Somateria mollissima, king eider Somateria spectabilis, and spectacled eider Somateria fischeri are all closely related and of the same genus. The Steller’s eider Polysticta stelleri is more distantly related and has a genus all its own. The following anecdotes are a collection of stories from my work in Alaska before I came to the San Diego Zoo.

The wonderful king eider is truly a regal bird. The breeding male has a beautiful red bill, a bright orange-yellow cere (the top of the base of its bill), greenish cheeks, and a subtle purple/gray crown and nape (the back of its neck). This is coupled with a cream chest and a black back with little feathers that stick up and look like sails. Sounds amazing? Believe me, my description doesn’t do them justice. The female is, of course, quite drab by comparison. However, the female demonstrates her royalty by her devotion to her eggs. When the king eider female finishes laying her eggs, she stays on the nest for up to a week at a time without a break! While most duck moms take a daily “break” to eat, defecate, and stretch, the female king keeps her nest as secret as possible by remaining on her throne.

The common eider is bigger than life. Almost. Many years ago I had the privilege of working with this species, and what struck me the most about them was that they also believed that I was privileged to work with them!  Usually when a keeper enters a bird exhibit, one of two things happen: the bird flies or walks closer looking for a treat, or the bird flies or walks away seeking distance from potential danger. Well, the commons did neither; they stayed right where they were. Many times I had to carefully weave my way around the feathered “mines.” Oh, but I was surely in for a bite on my leg if I passed by without giving them a piece of krill, clam, or squid. Privileged, remember?

Next comes my favorite eider species, the spectacled eider. They are not massive like the commons. They aren’t flashy like the Steller’s. They aren’t regal like the kings. They are the clowns. There were days when I believed that they were sent to keep the humans entertained as we worked with the “real” eider species. Cleaning pools was always a chore with the Steller’s eiders. They were so skittish that we had to move slowly or else they could spook and fall into the empty pool. We had the opposite problem with the spectacled eiders. The specs would wait until our back was turned and would line up at the edge of the empty pool. They would then start their own version of American Gladiators and try to knock each other off the ledge. Many keepers turned just in time to see one duck get pinched in the rump by its buddy and sent over the edge (a short, harmless fall). As the rest of the flock fluttered about joyously at the misfortune of their friend, we would walk over, pick up the fallen bird, and place it in one of the full pools so the whole episode could start all over. It was impossible to be bored when there were specs around!

Check back soon for The Secret Life of Eiders: Part II, where we will learn about the gorgeous, but aloof, Steller’s eider.

Mike Grue is a senior keeper at the San Diego Zoo. Read his previous post, Dabbling vs Diving Ducks.



Elephant Antics

The Safari Park’s African elephant herd continues to thrive, and we are all eagerly awaiting the arrival of Swazi’s second calf, which is due late July or early August. Look for physical changes in our matriarch as she prepares to welcome her baby.  Will son Macembe (Mac) be a good big brother? Time will tell, of course, but so far Mac is one super cool, laid-back kid. Like his mom, Mac has long legs and is a quick-learning and confident two year old.

You’d think that Umngani, mother of three, would have her trunk full taking care of her brood. Yet she has been spending her time lately enticing Msholo, our lone bull, to come hither! He, of course, is happy to play along, and there may be breeding between the two soon. Luckily for Umngani and her raging hormones, daughter Khosi, who is almost six years old, is more than willing to babysit younger brothers Ingadze and Neepo, freeing her mom to flirt with the handsome Msholo. Ingadze is now three years old and has been the kindest big brother to little brother Inhlonipho. Keepers describe Neepo as a wild, high-energy boy who will have his first birthday in September. Neepo loves to sound his little trumpet and chase the keepers along the exhibit’s fenceline. He has recently taken up a new talent: hopping!

Msholo has integrated very well with the herd. He is gentle with the little ones and attentive to the ladies. Even Ndula will occasionally interact with him, and she never interacted with Mabu (except during estrus and would then make him work!) Perhaps it’s because her oldest son, Vus’musi, has become best buddies with Msholo. The two play wrestle often, especially in the pool. Although he is much larger than Musi, now 8 years old, Msholo gets on the younger elephant’s level to help make the wrestling matches more even. What a guy! Ndula’s other son, Luti, is 2½ years old and has replaced his big brother as a momma’s boy. Keepers say Luti is shy and cautious about learning new things, although when he gets real excited, he hops on his rear legs, too!

