Animals and Plants

Animals and Plants

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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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10 Tiger Vines for Global Tiger Day

You can be a hero for wildlife by visiting the Zoo or Safari Park, or by joining the San Diego Zoo Global Wildlife Conservancy, which supports our tiger project in Way Kambas National Park in Sumatra, Indonesia.

For more fun animal videos, follow the San Diego Zoo Safari Park.

Jenn Beening is the social media planner for San Diego Zoo Global. Read her previous post, 21 Terrific Tiger Facts.

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Frog Nanny

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Tending to tadpoles means carefully monitoring water quality and providing a constant supply of food.

Frog nanny is not an official job title, but it’s been my reality this year. I’m the “nanny” for some 1,176 healthy mountain yellow-legged frog (MYLF) tadpoles.  This iconic California species is one of the most endangered frogs in North America. San Diego Zoo Global has been involved in the MYLF recovery program since 2009, and captive breeding has been an important component of our efforts to re-introduce froglets into their natural habitat in the Sierra Mountains. However, with little information on MYLF life history, the care and reproduction of these frogs in captivity presents many challenges.

I have been working on this project full-time since last October. As I enter the lab and look into the 100-gallon containers holding the result of this years’ extremely productive breeding season, a feeling of excitement and nervousness comes over me. It takes about a month and a half for MYLF embryos to hatch out into free-swimming tadpoles, and in the meantime, they require daily preening. Early in the breeding season, I start my day by counting and cataloging over 1,800 embryos. Something like picking ticks off a chimpanzee, this entails cutting through the surrounding egg jelly and extracting any unfertilized or dead embryos from neighboring healthy ones. Sitting at the dissecting microscope, I examine and record what stage of development each embryo has reached every day. By the afternoon, I am all but cross-eyed. I walk around with constant images of beautifully formed black spheres in my mind’s eye. As the embryos grow and thrive, the stress of getting them through the early stage of development is taken over by concerns for stage two of tadpole rearing.

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These black specks are mountain yellow-legged frog embryos.

So what is stage two? We begin by focusing on what tadpoles need. MYLF tadpoles require cold, clean water, constant feeding, and plenty of space to grow. Like most infants, tadpoles are voracious eaters and require a constant supply of food. If too much food is offered, it accumulates in the tank, causing water quality issues. Too little food, and big brother Jake might start nibbling on his smaller sibling Fred. Cannibalism is not uncommon in amphibian species, so all I can do to stop Jake from eating his brothers and sisters is make sure I feed him enough.

Amphibian nutrition is a work in progress, and little is known of individual species’ requirements. This year, I have gone from reproductive physiologist to dietician. Researching amphibian nutrition is complicated by the specific needs of each life stage. Luckily, I have a supporting team of professional nutritionists and a wealth of knowledge and years of experience, courtesy of Brett Baldwin and David Grubaugh, amphibian/reptile keepers at the Zoo.

Controlling water quality is another daily necessity. The difference between clean and pristine can be subtle, and can affect growth and development in ways that may not be apparent until it is too late (like during metamorphosis). Armed with the HACH colorimeter DR-900, a small team of us (Nicole Gardner, senior research associate; Bryan King, research associate; me; and our weekly volunteers, Jaia Kaelberer, Janice Hale, and Jim Marsh) conduct daily screenings of the water in which our tadpoles live. Based on data we have collected on the water quality in MYLF habitat, we have specific parameters to which we can set our water standards in the lab.

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Helping to raise new generations of mountain yellow-legged frogs is challenging, but rewarding.

They say “be careful what you wish for.” This year, we wished for a handful of MYLF egg clutches to be laid and for a couple of hundred embryos to survive. Instead, we got almost 2,000 eggs! As they grow, we become faced with a new challenge—overcrowding. To my relief, the solution becomes clear; together with our partners at the US Geological Survey and the Department of Fish and Wildlife, we decide to split our bountiful cohort of tadpoles into smaller groups. At the end of May, 711 lucky tadpoles made their triumphant way back to the wild, and 400 of their brothers and sisters stayed here with us. They will be “headstarted” and returned to the wild as froglets.

