Observation fields make your observation more information rich and easier to search. You can usually add observation fields to other people's observations, too, which makes observation fields useful for research projects. For example, in the project Sphingids at Flowers ( https://www.inaturalist.org/projects/sphingids-at-flowers ) many of the observations use the field "Nectar plant" to record what plant the moth was feeding from.

Anyone can make new observation fields, which are then available to everyone. This is useful if you need something specific, but it also results in redundancy, as many people have made similar fields. I try to use the same field for the same thing for all of my observations that need it, so that when I use that field to search, I get all of my observations that fit.

For example, iNaturalist currently (7/2024) displays 561 pages of observation fields to choose from, each page with about 30 fields ( https://www.inaturalist.org/observation_fields ). A quick search for the topic of "nectar" brings up a list of 19 fields: https://www.inaturalist.org/observation_fields?utf8=%E2%9C%93&q=nectar&commit=Search

If you click the name of one of these fields, you'll get a list of all of the observations and projects that use it.

Some of my favorite observation fields:

Nectar / Pollen delivering plant: A one-size-fits-all field for a pollinator visiting a flower. It's a good fit for butterflies that only feed on nectar, and I like it better than "nectar plant" for bees, since bees may be gathering pollen as well. This field uses taxon data, so it will give you dropdown name options once you've typed a few letters.

Associated observation: This is a text field where you can paste in the web address of another observation. I use this to link pollinator observations to an observation of the plant they were visiting. You can also use it to link observations of predators and prey, or observations resulting from several species in one photo.

Other Organism: This is a taxon field where you can identify another organism in your photos. I use this to record things like what type of tree the squirrel was sitting in when my photos aren't nice enough to bother with also making a tree observation.

Host Plant ID: Good for recording what your caterpillar was eating.

Some examples of my observations that use observation fields:
Dogbane leaf beetles: https://www.inaturalist.org/observations/227773981
Orange Sulphur: https://www.inaturalist.org/observations/228753262
Sunburst Lichen: https://www.inaturalist.org/observations/128633597

I got this fun link via the iNat Forum. Insert a project name and try it out: https://www.inaturalist.org/projects/my-kentucky-yard/stats_slideshow

The "most observed species" slide is particularly interesting, since it compares introduced versus threatened.

Want to see a taxonomically ordered list of all the organisms for a project? This fun little search string from the iNaturalist forum (and from bouteloua via dianastuder) gives you an ordered list of all the organisms in a particular project (in this case, for my yard):

https://www.inaturalist.org/observations/taxa?projects=my-kentucky-yard

This makes it easier to spot particularly diverse groups. For example, I know I have a good array of woodpeckers (4 species in family Picidae), but not knowing the bird families well, I was a bit surprised to realize they were rivaled by 4 species of orioles & blackbirds (family Icteridae) and 4 species of finches (family Fringillidae) and outnumbered by sparrows & co. (family Passerellidae, 5 species). However, 9 species of orbweavers (family Araneidae) mean the spiders have even higher family diversity, and don't get me started on the butterflies...

I've been aiming for a diverse virtual yard, and now have observations of 400 taxa. What's changed from My Kentucky Yard at 200? My yard organisms still fall into just three kingdoms: Animalia (was 168 species, now 329), Plantae (was 27 species, now 58), and Fungi (was 5 species, now 13).

According to Kentucky's Natural Heritage: An Illustrated Guide to Biodiversity (Abernathy et al., 2010) approximate species counts for Kentucky arthropods are: 15,200 insects, 500 arachnids, 100 crustaceans. For vertebrate species: 370 birds, 250 fish, 70 mammals, 50 reptiles, 50 amphibians. Kentucky also has 380 species of molluscs.
See the KET PBS site for a nice module with graphics: https://ket.pbslearningmedia.org/resource/knh.ssgroup/selectspeciesgroup/

ANIMALS in my yard so far: Arthropods 273 taxa including arachnids (24 species), a crustacean, insects (245 species), 2 myriapods (both centipedes), and an entognathan (they looked like insects). Vertebrates 54 taxa including birds (37 species), mammals (8 species), amphibians (5 species), and reptiles (4 species). I've also documented two molluscs (a slug and a snail).

A QUICK EDUCATIONAL TANGENT: iNaturalist makes it easy to search and browse based on the ranks of biological classification. This is a great way to learn to recognize the main types of organisms you're likely encounter when you're out and about.
A brief refresher on how rank-based classification works: We start large, then subdivide the big, broad groups into smaller, more specific groups. Our goal is to follow how the organisms are related, so that members of smaller groups are more closely related to each other than members of larger groups. The main ranks of classification from largest to smallest are: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
(A quick way to remember this: Dearest Karl poured catsup on father's good shirt.)

Applying this to the big groups of animals, in my yard, you'd get this:
Domain Eukarya (Organisms whose cells have nuclei. If you can see it without a microscope, it's probably in this group. Plants, animals, fungi, and protists are all included here.)
Kingdom Animalia: Multicellular eukaryotes that are heterotrophic -- they have to eat stuff for nutrients -- and lack cell walls.
Phylum Arthropoda: Invertebrates with exoskeletons, like insects, spiders, and crustaceans.
Phylum Chordata: Animals with backbones and their close relatives. In my yard: birds, mammals, fish, reptiles, amphibians.
Phylum Mollusca: Soft-bodied invertebrates, (usually) with shells, which on land in Kentucky is snails and slugs.

