Guest post by Jim Lemon
For all our Ohio Odonata species, we have made maps of where they have been reported, by county, and color coded to how recently a species has been reported. White means no observations (and a shot at a county record), and the darker the more recent. Wait – there’s more – new county records are indicated for the last three years – 2018 is the biggest dot, 2017 slightly smaller, then smallest for 2016. We also include the adult record count to provide an idea of how common things are, and flight period (but we also have separate charts on the frequency). Maps for all species can be found at: https://u.osu.edu/ohioodonatasurvey/species-distributions-across-ohio/
A couple examples –
Look at Blue Dasher – all dark blue – somebody submitted an observation from every Ohio county in 2018! Our only species for 2018 with this distinction. We also see that it’s been recorded from late Apr through late Oct – a long flight. With almost 2900 records, it is one of our most common dragons.
Now look at Comet Darner – see all three different dot sizes. Also note the wide distribution across the state – these things are terrific flyers. Note the color variation – older records are not as dark. These are probably in every county at some point – you just need to be in the right place at the right time. Comet flight is shorter (Jun-Jul) than the Blue Dasher, and has considerably fewer observations – so, more of a challenge!
Finally, look at Swift Setwing, one of our newest Odonates. First observed in Champaign Co in 2014, then Greene Co in 2016 (small dot), Muskingum and Montgomery in 2017 (medium dot), then five new counties in 2018 (big dots). This is an example of range expansion. There are no “old” records – so the location counties are all the darkest color. Then look at the spread – Swift Setwing wouldn’t be a surprise anywhere in the state. If we continue the trend, we should find 5 or more new county records in 2019.
Next look at Unicorn Clubtail. While its’ numbers are lower than Blue Dasher, we still see a reasonable curve with a tighter peak – pretty much in June. While we see a data point in September, specifically finding a Unicorn after mid-July would be pretty uncommon. Given the widespread range for Unicorn Clubtails, search for them in June in any of the 22 counties where they have not yet been reported.
Last example – Blue Corporal. After the first survey, Blue Corporal was listed as endangered. This may still be true, but we have been seeing more of them recently. But you have to look early – and in our southern counties. The chart shows them appearing in April, with a quick rise to mid-May and then a steep drop-off. So, short early flight and apparently limited range – can we find them expanding? See also our separate blog post on the Blue Corporal here: https://u.osu.edu/ohioodonatasurvey/2019/03/01/rare-dragons-the-blue-corporal-ladona-deplanata/