As is now traditional for my laboratory, here’s a plain-language summary of the paper:

Tree canopies, including those in deciduous forests in southern Quebec, are important for many different animals, including insects and spiders. These small, marvelous creatures crawl up and down trees with regularity, feed upon the leaves of trees, feed upon each other, and are food for animals such as birds and bats. Past research has shown that many species of insects and spiders live in tree canopies, and in general, more insects and spiders are found closer to the ground compared to the very tops of the trees. This makes sense, since deciduous tree canopies often need to be recolonized each spring, and tree canopies are relatively harsh environments – they are windy, hot, and often-dry places as compared to the forest floor.  What we don’t know, however, is whether the insects and spiders avoid the tree canopies because they may be eaten more frequently in the canopy as compared to the understory. The objective of this research was to test this question directly, and find out whether insects and spiders are arranging themselves, vertically, because predators may be preferentially feeding on them along this vertical gradient. This is a very important area of study since biodiversity is highly valued and important in forests, but we cannot fully appreciate the status of this diversity without discovering what controls it.

Our mobile aerial lift platform. TO THE CANOPY!

We did this work by using two experiments that involved manipulating different factors so we could get at our question in the most direct way possible. In the first experiment, we made ‘cages’ out of chicken wire and enclosed branches of sugar maple trees in the cages. We did this at the ground level all the way to the tops of trees, using a ‘mobile aerial lift platform’. These cages acted to keep out large predators, such as birds, but allowed insects and spiders to live normally on the vegetation. We counted, identified, and tracked the insects and spiders both within these cages, and in adjacent branches that did not have cages (the ‘control’). By comparing the control to the cage, we could find out whether feeding activity by larger vertebrate predators affected insects and spiders, and whether this differed when comparing the ground to the top of the trees. In the second experiment, we used small pins and attached live mealy worms (larvae of beetles) to the trunks of trees, and we did this in the understory all the way up to the canopy. We watched what happened to these mealy worms, and compared what happened during the day and overnight. This is called a ‘bait trial’, and let us figure out what sort of predators are out there in the environment, and in our case, whether they fed more often in the canopy compared to the ground-level. This second experiment was designed for seeing the effects of insect and spider predators along a vertical gradient whereas the first experiment was focused more on vertebrate predators (e.g., birds).

Munch munch. Carpenter ants feeding on mealworms.

Our results from the first experiment showed that the cages had an effect: more insects and spiders were found when they were protected from predation by birds. Birds are playing a big role in forest canopies: they are feeding on insects and spiders, and in the absence of vertebrate predators, you might speculate more insects and spiders would occupy trees. Our second experiment showed that ants were important predators along the tree trunks, and overall, the most invertebrate predators were found in the lower canopy. Both experiments, together, confirmed that the understory contained the most insects and spiders, and was also the place with the highest amount of predation pressure.  The take-home message is that there is an effect of predation on insects and spiders in deciduous forests, and this effect changes if you are in the understory as compared to the top of the canopy. We also learned and confirmed that insects and spiders remain a key element of a ‘whole tree’ food web that includes vertebrates such as birds, and that predators in trees tend to feed on insects and spiders along a gradient. Where there is more food, there is more predation pressure! Our work was unique and novel because this is the first time a study of predation pressure was done along a vertical gradient in deciduous forests. It will help better guide our understanding of forest biodiversity, and the processes that govern this diversity.

A more detailed discussion of this work is posted on the PeerJ blog.

Wildlife

Walking across the tundra brings sights of circling rough-legged hawks and the sounds of jaegers. We were able to find spots where the hawks like to sit (at higher elevations, on a pile of rocks and boulders). The vegetation is particularly rich under these perches, as the nutrient inputs are very high! We could also find feathers, and pellets – these pellets are a tidy package – a mass that represents the undigested parts of a bird’s food, regurgitated. These pellets can be dissected and you can find the tiny bones of small mammals. While in Cambridge Bay it was a particularly good year for lemmings, and thus a particularly good year for hawks, and snowy owls. Each day on the tundra, about a dozen different snowy owls were sighted. They were always just the right distance away, perched beautifully and peacefully on slight rise – a close look with the binoculars showed the owls staring right back, tracking our movements as we were tracking theirs. If you walk little closer, the owls take off, flying low and fast over the tundra.

Bird food. (otherwise known as lemming).

At times, off in the distance, it was also possible to see black, slow-moving shapes – unusual creatures, shaggy, and foreign to a boy from the south. These were muskoxen – chewing their way across the tundra. While in Cambridge Bay I spent some time with graduate students working on Muskox health, and I learned of the serious disease, lungworm, that is affecting these stunning mammals. Lungworm has been known from the mainland for some time, but only more recently on Victoria Island – climate change is a possible reason for this change in distribution. These nematodes use slugs or snails as intermediate hosts. Yes, there are slugs and snails in the Arctic!  Finally, it’s pretty difficult to talk about Cambridge Bay without mentioning the fish. The traditional name for this place, in Inuinnaqtun, is “good fishing place“, and that is an apt description. We ate fresh fish every day, enjoying Lake trout, Greenland cod, and the most delicious of all, Arctic Char. We were blessed with amazing weather during my week in Cambridge Bay, and our Sunday afternoon fishing trip on the ocean was picture-perfect.

