Field Trip at Woodland Park Zoo

I visited Woodland Park Zoo with Gwen and most of my peers on February 25th at around 9:30 am. It was a freezing day; though the sun came out at the end of the day, we tried to keep ourselves warm in some of those shelters. Due to the low temperature, some of the animals were lazy and hidden so it’s hard for me to take clear pictures. The reason why I chose this field trip is that I have never been to this zoo (what a shame!) and I thought it’s a good chance for me to explore it and learn something related to the course.

Luckily we saw nearly all kinds of animals in our 4 hrs trip! And here are the 5 types of animals I want to share: 

Gray Wolf

Figure 1. The two gray wolves hang around in their comfort zone.

The most interesting thing in the gray wolf exhibit was that we can see the elks hanging really close around them, which are one of the main food resources for gray wolves. Wolves have sharp teeth and claws for hunting. Their smelling and hearing senses are also very strong, which help them to find the prey better and faster. In order to survive well, wolves always live in packs and hunt cooperatively. I would expect to see a massive pair of shearing teeth (one in the top jaw, one in the bottom) that together create a strong, effective shear on the side of its mouth. with. An adult wolf can consume 4 to 7 pounds of meat each day. One interesting fact about wolves is that their favorite prey is huge deer species like moose. One pack of wolves are able to kill and eat 1 out of 16 moose they chased. A question that I have is: it says that wolves have been driven into the world’s remaining (and still shrinking) wild areas. So will the number of large deer species eliminate if the amount of gray wolves gets too high?

Figure 2. One of the gray wolves got his/ her lunch. Yay!!

What’s more, its nasal turbinates would be complex because it needs to smell very far away to know if there are foods around. As a carnivore, a sagittal crest would be found on its skull because exceptionally strong jaw muscles are especially important for predation. The wolves were either wandering/running or lying when we were there. Comparing gray wolves with coyotes, the most obvious difference is that they have different colors of fur. Gray wolves’ fur is light gray or even little black, but coyotes have light gray (mixed with slight brown) fur. Gray wolves are also bigger and heavier. Another difference is that coyotes have pointy and tall ears while gray wolves’ are round. They live in the northwest of Washington and the cascade regions. Wolves don’t just howl for fun, it’s a signal they send. They howl to find their crews, to reinforce relationships with their pack, and to warn any strangers that they didn’t friend

Brown Bear

Figure 3. A brown bear was being a contemplator.

The most interesting thing in the brown bear exhibit was seeing it suddenly stood up for a couple seconds and how enormous it is! Brown bears are extremely strong; they can easily kill many large preys with just one blow. Brown bears have very long and strong claws that they mostly used for digging up food rather than defense. Moreover, they have very thick fur and layers of fat to keep themselves warm. Same as gray wolves, brown bears would have a sagittal crest since a strong jaw is very helpful for their predation. Canine teeth are the second characteristics that I could imagine; with those, they can firmly hold their food and tear them apart. Additionally, I would expect to see complex nasal turbinates. Same as gray wolves, they are the predators and would love to smell better. One quote that I noticed on the sign says, “When a pine needle falls in the forest, the eagle sees it, the deer hears it, and the bear smells it.” This implies how tremendous the smelling sense a bear has! I saw one brown bear in the zoo and it was lying next to the water lazily; looks cold and contemplative. I saw another type of bear in the zoo – sloth bear, which has black fur (brown bear, of course, has brown fur) and way smaller than the brown bear. Compare their diet; brown bears seem more like gourmet. They eat whatever seasonal plants, fruits, and animals. As John Muir said, “To him, almost everything is food except granite.”

Figure 4. Two sloth bears were sleeping with their faces covered.

On the contrary, sloth bears eat termites and other insects, grubs, grass, honey, eggs, carrion, fruits, berries, flowers and cultivated crops. I also noticed that the claws of sloth bears are shorter and less powerful since they don’t dig like brown bears do. Brown bears are actually rare in Washington, but there is a small population in the Selkirk Mountains of northeast Washington and North Cascades. The way to distinguish an adult male and female brown bear is very straight-forward. The female ones are much smaller and lighter (~175 to 450 lbs) than the male ones (over 1,000 lbs). A mother brown bear usually gives birth to “twins” at once and they are very tiny when they were born (less than 1lb). I wish I could have seen a baby brown bear!! Since brown bears love salmons so much, is there a bigger threat of the living of salmons because it seems like the amount of salmons in PNW is reducing every year. Regardless of over-hunting of human beings, will this put salmons at the edge of extinction faster?

