New episode of the podcast is up! You can listen over on Podbean, or wherever you get your podcasts. I am continuing with my detailed book review of 'Honeybee Democracy' by Thomas Seeley. This episode's chapter digs a little deeper into how bees reach an agreement on their nest site. It also discusses what a dream home vs a mediocre home looks like to honeybees, and how this helped Thomas Seeley narrow down honeybee nest site preferences even more. There's a lot of good information! I hope you enjoy it as much as I do. I continue to be endlessly fascinated by these incredible little insects!
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Homestead Updates
My red hen, Agnes, has been acting odd on and off for a while. She would occasionally look a bit droopy and ill but would then bounce back and act completely normal so I assumed that it was the winter weather that was getting to her. On Feb 8th, however, she seemed especially droopy and sad so I scooped her up for a body check. There was nothing in her crop and I could feel her breastbone but her abdomen was swollen and quite hard. It reminded me of Bubbles, who I euthanized due to egg yolk peritonitis. I made a vet appointment, thinking I would likely need to euthanize her, but the vet was actually optimistic. The material in her abdomen was fluid and could be drained. We decided to ultrasound her to make sure it wasn’t a liver or heart issue (it wasn’t) and then the vet drained the fluid from her abdominal cavity. A lot came out! The vet then put her on antibiotics and strong anti-inflammatory medications and I brought her inside so I could isolate her and keep her warm. She was so much brighter after getting all that fluid drained! There was no sign of egg yolks or whites in the fluid so the vet is leaning towards some kind of reproductive issue that could be treatable. Fingers crossed! I set her up in the chicken hospital and she ate for me right away and took her meds like a champ. I am cautiously optimistic! She could recover and go on to have no issues but there’s a chance she’ll fill up with fluid again and we might need to let her go. As of the time of writing, she is brighter and eating again but not as much as I’d like. There is still some fluid in her abdomen but not a lot and it doesn’t seem to be growing in size. The saddest thing is that she’s lonely and calling for her flock a lot! Breaks my heart to hear it. Otherwise, though, she’s doing really well.
Small songbirds have been getting into the run, and then the door needed repairs in freezing weather, which was no fun. The small birds have figured out that the chicken wire is large enough for them to get through but then they often panic if they fly up against the bird netting roof, or low into the hardwire cloth. I’ve had to open the door wide and gently shoo them out. Said door started coming apart so I was out in the cold trying to fix it with new screws. I managed to lose a drill bit somewhere in the snow, and I really hope I will find it in the spring.
Chip drop delivery! If you haven't heard of Chip Drop, it's a website where you can add your details and receive free wood chips and/or logs from local tree companies. I hadn't had success with it previously but realised that winter is probably the better time to sign up (lots of tree damage from storms and snow), and sure enough I received a truck full of beautiful, fragrant wood chips! There is no need to buy mulch this year now and can put that money towards a big top soil delivery. Yah!!
The lot next to our house has gone up for sale and I am super nervous about someone building on it. The current asking price is much higher than the median value of land for this area so potentially we could talk them down on the price. That said, we don’t have a use for this lot; we would just be buying to prevent someone from building. It’s not exactly a sound investment, honestly, and it’s not like we’re floating in liquid cash. We’ve decided to wait and see for now but we are going to have a survey done of our property and have the boundary marked so, if it does sell, we will know exactly where the boundaries are. Our biggest concern would be if we don’t own the trees that run between the two lots. If those were cut down, we’d be very upset. They’re a bit ragged and need some TLC but they provide an extra visual barrier, as well as a home to a number of different birds. They also provide a partial wind block. We shall see what happens.
Hive Updates
Feb 12th, we had a 'mild' afternoon (30F, sunny, no wind) so I decided to run out to the hives to add more sugar to their feeders. We have had very cold weather that is only going to get worse, and this is the first chance I have had to get out there and throw on more food without risking chilling the bees. Sadly, I quickly discovered that my Saskatraz mother hive, and the 2 nucleus colonies, had perished. An inspection revealed that they still had honey and fondant but had starved. It looked as if all of the colonies just didn’t have the population needed to maintain a cluster large enough to remain in contact with, or close enough to, the food. As a result, they all starved. I’m not surprised I lost these colonies as they had a lot stacked against them; high varroa mite counts even going into winter and less honey stores than I was comfortable with. The nucs also had a small population and some equipment issues, which I’ll discuss in more detail on my podcast.