Good fishing place.

Landscape and light

It’s hard to explain the North to people who have never experienced it, but let me try:

The landscape is breathtaking in its starkness.  The tundra rolls out like a grey/green/brown carpet, as far as the eye can see. It’s broken up by ponds, streams, and lakes, and broken up by slight changes in elevation. This results in a landscape that ripples with shadows and colours; a landscape that meanders, curls and curves depending on the underlying bedrock, sediment, glacial till, and permafrost. 

At first glance, the Arctic tundra appears homogenous, but after walking for hours upon hummocks and through cotton grass, you start to see the diversity of ecosystems, and the heterogeneity in microhabitats. It’s a landscape that is forever changing and providing plants and animals opportunities as well as challenges. I was in Cambridge Bay in early August, and it was evident that the summer season was ending.  In addition to the signs from the plants (lack of flowers) and wildlife (geese were moving in, in flocks; butterflies were seldom seen), the strongest evidence was the light. During the week I was in Cambridge Bay, there was about 18 hours of daylight each day, but the land is losing about 5 minutes of light each day – it’s a rapid change. Since Cambridge Bay is above the Arctic circle, it gets 24 hours light in June and early July, but by mid-August, summer is winding down. This means, however, that you can experience the most stunning sunsets – you can sit for hours and watch the sun approach the horizon from a remarkably shallow angle. The “magic” light is with you for hours. The kind of low light that makes everything slow down.  The kind of light that creates long, dancing shadows, and warms everything in a soft, gentle glow.

Reflection

To finish, I wanted to write a little bit about perspective. The Arctic makes you feel close to the earth. When standing on the tundra, the land before you contains no telephone lines, roads or apartment buildings. It’s very much like it was hundreds or thousands of years ago. You could start walking and you won’t likely see anyone else. The Arctic causes you to reflect and slow down. And most importantly, the Arctic makes you feel small. I think that’s an important feeling to have every now and then. The land is vast and old; we are small and young. Let’s remember we are here for a short while, and some of our time is probably well spent out in a forest, on a lake, or hiking the tundra.  Time on the land is time well spent, in part because it causes you to pause and reflect. I think the world would be a better place if we spent a little more time breathing in nature, and remembering what the earth is giving us and on how we ought to respect it a little more.  We owe it everything.

The Arctic makes me think of these things and for that I am grateful.

The clichés are true. I’ve been north many times, and each time the effect is stronger. Each time the landscape leaves a deeper impression. Over a couple of blog posts, I want to share reflections about the Arctic from my recent field trip to Cambridge Bay (Nunavut), and try to explain why I love it so much, and why Arctic research is my passion. I’ll also share a few of my favourite photographs from the trip.

Arctic Arthropods

I often write that “Arctic biodiversity is dominated by arthropods” and I stand firmly behind that statement. Despite the latitude of Cambridge Bay (at 69 degrees North), the tundra is alive with butterflies, bees, low-flying dipterans, and spiders.  On a warm day, you can sit in the tundra and watch the careful movements of spiders as they navigate their three-dimensional world, seeking prey, or simply sunning themselves.  Over the past few years our research team has documented over 300 species of spiders living across the Arctic and sub-Arctic, and although diversity drops at high latitudes, there are still over 20 species known from the low Arctic Islands, dropping to fewer than a dozen as you approach 80 degrees North.

Arctic wolf spider (Lycosidae), genus Alopecosa

Under rocks in flowing water you can find black fly larvae, swaying in the current. Sometimes you find the shield-shaped pupal cases, and if lucky, you can see the emerging adults. These emerging adults are sometimes adorned with red mites. There are arthropods living within the protection of Arctic willow; careful examination of Salix reveals red ‘berries’ which are actually galls. Opening these reveals a hidden life. A secret, protected room containing the larvae of a Hymenoptera.

An Arctic Lepidoptera (genus Boloria)

Research

A few years ago, the Federal Government announced a new Canadian High Arctic Research Station (CHARS), and it is to be built in Cambridge Bay over the next several years. This station will support and facilitate research in the North, in many different ways, from studies about effects of climate change on permafrost, to research on marine mammals. I am going to do my own research in Cambridge Bay, but with the aim of integrating research about arthropod biodiversity with other Arctic studies. I also hope to help in the development of a long-term monitoring plan, using arthropods as one of the focal taxon. Arthropods can tell us a lot about the world, and how it is changing, and long-term data are needed to ensure we have a clear sense of when ‘change’ is change that we need to pay particularly close attention to.

A malaise trap on the tundra – designed to collect flying insects

I was in Cambridge Bay to start to develop these kinds of projects, and to get to know the town, community and the land.  I also wanted to collect insects and spiders in the Arctic in the late-season. I’ve worked in the Arctic a lot over the last several years, and although we have done full-season (i.e., June-August) collecting on the mainland, our laboratory does not yet have a clear idea about seasonal occurrence of different species occurring on the Arctic islands. Therefore, I was doing some collecting so that data could be gathered about arthropods on Victoria island and the end of the summer. For all these reasons, Cambridge Bay was my ‘research home’ for a week or so.

History and People.