Everyone involved in this project lives and loves every moment. There is nothing more satisfying than watching a life form grow and thrive under your care. This year’s breeding season has exceeded all our expectations. If we take into account that less than one percent of MYLF tadpoles are estimated to survive to metamorphosis and only an estimated 200 adults remain in the wild, everyone currently involved in this project holds the key to this species’ survival. That can be stressful, but it is also a humbling honor. I am happy to speculate that this is going to be a good year for our MYLF program, and that I will have the chance to be part of their journey back to nature.

Natalie Calatayud is a research associate at the San Diego Zoo Institute for Conservation Research. Read her previous blog, Rocky Mountain High: Boreal Toads Going to a Place They’ve Never Been Before.

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Ahoy! Let’s Celebrate Xiao Liwu’s Birthday!

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Flashback to Xiao Liwu’s first photo at about a month old. Oh, that face!

Xiao Liwu’s 3rd Birthday is July 29th  but we are going to have his big party on August 1st for him, beginning at 9 a.m. (US Pacific Daylight Time), so mark your calendars and set your alarm!  We are looking forward to seeing what his ice cake (crafted by our creative Forage Team) looks like this year. We as a team always enjoy this little surprise and the only hint we have had is that it is orange. (You can read about how an ice cake is made here.)

“X marks the spot” when the Forage Team delivers the cake at 8:45 a.m., while we keepers put out all his enrichment.  The birthday boy will be able to come aboard his exhibit at 9:15 a.m., right after the Zoo opens so all of his crew and friends can be there to watch him enjoy his cake and “presents.”  Mr. Wu  has commandeered the cave exhibit, so his fans will have a bigger space to view the celebration.  This is also the better exhibit for Panda Cam viewing so all the Panda Fans that cannot be there in person can celebrate with us, too!

Mr. Wu still is our “Little Gift” and amazes us everyday. He is now 149.6 pounds (68 kilograms) and is still small but mighty. He has been going through the destructive phase, testing the limits of every climbing branch and log in his exhibit.  So be ready for the fact that there may be times that he falls or gets a new scrape, just like any young boy would.  He has many playful bouts of running around and enjoying his enrichment, but he still remains patient during his training sessions.  We have taken a little break with his blood pressure readings, as Bai Yun has been having full access to the training crate.

As keepers we look forward to this time to give all our pandas extra enrichment in celebration of this milestone—another year closer to being an adult (which usually is around five years of age).  If you are able to come to the celebration in person, please also stop over at our Volunteer table to learn about giant pandas and look at our special artifacts.

We know one day that Mr. Wu will add to the genetic diversity of future giant pandas and maybe even one day his future cubs will be candidates for release into the wild. In this way and so many others he is a “Little Gift” that keeps on giving!

Jennifer Becerra is a senior keeper at the San Diego Zoo. Read her previous post, Happy Anniversary, Gao Gao.

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Condor Chick: Getting Big!

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There she grows! Antiki is feathering out nicely.

Antiki, our California condor chick featured on this year’s San Diego Zoo Safari Park’s Condor Cam, is now over 100 days old and starting to get her “big bird” feathers! As many of our regular viewers have noticed, her flight feathers are growing in. Some of the first feathers that start to grow are the wing feathers. It is easy to see the feathers growing through the chick’s down—the down feathers are gray, but the new flight feathers are black. The long feathers that grow from the tip of the wing are called “primary feathers” and the feathers from the wrist to the armpit are “secondary feathers.” Primary and secondary feathers are the giant feathers that make the California condor’s wing so large and impressive; an adult can have a wingspan of up to 9 ½ feet! We are estimating our chick’s wingspan to be around 5 feet right now—between the size of a red-tailed hawk’s and a bald eagle’s. Her tail feathers are also starting to grow. They’re a little harder to see on camera, but you should be able to spot them soon.

