Sukie notes a summary of a new Black Footed Ferret study. Extremely rare and endangered critters.
However, a new factor threatens to undermine these hard-fought conservation gains: the continued eastward spread of the exotic bacterial disease plague, which is a quick and efficient killer of prairie dogs, and is caused by the same microbe that is implicated in the Black Death pandemics of the Middle Ages.
Using a new multi-species computer modeling approach, researchers have linked models of plague, prairie dogs, and black-footed ferrets to explore the consequences of ecological interactions in ways not possible using standard methods.
The results of this study, published in Journal of Applied Ecology, suggest that the continued survival of black-footed ferret populations requires landscapes larger than conservationists previously thought, and intensive management actions to reduce plague transmission.
“An alarming finding of our study is that there are few prairie dog complexes left that are large enough to support black-footed ferret populations given the severe threats they face—especially plague,” says Kevin Shoemaker, a post-doctoral scientist at Stony Brook University.
The full study is here.
Shoemaker, K. T., Lacy, R. C., Verant, M. L., Brook, B. W., Livieri, T. M., Miller, P. S., Fordham, D. A., Resit Akçakaya, H. (2014), Effects of prey metapopulation structure on the viability of black-footed ferrets in plague-impacted landscapes: a metamodelling approach. Journal of Applied Ecology. doi: 10.1111/1365-2664.12223
- disease spread;
- oscillatory population dynamics;
- predator–prey interactions;
- sensitivity analysis;
- spatial structure
- Species interactions have been largely ignored in extinction risk assessment. However, the black-footed ferret Mustela nigripesexemplifies a class of endangered species for which strong species interactions cannot be ignored. This species is an obligate predator of prairie dogs Cynomys spp., and sylvatic plague Yersinia pestis epizootics threaten to undermine recovery efforts by functionally eliminating the prey base. Multispecies ‘metamodelling’ techniques offer new opportunities for exploring population dynamics under strong species interdependencies and disease.
- To investigate ferret extinction risk in plague-affected landscapes, we simultaneously modelled plague epidemiological processes, prairie dog metapopulation dynamics and ferret demographic responses. Ferret population dynamics were investigated at an important release site (Conata Basin in South Dakota) and for 500 artificial prey landscapes spanning a wide range of realistic colony configurations (e.g. total area, # colonies, spatial clustering) and demographic characteristics.
- Our simulation models indicate that ferrets are unlikely to persist through episodes of plague at Conata Basin unless they can access prey resources from a wider region or unless management actions can otherwise substantially reduce plague transmission.
- We show that large, diffuse prairie dog metapopulations (those with colonies spread over a region >2500 km2) are most likely to support ferret populations in plague-affected landscapes. Our results also highlight the potential importance of metapopulation connectivity in fuelling plague epizootics and thereby imperilling black-footed ferret conservation efforts.
- We describe a cycle (c. 5- to 25-year period) of plague-driven population crashes that is an emergent property of our models, and which can destabilize ferret populations.
- Synthesis and applications. On the basis of our models, we conclude that few North American prairie dog complexes cover sufficient land area to sustain black-footed ferret populations through plague-driven crashes in prey abundance. Consequently, our results underscore the importance of working with many constituents to conserve large prairie dog landscapes in addition to continued development of plague mitigation tools. In addition, the strong relationship between plague-induced oscillatory prey cycles and predator population persistence highlights the potential conservation benefits of imposing strategic barriers to connectivity in areas over which plague outbreak cycles are strongly synchronous.
(great BBF images on the USFWS Flickr page)