After a hiatus of a few weeks, I finally managed to get out this weekend for some shooting! I went with my friend Florian to Stanley Park on a gorgeous sunny Saturday, to search out the creatures of the early springtime.
This past weekend was another work weekend, and in addition, I had a nasty cold. This precluded me from getting out for photography, but Catherine and I did expand our balcony bird buffet!
First off, we decided to see who would come for peanuts:
Second, a different position on the hummingbird feeder results in much better light! This female seems pretty pleased.
And a male to show off his nice gorget.
Here is a homemade suet ball that Catherine made, with all kinds of nuts and grains. The chickadees seemed pretty happy with it.
I also bought a bird feeder at the dollar store, which is not a bad little unit! Very low volume, but seems sturdy enough!
You can see in the photo above, and also in the reflection on the window the video setup. I am just using a light stand to hold the camera, weighed down by a jug of ethanol in a bag.
I have been rather busy these past few weeks working on top secret government stuff, so I have had not had much opportunity to get out and shoot. I was not such a big deal this week, as we have had miserable rainy weather for most of it. But yesterday turned out to be beautiful, so it was killing me a little to stay in and work. Luckily, interesting things have been happening at the hummingbird feeder, so I took a bit of time to set up some video. Since it it right on the balcony, I did not have to go far!
First of all, some HD video of various hummingbirds feeding.
Next, some less beautiful footage showing a female feeding. Any guesses what she might have been doing just previous to this?
Anyway, the hummingbirds were a nice treat on a working Sunday. I will try to get some more material on them when I get the chance!
It is a wonderful thing to give a talk to an enthusiastic audience, especially when comes with a chance to travel and meet new people. I was very lucky to have had this opportunity last week when I went to Houston Texas to give a talk on Red-throated Caracaras to the Houston Audubon Society.
Mary-Anne Weber, along with Juanita Perkins arranged for me to travel to Houston to give this talk, and were my most gracious hosts during my trip. I did not have to stay in a hotel, but instead stayed with my friend Cullen Geiselman, a bat researcher who I met at the Nouragues Station.
I am very grateful to have had this wonderful opportunity, and I thank all of the people who came out to hear me talk.
Sometimes the light of a cloudy day is beautiful for photography, making features soft and creamy, eliminating harsh shadows, and enhancing colours. But this is a bright cloudy day we are talking about, not a gloomy, dark and depressing day like we tend to get around Vancouver this time of year. On a day like that, the photographer can only do one thing: eat Cheetos and veg out.
But wait! There is something you can do to get nice defined images of wildlife despite the terrible conditions and your way-too-old, way-too-noisy Canon sensor. Of course! Supplemental light!
I tested out throwing some hard light from trigger-controlled flashguns on a few species at Stanley Park this Saturday, and I am pretty pleased with the results!
Overall, I like this method of shooting, but would prefer natural light. For a gloomy day, when all I would get otherwise is a noisy mess, this is a good thing to try. With an actual lighting assistant, I am sure it could be even more fun.
Photography brings me a great deal of pleasure, and I indulge in it whenever I can. A few years ago, I was with my dad, driving north from Victoria to my brother’s wedding. Along the way is Goldstream Park, a real gem where the Golstream River empties into Saanich Inlet. We had some time to kill, so we went out for a short stroll with our cameras. It was a beautiful fall day, although the early morning forest was still dark. After photographing some salamanders in the forest, I decided to check out the highway bridge over Niagara Creek for overwintering mosquitoes.
During my undergrad, I did an Honours thesis on overwintering mosquitoes, and one of my field sites was just upstream, at the railroad trestle above the creek. Here I found several species of mosquito, including Anopheles punctipennis, Culex tarsalis, Culex territans and Culiseta incidens. So when I checked out the highway bridge, I took a few shots of of the mosquitoes. Most of these were the large and very common Culiseta incidens, but I saw a smaller and browner one that I knew was a Culex. Not having many good shots of Culex tarsalis, I strained to reach the camera over my head to shoot the insect. Like many overwintering mosquitoes, this one was still able to fly, so I only got the one shot. Upon reviewing it however, I saw that it was not Culex tarsalis, as I expected, but rather Culex restuans! This species looks much like the common house mosquito, but is distinguished by the two light scale patches on the scutum. I had never encountered this species during my thesis research, as it had not been reported for BC. In talking with Dr. Peter Belton, he urged me to write up the sighting for the Journal of the Entomological Society of BC as a new species record for the province.
Several years passed, where I was busy with tropical field research, and I had put the Culex record on the back burner. When Dr. Belton presented me with a draft of the report, I knew I had to do my part. I added some detail to the manuscript and sent it off. Click here to see the paper!
Not bad for a quick snapshot. Here are some other pictures I took that day:
“Ants, particularly army ants, exert such strong predation pressure that they are considered to be the main driving force in the evolution of Neotropical social wasps, to the point of influencing their nest architecture.” -Corbara et al. 2009
It is not too surprising that many tropical ecologists consider ants to be such superior predators. Come across an army ant swarm, and you are likely to witness many hundreds of acts of predation playing out before your eyes on the jungle floor. An army ant swarm is like a blitzkreig, and it would seem that nothing can stand in its path. Even social wasps, normally so aggressive in nest defence, will abandon their nest immediately rather than risk the entire colony in a vain attempt to repel the tens of thousands of army ant raiders.
But is it really accurate to infer from these types of observations that the risk of predation by ants on nests of social wasps surpasses that of all other predators? This never really sat right with me, particularly considering how an army ant predation event on social wasps is a random, and probably relatively rare event. Army ants cannot see, and they do not target wasp nests in particular. Even those species which prefer preying on social insects are much more likely to be raiding other species of ants rather than wasps.
