Gray-fronted Dove

Mar23

This post is gonna be short; Catherine and I a prepping for a very long roadtrip to Texas, LA, and eventually to BC to start Catherine’s field season. This is just a video of a Grey-fronted Dove (Leptotila rufaxilla) feeding nestlings at the Nouragues Station in French Guiana.

This nest was right beside the showers in camp, and to get this footage, I set up my camera and started recording, leaving it there until the card filled or the battery ran out. This was a labour intensive process, as the majority of clips recorded were just the bird sitting there and the chicks sleeping.

I think that this clip of feeding made it all worthwhile though, as it gives a rare view of how the chicks “plug in” to the adult to receive their meal of “crop milk”

Weekend Expedition 70: Mississauga/Credit River

Mar7

On Sunday, Catherine and I went out to Mississauga, where we met up with Gil Wizen, one of my favourite macrophotographers to go out for a early spring hike around the woods above the Credit River. It was such a treat to be out with a fellow invertebrate zoologist, not having to explain why exactly we should flip over a given log, or pull up a piece of loose bark…How very rarely do we get to go out in the woods with another person with the same agenda!

The forest was snowy, but warming, and we are anticipating a major thaw through the week….Very soon, the famed Ontario salamander fauna will be on the move to vernal pools for breeding. This weekend we did not find any salamanders, but we did find a great variety of cool arthropods, thanks in no small part to diligent searching by Gil.

The wooded bluffs above the Credit River, near the Mississauga campus of U of T was where we wandered. The geology of this place looks pretty fascinating, with some thin layers of sandstone very near the surface, often pushed upward by tree roots.

Catherine and Gil on the way to the forest.

The mixed forest seemed to have abundant birdlife, and it would be good to come by earlier or later in the day to see if we could find some owls…

Many of the birds were doing what we were doing, probing under bark and looking in crevices for invertebrates.

One of our very first finds was also one of the coolest: A Dolomedes tenebrosus, looking fat and happy under some loose bark. This is a species in the fishing spider/nursery web spider family (Pisauridae), and it is usually found near water. They are undoubtedly major beneficiaries of abundant aquatic insect hatches in certain seasons.

Here is the same spider resting on a block of the sandstone cap that we found thrust up near the tree roots. The large eyes of these pisaurids are evident, and hint at relationships with wolf spiders, also in the Lycosoidea clade.

We found a much smaller Dolomedes tenebrosus nearby under some leaves. Interestingly, both of these spiders seemed not strongly affected by the cold, and were able to move about even though it was hovering near zero.

Gil examines a rotted and fallen trunk. I asked him whether he had done this sort of think since childhood, and it seems that like me he has always flipped logs and rocks looking for invertebrates. A born naturalist!

A caterpillar of Idia lubricalis (a hermiine erebid), also found under leaves. Thanks to Gil for the ID!

Like the previous week in Crother’s Woods, we also found a number of crab spiders and running crab spiders. Here is a running crab, likely a Philodromus species.

A small (Handsome Fungus, family Endomychidae) beetle found in fungus-rotted wood. This one has a very pleasingly-shaped pronotum and daintily-clubbed antennae.

Gil also uncovered some tiny psuedoscorpions, which was a treat to see.

Many thanks to Gil, for leading us to a very productive patch of woods. We look forward to getting out again soon!

Serious gull baths

Jan1

Catherine and I went to Beacon Hill Park yesterday, and were delighted to see some gulls having a pre-New Year’s bath in one of the ponds. With the winter sun making good highlights, the shots were a natural choice for pictures. What really strikes me about these bathing gulls is how they seem so serious about their hygiene routine. I suppose with the cold winter weather it helps to have maximum floof potential in your feathers before a long cold winter night.

Some winter spiders at Island View Beach

Dec31

Catherine and I are back in BC for Christmas, hanging out with my mom in Victoria. The weather has largely been atrocious, so the photo opportunities have been scarce. However, the past couple days has seen a bit of clearing, so we headed up to Island View to see what we could see.

A small male Pardosa was the first wolf we saw, and was surprisingly active, despite the freezing temperatures.

