Laci M. Gerhart Barley

Field Blog

Wild Davis Final Presentations!

Today was our last day in the Wild Davis class (sad face!) and today the students presented their final projects! We structured it as a little mini-conference, complete with snacks and sparkling juice (in actual wine glasses) for a classy little event. A short description (and photos!) of each students’ project is outlined below:

Arboretum Waterway: Turbidity and Secchi Depth (Anne Boyd)

Anne’s project related to water quality throughout the Arboretum waterway, measured using secchi depth and turbidity. A secchi disk estimates water quality through clarity – the deeper the disk goes in the water before you lose sight of it, the clearer the water is. Turbidity assesses the ‘cloudiness’ of the water by measuring particles suspended in the water column (like small algae). Professor Steven Sadro in Environmental Science and Policy loaned Anne the equipment and some bench space in his lab for the data collection! Anne hypothesized that water quality would be highest near the weir (since that was one of the reasons for the construction of the weirs) and lower as you move down the waterway away from the weir to more stagnant areas of the waterway. She found instead that the clearest location in the waterway was near the southwestern end, her second furthest site from the weir. She developed some new hypotheses to explain her unexpected data, including the impacts of runoff and point source inputs, shading by trees, and the ‘inputs’ of ducks, fish, and turtles.

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Anne also contributed my hands-down favorite photo from the class. I met up with each of the students during their individual projects to observe their data collection. After taking turbidity samples, Anne totally unprompted did the one thing people always want to photograph scientists doing – holding up a vial of liquid and looking at it very intently.

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The quintessential field science photo

The Wildlife of Davis: A Coloring Book (Ella Brydon)

Ella’s project was quite different from the other students’. Her ‘question’ related to how to get the general public (particularly other UC Davis students) interested in the wildlife of the Arboretum and the ecological interactions we had observed in class. Towards this goal, she developed a coloring book of Arboretum wildlife based on her own original drawings of organisms found there. Each page of the coloring book is accompanied by the scientific name, as well as interesting facts and identifying information for that organism, and color sketches of many of the organisms are included in the introduction to guide the colorer. We plan to print a couple bound copies of the coloring book and we may approach the Arboretum and the campus bookstore about a larger-scale printing effort to make the coloring book available to students.

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Squirrels, Squirrels, Squirrels! (and ducks)

Three of our students did projects on the squirrel population on campus. As even the most casual observer has noticed, there are MANY squirrels on campus. What they might not have noticed is that there are two species of squirrel – the fox squirrel (orangeish and commonly found around the MU), and the western gray squirrel (gray, and more common in the Arboretum area). The fox squirrel is introduced, while the gray squirrel is native.

Harrison Espino observed squirrel behavior at different locations, focusing on whether interactions with humans were active (approaching or fleeing) or passive (unresponsive) and how far individual squirrels traveled during his observation window (up to 45 feet in 20 minutes!).

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Nia Falkner compared tameness of squirrels and ducks on campus, noting how close individuals would let her get and their reactions (vocalizations, tail flicks) to her approach. Nia’s presentation included a particularly tame duck quacking along to Nia’s rendition of “Just the Two of Us”!

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Lisbeth Solis tracked foraging behavior in squirrels, particularly whether they were searching for food or begging from humans. She found that squirrels in the MU spend a much larger amount of time begging for food, while squirrels in other locations almost exclusively search on their own.

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Insect Preference for Sugar and Salt (Xinyu Gao)

Xinyu was interested in attracting flying insects to liquid solutions, based on her enjoyment of butterflies from her hometown. She put out tap water, 1% salt solution, and diluted honey and tracked insect visitation from late morning to after sunset. She found an interesting variety of organisms (more than just the insects she expected) including carpenter bees, flies, spiders, moths, and even a cat…. All of the baits experienced much higher visitation after dusk and the sugar bait had the highest visitation (salt was the lowest).

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A Study of Camponotus essigi (Isabelle Gilchrist)

Isabelle was inspired by our afternoon with Phil Ward and decided to track ant behavior she had noticed around Robbins Hall Annex. She observed ants moving up and down a tree trunk and into and out of Room 12 of the Annex. Attempting to gain access to Room 12 to determine where the ants were going led her on a wild goose chase across multiple departments, and even emails with higher admin! No one was able to answer her questions, or even unlock the door. Consequently, Isabelle reported that the room ‘belongs to the ants now.’ Keeping to the outdoor behavior, Isabelle attempted to ascertain if the ants were going into our out of the door and up or down the tree. She counted numbers of ants moving in each direction and collected some for weighing. She also photographed ants foraging and documented the relative abundance of major and minor workers. Her data indicate that ants coming down from the tree were heavier (presumably carrying food in their stomachs back to the colony) and that about 25% of the ants were worker ants. She also hypothesized that all ants around Robbins Hall Annex are part of one colony, since transporting ants from her area to a separate colony on campus resulted in attacks between the ants (which were not observed between ants traveling on/around the tree and the Annex).

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Which Trees are Best for Nesting? (Laura Poikonen)

Laura observed bird and squirrel nesting site choices in the Arboretum. She noted that squirrels and birds both prefer angiosperm trees, particularly ones with fuller foliage cover. She also noted that birds and squirrels do not use the same individual trees, perhaps because of nestling predation by squirrels. Laura also got some fabulous photos of bluebird nest holes in trees, which she took with her cell phone through the lens of her binoculars!