Arctic regions of Canada have a rich history – and a history that is both tragic and awe-inspiring. Residential schools, relocation programs and stories of substance abuse, are all part of the darker side of this history. For hundreds of years, Europeans saw the Arctic as a wild land that required navigating, and a land that contained a bounty of riches, from whales to minerals. A bounty that was available for the taking. The stories are remarkable, and evidence of them remain in places like Cambridge Bay, including the influence of the Catholic church and the wreck of Amundsen’s ship, the Maud.  The search for Franklin’s lost ships continues – while I was in Cambridge Bay, a ship departed, in search of the Erebus and the Terror.

The remnants of a Catholic church, built in Cambridge Bay in the early 1950s

The Maud, in its resting place. The townsite of Cambridge Bay is visible in the background

There has been a rebirth, however – Nunavut is a place of Inuit pride, and includes a wonderful balance between old traditions and new. The Inuit are marvellous – a people exhibiting patience, perseverance, kindness, good humour, and ingenuity. I heard stories of how runners on sleds could be made of frozen bodies of Arctic char, and the cross-braces from bones of wildlife, and frozen mosses would adorn the tops. If times were really tough, parts of the sled were edible.  Today, wood and rope is the preferred construction material!

Sled on the tundra: waiting for winter.

Inuit culture is alive and well. I was lucky to spend time on the land with some of the locals, and I learned of edible plants, leaves that can be burned to ward of mosquitoes, and about the lice on arctic hare pelts.  The Inuit are also fabulously artistic, well known for their carvings from bones and fur.

Looking out towards the Northwest Passage.

Stay tuned for Part 2, to come next week…

Sound boring?  Nothing is further from the truth. It’s an amazing way to spend time, here’s an example:

Yes, that label for a jumping spider species provides more than a name, locality and date. It provides a story. It confirms that spiders are hosts for parasitoid wasps, and it documents an ecological interaction; one that is stamped in time and place.

Every single specimen in a museum or research collection tells a story. There are untold riches on little pieces of paper linked to biological specimens. In addition to the usual name, place, and time, label data gives us varied and fascinating ecological stories. Here’s another one:

Yes, more evidence of one spider species preying upon another species. Intraguild predation, recorded and placed in a vial.

I love this next one – in part because you now know that bluebirds eat jumping spiders and that Arachnologists can identify the species based only on the male palp (that is all that was in the vial, it’s the little spider ‘bit’ at the bottom left). Um, I suppose the bird got the rest of the specimen!:

Label data can tell incredible stories!  Here’s a nice set of labels that show how Phidippus jumping spiders really, really get around:

Planes, automobiles, and boats.  (um, boats in Saskatchewan! A Province of relatively limited water, by Canadian standards).

Label data also provide insights into the characters of scientists. Below is an example of three different individuals all identifying the specimen as the same species. The three scientists, by the way, are preeminent Arachnologists in North America – I would trust any one of their identifications, but clearly they were not entirely sure, and all three had a look to confirm the identification. Three votes from Dondale, Maddison & Edwards, in three different decades! Yes, it’s Phidippus audax:

Label data provide an important historical context.  I was thrilled to see this label from 1917 collected by none other than Norman Criddle (Criddle is well known to Entomologists in Canada):

Label data provide opportunity to discuss, imagine and be inspired by biodiversity. I identified a species of jumping spider from a place called Sable Island. The species is one of the most attractive spiders in North America, Habronattus decorus. 

Sable Island is here:

So… the questions start. How did it get there? Presumably ballooning? Are these lovely critters still on Sable Island? What is the fauna of Sable Island? Is is a stable fauna? An old vial, stuck in a cabinet in Ottawa, opens to door to questions of dispersal, biogeography and biodiversity.

I think the message is clear: databasing provides a rich opportunity to paint a picture of a species, over time and over space.  

But here’s the problem: there are about 2700 vials of jumping spiders to database. Each one takes about 3 minutes to database, meaning it would take about 135 hours of work to database only 1 family of spiders, in one collection! And working in the collection is not free – paying students, travel time, lodging, etc. all take time and resources.

So far our laboratory got through about 400 specimens (15% of the Salticidae). We have barely made a dent.

This is an undeniable problem: We must capture these data and make them available for scientists to use.

How can we understand biodiversity change when most of our historical data are not yet digitized?

How can we begin to understand biodiversity patterns without knowing what is where, and when? 

When I wrote my previous post about the Canadian collection, I was pointed to Notes from Nature - an on-line resource where databasing is crowdsourced. This is a pretty neat idea – label data (and specimens) are photographed, uploaded to the site, and anyone in the world can transcribe the data.  It allows anyone with an interest in biodiversity to reach into a collection and learn the stories from the specimens.

I am hoping to try this out with spiders from Canada’s national collection. While in Ottawa, I tried taking photos of specimens, and tracked how much time it takes. It turns out it takes about 2 minutes to photograph the specimens and label. You must take out the spider, the label(s), arrange everything carefully and take photo(s). It then takes about 1 minute to edit the photo, and about 1.5 minutes for someone to enter data into a computer from a photograph instead of from the specimen itself. So, total time for databasing is 1-2 minutes longer than sitting in the collection and doing the databasing. The benefit, of course, is that there is good potential to actually get a collection databased from afar. Here’s an example of a photographed label and specimen, after editing:

Question: would YOU help database if you could go on-line and see these kinds of images? Does it grab your attention? Even if 20-30 people agreed to database 75 or so specimens, each, the Salticidae would be done! (and, of course, someone would have to take images, and edit them beforehand).

