Improved Estimation of Bird Abundance and Energy Consumption by Combining Point and Transect Observations

In this paper we exploit the relationship between these two types of observations to draw inferences about bioenergy consumption, to develop an improved estimator of bird abundance, and to derive error bars for abundance estimates. These results are implemented practically on a dataset consisting of point counts and transect surveys of Ecuadorian frugivore bird species in six different types of environment (three elevations and two degrees of forestation). By comparing bioenergy consumption models based on the two observation types, we clarify the dependence of bioenergy consumption on mean bird weight and mean fruit weight consumed by bird species. Additionally, we derive a procedure for forming an optimal linear combination of two relative abundance estimators based on point counts and transect observations respectively. The improvement in accuracy achieved by this combined estimator is verified by simulations applied to bird family data from the above-mentioned survey. Finally, we extend the procedure in order to obtain 90% confidence intervals for the bird family relative abundance estimates. These confidence intervals were also verified using simulations. ### Competing Interest Statement The authors have declared no competing interest.