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Punk Rock Polar Bears?

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Polar bears are champion swimmers!

One of the most frequently asked questions during the summer months at Polar Bear Plunge is “Why are the bears green?” The answer may surprise you!

The outer guard hairs on a polar bear’s coat are clear and hollow (like a straw), which means they often take on the color of whatever they happened to roll in. Wild bears mostly have only snow and ice to lie on, so they usually maintain the bright white color that you imagine when you picture a polar bear. Here at the Zoo, we like to provide Kalluk, Tatqiq, and Chinook with as many different substrates in their habitat as we can so that they have options when they choose to rest or roll around. This gives them an opportunity to exhibit species-specific behavior. Throughout their habitat they have access to grass, sand, mulch, dirt, pine needles, hay, and a couple of hammocks made out of used fire hose. You may have seen Chinook masquerading as a brown bear after a prolonged roll in the mulch or dirt.

That brings me back to the original question of “Why are the polar bears green?” Remember those hollow hairs? That tiny space in each hair is a great place for algae to live. The bears’ main exhibit pool is fresh water and during the summer, when the weather is warmer than usual, algae begin to grow on the pool floor. When our bears swim and brush up along the bottom or sides of the pool, they pick up some of the algae, which continue to grow inside the individual hairs! It is not a concern for the bears as we have an elaborate filtration system and excellent water quality team. It is unlikely that they even notice it, but it does give them a bit of a punk rock look. In the winter, around Christmas time, they look downright festive!

The discoloration will last until the bears molt in the springtime. For about two weeks in March to April, our bears glisten with a brilliant white color. Once they start rolling around in all that substrate we provide, they begin to take on the color of their environment and the cycle begins again.

Matthew Price is a senior keeper at the San Diego Zoo. Read his previous blog, Springtime for Polar Bears.

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Terns, Plovers, and People: Living in Harmony

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This beach on Naval Base Coronado is one site where field biologists are studying California least tern and snowy plover populations (U.S. Navy photo by S. McLaughlin, SDZG)

As field biologists, we are lucky to have some of the most beautiful offices in the world. Every day, my coworkers and I get to enjoy long walks on the beach, warm sunshine and the occasional passing dolphin pod. Of course with views like the one in the photo, we are working alongside many other people enjoying a day at the Pacific Ocean. It’s wonderful to see people appreciating the beach habitat we all love so much, especially when it’s done in a respectful and responsible way. So, here are a couple of thoughts from a field biologist.

Both the California least tern and western snowy plover are sensitive to human disturbance. While some bird species will remain on their nest until you are very nearly upon it, terns and plovers seem to hop off at the first sign of danger. Plovers can be seen in the vicinity of the nest, performing the broken-wing display to draw perceived predators away from their nest. Terns take a more aggressive approach, screeching at and dive-bombing anyone that approaches their nest; sometimes several members of the colony will join in to drive the threat away. With the numbers of terns and plovers at critically low levels, it’s important that the birds are able to spend their energy caring for their young, instead of chasing off disturbances.

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With chicks this cute and helpless, it’s easy to see why we want to protect California least tern populations. (U.S. Navy photo by S. McLaughlin, SDZG)

The most common instances of disturbance we see out in the field are people walking through the colony and dogs being allowed off leash in areas with nesting birds. In addition to upsetting the adult birds, these types of disturbances can result in trampled eggs and chicks, and stressed-out young. Luckily for all the recreational beach users out there, avoiding creating a disturbance is very easy! The most important step to take is observing and abiding by posted signs. If you are ever approached by a game warden or field biologist, don’t be afraid to ask questions. We love to talk about the terns and plovers, and outreach is an important part of our jobs!

The beaches of southern California and the birds that live there offer amazing opportunities for people to engage with nature. If we enjoy these resources respectfully and responsibly they will hopefully be here for many more years to come.

 

Stephanie McLaughlin is a research associate at the San Diego Zoo Institute for Conservation Research.

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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!