Great Gray Owls

I would say the great gray owl is the most boring animal I saw in the zoo because it exhibits with turning its back and butt to us. Yet, it makes me wonder what is it thinking and looking at, which makes it the most interesting thing. The great gray owls have dense, fluffy feathers that allow them to fly silently (in order to hunt) and insulate warmth in cold weather. A very special feature of the great gray owls is their facial disks, which help them direct sound to their ears. Same as the great gray owls, the snowy owls have the same characteristics of feathers and facial disks. Nevertheless, the snowy owls prefer to hunt in relatively low light while the great gray owls while the great gray owls like preying during the summer when they are raising chicks.

Figure 5. The great gray owl turned its back to us. Dang it 

Other than that, both kinds of owls hunt during days and nights. I would expect to see very huge orbits of an owl’s skull and their eyes placement will be in the front since it helps them to see better when they soar to hunt. I am not sure if I would see the sagittal crest on a skull of an owl because they are predators but they don’t need strong jaws to prey. So here is also my question: do owls have the sagittal crest? If not, what makes them great hunters except for their facial disks? I saw the great gray owl thinking about what its lunch would be on a branch of a tree or whatever exciting in its life. The great gray owls are mostly distributed in the southeast of the PNW. The body length of an owl is around 2 feet and it’s roughly 2 to 4 pounds.

River Otter

                                         Video 1. Social river otters played with kids.

The river otter was my favorite during the whole field trip since all the other animals are not very active due to the weather, but the river otter was super active. It was so naughty and playful; it also interacted with all the visitors. River otters have water-repelled fur for insulation when they swim. To help themselves to swim further and faster, river otters developed adaptations like webbed toes and a strong, rudder-like tail. They can swim up to 9 miles per hour. They also have big lungs that can hold lots of air. I did see one river otter and it was playing with the kids in the zoo. The first couple things I would expect to see on a skull of an otter are incisors that it uses to groom its fur; canines for stabbing through slippery fish; and cheek teeth (sharp and jagging edged) at the back of its jaw that it can use to grip and crunch through prey. Other than teeth, I might also observe is its sagittal crest since it’s a predator. And the third thing is the front but kind of sideway orbits because they are predators but also prey for some animals when they are on land. Comparing river otters with another kind of otter in tropical South America – giant otters, North American river otters are way smaller (5 feet long) than giant otters (8 feet long). They both have webbed feet, but the difference is that river otters need those to help with their swimming and giant otters need webbed feet to dive down to catch slow-moving fish that live on the riverbed. Rather than having the strong, rudder-like tail that river otters have, giant otters have flat, paddle-like tail to help them swim. Another very distinguishable characteristic that giant otters have is their cream-white throat markings. The pattern of these markings varies between otters so particular individuals can be identified by their spots. The two types of otters also have different diets. River otters like eating amphibians such as crayfish, frogs, snakes, lizards, and insects while fish is part of their diet. However, giant otters feed mostly only fish and crabs. River otters live on coastal shorelines, marshes, and estuaries; therefore, they can be found at the coastline in PNW. In order to find food, they also live from den to den as they travel up and down the shoreline. The dens are normally made in a riverside burrow, under rocks or plants, or in a beaver’s house (lodge). The river otters belong to the family Mustelids and they are not born swimmers, baby river otters need to learn from their parents how to swim and dive into the water to find food. I learned that otters are becoming more nocturnal in areas disturbed by people, will their eye orbits turn bigger or their nasal turbinates become more complex as time passes?

Elk

The most interesting thing about the elk exhibit was their habit of rubbing their antlers on trees. Elks are known for their huge antlers. The antlers are covered with a thin skin called velvet, which carries calcium and minerals needed for building strong bones. They are used to display to other males to assert dominance and also to females who are potential mates. Elks also have rich fur for retention of heat and protection from the weather; they are good swimmers that can swim as far as several km between islands. I would expect to see large, well-developed incisors on a skull of an elk because it needs those for cutting plant material. Additionally, elk would be equipped with complex nasal turbinates as well as sideway orbits since elk are herbivores, they need a very keen sense of smell and a wide field of vision to detect predators.