A larger female wolf was a bit less active, but still good to see.

Though the weather is cold, prey are still around and active, and in fact the widows we saw still had small capture webs. Not sure if they ever snack on these termites, but it is possible.

Many of the female widows were quiescent, though some could still move about.

As usual, there were immature males hanging out on the periphery of the females’ webs. These “winter males” are bigger, bulkier, and more like females than the summer crop.

It is likely that these “winter males” undergo more molts to achieve their greater size, and perhaps the bulk is needed to survive the freezing temperatures without feeding much. They could be well placed to secure early matings in the spring.

We traveled about the beach quite a bit, and believe now that the good widow habitat might be more extensive than we previously thought. It will require some careful mapping to determine though.

After returning from the beach, I went up to Mt. Tolmie and saw some more widows, including this large female, who was entirely black underneath. The habitat here is more patchy, but still supports decent widow populations.

At both Island View and M. Tolmie, we found quite a few overwintering cutworms.

Also found a tiny gnaphosid, which may be Sergiolus.

I ended the spidering by uncovering a sleeping Phidippus, under a small rock.

Counting wasp attacks: investigating alarm pheromones in yellowjackets

Nov30

This is a post to announce my new paper, which has a bit of a mouthful for a title: Developing a paired-target apparatus for quantitative testing of nest defense behavior by vespine wasps in response to con- or heterospecific nest defense pheromones

This is a paper that was long in the making, and there are two important things you should take away from it: 1) the bioassay setup is cool and 2) three species of the genus Vespula recognize each other’s alarm pheromones

OK, so why alarm pheromones? Well, many social insects coordinate their defences against predators using chemical signalling. These signals can arouse a colony into defensive behaviour, and often can be applied to attackers to attract other workers to attack the intruder. In some cases these chemicals are one and the same, in others, they may be different. No matter! Although our efforts here were part of an attempt to describe the alarm pheromone chemistry of these yellowjackets, we never did succeed in isolating the exact chemicals needed to mimic the naturally-occurring alarm pheromones.

Vespula pensylvanica, the western yellowjacket

Vespula alascensis, the common yellowjacket

Vespula germanica, the German yellowjacket

Many wasp species have their alarm pheromones in their venom sac, and presumably, when disturbed extrude a little venom to signal other workers, or deposit venom on nest predators to “mark” them for attack by the colony. We worked with three species of yellowjackets, Vespula pensylvanica, Vespula alascensis and Vespula germanica. The substances we tested in this study were venom sac extracts of these wasps dissolved in acetonitrile, an easy-to-work with polar solvent.

We dissected out venom sacs (the translucent jelly-bean looking thing) and crushed them in acetonitrile, at a rate of 1 sac per 10 microliters. We filtered the extracts and stored them cold for later use.

To test the effect of the putative alarm substances in these extracts, we needed a bioassay device. Because no standard protocol existed, I designed one that I hope will become the standard for any future experiments:

The paired-target bioassay

In 1995, Visscher and Vetter (yes, that Vetter! The spider guy!) developed a resonant-target attack counter for use in quantifying defensive attacks by yellowjackets and bumblebees. It so happens that when these flying stingmeisters attack, they fly at high speed toward their victim and strike it with force. Visscher and Vetter’s device utilized this important fact by surrounding an audio microphone with a resonant plastic target, and using an electrical counter to count the hits. The device requires construction of the counting circuit, but I thought, why not just record an audio file and count the strikes later?

Basically the device I designed is an elaboration of Visscher and Vetter’s strike counter, only it can be assembled with off-the-shelf components, and utilizes free software to count the strikes recorded to an audio file. In addition, my design is explicitly for use in paired assays, as wasp attack behaviour is often quite variable from one situation to the next, and experiments to test the effect of alarm pheromones can benefit greatly by pairing the treatment and control in each replicate. Think of it as blocking! at 9 am, the wasps are really feisty, and hundreds come out to strike, at 10:30, the attack is less fierce. If we did a control run with a single target at 9, and a treatment target at 10:30, we would be misled, but with a paired design we can determine that our treatment has an effect in both replicates. This saves immensely on the number of replicates required to see a difference.