After the wing and tail feathers fill in, the feathers on the chick’s back will start to grow, as well as the small feathers on the top of the wing (called “coverts”). Even though many new, black feathers will be covering parts of her body, she will still have lots of gray down showing, making it easy to differentiate her from her parents. Eventually, her light-colored skin will turn dark grey or black and be covered with fine, fuzzy feathers, but this won’t happen until well after she leaves the nest. Her skin will stay dark until she reaches maturity at 6 years and it turns pink-orange, just like her parents’, Sisquoc and Shatash.

The chick had her second health exam on June 25 during which our veterinary staff were able to administer her second, and final, West Nile virus inoculation. A blood sample was obtained and she weighed in at 13 pounds, 7 ounces (6.1 kilograms), over half of her projected adult weight. Even though our little girl is getting big, she still has room to grow!

The adult condors normally are fed four days per week. The other three days of the week, they are fasted. They often will not eat every day in the wild, sometimes fasting for up to two weeks, so our nutritionists recommend not feeding them every day to prevent obesity and food waste. Their diet, depending on the day, can consist of rats, rabbits, trout, beef spleen, or ground meat. We offer two to three pounds of food per bird per feeding day. When the condors are raising a chick, in addition to their normal diet, we offer extra food every day: 1 rat, 1.5 pounds of beef spleen, 1 trout, and half a pound of ground meat. They don’t end up feeding all of this food to the chick, but we want to be sure that they have enough for the growing baby. It’s difficult to calculate exactly how much food the chick is eating each day, but we estimate that she could be eating 1.5-2.5 pounds of food per day.

Many Condor Cam viewers have seen some rough-looking interactions between the chick and her parents. What may have been happening was a form of discipline. As the chick has gotten bigger, her begging displays and efforts have gotten more vigorous. These efforts can sometimes be bothersome or problematic for parents that just want some peace and quiet. The parents have two ways to make sure that the chick does not cause too much trouble while begging. They can leave immediately after providing food, which is what we’ve seen a lot of on Condor Cam; or they can discipline the unruly chick. This discipline can come in the form of the parent sitting or standing on the chick, or the parent may nip or tug at it. Either of these behaviors results in the chick being put in its place by the dominant bird in the nest, thus ending the undesired behavior. Sometimes, this discipline may occur before the chick acts up. Be mindful that this is perfectly normal for condors to do, even though it would be cruel for us to treat our own babies like that! When condors fledge, or leave the nest, they need to know how to interact with dominant birds at a feeding or roost site. This seemingly rough behavior from the parents will benefit the chick later when it encounters a big, unrelated bird that might not be as gentle.

There have been many questions regarding the chick being able to jump up on the nest box barrier. She hasn’t jumped up yet, but she may soon. Stay tuned for our next blog that will discuss this next big milestone!

Ron Webb is a senior keeper at the San Diego Zoo Safari Park. Read his previous blog, Say Hello to Antiki!

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Malayan Tigers, A Family Tradition at the San Diego Zoo

Having one offspring of a legendary pair is special. Having THREE is something else altogether. Mek and Paka, a breeding pair of Malayan tigers, are heroes in the fight against extinction. The latest in their long line of offspring, Cinta and Berani, are a pair of 18 month old sub-adult males that just sauntered into the Lost Forest at the San Diego Zoo. Cinta and Berani, aka “the Boys,” were born January 4th 2014 in a four-cub litter that also included two girls.

Brothers Berani & Cinta are inseparable. (photo by Penny Hyde)

Brothers Berani & Cinta are inseparable. (photo by Penny Hyde)

The addition of the youthful teenagers has been both joyful and a bit nerve-wracking! One particularly heart pounding moment came in the first few weeks of the boys exploring the recently renovated exhibit. At the end of May, Cinta and Berani were wading in the large pool in the lower exhibit when one decided to try to jump up the wall. Easily clearing 10 feet in a single bound, he gently fell back on his feet in the pool and wandered off to explore something else. Even though there was never a chance he could get out of the exhibit, it was still surprising to see how easily he leapt up a sheer wall. This was a true testament to how athletic and powerful these majestic creatures really are.

