Amongst the Red Alders is a great place to look for birds since the vegetation is relatively low and not very thick, giving birds enough habitat to roam without obscuring your chance to actually see them. In looking for birds, it is very helpful to gain some familiarity with the song or call associated with each species, because often you will hear them before you can see them. (point out any recognizable bird calls). On different occasions, the species we have seen here include Anna’s Hummingbird, the Black-Capped Chickadee, the White-Crowned Sparrow, the American Robin, and the Spotted Towhee.
Hummingbirds are actually more common than you might think, and it’s helpful if you can pick out the call to locate them, since they are so small. Their call is a very distinctive squeaky pitch, and they often perch on the tops of trees to be heard, making them easier to locate than one might think. The Black-Capped Chickadee call is an almost lazy sounding set of two whistles at two different notes. However, what is interesting is that they use their call to indicate the presence of predators to others in their flock or family. To do this, they add more “dee dee’s” to the call, and the more you hear, the greater the threat. White-Crowned Sparrows have a song that starts high and then descends. If we hear it, I will point out how some people hear “I’m a White-Crowned Sparrow” distinguishable in the song. Lastly, both the American Robin and the Spotted Towhee are related in the Thrush family. The American Robin song is quite melodic, while the Spotted Towhee tends to screech almost like a cat, ironically.
In order to see and hear more birds, we have found it helpful to play call-backs. This is when you play a recording of a song or call in order to try to get the bird to come closer. This practice however, should be done with care. Some people argue that this should not be done, because it introduces a stress into the bird’s environment. However, others argue that this is a viable way to allow people to better study and visualize birds, and that they will acclimate to the stress relatively quickly. We had some great success getting together a group of four Spotted Towhees in the woods when we played calls-backs. Let’s try a few now…
In a broadly defined sense, a disturbance is anything that removes living biomass from a system. This can take on a variety of forms such as fires, earthquakes, grazing, wind, disease, pests, and land use conversion (e.g. urbanization). Disturbance often serves to create a heterogeneous landscape that creates a variety of habitats. For example, grazing by animals might prevent any trees from growing in that area, and keeps it a grassland setting, since grass is one of the few groups of species that can survive heavy grazing. In fact, this is exactly what is happening here; escaped domestic rabbits have made it into Discovery Park and have been breeding like crazy. This is a location where we have often seen rabbits grazing. If you look at the vegetation, much of it is grass, which is short and sparse, even though other areas have quite tall grass. In fact, this entire area is surrounded by tall Red Alder trees, but there isn’t a single sapling in this gap. It seems that the rabbits prefer this location to graze; possibly because the surrounding trees provide cover and a quick getaway should a predator come along. This is a perfect example of heterogeneity. In an area that would otherwise be all Red Alder forest, there is this little patch of grassland, maintained by the rabbit shepherds of the grasslands. Now for bunny pictures!
We tried to get close, but it hopped away. Its little hopping is probably what is keeping it alive and from being eaten!
Site 7: Land Use
Judging from the buildings on the premises, what do you think was once here? What do you think the land was used for? As it turns out, this was established as a military base in 1896 to be artillery battery meant to defend Seattle and the south Puget Sound in case of a naval attack. Starting in 1902, it was repurposed for infantry use, with the construction of several new buildings to accommodate the soldiers. In 1938, the army offered to sell the land to the City of Seattle for a dollar an acre, but the city turned down the offer citing maintenance concerns. As World War II began, over 20,000 soldiers were stationed here, with 6,000 German and Italian prisoners there at any given time, typically en route to Hawaii for a more permanent imprisonment. Can you imagine that many people here? That is so many people! After the war, in the late 1950’s, the base was repurposed yet again into an anti-aircraft base, complete with state-of-the-art radar and anti-aircraft missiles. This was never necessary though, as no attack ever came. Finally, the army donated most of the land to the City of Seattle as Discovery Park in 1973. It was not until 2011 though, that the most of the remaining land was donated and the fort was closed. As you can see, some relics still remain. There a few buildings that weren’t demolished so they could house government employees. In fact, there is still an old radar station that the FAA still uses and is active. You can probably pick it out; it looks like a giant soccer ball!
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| The Fort in 1936, mostly for infantry use |
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| The Fort in the 1950's, complete with radar and anti-air missiles |
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| Discovery Park in 2009 |
Photo Credit: First two photos are from http://pauldorpat.com/seattle-now-and-then/seattle-now-then-fort-lawton-barracks/
Last photo is from http://commons.wikimedia.org/wiki/File:Aerial_view_of_Discovery_Park_and_Fort_Lawton_in_Seattle.jpg
Site 8: Invertebrates
This rosemary bush is a great place to see pollination in action and to observe some of the most visible invertebrates, namely bees. We have been able to identify two species of bees that pollinate this bush, as well as many other plant species. This is the Honey Bee, the prime bees responsible for honey production. This is the Yellow-Faced Bumblebee.
