The Schiffer-Tree hive for a “revolution in beekeeping”
Torben Schiffer presents on his website and in german TV (NDR broadcast „meinNachmittag – Der Bienenforscher aus Hamburg“ from 15.4.2019) the bee hive „Schiffer-Tree“ as the first species-appropriate bee hive at all. It is to protect the honey bees against manipulative interferences of humans and make nevertheless the beekeeping possible. It takes in requirement the beginning for a revolution in the bee keeping to be.
The hive is produced by the company Nova Ruder GmbH in Switzerland, the first 25 hives are almost completed and largely reserved. The price for one hive will be about 600€ + VAT & shipping. In addition a building instruction is to be published free of charge on the website of the Beenature-Project.
The first prototype was completed in February/March 2019. The Schiffer-Tree has not been tested so far.
The hive body is cylindrical and is closed at the top and bottom by solid tree segments. These 3 components are connected by 4 belts. The side walls are made of 6cm thick solid wood. The outer diameter of the tube is 33cm, the inner diameter 21cm and the height 90cm. The volume of the breeding chamber is 31l. The tube is held together by 3 steel belts with clamping screws. The entrance hole is a 6cm long tunnel, is located in the lower area and has a diameter of 4cm.
Due to the construction I consider problems caused by the moisture behaviour of wood (swelling and shrinking) to be likely. The deformations are particularly large in the tangential and radial directions of the wood anatomy. In the course of the seasons, the diameter of the tube can thus change by up to 1cm, which would mean the emergence of large forces in the construction (when swelling) or the falling down of the stainless steel rings (when shrinking). I do not consider the upgrade with the 5mm thick cork base to be sufficient, especially as plastic deformations also occur with cork under great pressure.
The stainless steel feet of the hive protrude only a few centimetres beyond the bottom of the hive. The tilting moment due to wind forces is up to twice as high as the static moment of the geometry of the hive, depending on the location within Germany (inland). The hive must therefore be additionally secured to prevent tipping over due to wind forces.
How to operate with the Schiffer-Tree
The bee hive is intended as a hive for beekeepers, an attachable honey chamber can be ordered. The honey bees build in the hive natural combs in the stable construction, a removal of the individual combs is not possible. There are no revision openings. An opening of the hive in the operation is not possible. Also a tilting of the hive to get a view from below on the honeycomb construction is practically hardly possible. A control of the varroa infestation by a screening board is not provided. The bee colony is deliberately unattainable for the beekeeper.
To keep the honey bees without any intervention of the beekeeper is certainly to be appreciated for a species-appropriate honey bee keeping, but should only be carried out by experienced beekeepers, who can conclude from the behavior of the honey bees on potential diseases. The complete refusal of revision openings represents an unsolvable problem also for the experienced beekeeper: In case of suspicion of serious diseases, or in case of an outbreak of a bee disease in the region, it has to be possible to examine the honeycomb structure.
Due to the chosen geometry, the winter bee cluster reaches to the side of the hive walls, probably as well as in a natural tree cavity. However, the natural tree cavity offers honeybees solid sidewalls. The Schiffer-Tree has a wall thickness of just 6cm, and thus only a fraction of what nature has offered bees for millions of years. The lateral thermal insulation of the Schiffertree is thus for the bee cluster even smaller than in a magazine hive. In these the thermal insulation around the winter cluster is acceptable due to the honeycomb construction existing there (provided that the insulating effect is not switched off by ventilation). The lateral thermal insulation available to the bee cluster in the Schiffertree corresponds at best to the thermal insulation available to a bee cluster in a magazine hive if there is exactly one empty honeycomb between it and the hive wall.
The thermal insulation of the honeycomb structure is also not taken into account in the comparative measurements of hive systems carried out. One can even read the heat insulating effect of the honeycomb construction from the data of HOBOS, whose team Torben Schiffer belongs to. This fact is not new either, it is the subject of various studies.
For example, Southwick determined in 1984 that the thermal insulation of the unoccupied honeycomb structure was on a par with that of solid wood (Thermal conductivity of wax comb and its effect on heat balance in colonial honey bees).
Thermal images to illustrate the theory
In order to demonstrate the supposedly good thermal insulation of the Schiffer-Tree and to compare it with other hive systems, 4 thermal images are presented. Of these thermal images only one has a colour/temperature legend. However, this legend is absolutely necessary to draw conclusions from the individual images. It is by no means the case that the legend of one picture is transferable to other pictures. The thermal imaging cameras select a new scaling / coloring for each image depending on the situation. To make matters worse, the significance of such thermal images is generally limited. The measured temperatures are quite inaccurate (±2°C), the measured values for different surfaces, materials, viewing angles and distances can only be compared to a limited extent.