Brothers Cinta & Berani snuggle up for a cat nap (photo by Deric Wagner)

Brothers Cinta & Berani snuggle up for a cat nap (photo by Deric Wagner)

The exhibit was not the biggest adjustment the boys had to make. Their brother Conner, twice their age and a quarter larger in size, is an imposing and dominant male. Connor made it his mission to scent mark the entire exhibit thoroughly. This marking can last for a month. While the boys are never in the same exhibit as Connor, they know he is around and they had to adjust to seeing and smelling a much larger male. This certainly put the boys in a nervous state, leading to some funny interactions and behaviors early on. Both Berani and Cinta were on high alert the first day they and Connor were out on their exhibits for the first time. They could see Connor through the double fence and never once turned their backs on him the entire day. All the while, Connor just sat on his rock, welcoming the new kids to the block.

Connor sharpening his tetherball skillz. #TigerTetherball (video by Rachel Pollard)

A video posted by San Diego Zoo (@sandiegozoo) on

Once things settled down and all the tigers were getting comfortable with their surroundings, we all moved on to the next phase, exhibit swapping. Both Connor and the boys have now had time in each of the two sections of the redesigned tiger exhibit and they are noticeably calmer as a result. Connor, still a relatively young male himself, continues to show his youthful attitude and exuberance for life. On the first night of Nighttime Zoo, Connor decided to put on a show. He managed to create his own version of The Bellagio water show by ripping up a water line to his drinker. Water sprayed everywhere and one happy tiger got to play in it. The repairs were made the next day and after a short test, Cinta and Berani were swapped into the previously flooded exhibit. They decided to team up and proceeded to tear the water line out of the drinker, just after it got repaired! I guess the boys think imitation is the best form of flattery.

Connor has reclaimed his renovated digs on Tiger Trail in the Lost Forest. #caturday (Pic by Mike Wilson) A photo posted by San Diego Zoo (@sandiegozoo) on

Just two months in with our rambunctious family of brothers, Connor, Cinta and Berani are all adjusting. The family fun and adventure shall continue!

Aimee Goldcamp is a keeper at the San Diego Zoo.

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Summer Pool Party – Animal Style

Summer is in full swing and you know what that means–pool parties! And not just for us; many animals also enjoy the life aquatic. Enjoy this roundup of animals who take to water like moths to flame.

Hippos

Hippos are water fiends. They’re actually adapted for life in the water and are found living in slow-moving rivers and lakes in Africa. With their eyes, ears, and nostrils on the top of the head, hippos can hear, see, and breathe while most of their body is underwater.

Elephants

Our behemoth pachyderm friends also don’t hate water. Elephants often spray themselves with water or roll in the mud or dust for protection from the sun and biting insects. They can also use their trunks as periscopes to breathe underwater, which is quite possibly one of the coolest adaptations ever.

Polar Bears

Polar bears practically live a perpetual pool party. The taxonomic name for polar bears is Ursus maritimus, which means sea bear, a fitting name for these champion swimmers. They have been known to swim more than 60 miles without rest in search of food, using their broad front feet for paddling and their back legs like rudders to steer.

A #polarbear can swim for up to 12 days & up to 426 miles. #regram #animals #nature #sandiegozoo

A photo posted by San Diego Zoo (@sandiegozoo) on

Jaguars

Jaguars would show you up at any pool party with their swimming prowess, helped along by super muscular limbs and large paws to paddle with. In fact, they typically live near water and have a taste for aquatic creatures. Jaguars have even been observed sitting quietly at the water’s edge, occasionally tapping the surface with their tail to attract fish.

Otters

Otters are the only species in the weasel family that enjoys constant pool parties. They spend most of their lives in water, and they’re built for it. Their streamlined bodies are perfect for diving and swimming. They also have webbed feet and can close off their ears and nose as they swim underwater. Otters can also see just as well underwater as they can above, and can stay submerged for five to eight minutes.

Penguins

Most birds are masters of the skies, but penguins prefer the sea. Penguins are fast swimmers allowing them to catch a variety of prey including sardines and anchovies, as well as squid and crustaceans.