Worried about my other colonies, I was delighted to find that the Saskatraz-daughter colony was still alive, as are queen Macha and queen Cerridwen. The latter colony is still my strongest with the cluster low in the hive. I am going to be making lots of nucs from that colony in the Spring! I really want to propagate those genes.
Gemma’s Random Corner: Keeping Bees Inside?
Sources/recommended reading:
My Canadian besty mentioned to me that the temps in Saskatoon (where she used to live at one point; now she’s in Newfoundland) are all in the -20 and -30C/-18 to -35F for the next week or so. This blew my mind not just because of how extreme those temps are but also because there are a number of honeybee apiaries out there, including the team that worked on creating the Saskatraz race of honeybees. So, how are they keeping these bees alive in such extreme cold temperatures? A quick search gave me the answer: they bring the hives inside.
My mind immediately filled with images of hives in my warm basement, which would soon be filled with now active and toasty warm bees, looking for a way out, and likely coming through the vents directly under my husband’s desk. But the reality is much more sensible!
Canadian beekeepers have actually been bringing their hives indoors for some time. Whether it’s a simple shed or a large building that looks more like a warehouse, bringing hives indoors can greatly increase their chance of winter survival, although a certain amount of investment and work needs to be done to ensure optimal conditions are meant.
The three most important elements to successfully overwintering hives inside are: temperature, carbon dioxide monitoring/ventilation, and light.
1/ Temperature: the goal of bringing bees inside is not to make them toasty warm as that will make them break the cluster, look for food, and potentially leave the building where they will then freeze to death in the cold outside temps. Instead, the building should be kept just above freezing. This temperature ensures the bees remain clustered and dormant. They will still need to utilize their winter honey stores but not as much as if they were combatting colder temps since, as we know, bees will shiver in order to generate heat. Colder temps means more bees shivering for longer to keep the center of the cluster warm. By bringing them inside, we make their winter work a little less intensive.
2/ Carbon dioxide monitoring/ventilation. Bees produce carbon dioxide as part of their normal metabolism and respiration, and this can quickly build up in an enclosed space. Making sure that any building that holds your hives has appropriate ventilation without being drafty is very important. There is also some evidence that varroa are susceptible to carbon dioxide fatality and will perish at lower levels than those that will kill honey bees. As a result, some beekeepers carefully monitor CO2 levels in their bee sheds, allowing it to build to a level fatal to the mites but not dangerous to the bees, before ventilating the building to allow fresh air to come in. This varroa control is an additional benefit to wintering hives inside.
3/ Light. Bee sheds need to be dark in order to prevent the queen from laying. Bees will still be able to navigate their cleansing flights in the dark. If light is needed, such as for inspections, it’s recommended to use a red light as bees cannot see this and so will not be unduly stimulated. From what I have read, when you move the hives back outside during the Spring, the sudden exposure to sunlight leads to the queen ramping up her egg production more sharply, and some keepers report getting a better laying rate from queens kept this way.
If you can meet the above conditions, as well as keep the inner area clean and dry, your bees will have the benefit of getting through winter without added stress, heavy feeding, wind chill, and potential moisture in the hive from rain and snow. Definitely something to think about for anyone keeping bees in the North where the winter can really drag on!
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On to the main topic!
Chapter 5: Agreement on Best Site
Love quarrels oft
in pleasing concord end.
-John Miller, Samson Agonistes, 1671
When scout bees reach a consensus, have they chosen the best possible nest site? Seeley says they have, and this chapter digs deeper into this question and answer.
Humans use a number of different tools to make decisions, often relying on simplified methods of choice called heuristics; these generally involve reducing the alternatives up for consideration
For instance, when looking for an apartment, one could limit the options by searching based on length of commute, price of rent, whether pets are allowed, etc.
If you were pressed for time and needed to find a new place to live ASAP, you could narrow your search by deciding on a series of acceptable (not necessarily optimal) factors, and then take the first apartment that meets all those factors
Neither of these decision-making methods guarantee the best result but they do assist in making the final decision to an acceptable level of personal comfort
In contrast, honeybees do not make decisions in this manner; we now know that scout bees consider at least 6 attributes when looking at sites (cavity volume, entrance height, entrance size, etc), and will seek out multiple locations for consideration
Martin Lindauer’s full-size swarms reported an average of 24 sites (13-34), and Seeley and Buhrman’s smaller swarms averaged 10 sites (5-13)
“Thus, a honeybee swarm pursues an unusually sophisticated strategy of decision making, one that involves nearly all of the information relevant to the problem of choosing the best place to build its new nest.” Pg.101
And how do they do this? It’s all due to their democratic decision making process.