OK, so here is how the device looks:

The vast majority of the components are very easy to acquire, and the only construction requires a bit of drilling and screwing in of wingnuts and bolts. Everything else is off-the-shelf, and the device folds up neatly for transport and storage. The targets are formed from thin black polystyrene weigh boats, which make a drum-like sound when struck, and they can be disposed of between each replicate so that residual alarm pheromone is not a problem.

Onour Moeri bringing the paired target device to the wasps.

Here is what it looks like when a wasp strikes a target:

The basic process of doing a bioassay is to place the device so that the targets are equidistant from the nest entrance, apply a test substance to one target, a control solvent to the other, start the recording, and then tap the nest entrance to get the wasps activated (note, this step not ALWAYS needed! Some nests are on high alert anyway!)

Here is a video of the device in operation, with audio derived directly from the paired microphones. In this case, the pheromone extract is placed on the left-hand side of the device.

After each assay, the device is removed, the targets replaced, and then the treatment and control are re-applied for another replicate. I always alternated the left-right placement from one replicate to the next, to avoid any side bias.

After a number of replicates (at least 10, better 15 to 20), the audio files are offloaded from the digital recorder, and split into treatment and control files for each replicate. You can use Audacity (a freeware program) to do this.

A simple oscillogram of each file often shows an effect: This is how the two oscillograms look for the left (top) and right (bottom) channels. As you can see, the left hand side experienced more strikes in this short clip.

But how to count these strikes effectively? Well, the solution is another freeware program, SoundRuler, developed by Marcos Gridi-Papp for his teaching in bioacoustics. My application of this software is really wasting its potential, but it works quite well for counting these loud percussive strikes!

In the SoundRuler interface, some simple rules for counting the strikes are programmed in, then automated counting of the entire range desired is simple:

The SoundRuler interface with an open audio file of 240 seconds.

The same file after automated counting enabled. In this case, 123 strikes were counted.

Alright! So that is the development of the paired-target bioassay device, as well as its operation. What did we use it for?

Well, we tested whether three species of ground nesting yellowjackets, Vespula pensylvanica, Vespula alascensis and Vespula germanica have an alarm pheromone in their venom sacs. We also tested whether or not these species would recognize the alarm pheromones of the other species. It turns out that they do!

So what would be the advantage of responding to the alarm pheromone of another yellowjacket species? Well, each of these species has a very similar life history, being ground-nesting, and needing to defend the nest from the same kinds of predators (bears, skunks, raccoons, humans). I can see the advantage of responding early to a “pheromone-marked” predator which had just attacked another species, stinging it and driving it away before it has the chance to attack your own nest. These alarm pheromones probably evolved once in the vulgaris species group, and there was no selection for differentiation, and possibly selection against it.

So there you have it! An inexpensive, easy to construct bioassay device that you can use to test alarm pheromones in large stinging wasps! A counting protocol that is easy and fast! What more could you want? Well, I suggest that the first thing you could wish for is very good luck and/or insight into the complicated chemistry of these alarm substances, but this study has at least provided some new tools to get there.

OK! So that is the paper. I hope you enjoyed it, and be sure to read the whole thing over at the journal website! In the meantime, please enjoy these awesome pictures of the bioassay device in operation.

A Birthday Outing in High Park

Nov18

So yesterday was my birthday, I am a little older and a little wiser, I think. Because the weather was fine, and I had not been out to take pictures recently, I decided to treat myself to a day of photography in High Park. The weather here in Toronto is getting much colder now, so it was a good thing that I got some awesome presents from Catherine to keep me warm.

A thick, warm hat, a thinner lighter hat, a wonderful sweater and a cool mug!

It was even personalized for me!

This mug is based on a design I made for a t-shirt a few years ago. It derived from a photo, and I manipulated it in Photoshop to look like a woodcut. If you want one yourself, click here. All proceeds to the Caracara Research Foundation (actually most proceeds is profit for Zazzle). If we can sell 40,000 of these, we are in business!