Tigers

Much like jaguars, tigers don’t shy away from a good dip in the water. Excellent and powerful swimmers, tigers are often found during the day relaxing or waiting to ambush prey in ponds, streams, and rivers.

Gharials

Gharials, like all crocodilians, are born knowing how to swim. As they grow older they become incredibly agile swimmers, moving through the water with ease by using their powerful, oar-like tails and strongly-webbed hind feet.

Photo by Bob Worthington

Photo by Bob Worthington

 

Can you think of any other animals who love water? Let us know in the comments.

 

Matt Steele is senior social media planner for San Diego Zoo Global. Read his previous post, Myths About Rhino Horn That Need To Go Away.

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A Little Switch

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A change of scenery will be enriching for active, curious Xiao Liwu.

On Friday our keepers decided to switch it up a bit for our panda bears (and for a particular tree); Xiao Liwu was moved into the first enclosure and Gao Gao moved to the “Keebler” side. This change of environment is nothing new to our bears (we do this every few months), and is a chance for guests and Panda Cam viewers to see some interesting behavior as the pandas get reacquainted with their new spot. Giant pandas are very good at scenting their territory, and when we are able to play “musical bears” we give them the chance to re-mark territory and exhibit some of those behaviors: scent marking in a handstand position as well as rubbing on trees and even on the ground. Not only is this fun for our guests to observe, it is a good behavior for our bears to express. Changing locations is a novel enrichment experience for the pandas.

The switch last week also gave our staff a chance to check out the little elm tree that Mr. Wu was exposing. For those of you who haven’t seen that particular enclosure over the years, it has gone through a few trees in its day. The first tree in the exhibit was knocked over by Su Lin, born in 2005. Luckily, nothing was damaged and we were able to secure her and the tree so that she could continue to use it as a climbing structure. We were then gifted with a young elm tree that Yun Zi (born 2009) tore apart during one of his many energy bursts. Shortly after that, we acquired the elm currently in the exhibit. We did our best to secure it so that the tree might stand a chance against a young, rowdy bear. So yesterday when our keepers discovered that little Mr. Wu had torn the plastic covering off the elm, they moved Gao Gao into the exhibit knowing that he probably wouldn’t destroy the tree.

Over the past ten years, I’ve watched cubs go through the many stages of adolescence, and they can be very destructive. The cubs learn how strong they are and like to test boundaries. And never forget how smart bears are and how curious they can be. As keepers, our job is to make sure that these bears go through these stages safely. For our researchers, this is a busy time watching and noting the many changes going on with our bears. This can often be fun for the observers as they watch the bears be a little silly and try out their abilities.

So while our staff does their best to restore the tree’s protective covering, enjoy watching the bears in a new—yet familiar—environment. Also keep an eye out for some smelling behaviors; after every storm I think we get some of the most fascinating behaviors from all of our animals as they investigate all the new smells kicked into the air.

Anastasia Jonilionis is a panda narrator and keeper at the San Diego Zoo. Read her previous blog, Thunder and Lightning.

Monitor’s note: We have recently updated our Blog Comment Policy. We ask that comments stay focused on the topic of the blog or what you observe on Panda Cam rather than animals or events at other institutions. Thank you!

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21 Terrific Tiger Facts

Wild populations of tigers are at an all-time low, but we haven’t lost hope. Understanding tiger behavior and implementing science-based conservation efforts can save these majestic big cats. Get ready for Global Tiger Day on July 29 with these fascinating facts.

There are six subspecies of tiger living today; Amur or Siberian, Bengal or Indian, Indochinese, Malayan, Sumatran, and South China.

There are six subspecies of tiger living today; Amur or Siberian, Bengal or Indian, Indochinese, Malayan, Sumatran, and South China.

3 tiger subspecies (Bali, Javan, and Caspian) are extinct, and the remaining six are all highly endangered due to poaching and habitat encroachment. | 21 Gripping Tiger Facts

3 tiger subspecies (Bali, Javan, and Caspian) are extinct, and the remaining six are all highly endangered due to poaching and habitat encroachment.