Best of N?
To determine whether scout bees reach an agreement on the best available site presented, Seeley realised that he needed to set up a ‘best of N’ study; this would involve offering a swarm a selection of artificial nest sites that all differed somehow in quality, which in turn would mean conducting the study somewhere with no natural nest sites to ensure the scouts would focus on the offered nests only
The goal was to see whether scouts really do reach a consensus on the optimal location
This idea was prompted by Seeley’s realisation that many things might affect the decision making process of a swarm
For instance, if the best nest site was introduced late in the process, would its supporters have a hard time recruiting bees who might already be supporting another site? Or, if presented early, could it lose status if the bees don’t transmit its true quality somehow? What if it is harder to find, making recruiting other bees a challenge?
To test the bees’ decision making skills, Seeley would conduct a series of controlled experiments
Mediocrity in 15 Liters
In the summer of 1997, Seeley returned to Appledore Island located in the Gulf of Maine
His first goal was to create an artificial nest site that would be considered acceptable but not ideal to the bees
He would present swarms with 5 nest boxes; 4 acceptable, and 1 ideal, to determine whether the swarms had optimal decision-making abilities
For his previous studies in the 1970s, Seeley knew that bees prefer nest cavities of a larger volume (40 liters) and with a small entrance (15 square-centimeters)
He decided to create a nest box that he could alter the volume of, as well as the entrance size
Each box had a volume of 40 liters but were fitted with a movable inner wall to reduce the volume to 20, 15, or 10 liters
Similarly, he could reduce the entrance with entrance reducers
The nest boxes were only to differ in cavity volume and entrance size so, to avoid external influence, all were placed inside an open-sided shelter, all of which faced the same direction and had identical exposure to wind, sun, and rain.
In early August, 1997, Seeley and a research assistant (his 13 year old nephew, Ethan Wolfson-Seeley) took 5 nest boxes, 5 shelters, the swarm stand he used to record bee dancers, and 3 hives of bees to the island
Within a few days of arrival, they had set up an artificial swarm on the porch of one of the Shoals Marine Laboratory buildings, and had placed 2 nest boxes on the North half of the island
Both sites (A and B) were 250 meters/820 feet from the swarm but oriented in slightly different directions
In order to attract the scouts, both boxes were set up with a large volume cavity of 40 liters and a small entrance of 15 square-centimeters
Seeley had concerns that, due to how the island buildings had increased since his last visit, other nest sites would attract and distract the bees
To deal with this, Seeley identified ‘rogue dancers’; bees on the swarm that danced for unknown locations; once spotted, these dancers were swiftly removed and euthanized (by freezing)
If these dancers for ‘rogue’ sites were not removed, they could quickly gain an enthusiastic following
Twice when this occurred, Seeley and his nephew were able to determine the location of the sites; one was a space beneath a pile of old boards, and one was a small cave in a stone wall
Seeley was able to end interest in these locations by opening up the spaces, effectively removing the cavity
One time, however, they were unable to locate an advertised location as it appeared to be somewhere deep within a tangle of poison ivy; as a result, they had to end the experiment with that swarm and try again with a new set of bees
Thankfully, the majority of the bees in the study focused on the nest boxes provided
Seeley first focused on entrance size, believing that enlarging the entrance size would make a nest box ‘mediocre but acceptable”. However, he soon learned that a large entrance caused a steep decline in interest from the scout bees.
