Duck species co-occurrence in hunter daily bags

• Published in: Wildlife Society bulletin 2015-03, Vol.39 (1), p.70-78
• Main Authors: Haugen, Matthew T., Vrtiska, Mark P., Powell, Larkin A.
• Format: Article
• Language: English
• Subjects: Bags; Central Flyway; Ducks; Female animals; Fish; Fowling; harvest; Modeling; multi-species management; Original Article; Parts Collection Survey; Species; Waterfowl; waterfowl regulations; Wildlife conservation; Wildlife management
• ISSN: 1938-5463; 2328-5540; 1938-5463; 2328-5540
• DOI: 10.1002/wsb.515

As multi-species harvest management gains support among waterfowl managers, increased understanding of duck species relationships during harvest is needed. We used U.S. Fish and Wildlife Service's Parts Collection Survey data from 2002 to 2011 to develop a matrix defining relationships among duck species harvested in the Central Flyway. We calculated conditional probabilities of co-occurrence in a hunter's daily bag (i.e.,P(B|A), the probability that species B was in a hunter bag, given that species A was in the same bag). We then performed 12 scenarios of hypothetical changes to species-specific regulations. We used Central Flyway harvest estimates from 2011 and probabilities of co-occurrence to predict the effects of regulatory changes on harvest. Hunters were more likely to harvest 2 species of diving ducks (P(Diving|Diving) = 0.37) than to harvest a diving duck given that a dabbling duck was also harvested the daily bag (P(Diving|Dabbling) = 0.12). Hunters also were more likely to harvest 2 ducks of the same species (and sex in the case of mallards [Anas platyrhynchos]) within a daily bag (meanP(A|A) = 0.31) than 2 ducks of different species (meanP(B|A) = 0.13). Traditionally, managers have focused on single-species assessments when considering regulatory changes, but harvest regulation changes may affect multiple duck species if harvest is redistributed to other species. Our data show a range of co-occurrence patterns of species commonly or rarely harvested together. Examination of the relationships among duck species during harvest provides critical insight for the development of appropriate regulations for multi-species management.