Woodland Park Zoo Field Trip by Meredith Swann

I chose to go on the zoo field trip on February 25th  partially due to its weekend timing, but also because I have many fond memories of going to the Phoenix Zoo in Arizona as a child. We arrived at the Woodland Park Zoo at about 10:00 AM, which both meant that the zoo was fairly empty and that we were there as many of the animals were fed.

We started with the gray wolves. Three or four of them were waiting on the side of the exhibit fairly close to the path, probably because it was so close to their feeding time (a zookeeper came out with food for them while we were watching). Their behavior was similar to domestic dogs, although more subdued; I caught several good pictures of one rolling and rubbing itself all over a stump in a very dog-like way. However, they were much larger, with bigger paws and ears and longer noses.

As predators adapted to hunt by scent, I would expect their skulls to have large and densely packed nasal turbinates, forward facing eyes, and a larger sagittal crest to allow them the jaw strength necessary to crush bone. Wolves do eat 4-7 pounds of meat a day, though some of it is in the form of smaller rodents where that jaw strength would not be necessary.

They howl to find each other, bond with their pack, and warn off strangers; this makes me wonder if it would be possible for a human to tell different wolf packs apart by the sound of their howling. At this point, there are very few wild wolves left living in Washington; they live only in the northeast part of the state. Most of their range is further north, in Canada.

The next exhibit we visited was the great gray owl. It was up in a tree, watching us as we approached, and very fluffed up; likely to keep warm in the colder weather. Unfortunately, between the foliage of the tree it was sitting in, the camouflage provided by its mottled gray feathers, and the mesh surrounding the exhibit it was difficult to get a good picture of it. However, it was about two feet tall; apparently their wingspan can be up to five feet wide. The sign on the exhibit listed them as one of the types of owls that flies silently; I wonder if this was an adaptation to how and when they hunt?

Unlike the snowy owls that we visited later, great gray owls stay mostly in trees in forested areas, live further south-year round, and hunt at night. This means that they don't need white feathers for camouflage against snow, but do need other ways to hunt prey than sight alone. Great gray owls hunt both by sight and by sound when necessary, so their skulls likely have large, forward facing orbitals and large auditory bullae, and the shape of their face funnels sound towards their ears. Their range, like the wolves, is mostly in the eastern side of the state and further north.

The snowy owl exhibit was not far from the great gray owl exhibit, making it easy to compare the two. There were two visible in there; one in back, and one on a perch closer to the front making no attempt to stay out of view. Snowy owls live much further north than great gray owls most of the time, though they do sometimes come down to the northwest areas of Washington in the winter when food gets too scarce in their usual habitats. Because they live in snowier areas on the ground, their feathers are adapted to provide camouflage against snowy patches and they have extra fluff on their talons to act as snowshoes. They also hunt during the day, rather than at night, and rely more on their eyesight and less on hearing and silent flight as a result. I would expect their skulls to have large forward-facing eye orbits and smaller bullae.

Both of the owls in the exhibit were almost entirely white, so they were likely adult males. Females and younger owls have black spotting on their feathers, likely to provide better camouflage against the ground when it is less snowy, since their nests are scraped-bare locations on the ground instead of in trees. I do wonder if this means the males don't provide as much help caring for the young.

We got lucky with the brown bear exhibit. While both visible animals were asleep (in torpor) due to the cold, one of them had chosen a spot directly next to a viewing window for a bed, so we could get a good look at it.

There was also a short movie available in a nearby small auditorium with information about remaining bear habitat and conservation attempts. Very few brown bears remain in Washington, mostly in the Cascades; most of them now live further north. We also learned there that although bears are omnivores, most of their diet actually comes from plants (which makes me wonder how they know which ones are safe to eat...). Despite this, I would still expect their skulls to show evidence of adaptations to meat eating and some predation: forward facing eyes, very large nasal turbinates, and a larger sagittal crest to allow them more jaw strength.

Brown bears are generally larger than black bears, the more common species in the US, and also have a more dished face and a hump between their shoulders. (Both have similar diets, though, although the black bear is less of an active predator.) Male brown bears can be over twice the size of females at over 1000 pounds. This is especially impressive considering that newborn cubs (typically born in pairs) are less than a pound.

The last of the animals we visited together on the northern trail was a river otter. There were two young boys running back and forth in front of the exhibit and she was following them underwater and throwing in acrobatics as she went; while this did make it difficult to catch a good picture of her, it was a lot of fun to watch. A nearby volunteer let me know she was pregnant.

While river otters have many adaptations for life in the water, such as webbed toes and water repellent fur, the young still need to be taught to swim and not to fear the water. (Do they also need to be taught how to waterproof themselves?) They are mustelids, like ferrets and weasels, and at this point their range is throughout Washington, Oregon, and even along the coast of California. Despite their name, they den near lakes or ponds as well as rivers among the roots of trees and in burrows built by other animals (like muskrats, woodchucks, and beavers.) Because they are predators, I would expect them to have forward-facing small orbitals (since they do not hunt by sight) with smaller nasal turbinates (since they also cannot hunt by scent underwater.) Sea otters live close to where river otters live (along the west coast), but they are much larger and spend almost their entire lives in the water. River otters spend more time on land. Both species are carnivorous.

After finishing exploring the northern trail, I moved on to explore the rest of the zoo by myself. I particularly wanted to go see the maned wolves in temperate forest area. Although maned wolves are a part of the Canidae family and are called "wolves," they actually aren't closely related to any other living canid. Their patterning is more similar to foxes than anything else, and they have very long legs; likely an adaptation to the taller grasses of their habitat, the grasslands. Unlike wolves or other larger canids they hunt alone, and are restricted to smaller prey as a result. They don't have much in common with the gray wolves aside from aspects of their overall shape.

I think the most interesting part of this field trip was seeing the dramatic extremes of speciation in action, particularly among the aviaries in the savanna and tropical rainforest areas. So many different bird species in a smaller space provided an immediate contrast of how different two species adapted to similar climates can be. My primary interests still lie more with Arthropoda than Chordata, but this did remind me that insects aren't the only ones with huge biodiversity.

On a more personal note, I think my favorite part was seeing Valkyrie the river otter chasing the boys. My roommate owns ferrets, which are also mustelids, and seeing the similarities in attitude was a lot of fun.