When offered a nest box with a volume of 40 liters and entrance of 15 centimeter-square, the scout bees showed great interest with an increasing number of scout bees investigating the nest
On August 10th, after one such box had been discovered by the bees at approximately 1pm, there were more than 10 bees showing interest by 2.30pm (just 1.5 hrs after discovery)
Seeley then enlarged the entrance from 15 centimeters-square to 60 cm-square at 2.30pm, and the number of bees plummeted until just 1-2 remained by 3pm
He then reduced the entrance back to 15 cm-square at 3pm, and the number of scout bees increased to 12 bees by 4.30pm
Once again, Seeley enlarged the entrance back to 60 cm-square and, by 6pm, only one lonely scout bee remained at the site
Seeley repeated this experiment the following day but enlarged the entrance to 30 cm-square to see if this size would be acceptable to the bees but, again, they lost interest
“These results, confirmed by those obtained from a second swarm a few days later, taught us that scout bees judge a nest box with a 30 or 60 cm-square entrance to be a low quality, probably even unacceptable, homesite.” Pg.108
Next, Seeley and his nephew attempted to create a medium-quality nest box by reducing the cavity volume below 40 liters
On August 13th, this trial started well with scout bees discovering both nest boxes later in the day
The next morning, Seeley kept one box at 40 liters and reduced the volume of the other box to 15 liters; both had an entrance of 15 cm-square
The number of scout bees to the larger, 40 liter box increased steadily until reaching a total of 9 bees by the early afternoon; the 15 liter box, meanwhile, attracted just 1-2 bees
Although it was clear that the scout bees were treating the larger box as a high quality site, could it be said that they viewed the smaller box as medium quality; one that is not highly desirable but still acceptable?
To test this, Seeley enlarged the opening of the 40 liter box to 60 cm-square at 12.30pm, and waited to see if interest would increase for the 15 liter box; it did!
The number of scouts at the 40 liter box with the enlarged entrance now decreased while the 15 liter box (with the 15 cm-square entrance) now had a high level of interest; in fact, at 1.28pm, the swarm took flight towards the 15 liter box.
To Seeley, this demonstrated that a 15 liter nest box with a 15 cm-square entrance is a mediocre but acceptable homesite for honeybees
Two additional trials were conducted with similar results; when presented with 2 nest boxes with differing volumes, scout bees would build up strongly for the 40 liter box than one that was smaller when both had 15 cm-square entrances. But if the 40 liter box’s entranced size increased to 60cm-square, the bees would favour the 15 liter box.
Window on a Bee’s Mind
“Further evidence that we had found the right formula for creating a mediocre but acceptable homicide came from observations made at the swarm cluster rather than at the nest boxes.” Pg.110
At the cluster, Seeley was able to identify which site the bees danced for based on the angle of their waggle run, as each site was carefully positioned so that their directions differed by exactly 30 degrees
Considering what is known about a forager’s waggle dance, Seeley thought the rules that applied to desirability of a food source and the ensuing dance would also apply to nest site desirability
A bee reporting on a bountiful food source will perform a strong dance of as many as 100 dance circuits that lasts for 200 seconds, versus a weak dance of just 10 dance circuits lasting 20 seconds, for a poor food source
We can see how the desirability of a food source correlates to dance strength and time, which provides a ‘window’ into a bee’s mind
To test this theory that nest site desirability could be seen via a bee’s dance strength, Seeley set up a video recorder to capture scout bees advertising for a 40 liter and 15 liter nest box
Both sites were advertised by scouts, which supports the idea that both are desirable but exactly how desirable?
Seeley found that the bees reporting the 40 liter box danced strongly with an average of 35 circuits that lasted for 85 seconds; whereas the 15 liter box was advertised with weaker dances consisting of an average of 14 circuits that lasted 45 seconds
This supports the previous study’s findings that bees consider a 15 liter box to be an acceptable but mediocre nest site; acceptability is determined by the scouts advertising the box’s location, and the mediocrity is evidenced by the weak dances (i.e. the bees aren’t thrilled but they'll take it!)
Critical Experiment
Seeley’s time on Appledore Island during August 1997 had led to him learning how to fine tune his experimental nest boxes for his primary experiment: offering a swarm the choice of 5 nest boxes, 4 of them ‘fixer-uppers’ and one of them a ‘dream home’
Seeley had to postpone this experiment to the following summer due to his teaching commitments at Cornell
When he returned to the island in June 1998, he brought with him Susannah Buhrman (previously mentioned)
The pair set up 5 nest boxes in a fan-shaped position (at least 15 degrees apart) on the east side of the island, approximately 250 meters from the swarm
Each trial began by arranging the boxes so that only one offered a 40 liter volume, while the others were modified to 15 liters. They then mounted the swarm on the swarm stand and waited for scout bees to mobilize.
