Updated: Jul 29, 2020
Sandhill Cranes can differ greatly in size. Often, the size difference is attributed to age. However, we have multiple subspecies of Sandhill Crane in the United States, and these subspecies can vary greatly in size!
Lesser Sandhill Crane vs Greater/Canadian Sandhill Crane
During migration, birders and crane enthusiasts often see smaller cranes mixed in with larger cranes (or vice-versa). A thought often arises that these small cranes are juvenile cranes. However, by migration time (spring or fall) "juvenile" cranes are full-size. So, what causes these cranes to be smaller? The difference in size is due to different varieties of Sandhill Crane, which we refer to as subspecies. Let's take a look at the three subspecies of migratory Sandhill Crane, and how we can identify them.
First, though, let's make sure we have an understanding of the term subspecies.
What does it mean to be a subspecies? Great question, and 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).
There are 3 accepted subspecies of migratory Sandhill Crane in the US:
1. Lesser Sandhill Crane - Antigone canadensis canadensis - This subspecies is the smallest of the 3 migratory subspecies. Its breeding range is across arctic Canada.
2. Greater Sandhill Crane - Antigone canadensis tabida - This subspecies breeds from sw. British Columbia, including Vancouver I., east to the w. Great Lakes and south locally to Nevada, Colorado, and Tennessee.
3. Canadian Sandhill Crane - Antigone canadensis rowani - This subspecies is difficult (see: impossible) to identify from the Greater Sandhill Crane. Its breeding range is across subarctic and boreal Canada.
In this post, we will lump Greater and Canadian Sandhill Cranes together for simplicity. So, anywhere you see "Greater," assume Canadian is included.
Now, let's return to the identification of these crane subspecies.
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 these milestones. 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 the above photo (and two other factors), this bird was likely going into its second summer at the time of the photo. Meaning, it was born in 2018.
There is actually a decent amount of red present, though it is not vibrant. Vibrancy depends on many factors. Since the red area is bare skin, blood flow to the area is one of those factors. There are many reasons, including age, 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 skin 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 backward, indicating an even older bird. (Be proud bald men. In the crane world, your baldness would indicate you have high fecundity. You would be highly desirable.)
Crane Subspecies Identification Tips
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 Lessers. 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
Other Species of Crane in the US
While not as common, there are two other species of crane that can be found in the United States. The Whooping Crane is a highly endangered resident crane, and the Common Crane is a rare vagrant crane.
Whooping Cranes are distinct from Sandhill Cranes. They are larger, white, and have a more extensive red facial patch.
The Common Crane has more extensive black on its face than Sandhill and Whooping Cranes.
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
Range Map of the Sandhill Crane Subspecies
You can see, the range of Sandhill Cranes is quite extensive. During the breeding season, there are many areas you can find this charismatic species. In migration, the Rowe Sanctuary in Nebraska is unrivaled. In winter, Bosque del Apache NWR and Port Aransas NWR are THE places to be.
Common Crane taken by Kev Chapman under a CC BY 2.0 license.
Gerber, B. D., J. F. Dwyer, S. A. Nesbitt, R. C. Drewien, C. D. Littlefield, T. C. Tacha, and P. A. Vohs (2014). Sandhill Crane (Antigone canadensis), version 2.0. In The Birds of North America (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.31
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.
Whooping Crane taken by USFWS under a CC BY 2.0 license.