Survival rates for a declining population of bottlenose dolphins in Doubtful Sound, New Zealand: an information theoretic approach to assessing the role of human impacts

2009 ◽  
Vol 19 (6) ◽  
pp. 658-670 ◽  
Author(s):  
Rohan J. C. Currey ◽  
Stephen M. Dawson ◽  
Elisabeth Slooten ◽  
Karsten Schneider ◽  
David Lusseau ◽  
...  
Keyword(s):  
New Zealand ◽  
Human Impacts ◽  
Bottlenose Dolphins ◽  
Survival Rates ◽  
Theoretic Approach ◽  
Information Theoretic ◽  
Information Theoretic Approach

Paddlefish Management, Propagation, and Conservation in the 21st Century

2009 ◽  
Keyword(s):  
21St Century ◽  
Maximum Density ◽  
Larval Feeding ◽  
Theoretic Approach ◽  
Fish Hatchery ◽  
Information Theoretic ◽  
Prey Composition ◽  
Survival And Growth ◽  
Information Theoretic Approach

<em>Abstract</em>.—We evaluated the influence of prey composition and abundance on survival and growth of age-0 paddlefish <em>Polyodon spathula </em>in 0.5-ha rearing ponds. Cladoceran abundance was measured in the spring of 1999 (<em>n </em>= four ponds), 2000 (<em>n </em>= six ponds) and 2005 (<em>n </em>= five ponds) at Gavin’s Point National Fish Hatchery, South Dakota. Using an information theoretic approach, we found that density of small cladocerans (e.g., <em>Bosmina</em>) at the time of larval stocking was the best supported model in explaining paddlefish survival. In contrast, estimates of <em>Daphnia </em>abundance (initial, mean, and maximum density) were poor predictors of paddlefish survival. Neither the magnitude of <em>Daphnia </em>abundance nor whether abundance was increasing or decreasing in the ponds after stocking appeared to influence paddlefish survival. Paddlefish growth, however, was positively related to mean <em>Daphnia </em>abundance in ponds. These patterns highlight the need to better understand larval feeding ecology of paddlefish and the role of electrosensory detection as it relates to prey composition and abundance.

scholarly journals Nest Survival Estimation: A Review of Alternatives to the Mayfield Estimator

The Condor ◽  
2004 ◽  
Vol 106 (3) ◽  
pp. 472-484 ◽  
Author(s):  
Gretchen Jehle ◽  
Amy A. Yackel Adams ◽  
Julie A. Savidge ◽  
Susan K. Skagen
Keyword(s):  
Nest Success ◽  
Nest Survival ◽  
Survival Rates ◽  
Theoretic Approach ◽  
Program Mark ◽  
Information Theoretic ◽  
Biologically Relevant ◽  
Daily Survival ◽  
Mayfield Method ◽  
Information Theoretic Approach