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Balance Coming From Under Us: Decomposers of UC Davis (Abigail Rodriguez)

Abigail’s project focused on the underground communities of decomposers on the Davis campus. She compared litter composition and decomposer type and abundance at different soil locations around campus, finding that the more managed areas with landscaped lawns had no macroscopic decomposers at all. At more ‘natural’ locations throughout the Arboretum, a wide variety of organisms were found, including ants, earthworms, spiders, millipedes, and beetles.

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Finding Otter (Tristan Tran)

From the first day of class, Tristan was intrigued by the rumors of otters inhabiting the Arboretum waterway. He hoped to find one himself, so to guide his search, he developed an online survey about otter presence and behavior. He also spent time in the Arboretum looking for the otters himself and distributing the survey in person to others present in the Arboretum. While he did not find any otters during these observations, the findings of the survey were very interesting. Tristan compared survey responses of otter behavior and diet to published research. There was no consensus among the respondents on when otters are most active (they are mostly crepuscular) and little on their preferred habitat, identifying pretty much the entire waterway as ‘most likely habitat’. Most respondents believed otters used to be present in the waterway, but have left it recently due to draining of the waterway for construction and repair, or because of changes in water quality. First hand observations of otters were usually at least two years in the past (and most were four or more), which supported the assumption that the otters are not currently present. Many respondents (and Tristan himself) hope/believe that the otters may recolonize the waterway now in the coming years. When asked if he plans to continue his otter search throughout his tenure at UC Davis, Tristan responded that he spends a lot of time in the Arboretum for a variety of reasons, and will keep an eye out for the otters whenever he is there.

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I had an absolutely fantastic time in the Wild Davis class this quarter. Sharon and I had a great bunch of students who were all motivated and excited to get outside and do class a little differently each week. They had great ideas for their projects, really followed through on the data collection and analysis, and produced awesome papers and projects. Numerous students even asked us if it was ‘ok’ to go over on the length of the paper! I hope the students enjoyed the class as much as I did, and I really look forward to offering this class again in the future. Until next time…. keep it wild, Davis!

Wild Davis: Revisiting Campus Research Programs

Last Thursday marked the final group project week in the Wild Davis class! Following this week, students will be working on their individual projects, culminating in a paper and presentation over a campus ecological interaction they find interesting. Also, I missed posting about our wasp gall day a few weeks ago, so I’m including a latergram of that exercise here, too. Both of these exercises related to published research that has been done on the UC Davis campus, which provided the students with a background of data on the system we were observing.

Impacts of Wasp Gall on Herbivory of Oak Trees

The valley oak trees along the Arboretum sport numerous galls (commonly called ‘oak apples’) created by Andricus quercuscalifornicus, a gall-forming wasp, which lays its eggs in twigs of the oak trees. As the eggs develop into larvae, they elicit the development of galls which house and feed the larvae until they are mature and tunnel out of the gall. While the larvae are developing, the galls are reddish-green and resemble small apples (hence their nickname); however, once the mature wasps leave the gall, it dries out (‘senesces’ in scientific terms) and remains on the tree for several years before eventually falling to the ground and decomposing. Consequently, a given tree may carry hundreds of galls at various stages of development and senescence.

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In March of 2013, the EVE 180 class (Experimental Ecology and Evolution in the Field) performed an experiment on valley oak trees in the Putah Creek Riparian Reserve in which they documented arthropod communities prior to and following experimental removal of senesced galls from trees. The team removed over 5,000 galls from 52 different trees and found that gall removal resulted in a 59% increase in density of herbivorous arthropods. This difference was driven by the fact that senesced wasp galls are frequently occupied by Salticid spiders (my favorite! so cute!), which in turn reduce the arthropod community (and alter its composition) through their own predation. The study was later published in the journal Ecology, and is a great example of research opportunities for undergraduates at UC Davis.

Our class studied a different population of valley oaks – those occupying the Valley Oak Grove in the Arboretum. Instead of removing the galls and tracking changes in arthropod density through time, we observed gall density and arthropod density per tree. Students worked in pairs to count and identify arthropod communities on the trees, and to estimate the quantity of herbivore damage to leaves. We were also interested in whether trees near the waterway in the Arboretum contained more galls than those further away (since anecdotally, this appeared to be the case). While we didn’t find any strong correlations between oak galls and arthropod densities, leaf damage, or proximity to the waterway, we did find an impressive diversity of herbivorous and parasitic activity on the trees, and even some evidence of spider presence on senesced galls. One of the things I enjoyed about this session was seeing the quantity of parasitism and herbivore damage that an individual tree can sustain without it being obvious to a casual observer. My personal favorite was a leaf found by Isabelle Gilchrist, which had sustained leaf gall damage that altered the growth of the primary vein, compromising the entire size and shape of the leaf.

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Tracking Native and Introduced Turtle Populations in the Arboretum Waterway

Our last week focused on finding, identifying, and documenting the behavior of turtles in the Arboretum waterway. Though a number of species have been found in the waterway over the years, only two are common: the native western pond turtle, Emys marmorata, and the red-eared slider Trachemys scripta elegans, introduced to the waterway via release of unwanted pet turtles. I love turtles, and I spent probably more time than was strictly necessary doing recon (wandering the Arboretum with my long-lens SLR) for this exercise, which means I have a *lot* of adorable turtle photos.

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Our goals for the class exercise were to track how many turtles we saw of each species (and what this might mean for their relative population sizes) and whether or not there were differences in the types of basking perches they chose (which might indicate competition between the two species). Turtles present a few particular problems for this kind of project. First, given the clarity of the water in the Arboretum, we can only really observe turtles that are basking, or swimming near the surface. Second, the two species can be difficult to distinguish, especially from afar. Third, basking turtles tend not to…. do much… which can make 3-hour class observations somewhat boring.

