Nest
A natural nest encompasses more than just cell size.
A natural broodnest.
When bees swarm and establish a new nest, they assess nesting sites for suitability. Cavity volume, location, orientation, access and defensibility are a some factors checked when choosing a new nest site. When enough excitement is generated for a particular location, a colony swarms and builds a new nest.
The bee's ability to collectively assess and act, doesn't stop once inside a new cavity. Depending upon its shape and orientation, the bees construct a broodnest that gives them the best possible chance for survival and reproduction. That broodnest structure compliments the changing seasonal requirements and varied colony activities. Its form enhances colony function.
Typical core broodnest comb.
Nest Construction
My top bar hive bees, cluster in the first one third of the hive, nearest the entrance. The first comb building activity begins on top bars 3 to 5. Initially, comb building is confined within the cluster's physical limits, where the bees feed each other and keep the wax warm enough to work. At this point, most comb is extended horizontally. A few central combs are built vertically, beyond the clusters initial confines. As more comb is built, fewer bees can control the environment between the combs, which liberates more bees to work horizontally.
The bees build a few large storage and drone cells along the top bars. Then they transition into larger size worker cells. This transition is most pronounced on the comb nearest the entrance. Initially, worker comb is built faster there. Later, larger worker size cells and drone comb are completed on the comb farthest from the entrance. Once a few combs are long enough to isolate the environmental effects of the entrance, comb building is more uniform across its width, as well as its length. But the bees still build larger cells on the side farthest from the entrance.
Bees shift their comb building focus. Sometimes, comb is extended horizontally. Then suddenly, the focus shifts and moves towards the hive's front to work comb vertically. These shifts aren't related to the nectar flow. But rather on the colonies needs. I've often seen bees complete the small cell size nest area, near the entrance, during a strong honey flow, rather than work in the honey storage area toward the rear of the hive.
This cross section was created using Sketchup, Google's free 3D CAD program. You can download this 2 mb cross section then zoom it, rotate it, etc., inside Sketchup.
Cross section of a natural broodnest.
Nest Structure - Broodnest
The nest has a definite structure. Bees build straighter comb near the entrance. It's spaced at 1 1/4 inches and each comb is a close approximation of its neighbor. This is the brood rearing area of the broodnest. There, worker sized cells gradually taper from larger sized worker cells, at 5.4mm near the top bar, to 4.9mm small cell size half way down the com.
Comb in the broodnest area is parallel. The bees curve some comb ends slightly toward the hive's front.
Broodnest Core
Bees store and cap honey in the larger worker cell sizes, but they kept the smaller cell size areas open for brood rearing. And they cluster there during the winter. This is the broodnest's core. It's located toward the front nest's bottom edge, near the entrance.
Honey Storage Area
Typical honey storage comb. It seems chaotic with rapid cell size transition and orientation.
Toward the broodnest's rear, combs quickly transition into a honey storage area. This transition point is determined long before the bees complete the broodnest area. Yet, they can determine, before it's built, just how much space is needed for an optimum broodnest size.
The combs are thicker and wider spaced here. They contain a small amount of larger worker size cells near the comb's bottom edge. But most cells are drone size or larger. Cell orientation often appears chaotic. Different orientations and rapid transitions between patches of comb give that impression. I've never found small cell comb in the honey storage area.
Combs are parallel in the honey storage area, but straight comb isn't a priority. Sometimes the direction of comb is completely contrary to the broodnest comb. Here, combs often drastically curve toward the entrance.
Once the broodnest is complete, the honey storage area is extended toward the hive's rear until an optimum situation is reached. After that point, broodnest construction almost stops. After that, only minor broodnest construction occurs regardless of available space or nectar resources.
Oops
Sometimes comb is built that doesn't follow the broodnest structure. Bees are genetically wired to orient and build the right comb, at the right location. But, it's a delicate process with many factors involved. Top bar 7 of my hive, was drawn as a mirror image of the adjacent broodnest comb. Drone size cells were drawn down low, on the side nearest the entrance. Worker cells were drawn on the right side. I thought a comb was mistakenly reversed when I worked the hive. Early photos this top bar had a unique knot. The orientation was correct.
The bees had trouble working with this comb. Some shots indicate the bees attempted to rework the comb. Combs on either side of this one were drawn rapidly and smoothly finished off. The bottom edges of this comb remained ragged and this comb was never completely finished off.
Can bees make mistakes? I think they can, especially with a beekeepers help:>)
This comb was within the broodnest. The area in the lower left portion of the photo should be small cell sized worker comb to be consistent with combs on top bars 6 and 8.
The bees tolerated the drone size cell in the upper left of the shot. And they tolerated the larger worker sized cells to the upper right. But they couldn't tolerate the drone sized cells in the small cell sized broodnest core. The orientation and location of small cell comb is important. Or the bees wouldn't have had such problems with this comb.
Comb management is a delicate process. The bees balance many factors when building a broodnest. But they don't have any mechanism to handle comb that rotates, shifts, is inserted backwards or disappears.
Typical top bar hive comb management mixes up a broodnest. David managed his top bar hive that way and I've managed some that way also. Mine, that were managed that way, quickly developed parasitic mite syndrome(PMS) before the season's end. They required mite treatments to survive. When I re-arranged top bar hive comb to mimic a natural broodnest structure. Mites were seen in those hives, but they never developed PMS.
That's how important the broodnest structure is. Mess it up and you have messed up the hive.
Colony Intelligence
Broodnest location and structure remains constant even when bees shift their comb building focus elsewhere. How do different generations individually sense what comb is needed? If they couldn't sense it, each bee's effort wouldn't result in a structured broodnest, as each bee builds only a small part of a cell. And it takes several generations to build the nest.
Other beekeepers have observed this architecture in their own top bar hives. Some have seen it in feral colonies removed from buildings. And some ferals have survived for years without man's intervention.
Optimum Cavity Shapes/Sizes
Bees prefer a functional size cavity when selecting a home. Entrance size and location are also important. Bees from a more temperate climate prefer, larger, tighter cavities with a smaller entrance toward the bottom. Tropical bees are less selective and will use a smaller cavity. Or forgo the cavity and nest out in the open.
Shorter comb has less small cell core area than longer comb. Maybe some cavity shapes are more optimal for colony survival than others. For an optimum amount of small cell core area, a cavity must be tall enough.
Just how much small cell core area is needed? I don't know. Climate is probably a factor, but I'd rather have more small cell comb than less.
