January 20 - Ohio Odonata Numbers

Charting All the Data by Day

Here's a couple charts updated with the 2022 additions. Compare previous in the Feb 10 Journal.

First the total observations

This looks similar to last year, just with an adjusted scale (increase).

Jun 24 now busiest day with 2,401 observations, up by nearly 500 from last year's high of 1,921 on Jun 23.

The span of days with over 1,000 observations per day has expanded, now May 29 to Aug 15 (79 days). Last year's range was Jun 11 to Jul 20 (40 days).

Now the Species by Day

This chart is very similar to a year ago, you have to look pretty close to find differences.

The Species top day is Jun 23 with 113, followed closely by Jun 14 with 112, and Jun 15 with 111.

Jun dominates with 23 days over 100 species. We did add to the previous total, where a year ago Jun had 15 days with 100 or more species. Jul is the only other month with 100 species days at 3.

Publicado el 21 de enero de 2023 00:19 por jimlem jimlem


This supports the hypothesis that human observation activity is significantly influenced by the number of species. We are a species that keeps score, and this is one manifestation of it.

I’m confident that birders are also motivated by species richness, and the potential to find something relatively rare. I’ll bet similar charts could be drawn from avian observation patterns, with an activity peak during the spring migration. It would likely be even more skewed than the oda observation patterns.

INaturalist emphasizes tracking the existence of species. It does a good job of measuring Species Richness. In contrast to ebird, it doesn’t attempt to estimate species volume. INaturalist doesn’t measure Species Abundance. The daily iNaturalist observation must be impacted by the number of odonates flying in a day, but it’s a relatively weak correlation. There can be a lot of autumn meadowhawks active in a particular location on a warm fall day, but an observer would normally record fewer observations than they would if the same number of odonates were composed of multiple species.

What’s the historical discussion on the practicality and desirability of estimating odonate counts? I would expect it to be contentious. Citizen science was contentious in the 19th century and it always generates complaints. Personally, I don’t think it would be difficult to implement a 3 or 4 level scale for estimated count. Humans can often reliably make estimations within a logarithmic scale (one/some/many).


Publicado por jheiser hace 11 meses

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