I am keen to have your feedback…. I want to know if it’s an idea worth pursuing.

Do you want to learn stories from specimens? 

When starting at McGill over 10 years ago, I kick-started my research program by spending weeks in the field, and seemed to manage a lot of time with each of my graduate students during the field season.  However, time in the field was measured as weeks, and not months.  Now, as I look at my schedule, I’m “maybe” going to get one full week in the field this summer, and a fews days here and there helping with other projects going on in the lab. My time doing field work, actively collecting data, is minimal.

Deep thoughts: field work in the Arctic. Are these days long gone…?

Wait a second. One reason I got into this business was because I like to figure out neat stuff about nature, while being in nature. As a child, I always enjoyed being ‘in the field‘ (this is also known as ‘playing outside‘) and wanted to continue this as an adult. What happened?

Academics in my discipline of study (let’s call it ‘field ecology‘) and at my career stage (i.e., some years into the job) spend relatively little time in the field and the bulk of their time is a desk job, click-click-clicking away on a keyboard. Staring at a monitor. I know there are exceptions (and BIG congratulations on those of you who do manage to get outside to collect data, regularly!), but when I look around to my colleagues, most of them spend more looking out a window instead of being out that window. The time gets chewed up by other (important) priorities: grant writing, editing manuscripts, writing manuscripts, answering emails, reading papers, attending meetings, chairing meetings, going to conferences, preparing talks for those conferences, writing lectures, delivering lectures and so on. These are all the current demands on our time, and they are the things that the job requires! (for other relevant discussions about this, have a peek at this post by Sarah Boon, and I’ve previously written about how I spend my time).

Bottom line: most of my work duties are indoor activities. I am fortunate in that some of my teaching occurs outside, but that is not the norm.  The other thing that happens is ‘life’ – time with family is important to me, and time away from family is difficult. One reason I’ve spent less weeks away is because it’s tough on all of us and I like being around when the kids are growing up. There’s also that thing called a vacation – Academics typically their vacation time during the summer. (related to this is a post over at Dynamic Ecology titled “how often do you travel”, by Meg Duffy)

That is how I have traded field biology for a desk job.

I’m not alone: here are some responses from folks on Twitter when I asked about their experiences, and whether they have traded field biology for a desk job:

This is not a lament; this is not a sob story. In fact, perhaps many of us are OK with this transition from field biologist to ‘research manager’:

There is an important message here for people moving up through the Academic system: current PhD and MSc students need to recognize that the idea of landing an Academic job that gets you ‘out in the field’ a lot is probably a pipe dream.

I’ll end with some optimism: Even though things have changed, I think I can still call myself a  ’field ecologist’ and here’s why:

1) “Field Trips” can be short. It’s possible to capture an hour outside over lunch and collect data on Agelenopsis spiders in a hedge near the picnic table, or stop off at a bird banding station in the AM before work, or swing by a forest to check a pitfall trap on the way home. I have come to realize that field work need not be ‘weeks away’.  In many cases, it’s worth starting up a project that takes you outside regularly, at a local field site. This makes the field work an easier part of the day and you don’t need to schedule weeks away (nor will you need to schedule it months in advance). Keeping it simple, and keeping in manageable is important for me, given the other constraints on time.

2) Trade-offs: I spend time in the field instead of attending a lot of conferences. I have always enjoyed going to scientific conferences, but given the difficulties in getting away for extended periods of time, I realized that I could do field work, or attend conferences, but doing both is not always possible. One of my academic mentors discussed this with me soon after I had started my job at McGill (ironically, at a conference!); he said that when the weather is good, time was better spent collecting flies rather than sitting in a hotel basement. Good point. (By the way, summer-conference are kind of annoying because of this conflict!).  Networking at conferences is very valuable, but that face-to-face networking may not be as essential later in a career. Thanks to social media, it’s also possible to attend conferences virtually.

3) Live vicariously through students: My thoughts about field work are somewhat nostalgic and dreamy, and I forget about the problems. I forget about the flat tires, encounters with bears, the biting flies, and the exhaustion. I’m reminded of these things when my graduate students come back from the field, and sometimes I am happy I wasn’t with them. I can, instead, spend a day or two with them in the field, troubleshoot, help but not have to suffer through it all. I’m a ‘gentleman field biologist’ now. Is that lame? Is that pathetic? Nope. I’ve put in my time and can now have my field trips field with all the fun parts and less of the annoying parts.

4) Mixing vacations with field biology: I’ve not been all that successful at this, but I do know colleagues who manage to mix extended vacation time with field work. I do this on a smaller scale, and it typically includes carrying vials along with every trip, whether it is to the family cottage, or just a walk in the local forest. I’m always after records of pseudoscorpions, and have managed some nice finds while on vacation.  My family does, however, gives me strange looks when I go chasing after spiders or butterflies during lunch break while on a road trip. I can handle the ridicule –> it’s for science!