The earliest tiger fossils date back about two million years. | 21 Gripping Tiger Facts

The earliest tiger fossils date back about two million years.

In the last 100 years, we have lost 97 percent of wild tigers. | 21 Gripping Tiger Facts

In the last 100 years, we have lost 97 percent of wild tigers.

At the current rate, all wild tigers could be extinct in 5 years. | 21 Gripping Tiger Facts for Global Tiger Day

At the current rate, all wild tigers could be extinct in five years.

Tigers are ambush hunters, with only about 1 in 10 hunts resulting in a meal. | 21 Gripping Tiger Facts

Tigers are ambush hunters, with only about 1 in 10 hunts resulting in a meal.

Tigers have the largest canines of any big cat species, reaching 2.5 to 3 inches long. | 21 Gripping Tiger Facts

Tigers have the largest canines of any big cat species, reaching 2.5 to 3 inches long.

A tiger's tongue is covered with small, hard, hooked bumps called papillae—making it a perfect scraper to rasp off fur, feathers, and meat from bones. | 21 Gripping Tiger Facts

A tiger’s tongue is covered with small, hard, hooked bumps called papillae—making it a perfect scraper to rasp off fur, feathers, and meat from bones.

Tigers can take down prey 5 times their own weight. | 21 Gripping Tiger Facts

They can take down prey five times their own weight.

A tiger can cover a distance of up to 33 feet in one leap. | 21 Tiger Day Facts

A tiger can cover a distance of up to 33 feet in one leap.

Tigers are solitary cats, unless a female is raising cubs. | 21 Gripping Tiger Facts

Tigers are solitary cats, unless a female is raising cubs.

A tiger’s night vision is six times better than that of a human. | 21 Gripping Tiger Facts

A tiger’s night vision is six times better than that of a human.

Female tigers are about 20% smaller and lighter than males. | 21 Gripping Tiger Facts

Female tigers are about 20-percent smaller and lighter than males.

A tiger’s confrontational roar contains energy in the infrasonic range, below human hearing, which helps the sound carry over long distances. | 21 Gripping Tiger Facts

A tiger’s confrontational roar contains energy in the infrasonic range, below human hearing, which helps the sound carry over long distances.

Each tiger has a unique stripe pattern, most include more than 100 stripes. Researchers observing wild tigers can identify individuals by their particular stripes. | 21 Gripping Tiger Facts

Each tiger has a unique stripe pattern, most include more than 100 stripes. Researchers observing wild tigers can identify individuals by their particular stripes.

A tiger's stripes are skin deep. | 21 Gripping Tiger Facts

A tiger’s stripes are skin deep.

ITigers have white spots on the backs of their ears, which could serve as "false eyes," making the tiger look watchful to predators. These spots may also help communicate with other tigers, especially between a mom and her cubs. | 21 Gripping Tiger Facts

Tigers have white spots on the backs of their ears, which could serve as “false eyes,” making the tiger look watchful to predators. These spots may also help communicate with other tigers, especially between a mom and her cubs.

Tigers can sniff out hidden messages left by other tigers through scent marks. | 21 Gripping Tiger Facts

Tigers can sniff out hidden messages left by other tigers through scent marks.

Tigers have partially webbed toes and their claws can reach 4 inches long. | 21 Gripping Tiger Facts

Tigers have partially webbed toes and their claws can reach 4 inches long.

A tiger's front feet have an extra claw called a dewclaw, which is used specifically for climbing and gripping. | 21 Gripping Tiger Facts

A tiger’s front feet have an extra claw called a dewclaw, which is used specifically for climbing and gripping.

While most cats avoid it, tigers seek out water to swim and hunt. | 21 Gripping Tiger Facts

While most cats avoid it, tigers seek out water to swim and hunt.

While most cats avoid it, tigers seek out water to swim and hunt. | 21 Gripping Tiger Facts

Celebrate Global Tiger Day at the San Diego Zoo Safari Park’s Tiger Trail on July 29, 2015. Festivities include keeper demonstrations, tiger enrichment, conservation displays, and much more.

