Estimating Numbers of Birds

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A flock of geese in the Texas Panhandle Nov 28, 2010 – photo © Martin Reid

Estimating numbers is an essential part of birding, but the truth is we are pretty bad at it. Research shows that our estimates are often very wrong, and also very inconsistent. Fortunately that same research points to some strategies that can improve our estimating skills, and that’s what this course is about.

The first half of this course is about understanding the challenge:

  • Just how bad we are at estimating
  • A scientific perspective on the challenge
  • some of the things that can bias our estimates

The second part is about how we can improve:

  • How to “calibrate” your mental image of large numbers
  • The value of grouping a flock into “clusters” 
  • Some techniques for specific scenarios like streaming flocks, mixed-species flocks, etc

And lots of quiz questions throughout to test your new skills

Hopefully the information and practice that you get in this course will dramatically improve your estimating skills!

Take the Pre-test!

Before you get into the course, check your current estimating skills by taking the quiz linked here:

Take the Pre-Test here


If you want to jump right into the quizzes without reading anything, here are links to the three primary quizzes:

* the pre-test with no guidance and no feedback (try this first!)
* a guided quiz with feedback
* a multiple choice quiz with a limited range of numbers

About the quizzes:

In the quizzes you will see an image of dots or a photo of birds. Estimate the number of birds or dots in the photo, type your answer in the box, and click “next” or “check”. Answers must be in multiples of ten (e.g 60, 120, 410, …) to match the stored “correct” answers (except in a few questions dealing with very large numbers where answers need to be in multiples of 100).

Any answer within about 20% of the actual count is scored as correct. Any answer that is off by more than 20%, high or low, is scored as incorrect. You can ignore the list of numbers that appear alongside your answer, these are the numbers stored as correct answers.

The Cheat sheet

I’ve created a one page pdf showing several arrangements of 100 dots. You can save it on your phone or print it out and carry it in the field. Refer to it regularly to recalibrate your sense of 100 or compare it directly to the flock of birds in front of you. You could also try using it while taking the quizzes in this course.