For the very last post of Arachtober, I thought I would take some shots of the Halloweeniest spider on the west coast, Dysdera crocata. These orange and red beauties are specialist predators of terrestrial isopods (pillbugs) and have fangs equal to the task of envenomating these armoured prey. 
Female Black-throated Antshrike. Photo by Phil Stouffer. What an impressively fierce-looking bird!
Remember my post last week on the White Woodpecker preying on wasp nests? Well,if you browsed that issue of Revista Brasileira de Ornithologia, you may have noticed that I published an article on a similar topic!
This is another account of a bird preying on wasp nests, one that was completely unexpected. This involved the Black-throated Antshrike, Frederickena viridis. Black-throated Antshrikes are members of the Thamnophilidae, or antbirds, a largely Neotropical family known for being associates of army ants. Basically, these birds “attend” army ant raids and parasitize the ant colony by quickly grabbing the insects, lizards and arachnids that flee the approaching ant swarm.
Eciton burchellii army ants. These impressive swarm raiding ants kick up quite a lot of prey from the leaf litter, which antshrikes are only too happy to steal.
During fieldwork in 2010, we caught a male Black-throated Antshrike is doing its own dirty work, striking wasp nests, causing the wasps to abscond, and feeding on the brood. Here is the video (edited for time, as the whole attack sequence lasted 42 min):
A: Polybia scrobalis B: Polybia bistriata
The two wasp species in question were Polybia scrobalis and Polybia bistriata, which we had placed in a video arena for our experiments documenting Red-throated Caracara feeding behaviour. In some ways, you could say that the antshrike was parasitizing us! This was all recorded as intended by our automated video system, which reacts to motion in the video stream and records the action with a 5-s pre-recording buffer. On that morning, my field assistant Tanya Jones and I were just getting up and having breakfast when this antshrike was attacking. By the time we were done breakfast, the antshrike was too!
A few things to note: Unlike their behaviour with the Red-throated Caracaras, this Polybia scrobalis colony fought back. At 0:30, 1:22 and 1:45 in the video, you can see wasps attacking the antshrike, and in the second two instances, the antshrike plucking off the wasps.
Wasp on antshrike at ~30s
Wasp on antshrike at 1:22
Wasp on antshrike at 1:45
For comparison, here is an attack on the same wasp species by Red-throated Caracaras:
So why do the wasps attack the antshrike and not the caracaras? Can these wasps can evaluate the threat posed to the colony and adjust their defence/retreat appropriately? Maybe the wasps somehow evaluate the odds of successfully driving away a predator and abscond if nest defence is likely to be hopeless. After all, the workers which are killed in nest defence are still a loss. Continued defence piles up the losses, and if defeat is inevitable, it is better to retreat with your worker force intact.
Alternatively, it could be that the colony the caracaras attacked was worse off in some way, and more likely to abscond, but the possibility remains that wasp defensive behaviour against vertebrates is plastic. There is definitely room for some exciting research here.
Considering the White Woodpecker, the Black-throated Antshrike, and the Red-throated Caracara (among others) it seems that more and more vertebrate predators are being found that prey on wasp nests. In these cases, it appears that the birds are minimizing the risk of stinging by inducing the absconding response of their swarm-founding prey before moving in close to feed on the larvae.
While I was a little upset that these nests fell to the antshrike rather than giving me more data on caracara predation, getting a paper out of it and learning something new was well worth it.
Male Black-throated Antshrike. Photo by Phil Stouffer.
October is a month for spiders, being the time when many of the species which have grown large on summer’s bounty are settling down to lay eggs, or looking for overwintering sites. For spider photographers, it is like golden hour all month! If you search flickr for “Arachtober” you will find the photographic bounty that macrophotographers have amassed.
This Arachtober, I have not really been applying myself to spider photography, although I have made some dedicated efforts to secure shots of black widow defenses (for Catherine’s invited talk at last weekend’s ESBC conference), or Steatoda males and females, for my friend Chloe Gerak’s award-winning talk at the same conference.
Anyway, here are some shots and thoughts about my Arachtober.
Western black widow throwing silk on Catherine’s finger at Island View Beach.
Catherine gave a great talk on “dangerous spiders” at the ESBC conference, her first 1/2 hour talk. Her t-shirt (thanks Alex Wild!) serves as a great abstract of the talk.
Female Steatoda grossa with a bit of backlight highlighting her web. False black widows around here are not very black!
Chloe after delivering her awesome, award-winning talk entitled “How the false widow finds true love”.
Male and female Steatoda grossa juxtaposed for comparison.
A largish sac spider (Clubionidae) showing the large chelicerae typical of the family.
Putting the light a little behind the spider can help resolve some of the surface details and maintain a bit of mysteriousness at the same time.
More direct light makes for a less moody feel as the sac spider drinks water on a colourful leaf.
Arachtober is also a scary time for spiders. Here is an emesine thread-legged bug I found in a spider retreat, where it was likely feeding on spider eggs.
Fall foliage makes for a wonderful seasonal backdrop for this Hallowe’en spider villain.