Each of the phyla could then be divided into classes (like class Aves -- the birds -- from the vertebrates), but I've run out of energy...

FUNGI in my yard so far: 13 taxa, including plant pathogens, saprophytes, commensalists (lichens), and parasites of insects. Or, from a more taxonomic perspective, five ascomycetes and seven basidiomycetes.

PLANTS in my yard so far: Kentucky has about 2030 species of vascular plants (flowering plants, gymnosperms, and ferns & relatives). Observations from my yard document 57 species of angiosperms (some cultivated): 44 dicots and 13 monocots. I have also now documented my one gymnosperm (Eastern Redcedar).

Most organisms are adapted for specific habitats, conditions, or lifestyles, helping them get the resources they need by reducing competition with other organisms that need somewhat different resources. If your area provides a diversity of habitats and resource types (ex. shelters, foods, water sources) then it is likely to support a greater diversity of organisms than a more uniform area might.

I increase the diversity of butterflies I observe in my yard by diversifying the food sources provided. Most of us picture butterflies on flowers, but many species prefer rotting fruit or sap-flows from trees, and some are even drawn to things like poop or carrion. For example:

A Red-spotted Purple.
A Question Mark.
Swallowtails.

I recycle my summer watermelon rinds by making simple butterfly feeders. You can just put out a chunk of rind or some old fruit, but if it dries out too fast, the butterflies loose interest.

You can extend the life of your rind by placing it in a dish with just a little water (I'm experimenting with adding some gravel to that to prevent small insects from drowning), which keeps it moist and fermenting.

So far, I've had 11 species of butterflies visit, and one hungry caterpillar. Check out the rind-feeding butterfly species I've documented.

My feeder has also attracted a variety of other insects, and I get quite a bit of moth activity at night. Click here for all of the interesting, rind-related visitors.

If you prefer to limit your visitors to butterflies and moths, you can cover the top of your feeder with screen, keeping the fruit about 1 cm below it. The long proboscis of a butterfly will easily slip through to reach the fruit, but insects like flies and wasps don't have long enough mouthparts to feed there.

Of course, things like raccoons, possums, and curious cats can potentially be a problem. One reason I like using watermelon rinds is because they have enough sweet flesh left to feed lots of insects, but not so much to make them particularly interesting to vertebrates. I also use heavy ceramic dishes (sold to catch drips from potted plants) so that they are hard to knock over and unlikely to break even if they do get shoved around by curious mammals.

I'll be using my virtual yard as a source of examples for my Gardening for Wildlife class. Setting this project up, I thought it would be fun to get a decent number of taxa observed before classes start. Maybe 100? Pulling from almost 20 years worth of biological photos, that should be easy, right?

I've been aiming for diversity, and now have observations of 200 taxa posted, so this is a milestone. This is a dataset for my yard, and as a scientist, I now wonder: What's the data say?

Taxa from the yard fall into just three kingdoms: Animalia (168 species), Plantae (27 species), and Fungi (5 species). This is observer bias, as most life on Earth is microscopic. The number of bacteria, algae, protozoans, and microscopic fungi in the yard far exceeds all the large organisms I'll ever photograph.

According to Kentucky's Natural Heritage: An Illustrated Guide to Biodiversity (Abernathy et al., 2010) approximate species counts for Kentucky arthropods are: 15,200 insects, 500 arachnids, 100 crustaceans. For vertebrate species: 370 birds, 250 fish, 70 mammals, 50 reptiles, 50 amphibians. Kentucky also has 380 species of molluscs.
See the KET PBS site for a nice module with graphics: https://ket.pbslearningmedia.org/resource/knh.ssgroup/selectspeciesgroup/

ANIMALS in my yard so far: Arthropods are most diverse, with 132 taxa including arachnids (16 species), a crustacean, insects (113 species), a myriapod, and an entognathan (to a botanist, they look like insects). Vertebrates are next in line with 35 taxa including birds (22 species), mammals (6 species), amphibians (3 species), and reptiles (4 species). Only one lonely mollusc (a slug) has been documented. Considering that there's little aquatic habitat on my property, these counts generally reflect the relative sizes of the groups in the state, though the molluscs are under-represented.

FUNGI in my yard so far: Just five taxa: two plant pathogens, two saprophytes, and an ectoparasite of ladybugs. Or, from a more taxonomic perspective, two ascomycetes and three basidiomycetes. In my defense, most of my big fungi are on the ground in the shady woods and so hard to photograph. Plus, you really need microscopic views of spores for confident ID: so much work :(

PLANTS in my yard so far: Kentucky has about 2030 species of vascular plants (flowering plants, gymnosperms, and ferns & relatives). Observations from my yard document 27 species of angiosperms: 24 dicots and 3 monocots. This is observer bias again. My taxonomic training focused on angiosperms, and dicots in particular. There are plenty of mosses in the yard, a few ferns, and a gymnosperm (Eastern Redcedar).
As a botanist, I confess that I'm less likely to photograph a plant than an insect. For local plants, I typically a) already have a good photo somewhere, b) know it/ am confident I can ID it/ have no intention of IDing it (grasses = evil), or c) would rather have a pressed specimen. Insects, though, are cool, mysterious, and don't press well.

GOAL FOR THE FUTURE: Documenting more trees and shrubs.