Downtown Living

So what do these three species have in common?

Ferruginous Hawk (Buteo regalis)
Pueblo Co, CO 12/31/2005

Burrowing Owl (Athene cunicularia),
Henry Doorley Zoo, Omaha, NE  12/30/2011

Black-footed Ferret (Mustela nigripes)
Cheyenne Mt. Zoo, Colorado Springs, CO
12/27/2013

These are, from top to bottom, a Ferruginous Hawk (Buteo regalis), a Burrowing Owl (Athene cunicularia), and a Black-footed Ferret (Mustela nigripes). And what they share is an interest in these guys:

Black-tailed Prairie Dog (Cynomys ludovicianus) town,
Big Johnson Reservoir, El Paso Co, CO 12/24/2005

These are our old friends, Black-tailed Prairie Dogs (Cynomys ludovicianus), hanging out in a town in El Paso Co, Colorado.

All three species at the top of the post are associated with Prairie Dog towns in some respect. Ferruginous Hawks will happily prey on them, although they are quite willing to change diets when the opportunity arises. (1) Burrowing Owls rarely if ever eat Prairie Dogs, (2) but they do routinely appropriate unused Prairie Dog burrows, and on the Great Plains they are usually found on Prairie Dog towns. (3) Finally, Black-footed Ferrets are only found on Prairie Dog towns, using the burrows and happily dining on the occupants. (4)

Prairie Dogs have declined across their entire range (all 5 species, actually). While both the owls and the hawks can survive without Prairie Dogs, they usually do better on towns, and the Ferret would disappear completely without them. (Actually, in the 1970's, we thought that they had -- they were declared extinct in 1979, and rediscovered near Meteetsee, Wyoming in 1981.) Even if the Prairie Dogs don't disappear completely, if they become limited to small, isolated populations, those species that depend upon them may not be able to survive. Prairie Dog populations exist at a much higher density than any of the three predators shown above, so an area that's big enough for Prairie Dogs may not be for Ferruginous Hawks, for example. This is a case where a species that may not qualify for the Endangered Species List (Prairie Dogs) may nonetheless require a similar level of protection, simply to protect other species.

The Endangered Species Act has preserved quite a few fascinating critters -- but it was passed in 1973, and we've actually learned a few things about both ecology and conservation since then. Given the curious legal status of the act, it's probably worth considering how it could best be updated to account for our improving understanding of the natural world.

(1) Cartron, J. L. E., Polechla Jr, P. J., & Cook, R. R. (2004). Prey of nesting ferruginous hawks in New Mexico. The Southwestern Naturalist, 49(2), 270-276.

(2) York, M. M., Rosenberg, D. K., & Sturm, K. K. (2002). Diet and food-niche breadth of Burrowing Owls (Athene cunicularia) in the Imperial Valley, California.Western North American Naturalist, 62(3), 280-287.

(3) Tipton, H. C., Doherty Jr, P. F., & Dreitz, V. J. (2009). Abundance and density of mountain plover (Charadrius montanus) and burrowing owl (Athene cunicularia) in eastern Colorado. The Auk, 126(3), 493-499.

(4) Miller, B., Biggins, D., Hanebury, L., & Vargas, A. (1994). Reintroduction of the black-footed ferret (Mustela nigripes). In Creative conservation (pp. 455-464). Springer Netherlands.