This weekend was quite busy, with the Entomological Society of British Columbia conference taking place Friday and Saturday, taking up most of my time. The conference was quite good, and Catherine and I gave some well-received presentations. This Sunday, I celebrated by heading out to see what I could see in Stanley Park.
The fall colours really make for some gorgeous backgrounds, especially thrown out of focus with wide apertures.
The omnipresent diurnal raccoon crew near Lost Lagoon.
I added some more to my body of crow portraits. I especially like this one’s mouth!
Such gorgeous birds!
Not much was happening on the insect front, perhaps because of the recent heavy rains. I found this Meconema in the rhododendron garden.
Herons are always fun to shoot, even in relatively boring light.
Amanita muscaria, looking good enough to eat (probably shouldn’t though!)
Melanerpes candidus approaching the nest of social paper wasps. Photo by Miguel Rangel Jr. used under terms of a CC-BY-SA licence.
In the latest issue of Revista Brasileira de Ornithologia, I found a paper on a topic near and dear to my heart: birds preying on wasp nests. In this case, it is an account of the White Woodpecker, Melanerpes candidus preying on the nests of Polybia paulista. In this paper, Ivan Sazima describes the predation tactics used by this woodpecker when attacking a large, well-defended nest. Ivan conducted this research at Parque Ecológico Prof. Hermógenes de Freitas Leitão, in the state of São Paulo, Brazil.
Like the Red-throated Caracaras I studied, the White Woodpecker appears to exploit the absconding response of these swarm-founding wasps in order to secure its meal of wasp brood. Rather than inflicting rapid, catastrophic damage, however, the woodpecker takes its time, approaching the nest gradually and tapping the branch to which the nest is attached. During this approach, some of the wasps come out to sting, and if this gets too fierce, the woodpecker will retreat. Sazima attempted this tactic himself with a similar nest of P. paulista, and got stung severely for his efforts. Sazima suspects that the continuous nature of the woodpecker’s disturbance is what is required to induce the wasps to abandon their nest. Also, the agility of the birds at evading attacking wasps also means they can keep this harassment up longer than an unprotected human.
This paper is a valuable contribution to the study of wasp and bird behaviour, as it highlights that certain anti-predator strategies of social wasps (stinging, alarm recruitment) can be defeated by exploiting the evacuation swarming (absconding) behaviour of these wasps. Bearing this in mind, it is no wonder that so many species of swarm founding wasps have cryptic nests to escape the detection of diurnal vertebrate predators.
I especially love one of the concluding sentences:
The foraging behaviour of the White Woodpecker reported herein results from so-called anecdotic, natural history oriented observations, often disregarded by theory-trained biologists. Nevertheless, this kind of observation draws attention to phenomena that later may prove more widespread or commoner that previously thought.
I could not agree more. Please head over to read the paper yourself, as the photos of the behaviour are great, and the text well worth the read.
Photo by Márcio Vinícius Pinheiro, shared under the terms of a CC BY-NC-ND 2.0 licence.
Male Three-wattled Bellbird (photo by Michael Loukides) released under a CC-NC-SA licence.
I just received in an email a press release for the Zoo Conservation Outreach Group describing recent successes in fieldwork on Three-wattled Bellbirds (Procnias tricarunculatus) in Honduras. This project aims to use satellite tags to study the migratory movements of these endangered frugivores in the Sierra de Agalta cloud forests of Honduras. I have no doubt that Isidro Zuniga, our Honduran colleague during our last field season in Honduras was greatly involved in this research.
The big mystery surrounding these odd birds (Family Cotingidae) is their complex migratory movements between cloud forests in the region. Each of these cloud forests is like an individual island of habitat in a great sea of lower level pine forests and agriculturally-dominated valleys. The birds are very evident from July to September in the Sierra de Agalta cloud forest, but then disappear for the balance of the year. The team on the ground in Honduras, led by Dr. Robin Bjork, has managed to outfit four of these birds with satellite tags which are transmitting data already.
The data generated by these tagged birds should be very interesting to say the least, and will help identify key habitat for conservation efforts.
A bird in the hand is worth quite a bit! Male Three-wattled Bellbird outfitted with 5 g satellite tag.
This weekend, Catherine and I visited Victoria, for the Canadian Thanksgiving holiday. The weather was not super cooperative for outdoor activities, and Catherine was working hard on her PhD NSERC proposal, but we did manage one trip out to Island View Beach to check up on the local arthropods. I also went for a stroll in Uplands Park to get some of the following shots.
This is how the rain looked on Saturday morning…
Better to be sheltered inside, or under the eaves of a house!
Quite a few grasshoppers were out and about. This one I shot as it was hiding on a Garry Oak leaf (you can see I was holding a white card below).
A juvenile wolf spider looking odd and elegant with two very prominent eyes.
A Dysdera crocata male in Uplands Park.
An Aphaenogaster occidentalis worker carrying brood in Uplands Park. This species does well in Garry Oak meadows.
Catherine, my friend Jeff, and a borrowed golden retriever (Jackson) at Island View Beach.
The fall selection of resting Hymenoptera was much more limited than previously, with this impressively-ovipositored ichneumonid being the only example we could find.
