So, how many birds do you think there are in this picture?
Mostly Goldfinches (Carduelis carduelis) with some Common Redpolls (Carduelis flammea). Trekanten, Storvreta, December 27 2010.
The answer is 1358. (Well, approximately. Some might be a bit hidden in the photo and hard to see.) That's quite a lot of birds! Taking photos and counting birds on them are a very good way to more accurately assess the number of them than simply trying to approximate when you're out, at least if you're not an experienced bird-counter. I assume there are some people who count birds who can approximate correctly, but I can't.
But counting from a photo also seems like hard work. How do you know you haven't counted that little bird twice? The answer os very simple. Open the picture in Photoshop or similar (I use Gimp), put a grid over the picture, and use the paint tool to simply put a little dot of colour on every bird that has been counted. Count one square in the grid at a time, and note the number. This way you won't count anything twice, and if you get tired you can stop half-way through and continue later.
This is what my photo looked like when I was done: (this is the uncropped picture, the above one is cropped. So, eh, the above picture does not have 1358 birds in it, but a little less. The majority of birds are still there though, maybe 1250-1300 or so. My point still holds!)
The grid isn't shown since it was a feature in the program and not part of the picture. I just painted the number in each grid square, I'm sure some people can write down the numbers in a better way, but this worked for me. After I was done I simple added all the numbers I'd written down, and presto! I had the number of birds in the picture.
Of course I might have missed some birds, and maybe counted one too many somewhere where it was a bit hard to see, but the number should at least be more correct than me trying to approximate just using my eyes. Since this was a mixed flock of course it is a bit harder to tell how many of each species, but I approximated the Goldfinches to be about 80% with the rest being Common Redpolls (and a few other species in such low numbers I could count them, such as seven Twites, three Siskins and a single Linnet.)
I won't pretend it's not a bit tedious sitting there putting dots of paint on each and every bird in the picture though... ;-)
Part of the flock. Trekanten, Storvreta, December 27 2010.




