Aerobic capacity in wild satin bowerbirds: repeatability and effects of age, sex and condition

Abstract

SUMMARYIndividual variation in aerobic capacity has been extensively studied, especially with respect to condition, maturity or pathogen infection, and to gain insights into mechanistic foundations of performance. However, its relationship to mate competition is less well understood, particularly for animals in natural habitats. We examined aerobic capacity [maximum rate of O 2 consumption (V O2,max ) in forced exercise] in wild satin bowerbirds, an Australian passerine with a non-resource based mating system and strong intermale sexual competition. We tested for repeatability of mass and V O2,max , differences among age and sex classes, and effects of several condition indices. In adult males, we examined interactions between aerobic performance and bower ownership (required for male mating success). There was significant repeatability of mass and V O2,max within and between years, but between-year repeatability was lower than within-year repeatability. V O2,max varied with an overall scaling to mass 0.791 , but most variance in V O2,max was not explained by mass. Indicators of condition (tarsus and wing length asymmetry, the ratio of tarsus length to mass) were not correlated to V O2,max . Ectoparasite counts were weakly correlated to V O2,max across all age-sex classes but not within any class. Adult males, the cohort with the most intense levels of mating competition, had higher V O2,max than juvenile birds or adult females. However, there was no difference between the V O2,max of bower-owning males and that of males not known to hold bowers. Thus one major factor determining male reproductive success was not correlated to aerobic performance.

Intraspecific Correlations of Basal and Maximal Metabolic Rates in Birds and the Aerobic Capacity Model for the Evolution of Endothermy

“…These scopes are consistent with factorial scopes for thermogenesis for other birds, which generally range from 4–8 [4], with a maximum value of 9.0 from a previous study of summer-acclimatized house sparrows from Wisconsin [30]. Factorial aerobic scope for exercise in the hop-flutter wheel (MMR/BMR) was 7.8 for dark-eyed juncos in this study, a value lower than those for other temperate-zone bird species, which include 10.4 for red-eyed vireo [42], 10.6 for house sparrows [41] and 11.2 for satin bowerbirds (measured from allometrically predicted BMR [49]). Using the BMR value for winter-acclimatized American goldfinches from South Dakota from Liknes et al [34] of 1.04 ml O 2 min −1 , gives and estimated hop-flutter exercise factorial aerobic scope for goldfinches of 6.3, which is also lower than that for the other temperate-zone species.…”

“…For comparison, the allometric regression equation for MMR for tropical birds from [5] is included as the dashed line. MMR values for other temperate-zone bird species include satin bowerbird [49], red-eyed vireo [42] and house sparrow [41].…”

Within‐Individual Correlations Reveal Link Between a Behavioral Syndrome, Condition, and Cortisol in Free‐Ranging Belding's Ground Squirrels

“…CORT and BCI had significant repeatabilities, but were substantially lower than those of the behaviors. The relatively low repeatability of BCI in squirrels contrasts with other studies, such as Wilcoxon et al (2010), who found that BCI in Florida scrub jays (Aphelocoma coerulescens) was highly repeatable over roughly 6 mo (r = 0.64), and Chappell et al (2011) who found that BCI of wild satin bowerbirds (Ptilonorhynchus violaceus) was repeatable from year to year (r = 0.26). The repeatability of CORT in squirrels was similar to the repeatability of fecal corticosterone metabolites (r = 0.12) in yellow-bellied marmots recorded across multiple years (Marmota flaviventrus: Smith et al 2012) but substantially lower than the repeatability of plasma cortisol in alpine marmots (r = 0.76) (Ferrari et al 2013).…”

“…(), who found that BCI in Florida scrub jays ( Aphelocoma coerulescens ) was highly repeatable over roughly 6 mo ( r = 0.64), and Chappell et al. () who found that BCI of wild satin bowerbirds ( Ptilonorhynchus violaceus ) was repeatable from year to year ( r = 0.26). The repeatability of CORT in squirrels was similar to the repeatability of fecal corticosterone metabolites ( r = 0.12) in yellow‐bellied marmots recorded across multiple years ( Marmota flaviventrus : Smith et al.…”

Individual inconsistencies in basal and summit metabolic rate highlight flexibility of metabolic performance in a wintering passerine

“…Maximum metabolic output can be measured in endotherms as maximal metabolic rate elicited by locomotor exercise (maximal metabolic rate: MMR) or by shivering during cold exposure (M sum ). Pervious studies suggest that MMR is a repeatable trait (e.g., R = 0.80, Friedman et al, , R = 0.74, Hayes and O'Connor, , R = 0.82, Rezende et al, , R = 0.37, Chapell et al, ). However, only few studies reported repeatability values for M sum in birds and findings appear inconsistent (Swanson and Weinacht, ; Vézina et al, ; Swanson and King, ).…”