Debbie Andreen is an associate editor for San Diego Zoo Global. Read her previous post, Elephants Emanti and Kami.



Panda Update: Seeking Seclusion

Only time will tell if Bai Yun is indeed pregnant.

Bai Yun continues to demonstrate appropriate behavior for a pregnant (or pseudo-pregnant) female. One particular behavior, known as “seeking seclusion,” has led to a change in her access this week.

Until recently, Bai Yun was given free run of the behind-the-scenes area near her bedroom, including her sun room, garden room, tunnels and off-exhibit classroom. However, as her potential pregnancy wears on, she is more inclined to stay close to home, and doesn’t seem to like sleeping out on the climbing structure in the classroom anymore. She prefers tucked-away places, like the garden room platform or the den. As a result, we have shut the door on the classroom exhibit. It won’t open again until she demonstrates more interest in stretching her legs after the influence of her pregnancy hormones have worn off.

Seeking seclusion seems a smart move for a panda mother-to-be. Panda cubs are fragile, helpless and totally dependent upon their mothers for meeting all of their needs. The work involved in the constant care and nurturing of the panda neonate requires all of mother bear’s attention, and distractions in the area come at a cost to the mother and cub. If she is focused on external disturbances, mother bear has that much less attention to give to the activities inside her den. Tucking into a quiet, secluded space allows the female to focus on what is important: care of the cub, and her own rest and recovery.

As the days fly by, we can expect Bai Yun to continue to narrow her focus from the surrounding areas to the den. If she is indeed pregnant rather than pseudo-pregnant, we should see her spend most of the day in the den starting a few days before a birth. Currently, she is visiting the den 3-5 times each day for periods of up to 30 min at a time, but the majority of her day is spent in the garden room or bedroom.

We’ll keep you posted as to her progress.

Suzanne Hall is a senior research technician for the San Diego Zoo’s Institute for Conservation Research. Read her previous post, Panda Pregnancy Watch in Full Force.


Shaba’s Next Step

With Connie (left) gone, Shaba (right) is showing signs that she will integrate beautifully into the herd at Elephant Odyssey.

With the passing of elephant Connie at the San Diego Zoo, we know that many of our guests are concerned about her companion, Shaba (see post Elephant ICU Loses a Member). I’d like to take this opportunity to share some of the things we’ve observed from her that give us hope that she will adjust to life without her long-time companion and thrive in her new herd.

After their quarantine period ended, Connie and Shaba were given opportunities to explore some of the yards and come out into the Elephant Care Center stalls for their daily treatments. Shaba took to these new areas with eagerness. She has been curious about each new place, exploring every area that could possibly have a treat hiding in it (and usually there is something good to find).  She has also been very outgoing when it comes to meeting new elephants. She is the first to want to approach the fence and interact with them. She is gentle when she reaches through to smell and touch the others, and not frightened or put off when they are a little less gentle with her. From the beginning, we have seen signs that she will integrate beautifully into our herd.

Yesterday, the keepers and veterinary staff had the difficult but necessary task of relieving Connie of her pain and discomfort by euthanasia. It was emotional for everyone involved. Foremost in our minds was the uncertainty of how Shaba would react when we would bring her in to say goodbye. We know from various studies that elephants have some understanding of death, so when an elephant passes in our care, we give their herd mates a chance to see and touch the body. After we knew that Connie was gone, we cleared the area and stood silently as Shaba was lead into the special-needs facility. At first she was focused on all of the people, but after a moment she saw her friend. It was a solemn and precious experience to be in that room. Shaba approached Connie with some hesitation. She reached out and touched her trunk. She backed away for a moment and vocalized, but kept her eyes on Connie, came back, and touched her again. There was a keeper nearby with treats and an open door to the yard so Shaba could decide how long to stay and when to go. She walked over to her keeper for a treat and then back to Connie a couple of times before deciding to leave the area. In total the interaction lasted only a short time, but we believe it was a significant step in helping her to deal with her loss.