I countered these problems by 1) extensive recon (cute turtle photos!!) to identify the areas of the waterway where we are most likely to find turtles basking and swimming, 2) a crash course in turtle ID for the Wild Davis students, and 3) a short-term ethogram (behavioral table) based primarily around choice of basking habitat and “turtle plops,” which represented the ‘disturbability’ of the turtles (when they abandon their basking habitat due to human or other turtle interference).

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Turtle plop!

This exercise would have been impossible without the generous equipment loans of Santiago Ramirez, who let me borrow binoculars without a neck strap (the trust level!), Marcel Rejmanek, who might not even know I have his two pairs of binoculars, and Gail Patricelli, who handed me her THREE THOUSAND DOLLAR sighting scope and tripod with a casual “Don’t break it!” and a chuckle. I continue to be impressed by and proud of the generosity and collaborative nature of my colleagues. Gail’s sighting scope was perfect for the lake section of the waterway, which is the widest, and also where turtles like to bask on the cement embankment, out of view of the path on their own side, and the furthest possible distance from viewing on the opposite path. The photos below show the same Emys through my zoom lens SLR (which at any other part of the waterway is more than sufficient) and through Gail’s sighting scope. I also want to say a special thanks to Robyn Screen and Bob Thomson (both now at University of Hawai’i, Mānoa) who have studied these turtles (see links to studies below) and who could provide input on basking locations, turtle ID, and general fun facts about the turtles and their history.

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We found fewer turtles during class than on any of my recon visits, and particularly fewer native Emys. Still, we could do some good observations. We noted few differences in behavior or basking preference between the two species, though we observed more Trachemys in the water, and mostly only saw the Emys basking. We also noted that the juvenile turtles we saw (including the teensiest turtle I have ever found!) were all Trachemys – which might suggest this species recruits offspring better than Emys. Fortunately, on my recon trips, I saw numerous juvenile Emys, so the native turtles are also recruiting, although perhaps not as much as the Trachemys.

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After our observations, the students had a number of questions about the interactions between invasive and native turtles. Even if they have similar basking habitats, could the Trachemys outcompete Emys for food? With seeing so few juvenile Emys and so many  juvenile Trachemys, should we be worried about the native turtles’ population size? What could we do, in management terms, to remove the Trachemys from the waterway? How can we prevent more non-native turtle species from being introduced to the waterway?

Fortunately, some of the research done on the turtles has looked at a few of these questions. A 2003 study by Spinks et al quantified population sizes of the native Emys and nine other introduced species, finding that the Emys population had declined by 40% throughout the study period of six years. “Headstarting” the turtles (rearing juveniles in captivity and then releasing them to the waterway) did improve population sizes, but does not address the root causes of decline. A study by Lambert et al in 2013 did find differences in basking habitat, which recommended management practices the Arboretum could undertake to provide more spaces for Emys (namely areas with low human presence, steep slopes, shallow water, and a concrete basking substrate). Another study currently under review by Lambert et al tracked the effect of Trachemys removal from the waterway on Emys basking preference. The team removed nearly 200 Trachemys turtles and then observed Emys behavior in response to this reduction in competition. Interestingly, the Emys primarily used the same basking locations they had used previously (abandoning some basking sites, but not expanding into others). This study also documented a pronounced east-west gradient in basking preference, with Trachemys primarily occupying the eastern end of the waterway and Emys more prevalent in the western end. It is worth noting here that our turtle observations were primarily in the western end of the waterway, where this study would have predicted our observations to include more Emys. These studies might lead us to some concern about the future of the native Emys turtles, but another study assessing population structure throughout the Sacramento Basin provides some hope. In 2010, Thomson et al reported relative distributions of Trachemys and Emys, finding that while the introduced Trachemys are present throughout the basin, they are concentrated in more urban areas with high human traffic (like the UC Davis Arboretum waterway) and are far less common throughout portions of the Emys range with less human impact, where the native turtles can still be found in abundance. Still, Emys marmorata is still listed as a Species of Special Concern in California, making continued observations of these populations important.

Wild Davis III: Evening Observations

*This post is a part of the Wild Davis course at UC Davis in which students must complete three timed observations of an urban habitat within the UC Davis campus or Davis city limits. As an instructor for this course, I joined the students in this exercise in order to provide a public example of the types of work the students do in this class. For more information on the course, you can read about my morning and mid-day observations, follow #wilddavis on Instagram and Twitter, and check out my posts on our in-class activities!*

The students’ evening observations are to occur near dusk, sometime between 6 and 8 pm, in the same location as their morning and mid-day observations. One of the goals of this exercise is to illustrate how variable a single location can be in activity level, diversity of organisms, etc throughout the diurnal period. They have now followed their chosen location from dawn, through noon, and into evening (we don’t ask them to do a mid-night observation, although that would also be interesting!). I completed my evening observation at the Wildhorse Agricultural Buffer earlier this week and this afternoon in class the students will discuss their experiences at their own locations.

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The stream

I want to be present for sunset, which is at the very end of our observation window, so I bike out to the spot about 7:15 pm. It is still fairly warm when I leave the house, and I have just been on the treadmill for an hour, so the cool breeze feels refreshing and I leave in a tank top and shorts. I soon regret this decision. I am still getting used to how much the temperatures cool at night here. In both Kansas and Hawai’i (where I have lived previously), the temperature didn’t drop so drastically when the sun set and so I’m rarely prepared for that, here.