Apart from the basically only limited significance of such thermal images and apart from the missing legends, the presented thermal images have no significance for another reason: In the hives photographed as well as in the measurement series there are no bee colonies with their honeycomb structure, but so-called “bee robots”, without honeycomb structure. These “bee robots” consist of a heater and an adjacent bowl for evaporating water. The heating tries now to maintain a set temperature at a place in the hive, the amount of water in the evaporation bowl is adapted to the heating capacity. In this way, the “bee robot” simulates the heating power and moisture output of a colony of bees. I think this is a good idea because this way it is possible to eliminate the fact that no two colonies are alike when comparing different hives. But since there are no beehives without honeycombs and since the honeycomb construction has a decisive influence on the thermal insulation of the whole system, this idea is only insufficiently implemented. The thermal images have no significance.
Influence of geometry on the heat balance of honeybees
Torben Schiffer assesses the geometry of the hive and the space available to the honeybees as extremely important for the honeybees. He does not provide evidence and research for this cognition. As reason he explains that the honey bees need the lateral restriction for heat protection reasons. That is wrong, the contrary is the fact: The lateral constriction takes the possibility for the honey bees of surrounding the bee cluster with its own insulation, the honeycomb construction. Because of the lateral restriction one must offer to the honey bees inevitably a reasonable thermal insulation by the construction of the hive!
Furthermore, the warm air should flow upwards and thus keep the honey supply warm above the bee cluster. Here again the thermal insulation of the honeycomb building with its resting air layers is ignored. It is to be assumed that there are almost no air movements not excited by the honey bees within the honeycomb building. Consequently there is also almost no heat transfer by air flows within the honeycomb construction. These assumptions are supported by HOBOS data already mentioned above and correspond to current views in terms of building physics. The contrary assumption should be substantiated in some way.
Although Torben Schiffer is wrong about his arguments, it may of course be that geometry actually has an effect on bee health. It would require extensive investigation. It is conceivable, for example, that honeybees in a high and slender geometry with good thermal insulation will find it easier to regulate moisture, or that there is no need to regulate it at all. But that is also only a theory.
No screw fittings to avoid thermal bridges
In principle, there is nothing to argue against dispensing with screw fittings, apart from the fact that the construction is more complex and expensive. In the construction of bee hives, I think it is a marketing gag to avoid screwed fittings in order to avoid thermal bridges.
Punctual thermal bridges arise in house construction, for example, when thermal insulation elements are screwed to a facade. Here screw fittings are attached in the direction of the temperature gradient and form a “bridge” between layers with strong temperature differences.
With the usual screw connections of bee hives, for example when screwing the side walls of magazine hives, there are only minimal temperature differences at the different ends of the screws. Heat losses are marginal and negligible.
The screw fittings on the magazine hive that can be identified by colour on the thermal images presented are probably due to the different materials/surfaces. However, a legend with colours and temperatures would be absolutely necessary in order to form an opinion about this.
What are the characteristics of a species-appropriate bee hive?
There is currently no agreement as to which characteristics a species-appropriate honeybee hive must have. However, it is widely agreed that the Western honeybee has used tree cavities as dwellings during its evolution and that these tree cavities were predominantly rotten cavities and woodpecker cavities. Accordingly, the properties which honeybees have found in such cavities over millions of years are to be assessed as species-appropriate.
A good thermal insulation, a low ventilation and the moisture behavior of wood I consider important characteristics and similarities of such tree cavities. But the geometry of the caves, for example, could also play a role.
On the subject of woodpecker cavities and wild honey bees there is extensive information in the article (unfortunateley only in german) „Ein bisher kaum beachteter Mosaikstein im Ökosystem Wald: Die wild lebende Honigbiene Apis mellifera und die Rolle von Spechten und Pilzen für ihr Überleben“ by Dipl. Biol. Sigrun Mittl.
In addition to the characteristics of the hive, the mode of operation also plays a decisive role in species-appropriate beekeeping. The most radical and species-appropriate mode of operation would be to treat the honey bees in no way, to leave them completely alone and not to take any honey away from them.
Conclusion on the Schiffer-Tree
The Schiffer-Tree is designed to reflect the characteristics of a species-appropriate dwelling for bees. This is only poorly realized. In the most important requirement it almost fails: thermal insulation.
The spent goal to protect the honey bees from “manipulative interventions of humans” is reached by the hive: The beekeeper just has no possibility to do so, the hive is not to be opened. For a hive intended for sale to the beekeeper, this circumstance is inappropriate and counterproductive.
The hive is untested, the construction needlessly complex and expensive. Due to the construction I consider damages of the hive by shrinkage and swelling forces of the wood to be likely.
There are better and proven solutions for a species-appropriate beekeeping, for example loghives with large diameters. If you are not afraid to build your own hive, you will find a cheap alternative here: Gruibert hive. However, it is also possible to achieve better results than the Schiffer-Tree by modifying standard hive systems.