Although I have largely traded field work for a desk job, there are still glimmers of exciting field work, and still opportunities to get outside and be reminded of the reasons why I originally got into this line of work. I am not depressed or sad about my desk job – I have the best job in the world, despite the the fact that I stare out the window and sometimes dream of field work. I also maintain that these things come in cycles – a few years ago I was away for a few weeks in the field, even if this year is less intensive. It’ll come around again, and perhaps I will write a post in the future that discusses how it’s possible to be a gritty, smelly, rough and tough field biologist again. For now, though, I must stop typing. It’s hard work and my fingers are a little sore.

Spider sex can be a dangerous and costly venture, the classic example being the (often) misunderstood act of sexual cannibalism (e.g., the black widow spider). However, many of the costs for males are not always so obvious: during copulation, the emboli of some male spiders may break off, which results in the male being unable to properly re-fill his palpal organ and mate again (Foelix 1996). Without this ability, the male’s future is essentially an early retirement. While sorting and identifying spiders for my dissertation research, I noticed that male Cybaeopsis euopla (a ‘hackledmesh’ weaver spider) seemed to frequently be missing one or both of their pedipalps.  Could this be another example of a copulation cost?

Looking to the literature, missing pedipalps are documented with some species – tiny males from the sexually dimorphic genus Tidarren (Theridiidae) will remove their own palps and this increases their running speed considerably (Ramos et al. 2004). Working with the same genus, Knofach and van Harten (2001) observed that females remove one of the male’s palps ‘after achieving genitalia coupling’. The female then proceeds to eat the male, while the detached palp acts as both a mating plug and continues to inseminate the female! Something similar happens with the species Nephilengys malabarensis and this fascinating biology was reported by science bloggers such as Ed Yong. In the wolf spider (Lycosidae) Pardosa milvina, frequent palpal losses were observed and effects on courtship and mating were studied by Lynam et al. (2006). Perhaps not surprisingly, these authors report that ‘intact males were less likely to be cannibalized and suffered fewer predatory attacks by females than autotomized males’.

With that background, I began counting the frequency of missing pedipalps for a sub-sample of the specimens of C. euopla. The objective was to assess the percentage of males were missing right, left, or both pedipalps and see if this related to phenology or other life-history events.

The samples came from a mixed-wood forest at the George Lake Field Station, located about 75 km NW of Edmonton, Alberta. This mature mixed-wood forest is dominated by trembling aspen and balsam poplar. Samples were collected using standard pitfall traps, and were part of several other projects on spider assemblages in mixed-wood boreal forests (e.g., see Buddle 2001).

Cybaeopsis euopla – lovely little spiders! (Photo by C. Buddle)

Cybaeopis euopla (Amaurobiidae) (formerly Callioplus euoplus) is widespread in Canada, ranging from the Maritimes to the far north-west (Leech 1972). Males are about 3.5 to 5 mm in length, and are pale orange to light brown in colour. Specimens are typically collected from the leaf-litter of closed-canopy deciduous forests (Leech 1972; Buddle et al. 2000). From a sample of 653 male C. euopla, I found a total of 309 (or 47%) to be missing either one or both pedipalps. This is an impressive number, and essentially means that about half the males in the population are missing the very parts of their bodies that are required for reproduction. Of the 309 that were missing pedipalps, 124 were missing the left pedipalp, 97 were missing the right pedipalp, and 88 were missing both. In virtually all cases, the pedipalp was severed at the trochanter-femur joint. So the most plausible explanations for missing pedipalps are:

• Pedipalp autotomy occurs during the act of copulation
• The female may remove the pedipalps before, during or after copulation
• C. euopla males may use their pedipalps in antagonistic courtship behaviours
• Perhaps pedipalps are frequently used to grapple with aggressive prey, and are thus damaged.

It would be difficult to relate missing pedipalps to the act of copulation without detailed studies of courtship and copulation in C. euopla. However, the fate of pedipalps could be determined indirectly if the frequency of missing pedipalps increased during the reproductive period. The period of reproduction for ground-dwelling spiders, such as C. euopla, can be assessed from the peak activity period for male and female spiders, inferred from a passive sampling technique such as pitfall trapping. Using a larger data-set for male and female C. euopla collected by pitfall traps set at the George Lake Field Station, it is evident that males are most active early in the season (early May through the end of June) (Figure 1). Females were found throughout the spring and summer months over two years, with a slight increase in late June (Figure 1). These results generally agree with Leech (1972), who suggests May and June are the main periods of activity for C. euopla. Thus, it is inferred that this species will mate primarily in the spring in central Alberta.

The next step is to ask whether the frequency of missing pedipalps is related to the hypothesized mating period. This was done by calculating the average percentage of males with missing pedipalps as a function of sampling date (Figure 2). In both sampling years, the percentage of males with missing pedipalps increased as the season progressed (Figure 2). Although the sample size for July samples was low (12 individuals), the average number missing pedipalps was over 80%. Furthermore, the earliest sampling date in 1999 (6 May), which collected over 200 individuals, had the lowest average percentage of males with missing pedipalps (< 20%). These results indirectly suggest that as the season progresses, and the spiders mate, males begin to lose their pedipalps. I can therefore likely exclude the possibility that palpal loss is related to aggressive prey, and the explanation is likely related to courtship or copulation.

This small study has raised as many questions as it has answered, and there are certainly other explanations that I have failed to mention. I invite fellow Arachnologists to comment on the phenomenon of missing pedipalps in C. euopla, and in other species.  I suspect pedipalp loss is widespread, but seriously understudied. Given this importance of palps to the fitness of spiders, future research is certainly warranted.

