TABLE OF CONTENTS

• How many taxa are represented by observations
  • Leaf Count
  • Species Count

A "taxon" is a node on the tree of life. Consider a simplified branch of the tree with the following 7 taxa in the Amphibian family Salamandridae. 

Now suppose we posted 9 observations and they were identified such that they were hanging on these taxa: 4 observations identified as Genus Nothophthalmus, 2 observations identified as Family Salamandridae, 2 observations identified as Taricha granulosa ssp. granulosa, and one observation identified as Taricha torosa. 

How many taxa are represented by observations

When you’re logged into iNaturalist, click on "Your Observations" in the header, which will take you to the Explore page.

The Observation tab displays the number of Observations (e.g. 9) and the "Species" tab displays the number of taxa represented by these observations (e.g. 3). But how exactly is iNaturalist counting here?

Leaf Count

The default way that iNaturalist counts the taxa represented by these observations is called the "leaf count." The leaf count avoids double counting (e.g. counting both Family Salamandridae and its child Genus Notophtalmus) by counting the number of distinct leaves of the taxonomic tree. The one caveat is that it rolls up subspecies (as well as other "infraspecies" like varieties) to their parent species so that observed subspecies are always included in the count.

To calculate the leaf count, iNaturalist first rolls up subspecies. For example, the two observations of Taricha granulosa ssp. granulosa above would be counted as two observations of Taricha granulosa. Then any observed taxa that are ancestors of other observed taxa in the set are removed. For example, Family Salamandridae is an ancestor of taxa like Genus Notophtalmus and is thus ignored. 

This means that the final count is 3 taxa: Genus Nothophthalmus represented by 4 observations, Taricha granulosa represented by 2 observations, and Taricha torosa represented by one observation. 

An advantage of the leaf count is that distinct taxa that have been observed but haven’t been identified to species are included (e.g. Genus Nothopthalamus), but it avoids double counting (e.g. Family Salamandridae and Taricha torosa). A disadvantage of the leaf count is that it can be confusing to explain and is costly to compute.

You may notice that the the tab on Your Observations is labeled "Species’"even though "Taxa" would be more correct as the count may include non-species ranks (e.g. Genus Nothophthalmus). We sometimes use the term Species rather than Taxa since it's more familiar to novices.

Notice that the Filters menu on Your Observations has a "2" next to it. 

This is because Your Observations is identical to the Explore page with just two changes to the default Explore filters. Unlike Explore, Your Observation checks the Your Observation filter to show observations from just you. Similarly, while the Explore page defaults to checking "Verifiable" observations (ie "Research" and "Needs ID" but not "Casual" observations), Your Observations has Verifiable unchecked and thus includes Casual observations in the count. 

Suppose the following Needs ID (NI), Research Grade (RG) and Casual (CA) observations. Checking "Verifiable" would ignore Taricha torosa since it's only represented by Casual observations. 

Species Count

When we display leaderboards of several counts side by side (e.g. the Observers tab on Explore or Projects), it is too computationally difficult to compute the leaf count for each. 

Here, iNaturalist displays the "species count" which entails rolling up infraspecies and then only counting species. In this example, the species count would be 2 

If you’d prefer the species count rather than the leaf count on the Species tab in Explore, use the Rank control in the Filters menu and set High to Species