AbstractReliable estimates of nest survival are essential for assessing strategies for avian conservation. We review the history of modifications and alternatives for estimating nest survival, with a focus on four techniques: apparent nest success, the Mayfield estimator, the Stanley method, and program MARK. The widely used Mayfield method avoids the known positive bias inherent in apparent nest success by estimating daily survival rates using the number of exposure days, eliminating the need to monitor nests from initiation. Concerns that some of Mayfield's assumptions were restrictive stimulated the development of new techniques. Stanley's method allows for calculation of stage-specific daily survival rates when transition and failure dates are unknown, and eliminates Mayfield's assumption that failure occurred midway through the nest-check interval. Program MARK obviates Mayfield's assumption of constant daily survival within nesting stages and evaluates variation in nest survival as a function of biologically relevant factors. These innovative methods facilitate the evaluation of nest survival using an information-theoretic approach. We illustrate use of these methods with Lark Bunting (Calamospiza melanocorys) nest data from the Pawnee National Grassland, Colorado. Nest survival estimates calculated using Mayfield, Stanley, and MARK methods were similar, but apparent nest success estimates ranged 1– 24% greater than the other estimates. MARK analysis revealed that survival of Lark Bunting nests differed between site–year groups, declined with both nest age and time in season, but did not vary with weather parameters. We encourage researchers to use these approaches to gain reliable and meaningful nest survival estimates.Estimación de la Supervivencia de Nidos: Una Revisión de las Alternativas del Estimador MayfieldResumen. Es esencial contar con estimaciones confiables de la supervivencia de nidos para evaluar las estrategias de conservación de las aves. Revisamos la historia de modificaciones y las alternativas para estimar la supervivencia de nidos, enfocándonos en cuatro técnicas: éxito aparente del nido, el estimador de Mayfield, el método de Stanley y el programa MARK. El método de Mayfield, ampliamente usado, evita el conocido sesgo positivo inherente al éxito aparente del nido mediante la estimación de tasas de supervivencia diaria usando el número de días de exposición, eliminando así la necesidad de monitorear los nidos desde el inicio. Las preocupaciones de que algunos de los supuestos del método de Mayfield son restrictivos estimularon el desarrollo de nuevas técnicas. El método de Stanley permite el cálculo de tasas de supervivencia diarias específicas para cada etapa cuando las fechas de transición y fracaso son desconocidas, y elimina el supuesto del método de Mayfield que sostiene que el fracaso ocurre en el medio del intervalo de monitoreo del nido. El programa MARK elimina el supuesto del método de Mayfield sobre supervivencia diaria constante dentro de las etapas de nidificación y evalúa la variación en la supervivencia de nidos como función de factores biológicamente relevantes. Estos métodos innovadores facilitan la evaluación de la supervivencia de nidos usando un enfoque teórico-informativo. Ilustramos el uso de estos métodos con datos de nidos de Calamospiza melanocorys provenientes de Pawnee National Grassland, Colorado. Las estimaciones de supervivencia de los nidos calculadas usando los métodos de Mayfield, Stanley y MARK fueron similares, pero las estimaciones del éxito aparente de los nidos fueron entre 1–24% mayores que las otras estimaciones. Los análisis con MARK revelaron que la supervivencia de los nidos de C. melanocorys difirió entre grupos de sitio-año, disminuyó con la edad del nido y el tiempo de la estación, pero no varió con parámetros climáticos. Estimulamos a los investigadores a usar estos enfoques para obtener estimaciones de supervivencia de nidos confiables y válidas.

The role of human disturbance in island biogeography of arthropods and plants: an information theoretic approach

2015 ◽  
Vol 42 (8) ◽  
pp. 1406-1417 ◽  
Author(s):  
Akihiro Nakamura ◽  
Chris J. Burwell ◽  
Christine L. Lambkin ◽  
Masatoshi Katabuchi ◽  
Andrew McDougall ◽  
...  
Keyword(s):  
Human Disturbance ◽  
Island Biogeography ◽  
Theoretic Approach ◽  
Information Theoretic ◽  
Information Theoretic Approach

Effects of flooding and riparian buffers on survival of muskrats (Ondatra zibethicus) across a flashiness gradient

2010 ◽  
Vol 88 (10) ◽  
pp. 1011-1020 ◽  
Author(s):  
A. A. Ahlers ◽  
R. L. Schooley ◽  
E. J. Heske ◽  
M. A. Mitchell
Keyword(s):  
American Mink ◽  
Survival Rates ◽  
Riparian Buffers ◽  
Theoretic Approach ◽  
Unstable Flow ◽  
Ondatra Zibethicus ◽  
Information Theoretic ◽  
Small Streams ◽  
Information Theoretic Approach ◽  
Flooding Events

Increased agricultural production within the Grand Prairie region, USA, has resulted in drainage of most natural wetlands within the landscape. Muskrats ( Ondatra zibethicus (L., 1766)) in this region have shifted much of their distribution to riparian habitats that have unstable flow regimes and flood inundation times that could be related to position within watersheds. We investigated predation risk of radio-marked riparian muskrats during flooding events in relation to landscape position. We used known-fate models and an information–theoretic approach to examine effects of age, season, hydrology, and riparian width on weekly survival rates. During flooding events, muskrats positioned farther from headwaters were displaced for longer, as well as exposed to predation from terrestrial predators for longer, than those positioned closer to headwaters. However, this increased exposure during floods did not translate into lower survival because most mortalities were due to predation by American mink ( Neovison vison (Schreber, 1777)) along stream edges during nonflooding periods. Weekly survival of muskrats was lower in winter (mean = 0.9377, SE = 0.1793) than in nonwinter (mean = 0.9770, SE = 0.0116) and was positively related to riparian width. Larger riparian buffers can increase muskrat survival in small streams and agricultural ditches within highly altered, human-dominated agroecosystems. Our study provides a rare example of linking riparian buffers to fitness for a stream-associated organism.

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