For the rest of the day Shaba was outside being introduced to Mary, our dominant female Asian elephant. They had a very good interaction. They touched and smelled each other through the fence on and off throughout the afternoon. Mary asserted her dominance from time to time, and Shaba behaved exactly the way a more submissive elephant should. We are confident that when the time comes to put them together in a yard, the process will go smoothly. Shaba spent the night in our biggest yard for the first time last night. It was also her first night without Connie, so we had a keeper here to observe her. She did very well. She spent a good amount of time near Mary at the fence and the rest of the time either sleeping or exploring. She has a very secure and independent personality.

We will continue to watch Shaba closely to make sure that she is coping with this difficult change as well as possible. We are grateful that Shaba had Connie with her to help her with the adjustment to her new home and that we had the wonderful opportunity to know Connie and to work with her. She will be missed not only by Shaba but by all of the staff and our guests who love and care for each of the animals here at Elephant Odyssey.

Nora Kigin is a keeper at the San Diego Zoo. Read her previous post, Connie and Shaba Out and About.



The World’s Rarest Cats: Growing Up

There is estimated to be about 30 Amur leopards left in the wild.

It’s been over three months since our trio of Amur leopard siblings debuted (watch the video) on Big Cat Trail at the San Diego Zoo. Personally it has been very rewarding to work with these cats, both because of their extreme rarity and because at this young age they are always very engaging!

With an estimated wild population of only 30 animals, the Amur leopard is literally on the razor’s edge of extinction. For comparison, our beloved and also endangered giant pandas have a wild population of approximately 1,500 individuals. The current plight of the Amur leopard makes our job of both breeding this species and raising awareness of its conservation that much more important. With hard work, it is hoped that the Amur leopard can follow in the footsteps of the California condor, a species who’s numbers were at one time equally as low but through dedicated work have now risen to become a conservation success story.

We have many reasons for hope for this species. Early this year, after urging from various conservation organizations, Russia established a new national park specifically for the purpose of protecting the Amur leopard. These rare cats have also recently been seen during camera-trap surveys in China, the first time they have been observed in China in recent history. If nothing else, viewing our youngsters’ escapades is sure to bring a smile to your face.

Zeya, the little girl, is the troublemaker of the bunch. She is most likely to start a playful tussle with one of her brothers, often using her patented “death from above” move. Primorye is the most affectionate of the group, often soliciting attention from the keepers. He’s also a bit of a goof ball and is the most likely to randomly fall off of something, with or without the help of one of his siblings. Koshka has a classical “cat attitude,” which some might consider grumpy or aloof, but he still has a playful side. During behind-the-scenes tours, he often hangs back until the antics of his siblings have the tour group totally engrossed. Then he springs forward, pounces, and hangs from the side of the exhibit for a while, just like a house cat on a screen door.

A lot of this play behavior is actually training for behaviors they would need to be successful living as adults in the wild. When the youngsters are play fighting, you may notice that they most commonly bite at each other’s necks. The neck is the most vulnerable spot on prey and a leopard’s preferred method of dispatching a future meal. You can also see them lugging around and stashing over-sized burlap bags stuffed full of hay. In the wild, a smart leopard goes to great lengths to conceal its kill, which often outweighs the leopard. Other predators such as the Amur tiger wouldn’t hesitate to steal away the meal the leopard worked so hard for.

These rambunctious felines are growing by leaps and bounds and are soon approaching the age that they would naturally disperse away from both their mother and siblings. I hope they will eventually be paired with mates to produce a next generation. Make sure to stop by and see these extraordinary cats while they are still in rare form.

Todd Speis is a senior keeper at the San Diego Zoo. Read his previous post, Snow Leopards: Love at Second Sight?


Big Cat Preferences, Part 3

Thanks to our dedicated animal care staff, we have now completed all the initial preference trials (see Big Cat Preferences and Big Cat Preferences, Part 2) with lions, tigers, and cheetahs. Our findings reveal that there are both species and individual differences in enrichment preference, which will help us make educated decisions when providing enrichment for our felids. Ensuring the highest quality of care for every animal in the collection is our top priority, and this is just one project leading toward that goal.