As I bike out to my observation bench, I take special note of the stream. With the exception of my mid-day observation (when it was bone dry), I have always seen a decent amount of water in this stream, and once enjoyed a chorus of evening frog calls from the overlooking bridge. Today there is some standing water, not enough for an actual flowing stream, and no frogs.

All along the path as I bike to the bench I hear crickets chirping along the edge of the gravel. I used to be deathly afraid of crickets, especially the large, shiny black ones that you’d find in back corners of the basement. I have never cared for crickets, but I distinctly remember when it became a legit phobia. One summer, when I was 9 or 10, my family helped my grandmother clean out her rural Iowa farmhouse and my job was to clear the garage of all the crickets, dead from the powdered insecticide she had laid down around the garage. Mostly, this meant sweeping up massive piles of dead cricket bodies; however, the powder along the garage door itself had melted in the summer sun and caked the dead crickets to the cement, so those had to be scrubbed off with a stiff brush. In retrospect, scrubbing insecticide-covered crickets by hand without any sort of protective equipment (not even gloves!) was probably a poor idea, but this was the early 90s in the rural midwest and I guess we didn’t think of that. Anyhow, I ended that part with my hands covered in mutilated and severed cricket parts, but they were at least dead. I was nearly finished and sweeping out the last of the dead bodies from a back corner of the garage when I bumped a board leaning against the wall with the backswing of my broom. It fell to the side and behind it six *living* crickets clung to the wall. My back was to a large unmovable tool bench, so getting away from the crickets required me to first take a step towards them, which I was certain would cause all six of the crickets to leap onto me and I would simply die of a heart attack. I froze; I tried to call for help and all that came out was a little gaspy squeak. I stood there without even blinking for what felt like an hour, but was probably more like 2 or 3 minutes, desperately clutching my broom and certain that if I even inhaled too deeply all the crickets would jump on me (which, again, would cause certain instant death by heart attack). My grandmother came to check if I had finished, saw me frozen in terror and said “Oh good! You found some more!” and casually walked over and pinched all the crickets’ heads between her fingers. I was close enough to hear them squelch.

In Kansas, we also had cave crickets (which my sister still calls “creepy spider crickets” due to their unusually long spider-like legs). In college, I once found a cave cricket in my apartment and threw textbooks at it from across the room until I smashed it. I distinctly recall that it was my massive Campbell Biology textbook (6th edition!) that finally did it in. It was so big it left a stain on my carpet, which I did not discover for three days – I left it under the textbook that long just to ensure it was really, *really* dead. But then I moved to Hawai’i and realized that compared to the giant Scolopendra centipedes (and their painful stings) and the flying 3-inch-long American cockroaches (commonly called B-52s in Hawaii, after the Cold War era bomber), crickets aren’t so bad, I guess.

I guess…

Anyway, all the crickets stayed in the cover of the grass along the path, so I could enjoy their chirping song without being creeped out. I do think their chirps are kind of lovely, so I’m trying to focus on that aspect of their biology and not recall cricket legs and pink pesticide powder all over my hands or the squelch of their heads in my grandmother’s fingers. I make a mental note to look up if California has cave crickets, as all my textbooks live on campus now, so I have insufficient ammunition against them at home.

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Sunset from my bench

Sitting on my bench, I am facing the setting sun, which casts a nice golden hue over the landscape. People mistakenly think that dawn and dusk are very similar. Dawn is a grayish blue, with a cool crisp quietness. Dusk is gold, warmer both in temperature and hue and striped by long shadows. I enjoy them both, in very different ways. I love the hopefulness of dawn, the inhalation of a new day and all its opportunities. Our last year in Hawai’i, my husband and I eschewed the late-night parties of New Year’s Eve and instead ushered in 2017 with a dawn hike to Makapu’u to watch the sun rise over the Pacific Ocean. It was the perfect start to the year, and one that we plan to continue for future new year’s days. I also love the calm restfulness of dusk, which feels like a long exhale into night. Everything (or at least the diurnal things) are finishing up their last tasks and tucking themselves away for the night, cozy and quiet. I now kind of wish we *had* asked the students to do a mid-night observation, to see activity of the nocturnal crowd. A 1:00 am observation, however, is probably a cruel and unusual assignment.

There are fewer animals out now than in the mid-day. I hear a number of red winged black birds – which it turns out was the unusual call I heard on my morning observation. There are a whole flock of them milling about the trees in my corner and across the golf course, though eventually most of them take off in a cacophony of wings and squawks and my corner becomes mostly quiet.

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The lilac bush is done blooming and has begun setting fruit, as has the Isomeris, which now resembles its common name of bladder pod. Consequently, I see no pollinators of any kind. I do see more humans on this visit than I have seen on the others – ten in total, with two dogs. They are mostly in pairs, and walking casually (as opposed to the morning joggers) and so they are louder, talking animatedly with one another as they pass my bench.

As the sun sets, the crickets quiet down and all I can hear is the soft rustle of the grass in the breeze. The breeze itself is cool, and after my workout I am evaporatively cooling more than I wish, but the last rays of the sun are still warm between the gusts of the breeze. I will be chilled through by the time I get home, but there is a hot shower and a snuggly kitten waiting for me there, so I don’t mind.

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Besides the redwings, I see only two other birds. One is a hummingbird, which I don’t get a very close look at, but after consulting my guidebook I’m pretty sure is a black-chinned. The other is a beautiful white-tailed kite, which I get to watch perform its characteristic hovering hunting behavior. It must not see anything it wants, though, because after a few minutes (and a couple dozen photos), it soars off without diving for a kill. It is beautiful to watch though, and I’m excited I happened to see it.

