Dear Readers, I know you are all agog to hear the results of my Open University science experiment with doughballs, and now that my assignment has been sent off, I can finally share what the results seemed to show.
You might remember that the task was to prepare some red and some yellow doughballs for the birds to enjoy, Typically for me, I decided that lard and flour wasn’t quite tasty enough, so I also incorporated some whizzed-up dry mealworms and some bird-friendly peanut butter. This all made the balls a little darker in colour than they would have been, and I wondered if the colours would be different enough for the birds to discern. I also took care to use bird-friendly colouring, which was probably not as strong as the artificial colours that some people used.
Then, I had to run twenty trials, ten with 45 red and 5 yellow balls, and then ten with 45 yellow and 5 red balls. The reason for this was that we were testing for two different things.
Firstly, were the birds just taking whichever colour was commonest without any regard for its features? If this was the case, they shouldn’t care which colour was presented, so long as there was lots of it.
Secondly, were the birds choosing one colour in preference to the other?
Well, the results are in, and the magpies were clearly choosing the red balls, even after I’d done all kinds of fancy statistical stuff to make sure it wasn’t by chance. How exciting! We know that birds have colour vision, and in my experience it’s the red berries in the garden that always go first, so I imagine that the red colour is an advertisement for ripeness.
The effect of choosing prey based on colour will depend on what kind of prey it is. If it’s an insect, and the red ones always get eaten, they will become rarer and rarer, until they finally find it hard to survive. If the prey is a berry, however, and it can survive a trip through the bird’s gut, being eaten is a great advantage, as the seeds will be dispersed far and wide. I expect to see lots of baby red doughballs popping up all over the garden.
Of course, like all scientific experiments this one opens up as many questions as it answers. Is it only these two magpies who prefer red, or all magpies, or indeed all birds? I know that many bird-pollinated flowers are red, so that might be an indication. Secondly, I wasn’t as careful as I could have been with the size of the balls, so did the birds also choose larger balls for preference? Finally, would the results have been even more marked if the difference between the colours was clearer?
At any rate, this was a most interesting experience, and it felt as if I was doing ‘real’ science. It will be fun to compare the results with my classmates, and to see if anyone had anything really strange ( I know that one woman was using her pet chickens to test out the theory, and another kept having her doughballs stolen by squirrels, who are pretty much colourblind as far as I know). And for now, I have so much excess dough that the magpies are enjoying it without having to do any work at all.
Our next experiment is on leaf stomata, which sounds rather less exciting, but I’ll keep you posted!
Looking forward to those baby red doughballs next year.
🙂
I have indeed been agog to hear the results of the doughball experiment and was disappointed not to find this post in my Reader yesterday, even though I checked both morning and evening! Thank you for remembering to let us know 🙂 I, like so many others, ignorantly coloured the water in the nectar feeder for some years. I haven’t for a long time now and the birds still find it whenever they need it. Perhaps they can smell the sweetness. Colouring of food is very different though – especially berries, I should think. The peach tree in our neighbour’s garden attracts birds as soon as the fruit shows a first flush of colour – so colour obviously indicates ripeness. Yellow and red are bright. I wonder how the experiment would have fared if the balls were blue and green respectively.
That would have been interesting, Anne!