If you happen to be in Vancouver this coming Sunday, please consider dropping by for my talk at UBC’s Beaty Biodiversity Museum.
The talk is at 1 pm at the Museum’s lecture hall. The talk is geared to a general audience, and will be filled with cool videos from our recent paper, as well as other unpublished stuff about territoriality and social behaviour.
Here is the blurb:
Red-throated Caracaras are way cool because…They are the wasp-murdering superheroes of the rainforest! Not many animals like to attack and eat social wasps because the stings of these insects are usually an effective defense. The Red-throated Caracara manages to overcome this defense daily, bringing 9 to 15 wasp nests per day to its chicks, and somehow avoiding a painful death from wasp stings. Sean McCann, PhD student at Simon Fraser University and his team investigated the nesting, territorial, and wasp predation behaviour of these wasp specialists over five years to get a better picture of the fascinating life history of these amazing birds.
2013 has been a great year for shooting as well as for getting my images out to people who are interested, via this blog! There are so many decent images to choose from, and I am a bit pressed for time right now, so I will organize the pictures that stood out for me phylogenetically.
Insects
One of the beautiful Ammophila featured in Ibycter Illustrated. Photographing sleeping Hymenoptera at sunrise gave me a new appreciation for mixing ambient and flash.
I love the way the dew sparkles on this Lycaenid.
In 2013, I got to indulge myself with many opportunities to shoot Coelioxys, my favourite Megachilid.
Using flowers as colourful backdrops was something I explored in the gardens this year.
Not the best technically, but it was great to come upon this scene of predation between Laphria and Apis. Productive slacking indeed!
Another Laphria found on a window provided a good long photo session so I could explore lighting against the sky.
Getting out to YVR with the Wildlife Control people was a really fun experience. This molting Peregrine tiercel was one of the better shots I ever got of a peregrine.
Red-throated Caracaras are specialist predators of the brood of social paper wasps, as our previous research confirmed. The big question we wanted to answer was: how do they manage to attack and subdue the workers of these well-defended wasp nests? A previous study by Jean-Marc Thiollay suggested that Red-throated Caracaras may possess a chemical repellent that keeps the wasps from approaching and attacking them, but this hypothesis was never tested.
We sought to shed more light on this by sampling chemicals from the birds and by observing the predation behavior firsthand.
To do this, we set up a “feeding station” to record the caracaras attacking wasps. We lured the caracaras near to the video arena by playing recordings of their vocalizations from an amplifier near the site. The birds would come to investigate the source of the calls, and once they saw the wasp nests we had set out there, the caracaras went in for the kill, and we captured the behaviour on video.
This is the video arena we set up in the forest behind the camp. Maintaining the condition of the “waterproof” video cables and connectors was very difficult in the rainy season!
These are the five species of paper wasps we managed to get the caracaras to attack.
The caracaras did not seem to have significant problems with the smaller wasp species Polybia bistriata, Polybia scrobalis or Polybia affinis. None of these seemed to attack the caracaras at all. But check out the following video of an attack on a larger Polybia jurinei nest:
The caracaras knocked two of these nests to the ground, and later flew down to retrieve them. In another attack on a nest of Polybia jurinei, the caracaras repeatedly slammed into the nest, and eventually the wasps abandoned their defense. These situations where the wasps abandon their nest represent a behaviour known as absconding. The swarm-founding wasps, with sufficient nest disturbance, can fly off en masse to quickly found a new nest elsewhere. They lose that batch of brood, but save the workers from an ultimately futile defense of the nest.
My suspicion is that larger nests than these would put up much more of a fight. Unfortunately, we never got to record attacks on some of the truly huge nests that can occur in the tropics. We did record the aftermath of one such attack on Polybia dimidiata:
The video data do tell us that the type of chemical defense envisioned by Thiollay does not seem to be how the caracaras avoid wasp stings, but we did look for potential chemical repellents anyway.
Sampling from a caracara face using solvent-soaked cotton swabs. We also sampled the feathers and feet, using both methanol and hexane.
