Jennifer M. Berens, Corina J. Logan, Melissa Folsom, Luisa Bergeron, Kelsey B. McCunePlease use the format "First name initials family name" as in "Marie S. Curie, Niels H. D. Bohr, Albert Einstein, John R. R. Tolkien, Donna T. Strickland"
Morphological variation among individuals has the potential to influence multiple life history characteristics such as dispersal, migration, reproductive fitness, and survival (Wilder, Raubenheimer, and Simpson (2016)). Theoretically, individuals that are in better “condition” (i.e. fat reserves, Labocha and Hayes (2012)) should be able to disperse or migrate further or more successfully, have greater reproductive fitness, and survive for longer (Wilder, Raubenheimer, and Simpson (2016)). Researchers have used a variety of morphological proxy variables to quantify condition (i.e., fat score, weight, ratio of weight to tarsus length, ratio of weight to wing chord length, Labocha, Schutz, and Hayes (2014)), however, there is mixed support regarding whether these proxy variables relate to life history characteristics (Wilder, Raubenheimer, and Simpson (2016); Labocha, Schutz, and Hayes (2014)). Additionally, although some researchers use multiple morphological proxy variables for condition (i.e. Warnock and Bishop (1998)), rarely has there been direct comparisons among proxies to validate that they measure the same trait. In this investigation, we will compare two condition proxies (fat score and the ratio of weight to tarsus length) to validate whether they measure the same trait in our study system, the great-tailed grackle (Quiscalus mexicanus). We will then test whether our morphological proxy variables correlate with reproductive success, measured as whether a female had a fledgling or not and whether a male held a territory containing nests or not. Results will improve our understanding of measures of condition in grackles, and birds in general, and the importance of condition for reproductive success - a necessary component for selection to act.
birds, great-tailed grackles, condition indices, reproductive success
Behaviour & Ethology, Conservation biology, Demography, Morphometrics, Preregistrations, Zoology