Introduction
Many of the particpants in the Migrating Kestrel project tell me how difficult it is to estimate the number of kestrels at the roost. There are many factors that we up against including the number of birds in the roost, the area of the roost trees, the poor light and if the birds arrive/leave in small or large groups. One area where we can try to improve these estimates of the number of kestrels is to improve our ability in estimating the number of kestrels in the air quickly. This document aims to give some guidelines on how to count bird flocks and kestrels in particular.
In the past, I have had competitions with colleagues in estimating bird flock size quickly, where we both estimate the number and then count them to see who was closer. I have noticed that I always tend to underestimate numbers, and those colleagues that have experience in water bird counts are much better than me at estimating the correct number.
In the slides below, I have provided a number of pictures of kestrels in the air (and one in a roost tree). The idea is that you look at the picture for 5-8 seconds (roughly the time you have when there is a huge burst from a roost) and then write down your estimate of the number of birds. You can then click on the link to the total, and after doing all the pictures, will have a good idea whether you typically underestimate or overestimate the numbers. You can also look at how good you are estimating bird numbers by seeing how far you are off from the total.
I would be very interested in the results. If you feel like participating, email your results to me (anthony@kestreling.com) and whether you have previous counting experience or not. If I get enough replies, I will post a report on kestreling.com.
Lastly, hopefully this exercise will also give you a bit of experience on estimating kestrel numbers, because you can go back to the pictures now that you know what the total and imprint in your mind what that number of kestrels look like. That, in itself, should improve our ability to count more accurately.
Pictures of kestrel flocks
Click on the picture to get a larger view (1024x786) [Note: if you computer screen is running at a resolution lower than this, you will not be able to see the whole picture on the screen and will have to scroll around to get an idea of the flock size.] Look at it for 5 seconds, then write down your estimate. You can then close the picture window to return to this page and click on the answer link to see how many birds were actually in the picture. In the answer link, I have also included the same picture but with all the birds numbered so you can check the count for yourself.
The picture is displayed in a new browser window which you can resize to display the whole picture if needed. You can close the window after your 5 seconds of counting.
The picture is displayed in a new browser window which you can resize to display the whole picture if needed. You can close the window after your 5 seconds of counting.
The picture is displayed in a new browser window which you can resize to display the whole picture if needed. You can close the window after your 5 seconds of counting.
The picture is displayed in a new browser window which you can resize to display the whole picture if needed. You can close the window after your 5 seconds of counting.
The picture is displayed in a new browser window which you can resize to display the whole picture if needed. You can close the window after your 5 seconds of counting.
How did you do? Email your results to me (anthony@kestreling.com) and whether you have previous counting experience or not. And, let me know if you have any suggestions how we can improve counting kestrel flocks so I can let the rest of the team know.
If you would like to see the trend of counters that have submitted their result to me, take a look at the Training Results section.