We anticipated that any potential chemical repellents would be detectable by the antennae of sympatric wasps, so we brought nests of Polybia bistriata back to the lab to test the caracara extract for compounds perceptible to wasps using coupled gas chromatography/electroantennography (GC/EAD)
As you can see from this example GC/EAD recording, Polybia bistriata antennae respond to several components of the caracara foot extract (the top trace shows the chemicals, the bottom shows the antenna’s response). Compound A is sulcatone, while the compounds labelled B are iridodial isomers, and compound C is a boring old fatty acid (which is found on most animals). Iridodial and sulcatone are repellent compounds, but best known from dolichoderine ants, such as Azteca.
We suspected that the caracaras may have picked up these compounds from Azteca ants. To follow up, we sampled Azteca chartifex near the field station at Saut Pararé and compared their pygidial gland secretions with the caracara foot extracts using GC/MS.
At the top is the GC/MS trace of the Azteca sample, at the bottom is the trace from the caracara feet. Notice the shared ketones and the iridodial isomers. We found these ant-type compounds only on the feet, suggesting that the caracaras are attacked by Azteca while perching.
And this is why we suspect caracaras come into contact with Azteca! Polybia rejecta nests in close association with Azteca, which protect the wasp nests from army ants. It could well be that the caracaras are attacked by Azteca while preying on these wasps. It is also possible that the caracaras are just incidentally attacked while perching on Azteca-infested trees. Photo provided by Pablo Servigne.
In summary, the caracaras do not have much difficulty with smaller species such as P. bistriata; just tearing into the nest is sufficient to cause these wasps to abscond. With larger species, the caracaras have to use more persuasive tactics, such as knocking the nest to the ground or striking it repeatedly. While it does not seem the caracaras have chemical repellents, the discovery of the ant-derived defensive chemicals highlights the surprisingly intricate connections between organisms in the rainforest.
A female harrier scarfs down her Christmas sparrow.
Vancouver is generally known for its green wintertime conditions, but sometimes we do get a bit of snow. We had a 10-15 cm dump on Friday morning, which made getting around a bit difficult. I was running errands on the weekend, but brought my camera out anyway, and managed a decent haul of bird pictures out in Delta.
A harrier on the hunt.
The birds were not the only ones hunting at Boundary Bay, as about 20 people were out on the mud blasting away at ducks with shotguns, It is more than a little ironic that the place is full of signs telling folks not to disturb wildlife, but shooting at them is A-OK.
Heron on the prowl for voles.
A nice little Red-tailed Hawk/
The eagle disapproves, as usual.
I was a bit shocked to see a live caterpillar moving along the snow, but I figure it may have been dislodged by a foraging bird.
I realize that the Weekend Expedition is getting a bit repetitive, and I resolve in the New Year to shake things up a bit. In fact, I make you a promise. Starting in January, things will be different around here!
I did get away again this weekend, and it was back to Reifel Bird Sanctuary, again with Wild Research.This time, it was not as productive WRT raptors as previous visits, but we did see a Peregrine, some eagles, a Cooper’s Hawk, and a Rough-legged Hawk. The main attraction of Reifel is the ridiculously human-acclimated birds. Cranes feeding from your hand, chickadees landing everywhere…It is like a meetup group for bird flu lovers!
The cold winter air has moved on, and the canals and ponds are melting. The atmosphere was very much like standing in front of a cool mist humidifier.
Mike Hrabar captured this shot of some artistic use of the GoPro to record feeding pigeons.
Mike shooting with his new 300!
The reflection from the ice really makes these ducks pop.
Paul Levesque channeling Steve Zissou.
incoming cranes!
I just love the calls of these elegant birds.
After Reifel, Mike and I headed down to 64th St. (On Boundary Bay) to check out some Long-eared Owls. This one was the only one there, and not very active. Pretty though!
I am always a fan of raptors, and have a special place in my heart for social and predation behaviour. Here is a story that combines all three! In the latest issue of Journal of Raptor Research, a remarkable observation of a large group of Golden Eagles harassing elk on a steep ridge is reported (but paywalled).
Matt O’Connell and Michael Kochert witnessed and filmed the astonishing sight of at least 8 eagles repeatedly stooping at a group of elk, either trying to drive them off a cliff, or perhaps just playing around.
Golden Eagles are known to prey on ungulates, sometimes by driving them off cliffs, but the authors are cautious at definitively stating the motivation of these birds. I would suggest that the hypothesis of play and that of predation are not mutually exclusive. I could certainly see a great selective advantage for these carnivorous birds to engage in “play” that sometimes results in the grisly death of a large ungulate.
