After being asked many times how it is possible to differentiate Fish Crows and American Crows, I decided to make a distribution map for these very similar species. Though it is very difficult to visually distinguish them, it can be possible in some places to determine which species you have just based on the location.
I’m in a GIS class at my university so using what we’ve learned about ArcGIS and dating importing I used research grade observations on our very own iNaturalist to create this map!
Nice map! I think it would be best used in a journal post on iNat itself. You could explain a bit about how you made the map and how it can be used. You can then link to the journal post in comments on iNat. A lot of users have taken this approach to help people answer common id questions or deal with situations and it can be very helpful.
I don’t think they separate by location. I get both species in my yard. I can’t tell them apart by sight unless they are side-by-side which they never do at my place. They visit at different times, don’t associate with each other. I record an audio clip to use for ID purposes. Sometimes I don’t even bother trying to get a photo to go with the audio.
Here in NE Ohio fish crows are not very common. They do have spots where they are regularly seen but, there are often American crows in the same area. We try to identify fish crows by their calls. They usually stay together even when they are with a large group of American crows in late fall. So, when we see a group of smaller crows, we try to listen to them. Usually, it is fairly easy to distinguish them from American crows this way (by call). But, in summer, one has to be careful not to confuse an immature American crow with a fish crow. Most people who use eBird here try to submit an audio recording or describe the call in the comments if they find what appears to be a fish crow.
Some locations (such as the Everglades w/ American Crows and St. Pete w/ Fish Crows) have only that species in the area. However, it is true that most of their range overlaps. I just thought the map would be in an interesting way to visualize their distribution and make it easier to explain how location can be a valid way of identifying the species. Sometimes, I’ll see people identify them on iNat and put “by location” as the reason they were able to identify it. That’s technically true, but I made this map as a visual explanation for why that can be. Truely though, the best way to tell is to audibly hear them.
Interesting! I’ve only ever lived in Florida so I don’t know much about how they behave/flock in other states, especially a land-locked state. Here, you can typically get a rough estimate on which species is more likely based on the location (Fish Crows are usually found in coastal regions and are less the more inland you go), but the call is the most definitive way to tell
Thank you so much! I’m planning on experimenting with other ways iNaturalist data can be used in mapping. This project was just something I did for fun and to familiarize myself with the process of uploading the data to ArcGIS, but I’m also going to be using iNaturalist data for my final project in the GIS class I’m currently in. If all goes well, maybe I’ll make another thread with the presentation when it’s done :)
In my experience and research crows absolutely do separate by location, as Neil has demonstrated in his map. Places like the Everglades have nothing but AMCR, and St Pete have nothing but FICR; and some places like Tampa have both.