As anyone who follows me on Twitter will already know, most of my tweets these days involve shameless, predictable NQS blog post promotion. Yesterday though, I got a bit out of character. It all started with a BTO tweet that appeared on my Twitter feed, and is reproduced in the screenshot below. I'd like to ask a favour please. Before you plough on through the rest of this post take a few moments to digest the BTO tweet. What does the tweet tell you? How do you read it? What message do you think the BTO is trying to convey here? What is the motive for posting such a tweet?
You get the point. I'm just asking for a bit of analysis. I'd be grateful to hear what you think. Anyway, here it is:
Right then, here's what I thought...
First off, I distrust numbers. 23% eh? How exactly did they measure the 77% that were not brought home? That was my initial reaction. A cynical one. I couldn't access the 'bit.ly/2h5ta1P' link so simply replied to the tweet and asked my question. I received a very quick and helpful reply, thus:
However, before I go on I must mention something else that I thought on reading the original BTO tweet. I thought we were talking about birds. After all, we have a photo of a cat and a bird, the BTO is an organisation centred upon birds, and so surely what this tweet is conveying to us is the concern that for every one bird that is brought home, another three are killed and left. Oh, and I also thought we were talking about British birds (British Trust for Ornithology?).
Yes, I made assumptions. That's why I am curious how others see this tweet. Incidentally Mrs NQS read it exactly the same, without any prompting from me.
Anyway, in another tweet Becky Thomas kindly added that she had given the presentation at the BTO Conference, in case I had any other questions. I replied thanks, but that I'd read the research paper first and come back to her if necessary.
So I read the research paper. Fascinating stuff. And how did they know how many victims the cats brought home vs didn't bring home? By mounting little cameras on their study cats! Of course, why hadn't I worked that out myself?! I read on...
The study took place in the state of Georgia, USA. Not Britain. The cats involved were ordinary pet cats who were allowed outdoors, in various habitats ranging from urban to rural - 55 cats in total. Data were collected over one year. The cats were divided into four groups of 12-15 each, and each group monitored for just one season, i.e. spring, summer, fall or winter. Of those 55 cats, the paper said that 44% displayed hunting activity, i.e. stalking, chasing, etc. As 44% of 55 = 24.2 I'm assuming that 24 of the 55 cats displayed hunting activity. Of those 24, just 16 made one or more successful kills. The total number of creatures killed was 39, all of which were identifiable thanks to the cameras, the vast majority to species. Of those 39 kills, just five were birds. FIVE!
Look again at that original tweet! The tweet is all about birds isn't it?
Ah, but is it? What the research paper does not do is tell you how many of those five birds were brought home; it simply tells you the percentage of prey brought home. Which, in fairness, is exactly what the BTO tweet says too. It's not how I read it though! You?
So off I go again, tippy-tapping away on Twitter like some deranged pedant...
And there we are, the latest storm in my little teacup. I'll be honest, that BTO tweet annoyed me. I thought it was inflammatory. Everyone knows the cat/bird issue is emotive, and I couldn't see any realistic purpose to this tweet beyond stirring things up. Why do that? And after reading the research paper upon which that 23% is based I also feel the tweet is disingenuous.
The BTO tweet was sent on 3 December, and between then and now it has been retweeted 72 times. I wonder what it's achieved. No doubt it has reinforced the views of those who think cats are instruments of Satan, and it's wound up one or two number pedants like me, but what else? We are bombarded every day with statistics designed to uphold a viewpoint or justify some course of action. When those numbers support our own opinion we love them, and when they don't, we point out how they've been twisted and misapplied. Yet nearly all of them are not to be trusted. That tweet does not say reassuring things about other numbers the BTO might publish...
Oh, and three of those 39 confirmed kills were worms. Fact.