In general, I do visit the points in the same order and roughly the same time of day. This really isn’t a problem for bias because I’m not trying to glean information from that point but rather that habitat type. It’s amazing how variable bird activity is. You can visit the same point at the same time of day and one day it can be hopping and the next week completely dead. While things are generally more active earlier in the morning, even that rule isn’t universal.

That’s what the large number of points (40 in each habitat type) and 4 repetitions is for — to account for any bias that comes from minor variations in weather conditions and differences in bird activity.

You’ve hit the nail on the head — the single most important variable of this study is the skill of the observer. Without an observer that really knows what they’re doing, the value of a study like this is nill.

As far as a prescribed method, I generally stand still at the point itself. If I see a bird fly in and need to move a few steps to get a look at it, I’ll do that. But I do not walk around actively looking for birds, nor should I. (As you walk away from the point, you get much further away from the 50 meter boundary behind you, and closer to the 50 meter boundary in front of you, thus making it very difficult to judge if a bird’s within your circle).

I would not say that it’s assumed that every competent observer will notice everything within 50 meters as much as it is determined by comparing studies with differing distances that 50 meters works best. (This methodology is largely one that’s been refined over serveral decades of trial, error, and comparison). I should also point out that I see very few birds compared to hearing them. Thus 50m is a distance at which I can hear everything. Get much further than that, and the observer is going to detect species with “loud” songs or calls more frequently than those with “quiet” songs or calls.

Finally, in regards to your last question — I always equate this to God and the problem of evil. He gives me the gift of birding while neglecting the gift of being a morning person. (I’m completely joking of course).

I could always have picked herpatology. I would have been working every afternoon in the desert. Some call it Hell. Mammalogy would be a good fit for the person that likes to stay up late. All the little furry critters are active at night, but then again, they’re all brown. I like brown, but a little variety is nice too. Botony can be very unfairly made fun of as food science (everything eats plants after all) and while entomology is truly fascinating, I perfer a group that I can actualy wrap my mind around. There’s 10,000 species of birds and arond 420,000 species of beetles alone. Too much.

Thanks for the explanation. I now have a much better idea of what you’re up to out there.

When you run a transect, do you always visit the points in the same order? If so, do you make sure that other transects visit the habitat types in a different order? Otherwise I could imagine some biases in the data due to the exact time of day you visit a particular habitat type.

Also, if studies of this type are done by single observers, there would seem to be no way to control for the skill of the observer. You might notice everything, while another observer might be so bad that he’d miss a turkey vulture unless it landed on his head. (I suspect I’m more of the latter than the former.) Is there a prescribed method for how you scan each point on your transect? Is it just assumed that every field biologist is competent enough as an observer to notice pretty much everything within 50 meters of the transect point?

Lastly, why on earth would you pick a profession that requires you to be up before sunrise every day?

Regards,
Keith S.