References:

Buddle, C. (2001). Spiders (Araneae) associated with downed woody material in a deciduous forest in central Alberta, Canada Agricultural and Forest Entomology, 3 (4), 241-251 DOI: 10.1046/j.1461-9555.2001.00103.x

Buddle, C., Spence, J., & Langor, D. (2000). Succession of boreal forest spider assemblages following wildfire and harvesting Ecography, 23 (4), 424-436 DOI: 10.1034/j.1600-0587.2000.230405.x

Foelix, R.M. 1996. The Biology of Spiders. Oxford University Press.

Knoflach, B., & van Harten, A. (2001). Tidarren argo sp. nov. (Araneae: Theridiidae) and its exceptional copulatory behaviour: emasculation, male palpal organ as a mating plug and sexual cannibalism Journal of Zoology, 254 (4), 449-459 DOI: 10.1017/S0952836901000954

Leech, R. 1972. A revision of the nearctic Amaurobiidae (Arachnida: Araneida). Memoirs of the Entomological Society of Canada 84: 1-182.

Lynam, E., Owens, J., & Persons, M. (2006). The Influence of Pedipalp Autotomy on the Courtship and Mating Behavior of Pardosa milvina (Araneae: Lycosidae) Journal of Insect Behavior, 19 (1), 63-75 DOI: 10.1007/s10905-005-9008-x

Ramos, M. (2004). Overcoming an evolutionary conflict: Removal of a reproductive organ greatly increases locomotor performance Proceedings of the National Academy of Sciences, 101 (14), 4883-4887 DOI: 10.1073/pnas.0400324101

A spider about to launch! Photo by Bryan Reynolds, reproduced here with permission.

Many, many people have recognized this amazing ability of spiders to get to places effectively and quickly.  During his voyages on the HMS Beagle, Darwin observed and commented on this. He noticed spiders landing on the ship when they were far offshore.  Here’s a lovely quote:

      These, glittering in the sunshine, might be compared to diverging rays of light; they were not, however, straight, but in undulations like films of silk blown by the wind.

-Charles Darwin, Voyage of the Beagle, 1832

A wonderful paper titled “Distribution of Insects, Spiders, and Mites in the Air” (Glick 1939) also discusses aerial plankton. In this work, Glick reports on how a plane was used to collect arthropods in the skies – this was done by modifying the plane so it had a collection net attached to it.  Spiders were among the most commonly collected taxa, and were found up to 15,000 ft in altitude.   Glick followed this up with work published in 1957, and spiders were again reported as common aerial plankton.

Convinced?  Spiders really are everywhere and can get anywhere – from dominating the tundra, to floating far above as tiny eight-legged aeronauts.

This takes me (finally) to the point of this post, and some reflection about a paper by Hodkinson et al. (2001), titled “What a wonderful web they weave: spiders, nutrient capture and early ecosystem development in the high Arctic – some counter-intuitive ideas on community assembly”.  In this work, the authors provide some data about aerial plankton in a series of sites representing different stages of succession in Midtre Lovénbreen – a ‘small valley’ glacier in Spitsbergen (a Norwegian high Arctic Island).   This forum paper was meant to present an idea about ecosystem development in the Arctic, with a focus on spiders and other aerial plankton and their relationship to nutrients.

• Spiders are among the first to arrive due to their amazing abilities at dispersal and colonization.

• Many spiders will just die, and their sad, little bodies will decompose and leave behind nutrients.

• Many of the spider species that arrive will build webs, and the silk contains many nutrients. Regardless of whether the silk successfully captures prey, the silk will eventually be a hot-spot of nutrients.

• A lot of other aerial plankton will hit these webs – this will include other arthropods (Hodkinson et al. rightfully point out the importance of Chironomids, or midges, as key prey for spiders in the north) and these prey may or may not be eaten by spiders.  The aerial plankton also includes other ‘debris’ that would be floating around (fungal spores, dirt, etc).  The webs capture all these goodies, and act as a concentrated area for a growing soup of nutrients.

• The spider webs will collect moisture.  In Arctic systems, dry polar-deserts, and many other newly created habitats, the accumulation of moisture is rather essential for continued ecosystem development.

Taken together, Hodkinson et al. (2001) argue that spiders and their webs represent little pockets of concentrated nutrients in landscapes that are void of much other life.  These hotspots could be catalysts for ecosystem development in systems that are starting from scratch.  I really like this idea – not only does is stir up the imagination (little spiders gently falling from the sky, landing on habitat never before touched by animals, and providing the start of an ecosystem…), it really makes some biological sense.  Ecosystem development requires nutrients and substrates – of course, these would both be available without spiders, but our eight-legged friends are helping move things a long a little more quickly.

The paper by Hodkinson et al. has been cited less than I would have expected.   Although they don’t provide any experimental data, their ideas are interesting and relevant and should be studied in detail. Recently, a few papers have come out that are taking the ideas to the next level.  Konig et al. (2011) studied arthropods of glacier foregrounds in the Alps. They found that although Collembola and other ‘decomposers’ are quite important in early successional stages, overall, generalist predators (including spiders) were dominant and using stable isotope analyses, they showed that these generalist predators often ate each other – an interaction known as intraguild predation.