Once scout bees began to appear, one person monitored the dancers at the cluster, removing any scouts who danced for sites than the supplied boxes, while the other checked the nest boxes every 30 minutes for scout bees
5 trials of the experiment were completed in total with a new swarm used each time, and with a different box presented as the ideal 40 liters (by adjusting volume settings as opposed to moving one 40 liter box to a new location)
The results showed that:
All, or nearly all, 5 nest boxes were discovered in all 5 trials, indicating that the swarm had full knowledge of the available sites
The bees did not discover the sites simultaneously, though all were found in one day
Most critically, the ‘excellent’ nest box was never found first. This is noteworthy because it means that, due to timing, the best site starts out behind in the race for support and yet, in 4 of the 5 trials, it still became the top choice.
“The 5 swarms did not achieve a perfect 5-for-5 score in this choice test, but they did demonstrate impressive skill in decision making.” Pg.113
How do we know that this result (4 out of 5) is due to decision making and not chance? Maths!
Seeley notes that, if the swarm had chosen at random from the 5 options presented, then the probability of choosing the best site in 4 out of 5 trials is a mere 0.0064 (or 0.64%)
To put it another way, to get a 4 out of 5 outcome purely by chance, one would need to repeat the experiment 156 times for this result to occur (1/156 = 0.0064)
“It is clear, therefore, that compared to relying on chance, the democratic decision-making process found in a honeybee swarm greatly increases a swarm’s likelihood of selecting for its future home from the best candidate sites located by the intrepid scout bees.” Pg.115
Trial 4 of the ‘best of 5’ choice test chose a mediocre site. Why? For some unknown reason, the 2 scout bees that discovered the ideal site did not waggle dance to advertise for it. As a result, the swarm ‘overlooked’ this location and attention focused on one of the mediocre sites.
We see then how important it is to success that all acceptable options are reported by scout bees
“In the next chapter, we will see that the bees have a nifty rule of house-hunting behaviour that normally results in every respectable housing option found by a swarm’s scout bees getting included in their debate.” Pg. 115
Swarm Knows Best
When considering why honeybees might prefer a 40 liter nest volume over a nest of 15 liters, it’s natural to assume that natural selection has led to this preference as a larger cavity means a larger store of honey to get the bees through the cold winter months
In other words, the 40 liter cavity offers a greater chance of survival since studies have shown that winter starvation is a major cause of colony death (especially newly established colonies)
In studies of other animals, including mammals and reptiles, nest-site preference has shown to increase survival chance and therefore reproductive success
To test this, Seeley decided to set up an experiment that allowed him to compare the survival chances of bees living in a nest that embodies their preferences versus one that does not
He started his experiment in 2002, installing artificial swarms in two groups of differing sized hives in the spring, left them alone over the summer, and then noted whether the colonies had different rates of survivability that winter
Each swarm contained around 10,000 bees (typical size of a natural swarm), and Seeley chose hives that contained 5 or 15 rectangular wooden frames (like those used in Langstroth hives)
5 frames is roughly equal to the amount of comb that can be built in a 15 liter volume cavity, while 15 frames is equal to the comb of a 40 liter volume cavity
Since a natural swarm is more likely to nest in an empty tree cavity with no existing comb, Seeley used empty frames in his test hives; alternating one empty frame with one that contained foundation so that comb would be built straight/neatly
Each time he conducted this experiment, Seeley set up 5 colonies in each type of hive (5 frame vs 15) in early June, and then followed them for the next 12 months to see which survived to the following Spring
He replicated this experiment 3 times: 2002-2003, 2003-2004, and 2004-2005; a total of 30 colonies
Those colonies in the 15 frame hives had a winter survival rate of 0.73/73% (11 of 15 colonies), while those in the 5 frame hives had a dramatically lower survival rate of 0.27/27% (4 of 15 colonies)
The chance of such a large difference in colony survival between the two groups is just 0.02/2%; therefore, survival is not random, and the size of the nest cavity has a direct effect on winter survival
Seeley weighed each colony’s hive in June and then again in October, and found a big difference in average weight between the two groups; the 15 frame hives averaged a weight gain of 23kg/51lbs, versus just 10kg/22lbs for the 5 frame hives
This weight consists primarily of honey; their winter food
Of those colonies that perished, an inspection found the frames empty of honey, indicating that the bees starved to death
“These stark statistics on colony survival as a function of hive roominess are solid evidence that swarms really do know best about their housing needs, and in exercising their nest-site preferences they really do make good decisions.” Pg. 117
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And that's it for this chapter! Next episode, we forge ahead to chapter 6: Building a Consensus. Thanks for listening and reading! Stay safe out there!