How would army ants stack up against a true specialist wasp predator, such as the Red-throated Caracara? Luckily, I had some data to work with to answer these questions. I have written this up in a paper in Insectes Sociaux, which unfortunately is not open access, but you can email me for a copy!
A Polybia nest brought via an overhead branch.
From our nest camera study in 2008 and 2009, we had footage which showed adult provisioning of single caracara chicks (McCann et al. 2010). In order to calculate the number of wasp nests per day consumed by the chicks, we lumped all events of provisioning with nest fragments of the same genus being brought within 30 min of each other.
Each of these events was then termed a “unique nest delivery”. By summing the unique nest deliveries daily for the two sampling periods, we found that a single caracara chick eats between 7.8 and 12.4 nests per day. If we assume that the adults are eating just as many wasp nests, a group of 6 adults would consume 46-74 nests per day (not counting the chick). On a per-hectare basis, caracaras could possibly be consuming 0.117-0.186 nests/ha/day.
To compare this rate of predation with that of army ants, we needed an estimate of army ant density. Unfortunately, only one method for assessing Eciton density has been developed, for Eciton burchellii.
This method was developed by Nigel Franks, and relies on the predictable behaviour of swarms of this species (Franks 1982). These ants raid in a roughly linear column from their bivouac site, extending the raid 7 m per hour. The landscape at any given time is thus like a plane with many lines of ants of similar length scattered about it at random. The probability of encountering a swarm is thus proportional to the density of colonies in the area, and by repeated walks of suitable length, an estimate of the total density can be made. Mathematically-inclined readers may realize this is an extension of the problem of Buffon’s Needle*, and relies on similar calculations Incidentally, Buffon also published the first species description of the Red-throated Caracara. You can read about that here.
Catherine Scott and I went to the Nouragues station in 2012 to perform an estimate of the Eciton burchellii density in order to calculate the potential impact of army ant predation on social wasps.
Our estimate for Eciton burchellii density was a moderate 0.021 swarms/ha, pretty well comparable to other lowland rainforest sites. But how many wasp nests could each swarm take? Well, there is no easy answer for this, but there was only one study that documented rates of army ant predation on social wasps. Ruth Chadab published an estimate of 1-3 nests per day taken by Eciton hamatum, a related species with a greater predilection for social insect nest plundering (Chadab, 1979). Because we had no estimate for daily wasp nest predation for E. burchellii, we used Ruth Chadab’s estimate of 3 nests per day as a rough approximation. This translates into 0.06 nests/ha/day, or 24 nests per day in a 400 ha caracara territory.
We conclude that Red-throated Caracaras, as specialist wasp predators, are comparable to army ants in their predatory impact on social wasps. Taken together with other species, such as monkeys, antshrikes (McCann et al. 2014) and woodpeckers (Sazima 2014), social wasps are at considerable risk from vertebrates.
So what about vertebrate predators and the adaptations of social wasps against them? If we look carefully at social wasp behaviour, it is easy to see how much vertebrate predation has influenced both behaviour and nest architecture. For one, massed stinging attacks are ineffective against ants, and are definitely a feature that protects wasp colonies from vertebrate attack. Audible warnings, such as those produce by Synoeca, would not be effective against ants, nor would visual camouflage (ants hunt by scent, and army ants cannot see anyway).
Likewise, armouring of a nest, such as is seen in some Epipona and Chartergus wasps (Richards 1978), would have limited effect on ants, as they can enter and take prey through any opening a wasp can. Analogous armouring consisting of a mud envelope is evident in this Polybia singularis nest. In 5 seasons I worked at the Nouragues camp, this nest never fell prey to the caracaras. What is notable about the nests of most wasps with armoured envelopes is that they are often located high up in trees, easily visible on distal branches. The wasps may gain some protection from ants by nesting so high, which they can afford because they are (by virtue of the strength of their nest) already relatively safe from vertebrate attack.
As more and more naturalists describe and publish their observations of Neotropical biology, we are continually discovering new things. I hope that this study, gained in a few short months of research adds to the understanding of the role of vertebrates as predators of social wasps, especially the important role of the Red-throated Caracara. In a future post I will take up the issue of the diversity of wasps taken by caracaras, and what some of the numbers might mean for tropical wasp biologists.
Please do go and read the paper, and if you do not have access to it email me for a copy!
CHADAB, R. 1979. Army ant predation on social wasps. PhD Thesis. University of Connecticut, Storrs, CT.
CORBARA, B., CARPENTER, J. M., CÉRÉGHINO, R., LEPONCE, M., GIBERNAU, M., and DEJEAN, A. 2009. Diversity and nest site selection of social wasps along Guianese forest edges: assessing the influence of arboreal ants. C. R. Biol. 332:470–479.
MCCANN, S., MOERI, O., JONES, T., O’DONNELL, S., and GRIES, G. 2010. Nesting and Nest-Provisioning of the Red-throated Caracara (Ibycter americanus) in Central French Guiana. J. Raptor Res. 44:236–240.
RICHARDS, O. W. 1978. The social wasps of the Americas excluding the Vespinae, p. vii, 580 p., 4 p. of plates : ill. (some col.) ; 2. British Museum (Natural History), London.
We have been basking in warm, moist air here on the West Coast, while the rest of the country is freezing in Arctic outflows. This “Pineapple Express” has brought a lot of rain over the past week, but that is now letting up. Yesterday was calm and foggy, and a bit eerie in its warmth. I was in Victoria, so I went walkabout to see what I could see.