Wild turkey (Meleagris gallopavo) populations are broadly distributed, occupy a variety of habitats, and have demographic rates that are heterogeneous through space and time. Dynamics of turkey populations are sensitive to the magnitude of fall either‐sex harvest, yet there have been few attempts to study performance of fall harvests systematically across a range of plausible demographic scenarios. Thus robustness of existing recommendations to structural uncertainty in population dynamics is marginally understood. We used a stochastic, sex‐specific theta‐logistic model to simulate performance of fall harvests (0–15%) across scenarios representing uncertainty about current rates of population productivity (3 levels), female losses during spring hunting (2 levels), and spring male harvest (3 levels), with uncertainty in the strength of density dependence as a common attribute. We demonstrated that performance of previously recommended fall harvests was not robust to changes in demographic parameters that occur within and among populations, and thus previous management recommendations may not be appropriate for all regions. Fall harvest rates capable of maintaining large populations with high probability varied from 0–6% with changes to population productivity, when median male and female spring harvests were 30% and 5%, respectively. In general, risks and management tradeoffs accompanying fall harvests were tightly linked to assumed values of population parameters, where changes to productivity and female loss had particularly strong effects on management outcomes. Specifically, reduced productivity or increased female loss decreased the ability to maintain large populations for a given fall harvest rate. Thus, fall harvest recommendations deduced from models that considered only a small portion of the demographic parameter space may not meet modern management objectives over a broader range of conditions. Moreover, our results suggest that future management could be improved by reducing structural uncertainty about turkey demography to allow for region‐specific harvest strategies, or by using decision‐theoretic approaches to identify harvest strategies that are robust to uncertainty about population parameters. © 2017 The Wildlife Society.
Pereda-Solís, M. (2017). La abundancia de aves acuáticas (Anseriformes) en relación con la complejidad del paisaje en un sitio Ramsar del norte de México. Acta Zoológica Mexicana (n.s.), 33(2), 199-210. RESUMEN. La abundancia de aves acuáticas (Anseriformes) en re-lación con la complejidad del paisaje en un sitio Ramsar del norte de México. Se evaluó la respuesta de las poblaciones de aves acuáticas (Anseriformes) a la estructura del paisaje en un sitio Ramsar en el estado de Durango, México. Se delimitaron los cuerpos de agua pre-sentes durante el invierno mediante el cálculo del Índice Diferencial Normalizado de Vegetación (NDVI) en imágenes LANDSAT, cu-briendo un periodo de 35 años (1979-2014). El área de estudio se clasificó en ambientes acuáticos y terrestres. Se calcularon índices de fragmentación como descriptores de la complejidad del paisaje, creada por la abundancia y distribución de los cuerpos de agua. La informa-ción poblacional de aves acuáticas se obtuvo de los conteos invernales realizados entre 1979 y 2014 por el U.S. Fish and Wildlife Service (USFWS) y por la Secretaría de Medio Ambiente y Recursos Natu-rales (SEMARNAT). La superficie ocupada por los cuerpos de agua mostró una marcada oscilación de 4,000 a 29,000 ha. La forma, la extensión y el nivel de aislamiento de los cuerpos de agua, fueron los factores más importantes para las aves acuáticas. La complejidad en la forma de los humedales tuvo un efecto positivo sobre la presencia de aves, mientras que las grandes extensiones de agua, se relacionan con una reducción en el tamaño de las poblaciones. Los resultados sugie-ren que esta región puede resultar más atractiva para los gansos cuando Chacón, J.E., Pompa-García, M., Treviño-Garza, E., Martínez-Guerrero, J., Aguirre-Salado, C., & Pereda-Solís, M. (2017). Waterfowl abundance in relation to landscape complexity in a Ramsar site of Northern Mexico. Acta Zoológica Mexicana (n.s.), 33(2), 199-210. ABSTRACT. The response of waterfowl (Anseriformes) populations to the landscape structure was evaluated in a Ramsar site in the state of Durango, Mexico. Water bodies present during the winter were delimited using the calculation of the normalized differential vegetation index (NDVI) in LANDSAT images, covering a period of 35 years (1979-2014). The study area was categorized into aquatic and terrestrial environments. Indices of fragmentation were calculated as de-scriptors of landscape complexity, represented by the abundance and distribution of the water bodies. Waterfowl populational information was obtained from winter counts conducted between 1979 and 2014 by the U.S. Fish and Wildlife Service (USFWS) and by the Mexican Ministry of Environment and Natural Resources (SEMARNAT, by its Spanish acronym). The area occupied by the water bodies presented a marked oscillation of 4,000 to 29,000 ha. The shape, area and isolation of the wetland landscape were the most important factors for the wa-terfowl. The shape complexity had a positive effect on the presences of birds, while large areas reduced the w...
Achieving state wildlife agency biological goals for deer (Odocoileus spp.) and turkey (Meleagris gallopavo) rely on high quality data collection via hunter harvest surveys. Concomitantly, better information is needed to optimize harvest survey methods. From 2017 to 2019, we surveyed North Dakota, USA, deer and fall turkey hunters using a self-administered mail survey as a control and 3 mixed-mode, internet/mail surveys to evaluate the efficacy of alternative survey designs for estimating harvest of game populations and informing future management. We measured response rates across segments of North Dakota deer and fall turkey hunters, and across mixed-mode treatments that could easily be implemented with existing wildlife agency resources. We also determined whether early survey respondents were more likely to harvest deer or turkey. Finally, we estimated the effects of demographic factors that may be associated with hunters returning survey treatment modes to further North Dakota Game and Fish Department's ability to tailor surveys to certain hunter groups. We found that internet-mail and mail-internet treatments resulted in significantly higher response rates than a traditional mail-only survey mode. We also found that hunters who successfully harvested an animal were more likely to return questionnaires shortly after the initial wave of surveying. Finally, we found that older, nonresident, and urban hunters were more likely to return questionnaires.
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