Resting snakes were about though; this garter snake was torpid and remained in a ball rather than trying to flee when we found her under a log.
Spiders were to be found in large numbers though, this being Arachtober and all. Here is a tetragnathid backlit with a bare flash.
Here is a running crab spider, of the genus Tibellus; the same one appears at the top of the post. These are very elegant-looking little spiders, and make great photographic subjects.
Most of the creatures we found were covered by a light dew. This cranefly sparkles.
This female Araneus diadematus was particularly large. That is Catherine’s finger for scale.
Speaking of large, here is a giant! A giant house spider, formerly Tegenaria duellica, now this species is called Eratigena atrica. Since Catherine is scheduled to give an upcoming talk on spider bites (and how they are very unlikely) at the ESBC conference, we decided for an illustrative photo shoot.
Here is the same spider sinking her fangs into resting peacefully on Catherine’s nose.
Apparently, the feet tickle. Not that I would ever try this, that would be crazy.
A female Castianeira we found under some old plywood.
A penultimate male black widow. These ones that overwinter always seem to be more robust and darker than the juveniles that develop quickly in the summer. I would imagine this is a textbook example of phenotypic plasticity; one that deserves more careful study.
Again with an eye to Catherine’s upcoming talk, we took some shots of black widow defensive behaviour. Here a female throws glue-like silk on an offending finger. This is so reliable, I might have to try this in a studio setting with some nice backlight!
Last but not least, on our final morning in Victoria, we walked on Mt. Tolmie, where we found this male Anna’s hummingbird, still defending territory. It is impressive these little birds are still nesting in the cold wet fall!
This past week has been pretty busy, so getting out and shooting has not really been on my list of accomplishments (my “Ta Da!” list). On Tuesday, I did manage to get interviewed by Global News about invasive ants, and then schlepped across town to assist my friend Tanya Stemberger with a field exercise for high school students in the Future Science Leaders program.
Due to high tides, the planned transect based survey of intertidal organisms had to be scrubbed, so instead, we attempted a transect-based survey of a forest near Lost Lagoon in Stanley Park.
I planned to show the students a simple technique for sampling called beating, wherein you strike foliage forcefully and collect any falling arthropods in a sheet placed below. We used small photographic shoot-through umbrellas to do our collection, and then used a simple aspirator to collect the catch. We had planned on sampling 5 sites along a 50 m transect, beating 4 small bushes at each site. Due to time constraints, we only managed to get a single site done.
Nonetheless, with only beating 4 bushes (2 salal, 2 salmonberry) we secured 25 spiders, 1 isopod and 1 harvestman. Many of these spiders were tiny juveniles, but some were just tiny adults. Identifying them in the field was definitely not going to happen in the limited time frame, but there may be hope of at least getting some identifications. Here are some of the spiders that were large enough to photograph well:
1
2
3
4
5
It seems the spider diversity seems pretty high, and interestingly, of these spiders I photographed, 4 of the 5 are males.
The most striking thing about this sample (to me anyhow) was the lack of insects. Usually, at this time of year, I expect to see barklice (Psocoptera), springtails (Collembolla) and perhaps a stinkbug (Pentatomidae) or plant bug (Miridae). Nonetheless, it is tough to draw conclusions about the diversity of taxa we found, with only one sample being taken.
Of course, finding such a predator-biased range of taxa seems a little strange, until you consider that every sampling method has its biases. In the fall, when plant growth is limited, finding phytophagous insects out and about is much more difficult, but at a sites such as this, adjacent to a large freshwater source (Lost Lagoon) there is ample prey for web building spiders. These freshwater bodies are still producing abundant chironomid midges, and a few caddisflies.
All in all, this was a great (albeit short) little introduction to terrestrial arthropod sampling. Special thanks to the Stanley Park Ecology Society volunteers for leading us on the great nature walk!
This weekend, Catherine and I were invited by Sofi Hindmarch and Brian Coote (along with his kids Alexa and Jamie) to go down to Mt. Baker, a stratovolcano in Washington State near the Canadian border. On Sunday, we went on a trip to Lake Ann, a 13 km alpine trail. Catherine had to sit this one out due to knee issues, but I went to document our trip. This was my first outing to the alpine zone in quite a while, and it was not disappointing!
A Hericium abietis! These are great edibles, but as we were in a reserve, we did not take it. There were also numerous King Boletes nearby.
Alexa stops for a water break.
The view going up the trail, Sofi in the lead, followed by Jamie and Alexa.
Near the crest!
An American Pika, Ochotona princeps. These odd lagomorphs make a whistling alarm call when disturbed.
These animals prefer talus slopes, and spend much of the summer gathering and drying plant material for a long cold winter buried beneath the snow.
We saw these giving alarm calls in response to both Red-tailed Hawks and some kind of mustelid (possibly a marten or a mink).
At the end point of our trip, I found this wolf spider under a rock.
To prove we did it: Brian, Sofi, Jamie and Alexa in front of Lake Ann.
Of course, on the way down I could not resist more pika shots.
Awww!
Yet another pika scanning the skies.
Blueberry break on the way back.
Much needed fuel for the last leg of the trip.
