Estimating numbers in flocks of birds is a skill that birders need to practice, but we rarely get a chance to test ourselves. We see a flock, guess the total number, and write it down. We might be off by a large margin, but we’ll never know.
Here is a quiz (and more to come) that will give you a chance to test your accuracy. These are lentils, photographed against a white background, but they simulate birds pretty well, I think.
One estimating technique you can try is to count the “flock” in segments. That is, count ten to see what a group of ten looks like, then superimpose that group across the flock, counting in groups of ten. Or you can just “eyeball” the flock of lentils and take a guess. Good luck, and feel free to offer suggestions or encouragement in the comments.