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Full-Text Articles in Life Sciences

Estimating Nests Not Present At The Time Of Breeding Surveys: An Important Consideration In Assessing Nesting Populations, Peter C. Frederick, Julie A. Heath, Robert Bennetts, Heinz Hafner Apr 2006

Estimating Nests Not Present At The Time Of Breeding Surveys: An Important Consideration In Assessing Nesting Populations, Peter C. Frederick, Julie A. Heath, Robert Bennetts, Heinz Hafner

Julie Heath

Counts of nest starts are often used as indicators of the size of avian nesting populations, or of avian productivity. However, the accuracy of single or repeated counts of unmarked nests over time for estimating seasonal numbers of nests may be strongly affected by nest events that fall in between survey dates, or that occurred prior to or after the survey period. Accuracy may also be affected by uncertainty in the interpretation of counts due to overlap between starting and ending dates of asynchronous nests during the intervisit interval. To measure the combined magnitude of these effects on survey accuracy ...


Channel-Reach Morphology Dependence On Energy, Scale, And Hydroclimatic Processes With Implications For Prediction Using Geospatial Data, Alejandro N. Flores, Brian P. Bledsoe, Christopher O. Cuhaciyan, Ellen E. Wohl Jan 2006

Channel-Reach Morphology Dependence On Energy, Scale, And Hydroclimatic Processes With Implications For Prediction Using Geospatial Data, Alejandro N. Flores, Brian P. Bledsoe, Christopher O. Cuhaciyan, Ellen E. Wohl

Alejandro N. Flores

Channel types found in mountain drainages occupy characteristic but intergrading ranges of bed slope that reflect a dynamic balance between erosive energy and channel boundary resistance. Using a classification and regression tree (CART) modeling approach, we demonstrate that drainage area scaling of channel slopes provides better discrimination of these forms than slope alone among supply- and capacity-limited sites. Analysis of 270 stream reaches in the western United States exhibiting four common mountain channel types reveals that these types exist within relatively discrete ranges of an index of specific stream power. We also demonstrate associations among regional interannual precipitation variability, discharge ...