Updated: Feb 9
A recent email about two cranes that differed in size, pushed me to write up a little post on Sandhill Cranes in Wyoming. The first part of the post will address Lesser vs Greater Sandhill Cranes, and the second part of the post will give some tips on where to go to see the cranes. As always, make sure to Like Us on Facebook, share our posts with your bird friends, and subscribe to our blog right HERE!
Lesser Sandhill Crane vs Greater Sandhill Crane
When the cranes leave for winter, "juvenile" cranes are fully grown. Why is this important information? Occasionally, some people will assume a smaller crane is a younger crane. What some may think of as a younger bird, may actually be a different subspecies of the Sandhill Crane. Let's take a look at those three subspecies.
There are 3 accepted subspecies of migratory Sandhill Crane in the US:
Lesser Sandhill Crane - Antigone canadensis canadensis
Greater Sandhill Crane - Antigone canadensis tabida
Canadian Sandhill Crane - Antigone canadensis rowani
What does it mean to be a subspecies? Great question, I'm glad I asked. A species is an interbreeding population of organisms that typically cannot breed with another species and produce viable offspring. (There are many exceptions to this rule, don't get bogged down in the minutia.) The species, in this case, is Antigone canadensis, or the Sandhill Crane. A subspecies could be categorized as an often distinct, interbreeding population below the species level; they can breed with other subspecies, but do not typically do so. Didn't understand any of that? I will make it easier using our Sandhill Crane example. The species is Sandhill Crane, and let's use the Greater and Lesser as our subspecies. Anything in that species can breed together, however, the Greater and Lesser usually will not interbreed. To use caveman lingo, big crane (Greater Sandhill Crane) not want copulate with small crane (Lesser Sandhill Crane).
Easy enough? Brain hurt? It only becomes more tedious from here (to write, that is).
Back to our small cranes.
Juvenile cranes have fully feathered heads until winter/spring. Each molt after they leave the nesting grounds, the feathering slowly recedes further, until "adulthood." It may even progress further as the bird ages, just like my hairline is doing. That is the red visible to most people. It is often confused as feathering, but it is skin! Field guides, such as The Sibley Guide to Birds, do not always mention that the red field mark is skin. And they only address the field mark with true juveniles vs adults, forgetting about the ages between. This amount of red can help us age birds, and we can use it to help us identify to subspecies. Take a look at the bird below.
Based on feathering on the head of the bird in my photo (and two other factors), my bird is likely going into its second summer. Meaning, it was born in 2018. There is actually a decent amount of red present, though it is not vibrant. The vibrancy depends on many factors. It is bare skin, so blood flow to the area plays a role. There are many reasons as to why the skin is not the vibrant red seen in the adjacent Greater Sandhill Cranes. Remember, there is some thought that the "ornament" of the head may progress as the bird ages past what is known as its "definitive basic plumage." Meaning, even after reaching sexual maturity, the red skin may continue to develop backwards, indicating an even older bird. (Be proud bald men. In the crane world, your baldness would indicate you have a high fecundity. You would be highly desirable.)
What other ID cues can we use to separate the Greater and Lesser Sandhill Cranes? Here are five tips to help you:
1. Lessers have more roundish or "cute" heads.
2. Eye size to head size is more proportionate in the Lesser.
3. The length of the bare skin after the eye, before it angles to the top of the head, is minimal in Lesser's. In Canadian and Greater Sandhill Cranes, the red extends back further before angling towards the crown.
4. Difference in size. The Lesser is about 2 lbs lighter than the Greater, and even the largest of Lesser Sandhill Cranes, likely won't have a bill as long as the Greater's. Also, the length of the lower leg (tarsus) of the Lesser is never as long as the lower leg of the Greater.
5. The white cheek patch contrasts less in the Lesser than the Greater
Having written all of that, when you throw in Canadian Sandhill Crane, things get messy. So messy, you can ignore everything I just wrote. (I need a sarcasm font.) Seriously, it can make the ID harder, but let's stick to obvious Lesser vs Greater for now. Deep breath. The difficult part is over. Now, for aesthetically pleasing graphics and very few words.
Where to Find Sandhill Cranes in the United States
The map is pretty clear. During migration, spring and fall, the eastern side of the state sees fairly large concentrations of Sandhill Cranes. Check ag fields, large wetland complexes, etc to find these flocks. My personal recommendation: Table Mountain WHMA, which I will soon publish a Hotspot Highlight for. During summer, check the wetlands, especially around the lower elevations of our various mountain ranges. My personal recommendation for the breeding season: Sublette County, or either of the great parks.
Want to see Sandhill Crane movement in real-time? Check out this animation from eBird:
Sandhill Crane Abundance Animation: Fink, D., T. Auer, A. Johnston, M. Strimas-Mackey, M. Iliff, and S. Kelling. eBird Status and Trends. Version: November 2019. https://ebird.org/science/status-and-trends. Cornell Lab of Ornithology, Ithaca, New York.
Sandhill Crane Range Map: Fink, D., T. Auer, A. Johnston, M. Strimas-Mackey, M. Iliff, and S. Kelling. eBird Status and Trends. Version: November 2018. https://ebird.org/science/status-and-trends. Cornell Lab of Ornithology, Ithaca, New York.
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