The bumblebee is a major pollinator of many plants, but in particular are greatly important to plants in the Solanaceae family—this is the nightshade family which includes tomatoes, potatoes, bell peppers, and eggplant. The bumblebees are needed to pollinate these plants because the plants' reproductive structures require something called buzz pollination. The stamens, which carry the pollen in them, form a long cone shape that tucks both the pollen and the pistil, the female organ, inside. When a bumblebee comes along, in order to access the pollen which the bee uses as food, the stamen structure must be opened. The bee must vibrate its massive flight muscles with enough force to open the cone structure. In the process of the bee getting the pollen, the female pistil gets pollinated, so this system works to both the bee’s and the plant’s advantage. This system is known as mutualism. We will talk more about interactions at another site though. This is one of the reasons why people are concerned about the decline of native bee populations worldwide, since bumblebees are currently the only known organisms able to effectively pollinate Solanaceae plants.
In this area, other invertebrates we have seen include Lady Beetles, House Flies, and Carpenter Ants. These are all insects, which are the only group of invertebrates to have developed flight. Beetles are in an insect order called Coleoptera, which means “sheathed wing” and indicates the second pair of wings which are hardened and lie on top of the first pair of wings. Flies are in the insect order Diptera which means “two wings,” indicating that they use only one pair of wings. Lastly, ants are actually in the same order as bees and wasps, Hymenoptera, which means “membrane wing” and are distinguished by a small clasp in the waist.
Here we see a common sight, a swarm of Barn Swallows swooping and diving (show picture). This is a specialized behavior that helps them to feed almost exclusively on flying insects. Their boomerang shape allows them to glide effortlessly. They’re also actually a species that has co-evolved and been very successful living with humans, similar to the American Crow, who is another common species here. They like open spaces and have changed from building nests in caves to building them on the sides of buildings, usually barns, which gives this swallow its name. They tend to spread wherever humans colonize, suggesting a positive relationship between us and the Barn Swallow. These nests are usually cup-like and made out of mud and sticks so that it sticks to the sides of buildings. Another interesting behavior is that, as you can see, these birds are pretty social and swarm together whereas a lot of the other birds you see, other than crows, are frequently seen foraging in solitude. Barn Swallow parents sometimes get help from other birds to feed their young. These helpers at the nest are usually older siblings from previous clutches, but unrelated juveniles may help as well. At Nisqually National Wildlife Refuge, we saw the Barn Swallows working together to build their nests, as well. I saw around three birds, on average, working on one nest at a time.
As I mentioned, the American Crow is quite a social bird as well. They form groups and roost together to forage and defend territory. The urban ones display a marked intelligence. Our field guide remarks that the crow has flourished because "much of its survival strength lies in its ability to adapt to a variety of habitats, food resources, and environmental conditions." As such, this species persists here in the Pacific Northwest almost year-round. We've observed crows in Discovery Park, and they appear to be fairly nonchalant and unconcerned of predators. I speculate that, based on these two kinds of birds, perhaps birds that are more social or cooperative survive better under the pressures of human influence. Or, looking at it another way, humans may have actually created a new niche, the urban environment, where some species are actually more successful than they may otherwise be.
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| Barn Swallow |
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| American Crow |
Site 10: Species Interactions
Often times, species are interacting with each other right in front of our eyes, yet we don’t realize it. Before we step into this forested area, look around at the vegetation. Does it seem like the species here are helping each other? Probably not that much; these are the first species to come in after a disturbance, and their goal is just to colonize the area as soon as they can. Unfortunately for them, they are not good at preventing new species at coming in. Eventually, species that are better at competing come in, such as this Douglas Fir. This is when facilitation between species becomes more obvious. Douglas Fir generally loves the sun, and grows big when it gets plenty of it. This ends up creating quite a bit of shade, which then allows other plants, those that love the shade, to grow in that space. The perfect example of a shade-loving plant that grows well with the aid of the Doulas Fir is this Western Hemlock here. Western Hemlock is one of the few trees that are shade tolerant, and is easy to identify because if you look closely at the needles, they are all of varying length, which is how the Latin name Tsuga heterophylla came about (heterophylla meaning “different leaf”, or in this case, leaves of different lengths). Although it doesn’t seem like it, this kind of interaction is happening all the time; early colonizing species change the conditions of the environment to allow other species to come along and take their place. This sequential cycle of plants is called succession, and is often reset by large disturbances.