I often discuss Hodkinson et al.’s (2001) paper in lectures, and invariably I get the question “If spiders are first to arrive, what do they eat?“. I typically answer that spiders eat other spiders, and it’s reassuring to see literature that supports this claim.  In turn, intraguild predation itself contributes further to the accumulation of nutrients (more sad, little spider bodies littering the landscape…).

Placing this work in a more general framework, these ideas are pointing to the increased importance of predators in overall nutrient dynamics in ecosystems. I was thrilled to see a paper by Schmitz et al. (2010) that argues “predators can create heterogeneous or homogeneous nutrient distributions across natural landscapes“. Bingo. This is exactly what Hodkinson et al. were arguing – predators, such as spiders, can arrive quickly to an area, and in the context of newly formed ecosystems, may provide a hotspot for nutrients in an otherwise desolate landscape.

Although the Hodkinson et al. paper is over a decade old, it’s still relevant, and quite important. I suspect that if more newly created habitats are studied in detail, spiders will indeed prove to be catalysts for ecosystem development.

References:

Crawford, R., Sugg, P., & Edwards, J. (1995). Spider Arrival and Primary Establishment on Terrain Depopulated by Volcanic Eruption at Mount St. Helens, Washington American Midland Naturalist, 133 (1) DOI: 10.2307/2426348

Hodkinson, I., Coulson, S., Harrison, J., & Webb, N. (2001). What a wonderful web they weave: spiders, nutrient capture and early ecosystem development in the high Arctic – some counter-intuitive ideas on community assembly Oikos, 95 (2), 349-352 DOI: 10.1034/j.1600-0706.2001.950217.x

König, T., Kaufmann, R., & Scheu, S. (2011). The formation of terrestrial food webs in glacier foreland: Evidence for the pivotal role of decomposer prey and intraguild predation Pedobiologia, 54 (2), 147-152 DOI: 10.1016/j.pedobi.2010.12.004

Schmitz, O., Hawlena, D., & Trussell, G. (2010). Predator control of ecosystem nutrient dynamics Ecology Letters, 13 (10), 1199-1209 DOI: 10.1111/j.1461-0248.2010.01511.x

A special thanks to Bryan Reynolds for permission to use his photograph of the dispersing Pisaurid spider.  Please visit his work here.

A very nice Arctic beetle! (photo by C. Ernst, reproduced here with permission)

Here’s a plain-language summary of the work:

Although we often think of Arctic systems as cold and lifeless, Canada’s tundra habitats are home to a high diversity of arthropods (insects, spiders and their relatives). Beetles are important insects on the tundra – filling ecological roles as predators (feeding on other insects), herbivores (feeding on plants), mycophages (feeding on fungi), and necrophages (feeding on dead or decaying animals). In this research, we wanted to find out what happens to ground-dwelling Arctic beetles as a function of seasonality. We were curious about whether different species occurred at different times during the short Arctic summer, and whether the functions of the beetles changes over the summer. This is an important area of study because beetles perform important ecological functions, and knowing how these functions change over time may have broader implications for northern ecosystems. This is especially relevant in the Arctic since these systems have a short ‘active season’, and climate change is disproportionally affecting northern latitudes. If climate change alters an already short summer, what might happen to the beetles?

This research was done as part of the Northern Biodiversity Program (NBP) – a broad, integrative project about the diversity of insects and spiders across northern Canada. The NBP involved collecting samples at 12 sites in the Arctic, but at one of these sites (Kugluktuk, in Nunavut) we had an opportunity to do a more detailed collection over the entire summer of 2010. This involved setting out traps for the entire active season, from June through to August. These traps were plastic containers sunk into the ground – beetles that wander along the tundra fall unawares into these traps, which contain preservatives, and are trapped until a researcher collects the samples. Traps were placed in wet and (relatively) dry habitats so that we could compare the two habitats. After the collections were returned to our laboratory, the beetles were identified to species, counted, and the biomass of the beetles was estimated – biomass lets us determine what happens to the ‘amount of beetles’ on the tundra in addition to figuring out ‘how many’ (abundance) and ‘what kind’ (species) were in the traps. The beetles were also classified into their key ecological roles. The data were then compared as a function of when traps were serviced to let us assess what happens to beetles as a function of seasonality.

We collected over 2500 beetles, representing 50 different species – remarkably, 17 of these species represented new Territorial records. This means that 17 of the species that were identified had never before been recorded in all of Nunavut! Although many ecological functions were represented by the beetles we collected, most were predators. We documented that wet habitats had different kinds of beetle species than the drier tundra habitats, even though the actual number of species between the habitats did not differ. We also uncovered a seasonal affect on the functions of beetles in the system – as the season progressed, the beetles tended to be represented more by predators compared to earlier in the season, which was dominated by beetles representing a diversity of functions. The mean daily temperature also related to the seasonal change that was observed in the beetles.

PhD student Crystal Ernst, happily working on the Arctic tundra.

This work is one of the first to carefully quantify how beetles change during short Arctic summers. We found a diverse assemblage of beetles, filling a range of ecological roles. These ecological roles, however, do not stay the same all summer long, and the shifts in the beetles were related to mean daily temperature. Given that Arctic systems will be significantly affected by climate change, this is worrisome – if temperatures increase, or become more variable, this may affect ecosystem functions that are mediated by beetles. This is more evidence supporting the need to track climate change in the Arctic, and play close attention to the small animals of the tundra.