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I do not, sadly, see any burrowing owls. It is quite possible that my presence itself has prevented this, if they are easily disturbed into hiding. Still, the kite was an unexpected treat, and overall I have really enjoyed these observations. Sharon and I emphasized to the students some of the studies showing the effects of nature on cognitive function and mental health, and I have definitely experienced that on these observations. I might make a bike ride through the buffer, and a half hour or so on ‘my’ bench a regular routine. It’s also a nice practice exercise for my wildlife/landscape photography skills.

This afternoon in class, I’ll get to hear the students’ final observations. I’m curious if the more urban sites are very active during the evening, or if they are more like the morning observations. I do not generally stay on campus very late, though I know classes go well into the evening, so there may still be many people around campus at 8 pm. Regardless, I hope my students have also gotten to see something unexpected and interesting and I hope they found value in this exercise overall.

Wild Davis Gets Myrmecological!

Myrmecology: (mərməˈkäləjē) the branch of entomology that deals with ants. From the Greek myrmēx, or myrmēk, meaning ‘ant’

This week the Wild Davis course got to learn a fun new scientific word AND perform bait-trap surveys of ant populations in the southwest end of the Arboretum (near the White Flower Garden Gazebo). Our study questions related to bait preference and diversity of ant species in the area, particularly the diversity of native and introduced/invasive ant species. Sharon set out traps prior to class using peanut butter, pecan sandies, and canned tuna as bait. To help us with identification, we enlisted the aid of the wonderful and abundantly-knowledgeable Phil Ward in the Entomology Department here at UC Davis*.

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One of our bait traps containing (L-R) pecan sandies, peanut butter, and canned tuna. The flag and note cards are for location identification

Our study consisted of two parts: first, observe the abundances and diversity of ants on the different baits, noting environmental factors of the bait locations to determine what sorts of habitats recruit more ants to the bait; second, collect ants of each species we find for contribution to the Citizen Science project School of Ants, started by Phil’s former student Dr. Andrea Lucky. School of Ants uses student- and community- collected ants to track distributions of ant species across the entire United States. All you have to do is collect ants and mail them to Dr. Lucky at the University of Florida for identification!

The first part of our study ran into a little problem. It turns out that ants are not the only organisms in the Arboretum that are attracted to peanut butter, cookies, and tuna. Many of our bait traps (particularly those in the sun, which were more exposed and visible) were raided by scrub jays, mallards, ground squirrels, and even other insects. The ants preferred the shady baits, so we got a good selection anyhow.

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Our baits (which were within the landscaped beds and lawns around the gazebo) produced three species of ant:

  • the Argentine ant (Linepithema humile): a small, thin, grayish-brown ant native to (take a guess!) Argentina and other parts of south America. They were first found in California in the early 1900s (likely introduced through nursery plants) and are known for their aggression towards native species, frequently driving them to extinction. They prefer irrigated areas (like watered lawns and flower beds!) and so are common throughout the managed parts of the Arboretum.
  • the Pavement ant (Tetramorium immigrans): native to central Europe and also introduced in California, this ant is one of the most commonly found introduced ants in North America and gets its common name from his preference for urban habitat (including roadsides, pavement cracks, and buildings).
  • the Winter Honey ant (Prenolepis imparis): a common native California ant; one of the few native species that can persist in areas taken over by Argentine ants, likely due to differences in diurnal activity. These ants build deep underground nests and forage during times of year that are cooler than when most other ants are active (hence their common name of ‘winter’), meaning they compete less directly with other species, like the Argentine ant.

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As you can see in the photos, we found ants on all types of baits. They appeared to slightly prefer the cookies first, the peanut butter second, and the tuna third, though if we found ants at one bait in the location, we often found them at all three (assuming all three baits were unraided by other organisms).

Dr. Ward had brought along a pooter (that’s a real scientific tool for collecting ants. I did not make up the name) to help us easily collect ants off the bait. A pooter is a length of flexible rubber tubing with a filter about an inch from one end. You put that end near the ant to be collected, put your mouth on the other and and inhale. The ant is sucked up, caught by the filter (so you don’t inhale it) and you can trap it there with your thumb long enough to drop it into a baggie. Dr. Ward collected (pooted?) samples of each species of ant we found on the baits using this method. This was easily the most entertaining portion of the class.

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Near the gazebo is a less managed area of Arboretum land that houses a variety of native species. Since this area is not irrigated, it is too dry for the Argentine ants and provides a refuge for native species. Dr. Ward walked us through this area, showing us how to identify nests and individuals of different native species. We found evidence (nests or actual ants) of three additional native species:

  • Pheidole californica: this native ant is one of several species of seed-collecting ants. There were many of their nests visible along the path we walked, though in the heat of the afternoon, no actual ants were visible. If you look closely at the photo of the nest below, you will see that the orange pieces of the nest are actually small seeds harvested by the ants from nearby plants.
  •  the field ant (Formica moki): the nest of this species was spotted by yours truly (but who’s counting? :-D), with many workers running around. And I do mean running! A clear photo was rather difficult
  • the velvety tree ant (Liometopum occidnetale): this native ant was my particular favorite, nesting in an oak tree and scurrying over the entire trunk. The ants also have a particular smell – something akin to spoiled milk or vinegar. This ant also has an interesting ecology, with several other insect species in symbiosis either as parasites, mimics, or co-inhabitors of the nest. If the velvety tree ant is lost (for example, due to invasion by Argentine ants), their symbionts are also at risk.

