In July, this past year, my family and I went across the Kachemak Bay during a very low tide, and all I did almost the whole time was photograph anything I could find. Tidepool creatures, seashells, bones, shore plants, and insects. I ended up with 126 observations and 145 life list firsts.
My best is 69 life firsts which is composed of 28 new taxa out of 62 observations achieved on July 8, 2024. The observations were all insects and spiders. It was a combination of sweep netting and mothing. The whole week was quite productive.
If you go to your calendar, then the pages for each day will show the life-list firsts for that day. No way to quickly see the top day overall though, you just have to check through all your top days.
In the summer of 2023 I spent a week visiting family in the United States – a different continent for me – so the likelihood of observations triggering life list firsts was much higher. As a result, I have:
Locally, in South Korea, I recorded 40 life list firsts from 109 observations last spring during a visit to the National Arboretum of Korea. That feels rather impressive since (a) I’ve been using iNaturalist since 2015 so I’m seeing fewer days with large ‘firsts’ numbers and (b) the National Arboretum is on the other side of a mountain I hike here in Uijeongbu so I wasn’t exploring somewhere completely new.
The year before that I also had a day with 50 life list firsts from 131 observations during a walk around the base of Mt. Soyo in Dongducheon – somewhere I’ve visited several times in the past. Also, despite it being a mountain, many of my observations were made while walking up the asphalt access road.
Without checking every date on my calendar, 70 firsts from 30 observations in 2016 might be my largest firsts : observations ratio due to it being near the start of when I used iNaturalist, back when most every upload triggered a life list first.
Your highest firsts:observations ratio is probably the day of the earliest observations you have on iNaturalist - everything that day would be a first, from “life” to species (unless you have a lot of observations of a few related taxa that day). My highest ratio seems to be 9 (18:2) from the first day I posted two plants. It would have been higher if I had only posted one of them.
Great point. My oldest date with observations is two plants that gave me 21 life list firsts. The next entry is one animal that gave me 12 life list firsts.
As you said, only posting one plant would have resulted in a higher ratio.
For me the days with the highest number of life firsts are always one of the first days in a new place. Out of those the highest one is in Hong Kong, which was my first time in Asia, where I got 187 life firsts out of 117 observations, not bad!
One way to narrow it down is to go to your Year in Review and scroll down to the Newly Added Species section. Below the large bars is a bar chart of your entire iNat “career” by month. You can see which month has the most new-to-you species.
I’m pretty sure my biggest day was my first full day in Australia, a new-to-me continent. I had a knowledgeable local guide in @thebeachcomber and we visited multiple areas including a forest, a wetland, and a beach.
It wasn’t the highest for number of different taxa, though. That record goes to a Spring hike along the Lava Bluffs trail in Calaveras Big Trees State Park in California. Just an absolutely overwhelming number of wildflowers and insects that day. The colors and the scents were so very vivid!