So there is still a little bit of colour in the trees, but they are looking mighty stark. A deciduous forest in winter is a place with very little shade and you can see into it quite fa. As for arthropods, I did not see many!

I found four of these bald-faced hornet nests. I do not have the same rate of discovery in the summer, when there are actually hornets around!

This is what the Eastern Gray Squirrel looks like when alive in its native habitat. There are an absolute ton of them in High Park, about evenly mixed between black and gray morphs. These rodents feed on seeds, primarily acorns, as well as handouts from people. I saw another one eating a tortilla. With this abundance of squirrels, there are also squirrel predators, such as Red-tailed Hawks and a few owls. I saw a hawk, but no owl, but I did find this:

A raptor pellet comprised mainly of squirrel fur. I looked around in the few conifers nearby for hiding raptors, but did not see any. The way a still bird can hide against the bark though, makes me think one may have been there anyway.

One advantage of winter is how low the sun stays all day. Even near noon you can find this slanting angle of light that is much more flattering to subjects than full sun in summer.

The squirrels were the most abundant wildlife I saw, even outnumbering people on this cold Tuesday. I think Toronto could use a good crow population though, as I kind of miss them!

At the southeastern end of the park, I came upon a small flock of chickadees and a couple cardinals. This is a female that appeared to be accompanying a male. I wonder if their pair bonds persist through the winter….

The male remains pretty splendid, even in winter, and these birds are not very shy. They are certainly more brightly coloured than the cardinals I saw in French Guiana!

So that about sums up my birthday walk in the park. It was not the most productive trip, and as winter sets in I would hope to have better photography days once in a while. One of the difficulties of Toronto compared to Vancouver is that Toronto is a place that animals migrate FROM rather than TO, as it is pretty much smack in the middle of a very cold continental region. There will be no winter hummingbirds, or loons or even many ducks. Just the hardy chickadees, nuthatches, jays and others that make this cold place their home year-round.

A fall ramble: High Park and Humber Bay

Nov2

Because Ontario is harsh, and the invertebrates are quickly going to ground, I decided to do two days of outings this weekend! In addition to our trip to Leslie Spit on Saturday, I went out alone to High Park on Sunday to see what I could find.

The herbaceous vegetation was mostly dead, with very few insects out and about.

I found these Leptoglossus occidentalis (western conifer seed bug) behind some boards, getting ready to overwinter. These were not present in Toronto when I was a kid.

Behind the same boards I also found a Agelenopsis on an egg sac. I replaced her carefully after this shot.

This very orange Araneus diadematus was also on an egg sac. She also posed, and then I put her back on her sac. It is doubtful the adults ever survive the winter here.

This Phidippus audax was much more orange than others we have found so far.

Not sure why it was missing a palp, but it will probably regrow, as this one was still small.

At Humber Bay, I found some hungry wasp queens. Luckily I had a vial of honey on hand. This one ate so much she could barely fly afterward, but it should fatten her up for the winter.

Yum!

I was delighted to find this brown snake, AKA Dekay’s snake (Storeria dekayi) moving along a fence.

I encountered these small snakes often when I was a kid. The juveniles of this species are quite beautiful,and the adults have their own subdued charm.

These snakes are natricines, related to garter snakes. They occur in Eastern N. America all the way down to Guatemala.

This shot shows the faint iridescence of the scales

All in all, I was glad I went out! This kind of break from the downtown chaos will hopefully keep me sane!

Spider predation!

Jul9

Nothing to see here, just a couple of cool spider species engaged in predation!

Misumena vatia (in white form) consuming a fly. These are called the goldenrod crab spider, but I find them on may flowers.

This plump one was the same one I had photographed on foxglove in the last post.

Misumena vatia in the yellow form with a fly. This one is not yet an adult.

Ambush predators are so cool.

A Phidippus jumping spider with another jumping spider!

You could share this and say she is carrying her babies to safety…Who will believe you will tell you a lot about your friends!

I wonder if these spiders make a lot of their living by preying on other jumpers. They seem to relish them!