Reference:

Ernst, C., & Buddle, C. (2013). Seasonal patterns in the structure of epigeic beetle (Coleoptera) assemblages in two subarctic habitats in Nunavut, Canada The Canadian Entomologist, 145 (02), 171-183 DOI: 10.4039/tce.2012.111

1. Just look at this SEM of a pseudoscorpion!

A little while ago, my Arachnid friends and colleagues from Alberta, Heather Proctor and Dave Walter, forwarded me a stunning image of a pseudoscorpion taken with a scanning electron microscope (SEM).  Dave was kind enough to give me permission to share it here:

SEM of a pseudoscorpion (Chernetidae) – copyright D. Walter (reproduced here with permission)

There really is something lovely about getting up close and personal with these little Arachnids. I don’t know this species, but it’s definitely in the family Chernetidae – a relatively diverse family, quite common across Canada.  My favourite Yukon species, Wyochernes asiaticus, is also a Chernetid.   Dave Walter really does some magic with his SEM images, and you are encouraged to check out is macromite blog (his home bug garden blog is also worth a peek!).

2.  Just look at these videos about collecting pseudoscropions in the wild! 

Speaking of my favourite Yukon species, I took a lot of videos of field work in the Yukon last summer and I wanted to share a few with you, here.  Although our larger purpose for the trip was to complete some follow-up field work for the Northern Biodiversity Program, I also wanted to collect additional specimens of a wonderful pseudoscorpion species.  The first video provides some context to the work, and gives you a bit of a flavour of the landscape up near the Yukon – Northwest Territory border in Canada:

Typically, pseudoscorpions are not that commonly encountered.  In my experience, when they are encountered, you tend to see one or two.  What is truly amazing is the sheer abundance of this species found under rocks in creek/river beds in the Yukon.  Furthermore, you can see and collect multiple life stages, including females with eggs.  This short video gives a taste for this abundance.

The third and final video is a big goofy, and highlight the ‘collecting gear’ and appropriate field attire for becoming a “pseudoscorpion hunter“.  I am continually on a crusade to help generate enthusiasm for Arachnids, whether it is dispelling myths, or trying to inspire others to become Arachnologists (you know, we do need Arachnologists in Canada!).

One important caveat:  you may NOT simply run to the Yukon and flip rocks to collect pseudoscorpions – many parts of the world, including the Yukon, have strict guidelines about what you can collect.  Permits are required, and be sure to check into this before you plan on becoming an Arachnologist!

3.  Just look at this pseudoscorpion necklace!

To further illustrate my rather quirky obsession, I managed to find a wonderful person on Etsy who was able to make me a pendant with a pseudoscorpion design:

The pseudoscorpion necklace. You want one.

Not only that, this design is actually from a photography I took a few years ago, and is an accurate depiction of the cosmopoliton species Chelifer cancroides.

Chelifer cancroides – my photo which was used to design the pendant

I KNOW you want to get yourself one of these… start a conversation with Lynn.  Get yourself one of these necklaces and stand proud with other pseudoscorpionologists!

In sum, I do hope you find this post interesting, hopefully fun, and has whetted your appetite from more information about curious critters.

Stay tuned… I will continue to post more about Arachnids…

Laura identified a LOT of wasps, recorded the type of host attacked (e.g. plant-feeding hosts versus hosts that are predators), and the body size of two species of wasps that were commonly collected in all time periods.  We found no clear pattern of change in most aspects of the parasitoid wasp community on Ellesmere Island over past 50 years, even though temperature and precipitation have increased significantly during the same period. However, there were some signs that parasitoids of plant-feeding insects may be more affected more than other groups: one common parasitoid species that was abundant in 1960s hasn’t been collected since then, and the community in the 2010 study contained fewer parasitoids of plant-feeding insects than previous studies.

Some members of the Northern Biodiversity Program working in the Yukon in 2012. (l-r, Chris Buddle, Laura Timms, Crystal Ernst and Katie Sim)

Laura takes it as a good sign that no major changes in the ecology of the high Arctic parasitoid community have been observed, but isn’t taking it for granted that the community will remain unaffected for long.  At 82°N, Ellesmere Island is relatively isolated, but other research has found that parasitoid communities further south are changing dramatically (Fernandez-Triana et al 2011).

Laura has the following comment about our work: “We hope that our findings will be used as baseline data for ongoing monitoring on Ellesmere Island”, said Timms.  “We know so little about these high Arctic insect communities, we should learn as much as possible about them while they are still intact.”

References

Timms, L., Bennett, A., Buddle, C., & Wheeler, T. (2013). Assessing five decades of change in a high Arctic parasitoid community Ecography DOI: 10.1111/j.1600-0587.2012.00278.x

Fernandez-Triana, J., Smith, M., Boudreault, C., Goulet, H., Hebert, P., Smith, A., & Roughley, R. (2011). A Poorly Known High-Latitude Parasitoid Wasp Community: Unexpected Diversity and Dramatic Changes through Time PLoS ONE, 6 (8) DOI: 10.1371/journal.pone.0023719