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Dr. Ward again used the pooter to collect ants of each of the native species we found. Formica moki ants produce formic acid, which Dr. Ward got a coughing lungfull of when he collected them – a generous sacrifice in the name of citizen science!

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This class period may have been my favorite thus far in the Wild Davis class. It was a great chance to show the students the diversity and ecological importance of a group of organisms that are often overlooked, and a great chance to showcase the depth and breadth of knowledge that students have access to in their professors here on campus. Sharon and I are grateful to Dr. Ward for his contribution to this making this session such a success, and we look forward to contributing the specimens he collected to the School of Ants database!

*all ant information presented here is reproduced from Dr. Ward’s conversations with the Wild Davis students, from the Ant Guide Dr. Ward developed for the Arboretum, or from Dr. Ward’s research page and links therein.

Wild Davis II: Mid-Day Observation

**This post is a part of the Wild Davis course at UC Davis in which students must complete three timed observations of an urban habitat within the UC Davis campus or Davis city limits. As an instructor for this course, I joined the students in this exercise in order to provide a public example of the types of work the students do in this class. For more information on the course, you can read about my morning observation, follow #wilddavis on Instagram and Twitter, and check back here for more posts throughout the quarter!**

The second observations for the Wild Davis class are to occur at mid day (between 11 am and 1 pm), in the same location as the morning observations. I did my observation on Sunday April 22nd, as I can’t get away from work over the lunch hour on weekdays, and it seemed fitting to do an ecological observation exercise on Earth Day.

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The city mowed along the path since I was here last week, which at first has me concerned for the bunnies and ground squirrels, but as you can see in the photo, only a narrow strip next to the path has been mowed, and much grassy cover remains.

I realize as I’m biking to my bench that I have only walked this path in the evening, around sunset, and last week at dawn. In the daylight, I’m surprised at how much closer the housing development and golf course seem. I expect both the path and the golf course to be heavily trafficked on a warm Sunday afternoon, but I see only seven people along the path (not much more than I saw on the morning observation), though this time most folks have their dog with them. The golf course is a bit busier – I see three groups go by – but they are far enough away that I can’t hear them, with the exception of a single “Woo!!” that echoes its way to my bench after what must have been a particularly nice shot.

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the path on the right, with the golf course on the left

It is warm and sunny today, a much more enjoyable environment than the chilly, foggy morning observation (I’m wearing a tank top and capris instead of a hoodie and two pairs of sweatpants). There is a slight warm breeze, which keeps me from getting too hot, even in the full sun. I close my eyes and inhale, but all I can smell is the sunscreen I applied before I biked out here. I have to get really close to even the lilacs before I can smell them over my own scent.

I don’t hear as many human noises as I did in the morning. I can’t hear the highway traffic, and the golf grounds crews aren’t working this late in the day. I do hear two jumbo jets that fly almost directly over me, heading south. This surprises me, since I have not noticed jets overhead anywhere else in town, but perhaps I just haven’t been paying attention.

I am also surprised by the lack of water in the little creek. In the few times I have been down this path, it has always had a decent amount of water in it, but today, it is completely dry. Just two weeks ago, my husband and I stood here at dusk and listened to a chorus of little frogs, and I wonder where they have gone to now. Perhaps to one of the water features in the golf course. I wonder now how ephemeral this stream is, and I make a point to check it on my evening visit in another week.

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No chorus of frogs in the dry streambed…

The animal activity is also different from my morning observation. I see no sparrows, and no bunnies. There are two ground squirrels perched on the fence about 15 feet apart periodically barking at each other through my entire 45 minutes. It is meant to be intimidating, but comes off pretty adorable to my ears.

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There are many birds, but not the sparrows I saw in the morning. Today, they are mostly mockingbirds, chattering noisily at each other and at me from nearly every tree. I hear the bees too – they are buzzing about the lilacs and the purple flowers growing close along the path. On the lilacs, I see a few honeybees, bumblebees, a hover fly, and a beautiful metallic green bottle fly. I think this is a lot of activity until I wander down to the Isomeris a few feet further down the path. There are so many individuals of so many species that I capture four or five apiece in the frame of my camera lens. Once, I even get two different pollinators on the exact same flower. I see a few butterflies this time, too, though all but one flutter by before I can be sure what they are. One is small and white, another medium sized and black, and the last is a western tiger swallowtail. As I’m scampering about to get a better look at the them, I startle a fence lizard out of an oak tree. I get very excited about this, since he is the first herpetofauna I’ve found on these observations. He stares at me without moving until I creep forward to get a picture and then he races back up his tree.

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The past few years, I’ve been dabbling in wildlife and landscape photography and pollination is hands-down my favorite thing to photograph. I enjoy the beauty and tiny-ness of the flowers and insects and the mutualism of the relationship. It is also a strange reproductive strategy when you think about it; to convince another living thing to carry your gametes to your mate. I don’t want to spend my entire observation staring at pollinators through the lens of my camera, so I make myself wait until the end of the 45 minutes to take most of my photos. Honestly, you could leave me with a camera in a wildflower meadow full of pollinators for hours (days?) and I’d be happy. I (mostly by accident) get a nice shot of a tiny little native bee with two massive Apis honeybees in the background on the Isomeris. Most folks love the honeybees, and they are certainly beautiful and an important ecological player. They are also introduced, from Europe, and can negatively impact populations of native bees (ex. bumble bees) which are also important pollinators of native and crop plant species, so much so that the Integrated Crop Pollination Project recommends (among other things) establishing wildflower corridors around crop fields to attract a diverse array of native pollinators in addition to managed and wild Apis hives. As beautiful as they are, I can’t help but notice how massive the Apis are compared to the native bees, which makes the native bees seem delicate and vulnerable by comparison. In the photos below, you can see how the honeybees bury their whole body in the flower while the tiny Lasioglossum perches precariously on the end of one anther. I don’t know the native California bees very well yet, so when I get back from my observation, I send a couple pictures to Neal Williams, an entomologist here at UCD who studies native pollinator ecology and he responds within hours with a genus-level ID for each one, and an offer to ID to species-level anything we can catch and bring it to him. One thing I love about academia is how total strangers will lend you their expertise at a moment’s notice – we are all lifelong learners and total nerds here, and we love sharing it.