Jenn Beening is the social media planner for San Diego Zoo Global. Read her previous post, How to Build a Pollinator Garden.
2

No Ligers Here

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San Diego Zoo Global is dedicated to helping to preserve—physically and genetically—endangered species like these Malayan tigers.

“What are you drawing?”

“A liger.”

“What’s a liger?”

“It’s pretty much my favorite animal. It’s like a lion and a tiger mixed…bred for its skills in magic.”

Napoleon Dynamite

I began working for the San Diego Zoo Institute for Conservation Research in the Reproductive Physiology department in 2003. After about a year, I noticed the most commonly asked question from kids touring the lab was: “Do you make ligers here?” I think we can thank the hit movie Napoleon Dynamite for that, but as the years have gone by, the question still arises often in many different forms. I think we all are fascinated to hear about animal hybrids—the mixing of two animals of different breeds, species, or genera—but what do hybrids mean to conservation and why do we not use our advanced reproductive technologies to create them in the lab?

There are many types of hybrids that exist such as intrasubpecific hybrids between two animals of different subspecies (like Bengal and Siberian tigers), interspecific hybrids between two animals from different species (for example, lions and tigers, resulting in a “liger” or “tigon”), and intergenic hybrids between animals of different genera (as happens when sheep and goats breed, resulting in a “geep” or “shoat”). While hybridization is often thought of as a man-made phenomenon, natural hybridization does occur. Most of us are familiar with mules, which are the product of a female horse mated with a male donkey. Mules are prized for their great strength and endurance, but all male mules and most female mules are incapable of producing offspring. This is common in hybrids because their genetic material is not perfectly matched. There is also a hybrid animal called the beefalo (prized for its meat) that is the offspring of a North American bison and a cow.

Those last two examples are domestic animal hybrids that possess traits valued by humans, yet there are many issues that occur when non-domestic animals hybridize. Wild animals have evolved over millions of years through natural selection, a process that increases the probability of survival and reproduction. Hybridization, however, can result in the loss of a morphological or behavioral trait that may be necessary for survival.

An example of this is when a mule deer that uses a “stotting” escape strategy breeds with a white-tailed deer, which employs a galloping escape strategy. The hybrid offspring inherits a slow and inefficient gait, making it vulnerable to predation. And in cases where domestic cats that have gone feral breed with wild cats, the offspring are not as genetically strong and this can affect their resistance to disease.
As climate changes occur and humans modify animal habitats, wild hybridization may become common. One such example is the “grolar bear”—the offspring of a grizzly and polar bear—that was seen in Canada. This hybrid could occur more frequently as polar bears, driven from their typical range due to melting sea ice, spend more time in grizzly territory.

If hybridization sometimes seems to create a more “fit” animal or occurs in the wild occasionally, why don’t we use our laboratory skills to create them? We have the ability to inseminate the egg of one animal with sperm from another closely related species and grow an embryo that could be placed into a host female of either species. But we don’t, simply because San Diego Zoo Global’s mission is to save species worldwide by combining our expertise in animal care and conservation science with our dedication to inspiring passion for nature. We are in the business of saving species not creating new ones.

There are exceptions to this rule, such as when a population becomes so small that it can no longer sustain itself. In this case, scientists may agree that hybridization with a closely related subspecies is the only chance for survival. This has been attempted with the Columbia Basin pygmy rabbit and its close cousin, the Idaho pygmy rabbit. The Florida panther population was brought back from the brink of extinction by releasing female Texas cougars into the habitat for hybridization—the result was a three-fold increase in the number of Florida panthers, and the hybrid offspring were genetically healthy, stronger, and longer-lived.

So, I am afraid you will not see any ligers or grolar bears being created in our lab but that is because we are working hard to help tigers, lions, polar bears, and grizzly bears maintain or grow their populations. We think they are pretty amazing just the way they have evolved.

Nicole Ravida is a research laboratory technician at the San Diego Zoo Institute for Conservation Research. Read her previous blog, No Scientist is an Island.