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Flower Index

  Ecology improves on Natural History by putting numbers to things.  Sometimes they are true counts e.g. population counts.  At other times they may be arbitrary scales.  Here numbers are used (which allows us to present data graphically) but they are replacements for descriptive terms such as “rare”, “common”, “abundant” etc.  They are not true numbers and you cannot perform statistical analysis on them.  Nevertheless they allow comparisons to be made with a greater clarity than verbal descriptions.

  I used an arbitrary 1-3 scale.  If there were very few bees on a flower it was a “1”, lots of bees were a “3”, anything in between was a “2”.  It is very subjective.  Another observer might make different judgements.  Even so, for one observer it allows a number to be put on the relative merits of different flowers.  Even between independent observers, while not agreeing on the exact number, they will be likely to place the attractiveness of the flowers in the roughly same relative order.

  Bumble bees are harder to deal with his way as you rarely see them in large numbers in one place.  In the end I found that by using just “1” and “3” for my observations the average of the observations came out within the range and the numbers for honey bees were then on a scale directly comparable with bumble bees.  Life is a lot easier if the same number means the same thing in terms of relative attractiveness.  We should remember that an average of arbritrary numbers is just a descriptive term of something in between the extremes.

    A flower that is moderately attractive to bees over many weeks may be more useful than a flower which is very attractive for just a few days.  Each week I would record the attractiveness of a wide variety of flowers to bees and I would multiply the average of my observations by the number of weeks a given flower was visited.  This I call the flower index.

  E.g. if, over 6 weeks, I observe values of 1, 3, 3, 2, 3, 2 then the average is 2.3 and the flower index is 14

  One final caveat is that when I say Bumble bees I mean all bees other than honey bees.  I don’t want to leave the other bees out but I cannot identify them all and separate records for dozens of species would get too complicated anyway.

  Other people have monitored flower attractiveness in other ways.  To read about these go to other observers.