So cool!

Country living

Jul6

So Catherine and I are enjoying a stay deep down south in Langley. We are about 200 m from the US border, and are house, dog, cat, and mouse sitting here for Sofi and her partner Brian. The animals, being motile, homeostatic organisms, are quite easy to care for. The plants, during this ridiculous heatwave and drought, are suffering, even with daily watering!

Anyway, this is our home and family until Saturday, and we plan to make the most of it!

Callie, the dog, is one of our companions during our county sojourn.

Misto the cat looking elegant. What you can’t see is his special butt-hair trim that will spare us the pleasure of cleaning his rump daily.

Oreo the cat, an escape artist, has successfully broken out 3 times during our residency. We used a camera to document his route, and sealed him in for good.

Oreo the cat, an escape artist, has successfully broken out 3 times during our residency. We used a camera to document her route, and sealed her in for good.

In the back 40 are some rabbits, deer, and coyotes. Here is a baby bunny that lives near the woodshed.

Familiar faces are to be found here too: there are lots of cellar spiders!

Here is a common house spider (Parasteatoda tepidariorum) with a great brood of eggsacs.

Out on my morning walk with Callie I found this gorgeous Misumena vatia (goldenrod crab spider) with a big catch.

Here is some more successful predation, this time an Enoplognatha ovata with a crane fly.

There are a bunch of Rufous Hummingbirds here, many of them brood of this year.

Again, out for a morning walk with Callie, I shot this gorgeous Tibellus oblongus (a type of running crab spider) with an egg sac! I really took a lot of pics of this beauty, so let me know what you think!

Mixing in dawn light is one of my favorite techniques at the moment.

Against blue sky, because why not?

A Meet your Neighbours style shot.

Probably my favourite, this one against the hazy dawn sky (there are forest fires nearby!)

This one is shot with the YongNuo 35 mm with a Raynox DCR250.

Another with the 100 mm.

To round out this post, here is another crab spider, this time a male of Misumena vatia, with spider prey. I believe the spider is a sac spider (Clubionidae).

Rattlesnakes!

Jun29

I have been a bit remiss in continuing to tell the story of the trip Catherine and I took to the Okanagan Valley this spring. I apologize, and in recompense, offer one of the most exciting observations we made.

One of the species we had most hoped to see was the Pacific Rattlesnake, Crotalus oreganus. I was anticipating that being early in the spring, the snakes would still be close to their winter denning sites, perhaps engaged in mating. As it turned out, we were too late. The snakes had already left their den sites for more productive hunting grounds further down the valleys.

The Pacific Rattlesnake is BC’s only rattlesnake, and like many northerly populations of rattlesnakes, is a threatened species. The reasons for the rarity of these snakes is that they have been persecuted by humans, and their habitats are being threatened by development. Persecution of these snakes was particularly damaging as they rely on safe hibernation sites, free of freezing conditions, and must migrate to these sites en masse in the fall. This means that entire populations of the snakes may end up in just a few suitable caverns, where humans can find and destroy them. This is in fact what has happened, not just in BC, but all over North America wherever these denning sites occur. In BC, there was a bounty on the snakes, and some people made it their mission to destroy every snake they could, dynamiting and gassing the dens.

Snakes and roads don’t mix: my unfortunate first encounter with a Pacific Rattlesnake. The snake was decapitated by a truck I was driving, Aug 22, 2008.

In addition, the seasonal migration also poses extreme risk as the snakes must often cross roads to get to where they are going. Needless to say, cars do not mix well with snakes, and death on the roads is undoubtedly a major threat to the species. I know this all too well, as my first encounter with this species was a fatal one. Years ago, I was driving a truck doing fieldwork in the Similkameen, and hit a snake on the way to a campsite. I felt terrible about this, but by the time I saw the snake, it was too late.
Later that evening, I walked out on the road I had driven up, and saw 7 more freshly killed rattlesnakes! This was likely due to an active log hauling operation using the roadway, but really even a modest amount of vehicle traffic would kill snakes. The 8 I saw killed that day is a ridiculous amount of excess mortality for a long-lived and not very fecund animal, and it means that the population of these snakes is in decline.

