Archivos de Diario para abril 2018

26 de abril de 2018

DC Metro iNat data: 2017 and observations per new species

I made some predictions in a July 2017 journal post about how many observations, species and new species would be added to iNat from July to December for the DC metro area:

In previous years, the first half's observations accounted for about 49% of the year's final total, and 58% of the species. Extrapolating that to 2017 would mean 22,632 second-half observations, or 44,639 total 2017 observations (range: 39,729 - 50,888), and 4,183 species (range: 3,890 - 4,602), or about a 150% and 120% increase from 2016, respectively. How many of those species would be new records for the DC Metro area? A rough estimate is that, based on 2011-2016 trends, a new species for the DC Metro is recorded about every 30 observations. So, if I estimate 22,632 observations will be added in the second half of 2017, that would suggest 700 new species will be added (range: 550 - 890).

How'd my predictions fare? Some good, some not so good! As of today, iNaturalist shows approximately 54,000 total 2017 observations, which is about 10k higher than my estimate. I did better with the total number of species: iNat shows 4,174 species, an undercount of just 9 species compared to my prediction. I also predicted 700 new species would be added in the second half of 2017, and I did pretty well there too, as iNat shows a difference of 717 species from July 1 to December 31, 2017.

It was another year of growth for the DC-area iNaturalist community. Total 2017 observations (n=53,997) exceeded all observations made prior to 2017 (n=53,024 obs). High watermarks were posted for number of species, observers, and identifiers. Six people broke the previous record for a single species count in the DC metro, including @krosenthal @mellis @peggyo @treegrow @ashley_bradford and the current record-holder @judygva at 1,035 species. Go Judy go!

While the overall effort (observers and identifiers) is increasing, it's becoming more and more challenging for new species to be identified in DC on iNaturalist. For example, out of a total 600 observations in 2011, about 174 species were new to iNaturalist. That means, on average, a new species was added for the DC metro every 3 observations or so. The number of observations needed to "find" a new species has climbed every year. In 2012, a new species was added every 5 observations. 2013, 8 observations. 2014, 9 observations. 2015, 13 observations. 2016, 23 observations. In 2017, we needed 43 observations on average to identify at least one species that had never been recorded in the DC area on iNaturalist. In fact, 2017 was the first year in which we recorded fewer number of new species than the year previous (~1255 new species in 2017 vs ~1326 new species in 2016).

The quantity of effort required to record a new species really varies across taxonomic groups. Here's some examples (based on stats downloaded Feb 2018), in order of decreasing effort required:
-- Amphibians (1 new species in 2017) = 920 observations to record 1 new Sp
-- Birds (16 new species recorded for DC area in 2017) = 327 observations to record 1 new Sp
-- Reptiles (5 new species in 2017) = 256 observations to record 1 new Sp
-- Mammals (6 new species in 2017) = 212 observations to record 1 new Sp
-- Ferns (7 new species in 2017) = 95 observations to record 1 new Sp
-- Arachnids (32 new species in 2017) = 43 observations to record 1 new Sp
-- Flowering plants (547 new species in 2017) = 40 observations to record 1 new Sp
-- Insects (413 new species in 2017) = 34 observations to record 1 new Sp
-- Ray-finned fish (13 new species in 2017) = 28 observations to record 1 new Sp
-- Protozoa (3 new species in 2017) = 27 observations to record 1 new Sp
-- Molluscs (18 new species in 2017) = 24 observations to record 1 new Sp
-- Fungi (146 new species in 2017) = 20 observations to record 1 new Sp
-- Mosses (13 new species in 2017) = 18 observations to record 1 new Sp

So if you want to record some new-to-iNat species for the DC metro area (say, for example, for the upcoming City Nature Challenge cc @carrieseltzer) AND you want to be lazy and/or strategic about your observation effort, my advice: get low and get wet and ignore terrestrial things with backbones. Mosses, fungi, molluscs, protozoans, and ray-finned fish would all be great targets for focused monitoring effort to find species that have never been recorded before on iNat in the DC Metro area. There appear to be hundreds of flowering plant and insect species to still identify, so keep looking at those things too. (And someone should get a microscope and start identifying the unicellular stuff!)

What are my 2018 predictions for DC metro iNat? Assuming observations and species grow at a similar rate compared to recent years, and new species become similarly challenging to find and identify, I predict:
-- 85,000 total observations (range: 75,000-95,000)
-- 5,000 total species
-- including 1,000 species that were previously unrecorded on iNat for this area

Now go outside and prove me wrong!

Publicado el 26 de abril de 2018 a las 09:38 AM por muir muir | 13 comentarios | Deja un comentario