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In class this week, the students will share their own mid-day observations. For the morning observations, I was impressed at the diversity of locations the students chose. They observed a variety of spots in the arboretum, an urban green space near a housing development, tucked-away corners of campus between lecture halls, managed campus gardens, etc etc. I look forward to hearing how different their mid-day observations were from the morning observations, particularly for those that chose campus locations that were mostly empty prior to 8 am in the morning. These sites will likely be very different in the hustle and bustle of the regular campus afternoon. And in two weeks, we will have the evening observations, when I will (fingers crossed!) perhaps get to see my burrowing owls.

 

Wild Davis Urban Ecology Scavenger Hunts

For the Wild Davis course, students will have to come up with an ecological research or natural history focused individual project. This week’s class exercise is a scavenger hunt brainstorming session to help them develop possible project ideas. Below are the scavenger hunt ‘items’ and what each of the groups (including Sharon and I!) ‘collected.’

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The squirrels were a common feature of many interactions

1. Mutualistic Interactions
– a hover fly pollinating a matilija poppy
– butterflies pollinating flowers
– ladybugs eating aphids off plants
Many of the mutualistic interactions we observed involved humans:
– a person with a guide dog
– Anne’s favorite man feeding his stray cat

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Hover fly and a matilija poppy

2. Non-Mutualistic Interactions
– herbivory by a duck
– ducks competing for food
– wasp galls on oak trees
– spider capturing prey on a web
– pathogens on plants
– squirrels digging up cached acorns

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wasp galls on campus valley oaks (photo by Sharon Strauss)

3. Interactions Between Humans and Animals
– squirrels ‘begging’ for food from humans
– horses housed at the equestrian center on campus
– humans feeding animals, including ducks and squirrels

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The squirrels on campus are really well fed.

4. Interactions Between Humans and Plants
– humans enjoying the shade of a large tree
– people taking pictures of flowers and animals
– Picnic Day tree signs, promoting value of trees

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These signs were hung up around campus for Picnic Day, they included stats on how much CO2 trees use, how long they live, and resources they require

5. Interactions Between Animals and Human-Made Objects
– a scrub jay perching on a signpost
– nest on the corner of a building
– squirrels hanging out on a trash can
– turtles basking on the cement retainers in the arboretum

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A phoebe uses the cement retaining wall as a vantage point for hunting

6. Interactions Between Plants and Human-Made Objects
– ivy on the wall of the Silo and the columns in front of Shields Library
– plants growing in the gutters of buildings
– redwood roots breaking through sidewalk
– trees in the arboretum with ID tags

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ivy growing on the Silo

7. Evidence of an Animal (but not the animal itself)
– a duck feather on the ground
– squirrel nest
– spiderwebs with no spider
–  various types of bird poo. There was a vigorous discussion on the visual identity of duck and songbird poo, with the latter being described as “high-velocity splatter”

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8. Interactions Involving Detritivores
– an earthworm in the leaf litter of the redwood grove
– roly poly in the soil
– mushrooms growing under a tree

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an earthworm in the redwood grove at the arboretum

9. Interactions Involving Invertebrates
– a hover fly pollinating a heuchera
– a spider building a web on a tree branch
– aphids on plants

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this plant is overrun with aphids (photo by Isabelle Gilchrist)

10. Interactions Involving a Plant that is NOT an Angiosperm or a Gymnosperm
– competition  between maidenhair fern and various angiosperms
– ferns in the redwood grove

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11. Interactions Involving an Organism that is NOT a Plant or an Animal
– fungal burl on tree
– fungus on the columns at Shields Library
– mushrooms in the redwood grove

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photo by Sharon Strauss

12. Interactions Between Organisms and Abiotic Aspects of the Environment
– seeds floating on the breeze
– butterflies floating on breeze
– ducks swimming in the waterway at the arboretum
– turtles basking on the cement retainers in the arboretum

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I didn’t technically get a shot of a seed on the breeze, but these ones were about to go!

 

Wild Davis I: Morning Observations

**This post is a part of the Wild Davis course at UC Davis in which students must complete three timed observations of an urban habitat within the UC Davis campus or Davis city limits. As an instructor for this course, I joined the students in this exercise in order to provide a public example of the types of work the students do in this class. For more information on the course, you can follow #wilddavis on Instagram and Twitter, and check back here for more posts throughout the quarter!**

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the entrance to the trail, off Covell Blvd

I choose to do my timed observations at the Wildhorse Agricultural Buffer, a 38-acre habitat corridor and walking trail located in north Davis conveniently near to my house. The buffer provides natural space around and between housing developments, the Wildhorse golf club, and the agricultural fields that abut town. In particular, it is sensitive habitat for a colony of burrowing owls, which I very much want to see. Since I have walked this path before, I know there is a small bench near the strip of burrowing owl habitat (or at least near the sign that says this is the area) where the path takes a left turn around the golf course and I choose this spot for my observations. The morning observations are supposed to occur between 6 and 8 am, and I get to my bench at about 6:15 on Tuesday morning.