If you would like to see the video, here it is below. What do you think?
References
Bergo, G. 1987. Eagles as predators on livestock and deer. Fauna Norvegica Series C, Cinclus10:95–102.
Deblinger, R.D. and A.W. Alldredge. 1996. Golden Eagle predation on pronghorns in Wyoming’s Great Divide Basin. Journal of Raptor Research 30:157–159.
Erwins, P.J. 1987. Golden Eagles attacking deer and sheep. Scottish Birds 14:209–210.
Zettergreen, B. 2006. Golden Eagle attacks and kills yearling mountain goat. Wildlife Afield3:27–28.
I thought it prudent to get a small video camera to document upcoming fieldwork, so that I can provide PR materials for granting agencies. For this purpose, I got a GoPro, a small “action cam” which has a watertight housing and super wide lens. To put it through its paces, Jeff, my brother and I took it down to Fisherman’s Wharf in Victoria for a close up look at the Harbour Seals. The following is the result.
Not bad eh? Given decent lighting, it does fine video. The still images from it in poor lighting are pretty noisy though, and it probably be best not to rely on it for still shots in the evening:
Nonetheless, it does have a certain gloomy charm.
With the SLR from the surface though, the seal image quality is much better.
The gulls were also looking fine against the reflection of the sky.
Today, very suddenly, I lost one of my best friends. Maggie had an accident while running around one of her favourite places, Mystic Vale in Victoria, falling suddenly from a height and dying nearly instantly.
Maggie was my mother’s dog, a golden retriever who I met for the first time in 2004. We quickly formed a strong bond, although I lived far away in Florida. Every time I would come home she would greet me with excitement, knowing that soon we would go adventuring together. Maggie loved the outdoors, and luckily enough, she lived in a great place where she could go running freely on outings with my mother once or twice a day.
We had some great fun exploring the wild lands around Victoria, swimming at the beach, or just curling up by the fire together after a long day. She was a great companion and a true friend.
I am completely devastated by her sudden passing, but there is consolation in knowing she died out there running around the forest, doing what she loved. Good bye my dear friend, I will miss you.
Heteropoda venatoria, a large huntsman spider introduced from Asia. I shared my mosquito rearing rooms in Florida with these monsters, who presumably ate the large American Cockroaches (also introduced) who lived there.
Thanks to global trade and human movement, you no longer need to travel the world to see the world of spiders. There are many introduced and exotic species in our own backyards. In fact, some of the most common spiders we see every day in North America are introduced from elsewhere. This page on BugGuide, compiled by Beatriz Moisset, served as a great reference; there are more than 57 species listed.
I have to wonder what kind competitive effects these introduced predators have had on the native fauna. Some of them are by far the most numerous spiders in a given habitat, and they must have pushed out some of the native species. As far as I know, this topic has received little study, although why that should be the case, I am not sure.
Anyway, here are some of the exotic spiders i have encountered over the years. I hope you enjoy them on this Spider Monday!
This is a Huntsman female I kept as a pet. My one attempt to get her a boyfriend ended badly, as he was quickly seized and devoured in a gruesome rejection scene.
Philodromus disparmale. These dapper fellows must have a rough life, as many times I find them with missing legs.
The female Philodromus dispar are more conventionally attired.
The Giant House Spider, Tegenaria duellica(also referred to as T. gigantea), is one of the most common spiders in urban BC. If someone tells you they found this “really huge spider” 9 times out of 10 it is this!
The less boldly-marked congener, Tegenaria agrestis, is commonly called the Hobo Spider.
There are several therediids introduced to North America as well, perhaps none so notorious as the brown widow, Latrodectus geometricus. This spider gets a bad rap for being dangerous, but its only crime is to its spider brethren. They can be exceedingly abundant, and probably compete strongly with the native tangle web-weaving spiders.
They are extraordinarily fecund: all these egg sacs seem to have been laid by a single female. The brown widow egg sacs always have this shape reminiscent of an anti-shipping mine.
Even some of the jumping spiders are introduced. Here is Salticus scenicus, the so-called zebra jumper.