The next phase of this project is being completed by Erin Lane, our Neeper Endowed Fellow, with the assistance of some of our wonderful volunteers. The project includes examining the effects of enrichment (scents and objects) on the 24-hour behavior of lions. We have installed cameras throughout the San Diego Zoo Safari Park’s lion exhibit to observe what the effects of the enrichment are both during the day and at night. This will also provide some insight into the activity budgets of the animals. For example, throughout the day a person might spend about 8 hours sleeping (33%), 1 hour commuting to and from work (4.2%), 9 hours working (37.5%), 2 hours cooking/eating (8.3%), 3 hours watching tv (12.5%), and 1 hour exercising (4.2%). We want to know what percentage of time the lions eat, sleep, rest, socialize, and play. This information will help us make sure that our enrichment program is keeping the animals active and healthy.

We will also be recording different behaviors such as scent marking, sniffing, and clawing to make sure we are providing opportunities for these behaviors, which are part of their natural behavior. Keep in mind that lions in the wild typically sleep between 16 and 20 hours a day (66.6% to 83.3%), and we hope our lions spend their time in a similar fashion. If you have been to the Safari Park’s Lion Camp before, you probably already know that they spend a good portion of their time sleeping just the way a lion should. The question is: how much?

Lance Miller is a scientist for the San Diego Zoo Institute for Conservation Research.


Biodiversity at Cocha Cashu

Early morning on the lake at the Cocha Cashu Biological Field Station

As someone interested in nature, and as a scientist with San Diego Zoo Global, over the years I’ve been fortunate enough to see four of the world’s eight bear species in the wild. Often these sightings occurred in circumstances that left my heart pounding with wonder, although I admit that once or twice I’d have preferred to know beforehand that all would end well. How many bear species can you list, without referring to a reference? Similarly, how many primate species can you list? They may be big charismatic mammals, but both bears and primates are a tiny fraction of the biodiversity in our world. On a recent trip to the Cocha Cashu Biological Station in southeast Perú, I gained a much better appreciation for the biodiversity of the lowland Amazonian rainforest. You’ve probably heard that tropical rainforests have incredibly biodiversity, but it’s one thing to ‘know’ in your head that the rainforest features amazing biodiversity, and it’s something else to ‘know’ it from experience.

A white-fronted capuchin monkey at the Cocha Cashu Biological Station

Jessica Groendijk, education and outreach coordinator for the Cocha Cashu Biological Station, has written about how she and I began a morning at the field station. We saw giant river otters in the wild! Thus began a truly memorable day in the field. After returning to camp, I quizzed Jessica over breakfast on her interpretation of the otters’ behavior, and various aspects of their ecology. Patiently she explained what was known and not known about giant river otter behavior, ecology, and conservation. She politely refrained from reminding me that most of this information was included in the book on giant river otters she co-authored with her husband. I did read the book, honest! It’s just that I read it a few years ago, and I hadn’t yet had my first cup of coffee…

After fueling up, we grabbed our gear and left camp with Cesar Flores, director of the Cocha Cashu Biological Station, and Luis Ramirez and Samantha Young, both of San Diego Zoo Global’s Conservation Education division, to become more familiar with the habitat and animals surrounding the field station. I’ve spent much more time in the cloud forest, and the tropical dry forest, than in the lowland Amazon rainforest, so the Amazon is like a different world to me. In my humble opinion, it is truly wonderful, in the full sense of that word.

The forest canopy at Cocha Cashu Biological Station

By the end of this day at Cocha Cashu, Jessica and I had not only seen giant river otters (!) and numerous bird species, we’d also seen seven species of wild primates: white-fronted capuchin monkeys, brown capuchin monkeys, spider monkeys, common squirrel monkeys, red howler monkeys, saddleback tamarins, and emperor tamarins. My heart got a decent workout.

Cocha Cashu has long been known as a great place to conduct biological field research, to better understand how things work in the lowland Amazon rainforest. After seeing the improvements Cesar and his staff have made since I last visited the station, and talking to these folks about their vision and goals, I’m hopeful that Cocha Cashu will continue to be a source of knowledge, and that this knowledge will help guide efforts to conserve the lowland rainforest and its diverse components.

Thanks again, Jessica, for allowing me to share a wonderful morning on the lake at Cocha Cashu, and thanks to Cesar and all the other people in Perú and in the US who made our visit, and our involvement at Cocha Cashu, a possibility.

