Relationships Among Body Mass, Fat, Wing Chord, Age, and Sex for 170 Species of Birds Banded at Powdermill Nature Reserve.—Robert S. Mulvihill, Robert C. Leberman, and Adrienne J. Leppold. Carnegie Museum of Natural History, Powdermill Nature Reserve, Rector, PA. Eastern Bird Banding Association Monograph No. 1. 184 pp. ISBN 0-9749063-0-1. $15.00 (spiral bound).
This monograph provides a wealth of data from birds banded at one of the longest-running bird-banding operations in the United States and is designed for use and reference by other researchers. The authors present data covering a wide variety of species, many having large sample sizes. Because this study comes from a region (the eastern United States) with many bird banders, it should prove useful as a reference manual for data on many ‘eastern’ species. Lastly, the authors encourage others with similarly extensive data to follow suit by summarizing and analyzing their datasets for use and reference of other banders.
The book begins with 14 pages of text introducing the data and describing analytical techniques. The bulk of this volume consists of two main data sections. The ‘Descriptive Statistics’ section provides body mass and wing-length data by age, sex, and fat categories for all species with greater than 10 captures. For species with small sample sizes (10 or fewer captures), data for each individual are provided. The ‘Graphs and Statistical Analysis’ section presents analyses on the 100 species in this study with sample sizes greater than 100 for both body mass and wing length. Specifically, the authors examined the data for age and sex effects on both wing length and body mass. Additional analyses included linear regressions relating wing length and fat scores to body mass. From the fat score by body mass regressions, the authors derived data such as estimated lean body mass and an estimated payload mass (fat mass of birds with highest fat scores). Also, histograms of wing lengths (by sex when data are available) are provided for each species.
As an example of some applicable results from this volume, consider the data relating lean body mass (from birds with 0 fat) and wing length amassed for the 100 most common birds at the site. The R2 (proportion of variation in body mass that can be explained by wing length) for most species (both sexes combined) ranged from 0.02 to 0.40 and values seemed pretty dispersed throughout this range. However, four Icterids (Red-winged Blackbirds [Agelaius phoeniceus], Rusty Blackbirds [Euphagus carolinus], Brown-headed Cowbirds [Molothrus ater], and Common Grackles [Quiscalus quiscula]) showed R2 values between 0.64 and 0.85, suggesting a much tighter relationship between these variables for these species. In contrast, two species, White-eyed Vireos (Vireo griseus) and Yellow-breasted Chats (Icteria virens), exhibited no relationship between lean mass and wing length. These are the type of data many researchers draw on for a variety of reasons—including investigations of energetic condition or morphological studies. Thus, knowing how these relate for 100 species (or maybe just that one species of interest) should be valuable to many researchers.
Complementing the main sections are three appendices. Appendix 1 shows the seasonal composition of samples of birds used in this study. Appendix 2 summarizes results of all one-way ANOVAs for effects of age and sex on body mass and wing length. Appendix 3 provides wing-length cutoffs for sex classes (based on birds sexed by physical evidence) for 19 species.
In summary, this monograph is a very useful contribution to the ornithological literature. The book presents raw data and analyses for a diverse bird community—one that has much overlap with bird communities encountered by many other banders. Additionally, it provides an example of how to summarize, analyze, and present vast quantities of banding data, which often go unpublished. Thus, it should serve as a valuable reference for many ornithologists, including banders and those interested in comparative studies.
