DOI: 10.5061/dryad.s1rn8pk8x
title: Modeling management strategies for chronic disease in wildlife: predictions for the control of respiratory disease in bighorn sheep

description: 1. Controlling persistent infectious disease in wildlife populations is an
 on-going challenge for wildlife managers and conservationists worldwide.
 2. Here, we develop a dynamic pathogen transmission model capturing key
 features of M. ovipneumoniae infection, a major cause of population
 declines in North American bighorn sheep (Ovis canadensis). We explore the
 effects of model assumptions and parameter values on disease dynamics,
 including density versus frequency dependent transmission, the inclusion
 of a carrier class versus a longer infectious period, host survival rates,
 disease-induced mortality and recovery rates, and the epidemic growth
 rate. 3. We compare the effectiveness of a suite of management actions
 following an epidemic, including test-and-remove,
 depopulation-and-reintroduction, range expansion, herd augmentation, and
 density reduction. 4. Our results suggest that test-and-remove,
 depopulation-and-reintroduction, and range expansion have the potential to
 facilitate recovery of persistently infected bighorn sheep herds
 post-epidemic. By contrast, augmentation could lead to worse outcomes than
 those expected in the absence of management. Management that improves host
 survival or reduces disease-induced mortality are also likely to improve
 population size and persistence of chronically infected herds. 5. Dynamic
 transmission models like the one employed here offer a structured, logical
 approach towards exploring hypotheses and can serve as a basis for
 planning field experiments and adaptive management. Models should be used
 iteratively with the field empirical approaches to triangulate on better
 approaches to wildlife management.
description: Data were gathered by Idaho Department of Fish and Game, Oregon
 Department of Fish and Wildlife, and Washington Department of Fish and
 Wildlife as part of the Hells Canyon Bighorn Sheep Initiative, under the
 coordination of E. Frances Cassirer. Field efforts consisted of at least
 biweekly (and often higher-resolution) aerial or ground survey of
 instrumented bighorn sheep ewes in the Hells Canyon system (specific herds
 indiciated in the Herd field). Dates of birth (DayInYear_birth) were taken
 to be the midpoint of the last survey of a ewe without a lamb and the
 first survey in which she had a lamb each year, unless lambs were clearly
 less than 72 hours old upon first observation. Lamb mortalities are
 recorded in the DayInYear_death field (the midpoint between the last
 observation the lamb was seen alive and the first observation in which it
 was not observed).
description: More details can be found in:  Cassirer, E.F.,
 Plowright, R.K., Manlove, K.R., Cross, P.C., Dobson, A.P., Potter, K.A.
 and Hudson, P.J., 2013. Spatio‐temporal dynamics of pneumonia in bighorn
 sheep. <em>Journal of Animal
 Ecology</em>, <em>82</em>(3), pp.518-528.
 and Cassirer, E.F., Manlove, K.R., Plowright,
 R.K. and Besser, T.E., 2017. Evidence for strain‐specific immunity to
 pneumonia in bighorn sheep. <em>The Journal of Wildlife
 Management</em>, <em>81</em>(1), pp.133-143.