Inference of the infection status of individuals using longitudinal testing data from cryptic populations: Towards a probabilistic approach to diagnosis

Effective control of many diseases requires the accurate detection of infected individuals. Confidently ascertaining whether an individual is infected can be challenging when diagnostic tests are imperfect and when some individuals go for long periods of time without being observed or sampled. Here, we use a multi-event capture-recapture approach to model imperfect observations of true epidemiological states. We describe a method for interpreting potentially disparate results from individuals sampled multiple times over an extended period, using empirical data from a wild badger population naturally infected with Mycobacterium bovis as an example. We examine the effect of sex, capture history and current and historical diagnostic test results on the probability of being truly infected, given any combination of diagnostic test results. In doing so, we move diagnosis away from the traditional binary classification of apparently infected versus uninfected to a probability-based interpretation which is updated each time an individual is re-sampled. Our findings identified temporal variation in infection status and suggest that capture probability is influenced by year, season and infection status. This novel approach to combining ecological and epidemiological data may aid disease management decision-making by providing a framework for the integration of multiple diagnostic test data with other information

INTRODUCTION OF WHOOPING CRANES IN EASTERN NORTH AMERICA

Whooping cranes (Grus americana) historically occurred throughout most of North America. A migration route last used prior to 1857 crossed the Appalachians to Atlantic Coast wintering grounds in coastal areas of New Jersey, South Carolina and river deltas farther south. The species disappeared from most eastern North American locations in the late 1800\u27s. The winter 1987 population consisted of 43 captive birds and 154 in 2 wild subpopulations. Pursuant to both Canadian and u.s. recovery plans, sites in Michigan-Ontario, Georgia and Rorida are being considered as potential release locations for establishing an eastern population. Cross-fostering, gentle release and other introduction techniques are being considered to effect that release

Waterfowl Population Status, 2000

In the traditional survey area (strata 1-18, 20-50, and 75-77), total duck abundance was 41.8 ± 0.7 million birds. This was similar (P=0.12) to last year’s record high estimate of 43.4 ± 0.7 million birds, and 27% above the long-term (i.e., 1955-99) average (P\u3c0.01). Mallard (Anas platyrhynchos) abundance was 9.5 ± 0.3 million, which is 12% below (P\u3c0.01) the 1999 estimate of 10.8 ± 0.3 million and 27% above the long-term average (P\u3c0.01). Blue-winged (Anas discors) and green-winged teal (Anas crecca) abundances were both at record high levels this spring. Blue-winged teal abundance was 7.4 ± 0.4 million, which was similar to last year’s estimate of 7.1 ± 0.4 million (P=0.61) and 69% above the long-term average (P\u3c0.01). Green-winged teal abundance was 3.2 ± 0.2 million, 80% above the long-term average (P\u3c0.04) and 21% higher than last year (P=0.03). Gadwall (Anas strepera; 3.2 ± 0.2 million, +100%), northern shovelers (Anas clypeata; 3.5 ± 0.2 million, +73%), and redheads (Aythya americana; 0.9 ± 0.1 million, +50%) were all above their long-term averages (P\u3c0.01), while northern pintails (Anas acuta; 2.9± 0.2 million, -33%) and scaup (Aythya marila and A. affinis combined; 4.0 ± 0.2 million, -25%) remained below their long-term averages (P\u3c0.01). American wigeon (Anas americana) and canvasback (Aythya valisineria) estimates were similar to those of last year (P≥0.42) and to long-term averages (P\u3e0.07). May conditions in the traditional survey area were generally drier than last year. The estimate of May ponds in Prairie Canada and the U.S. combined was 3.9 ± 0.1 million, down 41% from 1999 and 20% below the long-term average (P\u3c0.01). The eastern survey area comprises strata 51-56 and 62-69. The 2000 total duck population estimate for the eastern survey area was 3.2 ± 0.3 million birds. This was essentially identical to last year’s total duck estimate of 3.2 ± 0.2 million birds. Abundances of individual species were similar to last year, with the exception of scoters (Melanitta spp.; 182 ± 59 thousand, +288%, P=0.03) and green-winged teal (202 ± 29 thousand, -52%, P\u3c0.01)). The total duck fall flight index for 2000 is 90 million birds. This is 13 percent lower than last year’s record fall flight. Because of additions to the survey area for which we do not have production information, we propose to stop calculating the traditional fall-flight index for total ducks in the future. The Service may consider other alternatives to provide a reflection of duck abundance in the fall. The midcontinent mallard fall flight is predicted to be 11.3 million mallards, 16.2% lower than that of last year (P\u3c0.01)

Recreational Harvest and Incident-Response Protocols Reduce Human-Carnivore Conflicts in an Anthropogenic Landscape

Conserving viable large carnivore populations requires managing their interactions with humans in increasingly anthropogenic landscapes. Faced with declining budgets and escalating wildlife conflicts, agencies in North America continue to grapple with uncertainty surrounding the efficacy of socially divisive management actions such as harvest to reduce conflict. We used multistate capture–reencounter methods to estimate cause-specific mortality for a large sample (\u3e3500) of American black bears Ursus americanus in north-western New Jersey, USA over a 33-year period. Specifically, we focused on factors that might influence the probability of bears being harvested, lethally managed, or dying from other causes. We further analysed temporal correlations between \u3e26 000 human–black bear incidents reported between 2001 and 2013 and estimates of total mortality rates, and specifically, rates of harvest from newly implemented public hunts and lethal management. Adult females were twice as likely (0·163 ± 0·014) as adult males (0·087 ± 0·012) to be harvested during the study period. Cubs (0·444 ± 0·025) and yearlings (0·372 ± 0·022) had a higher probability of dying from other causes, primarily vehicle strikes, than adults (0·199 ± 0·008). Reports of nuisance behaviours in year t + 1 declined with increasing mortality resulting from harvest plus lethal management in year t (P = 0·028, R2 = 0·338). Adult bears previously designated as a nuisance and/or threat were more likely to be harvested (0·176 ± 0·025) than those never identified as a problem (0·109 ± 0·010). Across age classes, individuals assigned problem status, were significantly more likely to be lethally controlled. Synthesis and applications. Given continuing failures in conserving exploited carnivores, their recreational harvest and lethal management remain polarizing. Within this social-ecological system, the well-regulated harvest of carefully monitored black bear populations represents a pragmatic approach to achieve population objectives. Furthermore, the integration of harvest and incident-response management (both lethal and non-lethal practices) with educational programmes aimed at reducing anthropogenic attractants can result in subsequent reductions in problem behaviours reported