Russ Van Horn is a scientist in the Applied Animal Ecology Division of the San Diego Zoo Institute for Conservation Research. Read his previous post, Are Wild Areas a Luxury?


Elephant ICU Loses A Member

Connie will be greatly missed

We met Connie, a 45-year-old female Asian elephant from Reid Park Zoo, in February 2012 when she arrived at the San Diego Zoo destined for integration into our middle-aged and geriatric elephant herd. We received her medical records six months prior to her transfer and, in discussion with Reid Park Zoo veterinarians, began preparations for her ongoing health care at the Zoo’s Elephant Odyssey (EO). Monitoring her urine on a regular basis was on our agenda as we noted several bouts of urinary tract infections (UTI) over the past few years, a condition not uncommon in middle-aged to geriatric females, animal or human.

Connie seemed to adjust well to her keepers and life at our Elephant Care Center during her quarantine. She learned the touch and smell of the veterinary team. She gently put her trunk up to the mesh at breath level, curious to know who was visiting. Excited to build a good relationship with her, I’d place a few food pellets or produce in her trunk and meet her eyes, hoping she would know that all the things I would do or ask her to do were an effort to keep her healthy in her golden years. As time passed, and with the heightened observation period of quarantine, keepers did notice some of the same things as her Reid Park Zoo keepers that signaled concern for recurrent UTI: urine dribbling and discharge along with changes in attitude and food and water intake. I requested a sample of urine. How to get that, you might wonder? The keepers have a collection cup resting inside a loop of zip-tie on a telescoping pool-cleaning pole that they sneak under the elephant for a mid-stream catch. The samples supported evidence of infection from either the urinary or reproductive system. We treated with broad-spectrum antibiotics, and Connie seemed to feel much better over the next 10 days.

As other blogs mentioned, Connie and Shaba moved on to the next stage of EO life: meeting new elephants and exploring new places. Our veterinary minds did not move on quite as quickly; we want to know why medical events occur and place great emphasis on preventing problems. We began discussion for additional procedures and diagnostics to evaluate Connie and initiated regular urine monitoring.

Unfortunately, just two months later, Connie had a marked decrease in appetite and output. Whenever Connie chose not to eat medicine cleverly disguised in all sorts of food items and then chose not to eat or drink much of anything, we moved quickly to investigate.

Our special-needs facility (SNF) was designed to ease diagnostic evaluation and intensive care for our middle-aged to geriatric elephants. How? What is so special there? The elephant restraint device (ERD) has big, wide straps that we can wrap from the axillary (armpits) and inguinal (groin) regions up to steel beams on a hydraulic system that will support the weight of a leaning, weak, or sedated elephant. In addition, the ERD articulates to allow a mesh wall with windows and doors to come close to different parts of the body, giving RVTs (veterinary technicians, aka nurses) and veterinarians a chance to safely examine and access body parts, collect blood samples, place intravenous catheters, administer medications, and provide overall intensive care for a sick elephant.

Test results returned, and we were quite disappointed to learn that Connie was severely leukopenic [leuko=white blood cells; penic=decreased], suggesting that the immune system was fighting disease somewhere in the body. We instituted several antibiotics and transformed the SNF into an ICU unit and initiated more intensive treatment for Connie. After intramuscular injections of medications did not ‘fix’ her abnormal blood results or her overall attitude and appetite, we chose to sedate Connie for placement of IV catheters (back of the ear and inside of the back leg), administration of fluids (120L = 30 gallons for a 3,000 kg patient), and administration of medications both intravenously and into the colon (absorption occurs here as well). Connie was not keeping herself hydrated with her water intake (or electrolytes or nectar or other undercover tactics) nor was she taking in enough food for long-term sustenance, not to mention her lack of interest in taking any foods ‘doctored’ sneakily with medications.

We invited a reproductive and overall elephant specialist to join us in evaluation of her bladder, kidneys, and uterus to uncover any cause for the previously seen thick urinary discharge and/or the work of the immune system to combat her disease process. Unfortunately, we identified another serious problem atop the other ones—a lot of fluid floating in her abdomen. Fluid like this can cause problems with breathing and a full feeling in the belly and can come from some challenging diseases (heart or liver disease, cancer, vasculitis, ulcers), no matter what age or creature. None of the possible explanations suggested a good prognosis for Connie’s health. This examination did not reveal the root cause of her illness, but it confirmed that without intensively supporting her system, she would not survive.