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| Douglas-Fir, soaking up the sun |
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| Western Hemlock, hiding in the shade, being a recluse. |
Site 11: Forest Vegetation
Here underneath these towering trees are vegetation that need to be shade tolerate to survive. Can you identify a few? Looking at the lower vegetation, we can see a few of our common understory plants such as Fringecup, Western Trumpet Honeysuckle, Fireweed, Large-leaved Avens, Snowberry, Thimbleberry, Sword ferns, and Lady ferns. You can identify fringecup from its generally white, cup shaped flowers that are attached directly to a single stalk, while the majority of its leaves are attached to the base of the stalk. Most people have some idea what honeysuckle looks like from its opposite leaves and long, tubular orange flowers. Also worth noting is the petal arrangement; 4 upper petals and 1 lower petal is a defining characteristic for this genus (Lonicera). Fireweed truly earns its name, for when it blooms it is a brilliant stalk of pink, filled with 4-petaled flowers. Snowberry isn’t super obvious until it fruits with its pale white berries. Otherwise, you can identify it from its shrubby growth form, small white-pink tubular flowers, and opposite leaves. Don’t try to eat these white berries though; they’ve earned the name “Corpseberry”. Thimbleberry is a small shrub whose leaves look similar to those of a maple, except they are serrated. The flowers are white and 5 parted (5 petals and sepals), with many stamens. If you’re lucky, you can find them when they have edible red berries on them! In this area we also find two of our four native ferns; the sword and lady ferns. You can tell them apart because the sword fern is has fronds that are singlely compound, with the leaflets being sharply pointed with a small lobe pointing forward at the bottom. On the other hand, the lady fern has fronds that are doubly compound, and has a “lady-like” curvature overall.
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| General growth form of Fringecup |
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| Close-up of the flowers on Fringecup |
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| Large-leaved Avens |
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| Orange Trumpet Honeysuckle: look at the 4 upper petals and 1 lower! |
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| Sword Fern |
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Lady Fern: leaflets of leaflets!
Photo Credit: naturalhistory.crowspath.org |
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| Thimbleberry, with maple-like leaves |
Site 12: Soil
Note these unstable bluff signs. Of course most bluffs are unstable; however, we have a higher risk of landslides on bluffs here in the Pacific Northwest, especially when it rains. Does anyone know why? (field answers) It is because of our glacial soil layers, and the clay layer that makes soil slick and slippery. To understand how this came to be, we must understand the geologic history of this area.
About 14,000 years ago, this area was covered by glaciers reaching southwards from Canada. In fact, glaciers created a lobe shape that reached down into the Puget Sound region and helped further carve out the landscape before retreating. Much of the Puget Sound Troth was the result of a massive lake, called Glacial Lake Russell, that was formed when the glacier prevented drainage of water back into the ocean. When the glacier moved over it, it brought in soil and rocks that had been ground up by the movement of the heavy ice. As it progressed, the glacial soil began to fall out of the watery solution first farther away from the oncoming glacier, where the water is more calm. The soils falls out of solution in order of the smallest to largest particles. Accordingly, clay, the smallest particle, falls to the bottom of the lake bed first farthest from the glacier. It is then covered by the next largest particle, sand. As the glacier moves forward, it brings progressively larger pieces of soil with it that continue to stack. The next is silt and then finally, large pieces that are appropriately named glacial till. Thus the soil layers look like this (show picture). Pre-Lawton Sediments (soil here before the glaciers), Lawton Clay, Esperance Sand, Silt, and Glacial Till. When these soil layers sit on top of Pre-Lawton Sediments, the clay layer creates a landslide hazard. Water can permeate down through larger pieces of soil, like till, silt, and sand. However, clay is so small that water can’t really permeate through it, and so the water will actually runoff that soil layer underground. Just imagine your soil sitting on top of a bar of soap. The variety of soils in Washington beg for better knowledge of which soils are good for building on and for specific land uses, and for landowners to heed their predetermined nature.
Photo credit for soil diagram: http://www.tubbs.com/ic52/ic52.htm
Site 13: Geology
Here we are at the last stop to view the beautiful Olympic Mountain Range. Does anyone know what formed these peaks? (field answers) So it all has to do with plate tectonics. In fact, the interactions among the plates that compose the Earth’s crust are the reason for both the Olympic and the Cascade mountain ranges. Washington sits on the edge of a plate called the North American plate. Another plate called the Juan de Fuca plate that lies under the Pacific Ocean to the west of us is being pushed towards us, and in the process is sliding under the North American plate. This is called a subduction zone. This sliding also explains the historic earthquakes in our area.
The Olympic mountain range was formed as the basalt rock of the Juan de Fuca plate was scraped off the top of the plate as it was subducted under the North American Plate. In fact, you can find old ocean sediments filled with shells in the Olympics. The Cascade range is another testament to the consequences of a subduction zone. As the Juan de Fuca plate sinks under the North American plate, it begins melting back into magma. Some of this magma rises up through cracks in the North American plate and, over time, have formed this range which includes three volcanoes. Can you guess how many of these are active or inactive? (field answers) In fact, all three of them are active! These include Mount Baker at the northern tip of the Cascades, Glacier Peak, and Mount Rainier.
The mountains provide not only spectacular scenery, but can add so much to the amazing diversity of habitat and species we are privileged to see here in the Pacific Northwest!
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| Olympic Mountain Range |
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Washington's Subduction Zone
Photo: http://www.dailykos.com/story/2013/02/28/1188893/-Tsunami-Geology-and-the-Quileute-Nation# |
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