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The buffer path marked in yellow, and the location of my bench shown with a yellow star (map from DavisWiki)

It is cold this morning – just cold enough that I can see my breath – and damp from a fog that is rising. I bundled up for the bike ride to the buffer – having moved here from Hawai’i, I am not at all metabolically prepared for sitting on a stone bench on a chilly morning. I’m wearing a sweatshirt with the hood up, gloves, earmuffs, and two pairs of sweatpants; and I brought a thermos of hot coffee. Even through two pairs of sweatpants, the stone bench is too cold to sit on for long, so I meander around this section of the path.

From my bench, I can see quite a bit of the path, which was mostly empty this early on a cold weekday morning, though I did see 6 people either walking or jogging the path during my observation. I can see the Wildhorse housing development in the distance and the rolling hills of what I’m pretty sure is Hole 4 of the golf course. Behind me is a small patch of meadow, bordered by a wire fence that marks the edge of the buffer, and beyond that, an orchard. I can smell the smoke of a fireplace, and I can hear distant traffic and the mower and leaf blowers of a lawn crew in the golf course. A couple times I hear the whistle of a train a ways off.

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Once the lawn crew moves on, I hear the sparrows twittering to each other as they flit around the bushes. They are the busiest little bees this early in the morning, as it is too early for the actual bees. They will come near to me if I stand still, but even just a turn of my head sends them clamoring back to the safety of the redbuds. My spot is mostly grassy, but there are a few lilac bushes (in full bloom), a few redbud trees (mostly free of their buds now and just leafy green), and a few oak trees sporting some wasp galls. I notice that one of the redbud trees has green flagging ribbon tied to one branch, and two of the oak trees and a lilac bush have yellow flags planted at their bases. I wonder what these flags mean – perhaps the oak trees are under observation for their galls, although I see nothing unusual about the lilac bush and redbud tree that are also flagged.

As I biked in, I flushed a few rabbits from the path, but I see none in my area throughout the observation. I do see a hawk, being harried out of the golf course by a gull that repeatedly divebombs the hawk, even after it has fled to the orchard. The hawk forages for a bit in the orchard until the gull leaves and then makes his way back over the golf course. I see him going back and forth between the two, suggesting his hunting is easier in the managed landscapes than in the overgrown cover of the buffer. No wonder the bunnies and the sparrows like it here.

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Sunrise

Most of the people I see along the path come after the sun has just risen, a little before 7 am. They all say good morning, and one woman stops to chat about the weather. I wonder what they think of my presence here – I know how odd I must look. Given my cruiser bicycle, my thermos of coffee, my bulky double sweatpants (the outer pair of which are my husband’s plaid flannel sleep pants), and my note taking, I am clearly not here for exercise as they all are. Every person I see is white, and I wonder if they would smile and greet me if, instead of a 30-something white woman in oversize sweatpants and hoodie loitering about a back section of the path, I was a black teenager doing the exact same thing. To my knowledge, Davis is a safe town for everyone, but I wonder anyway. I am reminded of an essay by Evelyn White titled Black Women and the Wilderness, in which she fears the danger of being in the wild – not the fear of accidents or wild animals, but the fear of other humans and what they might do when you are out alone in the wilderness. I feel safe in this corner of the buffer, alone with the sparrows, as I have felt safe in most natural places all my life, and I wonder how much of that feeling is the privilege of being white.

“While the river’s roar gave me a certain comfort and my heart warmed when I gazed at the sun-dappled trees out of a classroom window, I didn’t want to get closer. I was certain that if I ventured outside to admire a meadow or to feel the cool ripples in a stream, I’d be taunted, attacked, raped, maybe even murdered because of the color of my skin.” ~Evelyn White

I finish my coffee just as my 45 minutes is up. As I bike back out of the buffer zone, a barn owl takes flight from the meadow to my right. For one instant, I think it is a burrowing owl and I get excited – but it is a barn owl, though I like them, too. I hear an unusual bird call from a tree near the trail’s entrance. I don’t recognize it, and I can’t seem to find the bird that is making it, despite the fact that the tree doesn’t have that many leaves. I’m reminded of another essay, this one by Annie Dillard, titled “Seeing” and found in her book Pilgrim at Tinker Creek. “Specialists can find the most incredibly well-hidden things,” she states, separating her ability at ‘seeing’ from that of the ‘specialists’. I keep meaning to mention this essay to the students in the Wild Davis course – don’t worry if you’re not good at seeing things right away (or ever), even ‘specialists’ struggle. I record the call so I can try to ID it later.

“I once spent a full three minutes looking at a bullfrog that was so unexpectedly large I couldn’t see it even though a dozen enthusiastic campers were shouting directions. Finally I asked, “What color am I looking for?” and a fellow said, “Green.” When at last I picked out the frog, I saw what painters are up against: the thing wasn’t green at all, but the color of wet hickory bark.” ~Annie Dillard

Tomorrow afternoon, I’ll get to hear about the students observations. We let them choose a place without any oversight, so I have no idea what types of locations they have chosen. I hope they saw, heard, smelled, felt something interesting. I hope they felt safe alone there at dawn. I hope they avoided distracting themselves with technology (as I did, mostly, with the exception of taking some photos). I hope their choices reflect the variety of habitats in and around the UCD campus. I hope each student’s experience is unique in some way and that they value sharing it with their classmates (and hearing about their classmates’ experiences). I hope they enjoyed it and that they saw whatever habitat they chose in a way they hadn’t seen it before.