Monday, 15 September 2014

Weighing the hive

One way to get an indication of what's happening inside a beehive without having to open it up is to weigh the hive. There are several reasons why this useful.

Firstly, weighing a hive can be done regardless of the weather. This is especially useful during winter when it's too cold/wet/windy to open the hive. Regular weighing allows the beekeeper to assess the amount of stores the hive has. This information can then be used to assess whether supplementary feeding may be required.

Secondly, weighing the hive does not disturb the hive environment. Understanding the importance of the hive temperature and humidity, how this affects hive health, and how to use this knowledge to look after your bees is important. Bees expend considerable energy to maintain the ideal temperatures and humidity inside the hive. Opening a hive and especially moving comb can cause rapid and dramatic shifts in both those variables and cause undue stress for the bees. According to David Heaf in his book The Bee-friendly Beekeeper, every opening of the hive that lets the heat out forces the bees to repair the damage - repropolising and repairing comb that may have been broken - and to restore the 'thermal structure' of the colony by extra heat producing activity. In winter, the cluster can take as much as 3 days to return to normal. Depending on the extent of comb manipulation, even in summer the restoration of the pre-opening condition could take as much as a day. Thomas Seeley, the well-known bee biologist, found in his 2007 study, Honey bees of the Arnot Forest: a population of feral colonies persisting with Varroa destructor in the north-eastern United States, that feral bee colonies left alone were able to better co-exist with Varroa mites than those managed in a more conventional way.  So while it is tempting to want to open your hive frequently to check for problems and progress it's worth bearing in mind that bees carefully manipulate the environment inside their hives and any disruption to that environment can cause or exacerbate the very problems that you are checking for.

The system we use to weigh our hive was invented by Andrew Janiak, convenor of the Natural Beekeeping group, of which we are members. Andrew and his clever beehive scales were featured on the ABC New Inventors television program where his scales won the Peoples' Choice award.  More details and a short video showing how the scales work can be seen here.

Essentially the system consists of a simple hinged timber platform that sits permanently under each hive, and a light weight portable frame that holds the scale. The scale is inserted between the two halves of the platform (at the rear of the hive) then the handle is moved to determine the weight.

Here are some photos of the platform. The hive is positioned on the base so that the entrance is above the hinged edge. (The hinged edge is on the left side in the first picture below)

Here's a picture of our hive sitting on the base:

The scale consists of a light-weight metal frame which is easily carried from hive to hive. The platforms are very cheap to produce, costing only about $4-5.00 each.

Here's a picture of the scale positioned on the base, ready to be used. A 'hive' consisting of a couple of empty boxes is being used here for demonstration purposes. You can see that with the handle in the down position the hook is raised. The legs of the frame are sitting in the metal guides. The metal guides can be seen more clearly in photo 2 above.

Frame sitting in position on base

Zero the scales before engaging the hook

To measure the weight of the hive you firstly position the scale so that it sits in the metal guides in the platform. The next step is to zero the scales and then lift the handle to allow the hook to move down so it can be manually attached to the platform. Once the hook is engaged, the handle is gently pushed down until it can move no further. Pushing the handle down raises the hook and thus the platform. Once the handle is in the fully 'down' position the weight is recorded. The scale has leverage of 1:10 so you only need to lift a tenth of the weight of the hive. It is also impossible to lift the hive more than a few cm, meaning there is less chance of disturbing the bees or toppling the hive.
Move the handle down to weigh the hive. This will raise the hook and in doing so, lift the base.
When handle is fully extended downwards and scale light stops flashing the weight is recorded.

The amount of force required to push the 2 halves of the platform apart determines the weight of the hive. The scale is actually set to show 1/2 of the weight of the hive, then you can multiply to get the whole weight.

By keeping regular weight records over the year the beekeeper can get a picture of how the hive is performing. Of course, to ensure consistency it's best to take the measurements at the same time of the day, preferably early evening when everyone is back inside for the night. That way your results will be comparable. The weight going into and out of winter is very useful to help determine how much in the way of stores the bees used over winter. Also, if you have several hives you can use this method to help identify any hives that may be struggling, allowing you to take the appropriate action before it's too late. Weight data is also a handy way to identify if there is a honey flow on as the hive will quickly put on weight.  We use weight data to help identify when a super is ready for harvesting.

While not removing the need for occasional inspections, weighing the hive reduces the need to continually open it up and disturb the bees. We've been weighing our hive on a weekly basis for over a year now, and thanks to Andrew's scales, it's quick and easy to do.  The information we're gathering is helping us better manage our bees and in our opinion it's definitely worth the small amount of effort involved.


No comments:

Post a Comment