On the lookout for snakes, spiders and whatever else we could see.

Every time Catherine and I were in likely areas, we would look at potential den sites with eyes keen for the snakes, but to no avail. We had a bit of inside info on historic den site locations, and so we felt well-prepared. Alas, the snakes did not show up. It was not until late in our trip that we checked out a site near Vaseux Lake. Here again we did not find any rattlers, but we did find a snake-catcher’s equipment in one of the likely den sites: tall boots and a large bucket. This was likely from someone in animal control or perhaps a pest control business that had used these to transport rattlesnakes to the den from someone’s house or other building in the fall (sometimes the snakes will end up in these locations on the way to their dens). This was most encouraging!

We occupied ourselves taking pictures of spiders and insects in the grasslands near the bluffs, always with an eye out for snakes. In the same area where we found the racer, I finally spotted one!

This was quite a small snake, and when I saw it, it was fleeing our approach (I had thought they might just stay still, like Bothrops). Unlike most snakes which I am familiar with, this is a pitviper, adapted for camouflage and ambush predation, rather than quick flight. We wanted to get some photos, so I picked the snake up on my monopod and placed it in an open area. The little snake was obviously not too pleased with this, but only gave a halfhearted, barely audible rattle. In addition, at no time did the snake strike the stick. It was fairly easy to keep the snake in place just by moving the monopod in front of its head, and it soon just settled in a defensive coil. This made it very easy to photograph, although if I had a polarizing filter for the brilliant sunshine, the shots would have been better!
The ease I had handling these snakes is in stark contrast to just about every other snake I have met. They are relatively slow and cumbersome animals (though the strike is likely very quick). I have no doubt any reasonably capable adult could move any “threatening” snake from their premises easily with a large bucket and a stick. Nonetheless, these snakes are still regularly (and legally) killed to “protect life and property”, which means that enforcement of their protected status is a nebulous concept.

The snake was absolutely beautiful, with chocolate-brown patches on a cream background.

This eye-level shot shows off the heat-sensitive pits (large holes on the front) which the snakes use to sense their warm-blooded prey. The vertically-slit pupils are a hallmark of predominantly-nocturnal snakes.

Landscape with reptile: a wide and close shot to show the surroundings.

This shot (like many of the previous shots) used a bit of fill flash in order to make the snake stand out.

This is how the snake looks in the grass. Very obvious if moving, but if coiled under a plant, it would be hard to spot.

After a short session (we did not want to stress the animal too much), I nudged it under a large rock, which would be a safe place for the animal to hide.

With these photos, it is obvious that the animal was manipulated into position for photography, and some might take issue with this from an ethical standpoint. I see where this comes from, and I agree somewhat. The snake obviously does not like being handled, and in point of fact, the majority of snakebite accidents probably happen as a result of handling. That being said, from the standpoint of this snake, what has occurred is that the snake was threatened, it could not escape, it stood its ground, and the dangerous animal (me) went away. In the life of one of these snakes, with hawks, cattle, dogs and cars to contend with, this is really small potatoes.

Anyway, it wasn’t long before we found a second, slightly larger rattler. This one was also fleeing, and in fact did not need capturing, as it took shelter under my backpack, getting caught around the straps in the process. Getting it into position for photography was just a matter of moving the pack to an open area and coaxing the snake out.

snake in a pack! Photo by Catherine Scott.

removing the reptile. Photo by Catherine Scott.

The sun was definitely more harsh in this shot, and a polarizing filter would have come in handy! You can tell that this larger rattler has molted more times than the other, as its rattle has more segments.

With this snake, I tried the 300 mm. It compresses the perspective, makes the colours pop a bit, and overall emphasizes the snake.

Again, a wide and close shot to put the snake in the landscape. This accomplishes the opposite of using a telephoto, but can also produce a pleasing composition.

After a short photo session, the snake just disappeared into the next rocky overhang. And that was the end of our rattlesnake adventure!

Ibycter

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