Figure 6. The elk was very far away but I could still see it rubbing its antlers.

Different from predators like brown bears and gray wolves, sideway orbits improve the herbivores’ sight fields even though that limits their binocular visions. I saw two elks and they were taking turns rubbing their antlers on trees, which I felt super interesting and here is one of my questions – what are the elk rubbing their antlers for? Comparing elk with deer, the first difference is that a deer is way smaller than an elk. Second, their diets seem a little different: Elk are browsers and feed on a variety of grasses found on the edges of woodlands; however, deer are grazers that prefer legumes but also eat shoots, leaves, and grasses. Other than these, they share most of the similarities such as mating in the fall and during that time males lose a significant portion of their body weight as they attempt to mate with as many females as possible. Elks are widely distributed in Coastal Pacific Northwest. Except for the one question I had, there are two more here: (1) Although elk and deer have two different diet styles, do elk compete with deer for food if they are lack of food resources because they are both herbivores? (2) I know that brown bears give birth to “twins”; do elk have one baby per time or “twins”?

Compare & Contrast

Due to my love to otters, I want to compare North American river otters to Asian small-clawed otters, which live in wetlands in India and Southeast Asia. Asian small-clawed otters are the smallest otters in the world. They weigh only about 11 pounds while North American river otters can grow up to 35 pounds. To distinguish Asian small-clawed otters from others, the most straightforward sign that they have is their pale, with variable patches of white on their faces, throats, and chests. They didn’t get their name for no reason: their small-clawed hands have nimble fingers! This is because they catch food with hands and they prefer water’s edge, muddy and sandy banks, and dense vegetation.

Figure 7.The river otter was swimming super fast.

On the contrary, North American river otters’ webbed limbs are for swimming only because they use mouth to catch food. The two otters’ tails are different as well – the tail of Asian small-clawed otters is flattened to help them keep balance on land and use it like a paddle in the water, while North American river otters have a rudder-like tail since they spend most of their time swimming and this can help them to swim faster. Another difference is shown in their diets. North American river otters love amphibians like frogs, snakes, and lizards, but Asian small-clawed otters feed on hard-shelled animals such as mussels and crabs. The only same food they both eat is fish.

Figure 8. The Asian small-clawed otter was hiding under the rock.

Of course, all kinds of otters love FISH!! The living style of Asian small-clawed otters is more similar to giant otters – they are always found in groups. The difference is giant otters live in a group of 5 – 10 to hunt together but Asian small-clawed otters always form a group of 12 to support and take care of each other. Although all otters are social, Asian small-clawed otters are the most social ones. They stay together as a family and the older otters always help to raise the youth, sounds pretty Asian style right? North American river otters not only communicate with each other with whistles, growls, chuckles, and screams; but also scent mark by using paired scent glands near the base of their tails or their urine. Asian small-clawed otters do the exact same thing, except for they are noisier and there are at least 12 known calls they have. I think their ancestral traits might be their flexible bodies that allow them to groom almost every inch of their fur; four relatively short legs that enable them to swim, walk, groom, and manipulate prey; and very small ears with valve-like structure, either rounded or pointed, enable them to close when in the water. And their derived traits would be the differences of their hands, tails, and diets, which depend on the regions and living styles they have.

Reflection

By comparing and contracting all the animals that we saw in the zoo, I realized how various can individual organisms (different patterns of throat markings of giant otters) and groups of organisms of any species. They are generalized into one big category while there are lots of differences they have according to their surroundings, which is related to what we learned about fitness and adaptation. Genotype variation and phenotype variation also play a very important part in the species varieties. My perspective on animal biology is about similarity and differentiation, which is pretty much what I experienced during this field trip. I don’t think the trip changed my perspective, but strengthened my knowledge and understanding of lives. I am very glad that I had an amazing time at the zoo, where I got to explore so many interesting creatures in person. And if I have to pick one, I think one of the most interesting things I learned is that gray wolves can hunt moose even though they are way bigger and have the strong antlers.