Since her arrival in San Diego, veterinarians, technicians, keepers, and managers have worked extensively with Connie to manage her health concerns. We saw improvements, but this time the response was not the same. Over the last couple of weeks, her condition continued to deteriorate and severely affect her quality of life. She was drinking about 1.5 gallons of water when she needs 75 gallons daily to live. Connie’s immune and organ systems simply were not keeping up with her disease. This morning, we made the heartbreaking decision to euthanize her when it became apparent that Connie would be unable to sustain herself. We know many of you will share in our loss as we say goodbye to Connie and hope that you know she will be greatly missed.

Tracy L. Clippinger is a senior veterinarian at the San Diego Zoo.


Dabbling vs Diving Ducks

Ducklings at the San Diego Zoo

If it walks like a duck, quacks like a duck, looks like a duck, it must be a duck. –Old Proverb

There are many different duck species in the world. In North America, we have the ubiquitous mallards, black ducks, northern pintails, and gadwalls. Wood ducks, green-winged teals, blue-winged teals, cinnamon teals, and widgeon’s also live here…and those are just the dabbling ducks! I’ve not even mentioned the numerous species that are classified as stiff-tailed ducks, including shelducks, steamerducks, torrent ducks, perching ducks, pochards, and diving ducks.

For this first entry in a series of blog posts on ducks, why don’t we look at the differences between the two most numerous types of ducks: dabblers and diving ducks. When most people think of a duck, they think of a dabbler. If you’ve ever seen a duck tip its butt up in the air and submerge its head to look for food, you’ve seen a duck dabbling! Mallards are the quintessential dabbling duck. They have relatively long bills, sit high in the water, have large wings, and their legs are located mid-body. In contrast, diving ducks like the harlequin and long-tailed duck have shorter bills, sit low in the water, have relatively smaller wings, and their legs are toward the rear of their body.

Why have these two different groups of ducks evolved such different body plans? It all depends on how these birds find food! Everything about dabblers is built to make them successful at the water’s surface. Having a high buoyancy, they sit high in the water and don’t have to paddle as hard to move around. Legs that are about mid-body allow them to walk on firm land with relative ease. Their long bills have grooves in them that allow them to filter food out of the water, and their big wings allow them to take off at a moment’s notice. As a result of all the advantages dabblers have at the surface, any food that is more than a few feet below the waterline is forever beyond their reach.

Enter the diving ducks! No, these guys don’t walk on land as well as their dabbling cousins due to their “rear-positioned” legs, nor can they filter-feed as well with their smaller bills. Having short wings means they can’t get airborne unless they first run on the water, flapping like the dickens. You could say that at the surface these guys are, well, sitting ducks. But wait! Below the waves these birds really shine!

Picture the long-tailed duck hen as she starts her ocean dive by exhaling most of the air in her body before plunging her head into the water. She then points herself straight down and flaps her wings. She starts her descent as she moves her head, neck, and body up and down the way an Olympic swimmer does the butterfly stroke. She picks up speed as her feet kick in a rhythmic motion as she cruises toward the bottom of the ocean, 200 feet below. Her whole body is working together in one sinuous movement with the intent of finding food. The water resists her wings more than the air does, so her species has evolved smaller wings that can overcome the effects of buoyancy pulling her back toward the surface. At the bottom, her small bill probes rocks and mud for small crustaceans and invertebrates. She finds one, eats it, and starts her ascent. She has used a lot of energy getting her meal, so she simply relaxes and lets her buoyant body be carried upward.  A minute later she breaks the surface and takes a well-deserved breath of air. Since she may not visit fresh water for many months, her body is already hard at work extracting the water from her food. The excess salt will be filtered out by her salt glands and extruded out of her nasal passages. She fluffs her feathers, takes a deep breath, exhales, and plunges below the water once more.

Quite an amazing journey for just one piece of food! At the San Diego Zoo, we have two exhibits located next to each other that house many of the dabbling and diving ducks mentioned above. They are found downhill from the main polar bear viewing area. Be sure to check them out!

Mike Grue is a senior keeper at the San Diego Zoo. Read his previous post, Green Woodhoopoe: Quirky or Clever?